**4. Traditional foods as functional foods and nutraceuticals**

Functional foods are in fact products that may look like or are a conventional food and be consumed as part of a usual diet, but apart from supplying nutrients they can reduce the risk of chronic diseases. Nutraceuticals are health promoting compounds or products that have been isolated or purified from food sources and they are generally sold in a medicinal (usually pill) form [14, 15]. Considering these definitions, we noticed that these products contain bioactive compounds called phytochemicals that are capable of modulating metabolic processes and resulting in the promotion of better health. By having antioxidant, anti-inflammatory, immunomodulatory, adaptogenic, anticancer, and several other health benefits, functional foods and nutraceuticals are used worldwide for the prevention and treatment of chronic diseases such as diabetes, arthritis, cardiovascular and respiratory disorders, neurodegenerative diseases, and cancer [12].

Leaves of *Manihot esculenta* and *Manihot glaziovii* contained amentoflavone, quercetin, quercetin-3-rutinoside, quercetin-3-glucoside, and kaempferol 3-rutinoside as flavonoids and caffeic acid, ferulic acid, gallic acid as phenolic acids. Cassava roots, cossettes and cassava flours contained phenolic acids, such as ferulic acid, as major compounds [8]. *Hibiscus acetosella* contained 2-O-trans-caffeoyl-hydroxycitric acid as major phenolic compounds and flavonoids such as quercetin-3-galactoside. *Hibiscus cannabinus and Hibiscus sabdariffa* contained neochlorogenic acid as major phenolic compounds and flavonoids such as quercetin-3-rutinoside,

**Figure 4.** Structures of phytochemicals (a) quercetin-3-O-rutinoside, (b) caffeic acid, (c) Caffeoyl-hydroxycitrique, and

**Figure 3.** TLC chromatogram of methanolic extracts from *M.esculenta* (varieties: *Chamusuku, Disanka, Kamonji, Mwambu, Tshibombi, TEM 419*), *M. glaziovii* with astragalin (ast), caffeic acid (caf), chlorogenic acid (chl), ferulic acid (fer), luteolin(lut), quercitrin(que) and rutin (rut) as standards; developed with ethyl acetate/formic acid/methanol/water (20:0.5:2.5:2; v/v/v/v) and visualized at 365 nm with natural products-PEG reagent. Flavonoids are detected as yellow-

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quercetin-3-glucoside and kaempferol 3-rutinoside (**Figure 4**) [16].

orange fluorescent spots and phenolic acids as blue fluorescent spots.

(d) verbascoside.

#### **4.1. Phytochemicals**

Phytochemicals are found in fruits, herbal teas, mushrooms, spices, vegetables and whole grains. They include an extremely heterogeneous class of compounds (polyphenolic compounds, carotenoids, tocopherols, phytosterols, and organo-sulfur compounds) with different chemical structures (hydrophilic or lipophilic).

TLC and HPLC-DAD analysis of methanolic extracts of the most consumed foodstuffs of Kahemba, have shown the presence of polyphenolic compounds in all extracts. TLC fingerprints of extracts showed the presence of glycosylated flavonoids (yellow, orange and green fluorescent spots) and phenolic acids (blue fluorescent spots) as major compounds especially for vegetables and herbal teas (**Figure 3**). Cassava flours, mushrooms and yams contain mainly phenolic acids. Flavonoids identified were derivatives of quercetin (rutin, hyperoside, isoquercitrin, quercitrin) and kaempferol (Kaempferol 3-O-glucoside, kaempferol 3-O-rutinoside). Phenolic acids were caffeic acid and its derivatives such chlorogenic acid ferulic acid and verbascoside.

Traditional Foods as Putative Sources of Antioxidants with Health Benefits in Konzo http://dx.doi.org/10.5772/intechopen.74523 123

tity of cassava flour paste represents more than 90% of the consumed meals. Previous studies showed that this dietary pattern is responsible for the persistence of konzo [9]. The Flora of province of Kwango is rich in traditional foods that are mostly unexploited. For this reason, Mbemba et al. assessed the nutritional value of some traditional foods by determining their relative amino acid composition, in order to contribute to the equilibration of the diet in the population of this area severely affected by malnutrition and konzo. Yams such as *D. alata* and *D. cayenensis* are the most widespread. Mbemba et al. reported that some dried yams are richer in proteins than cassava root and can be used with success to prepare porridge for children who represent the most at-risk population for konzo [13]. They are an alternative substitute for cassava especially as they are abundant during the dry season, a period corresponding to high outbreaks of konzo. Among the sources of animal proteins consumed, the fish *Chanmellabes tupus* (known locally as Misombi) and larvae are the foods economically

Functional foods are in fact products that may look like or are a conventional food and be consumed as part of a usual diet, but apart from supplying nutrients they can reduce the risk of chronic diseases. Nutraceuticals are health promoting compounds or products that have been isolated or purified from food sources and they are generally sold in a medicinal (usually pill) form [14, 15]. Considering these definitions, we noticed that these products contain bioactive compounds called phytochemicals that are capable of modulating metabolic processes and resulting in the promotion of better health. By having antioxidant, anti-inflammatory, immunomodulatory, adaptogenic, anticancer, and several other health benefits, functional foods and nutraceuticals are used worldwide for the prevention and treatment of chronic diseases such as diabetes, arthritis, cardiovascular and respiratory disorders, neurodegenerative dis-

Phytochemicals are found in fruits, herbal teas, mushrooms, spices, vegetables and whole grains. They include an extremely heterogeneous class of compounds (polyphenolic compounds, carotenoids, tocopherols, phytosterols, and organo-sulfur compounds) with differ-

TLC and HPLC-DAD analysis of methanolic extracts of the most consumed foodstuffs of Kahemba, have shown the presence of polyphenolic compounds in all extracts. TLC fingerprints of extracts showed the presence of glycosylated flavonoids (yellow, orange and green fluorescent spots) and phenolic acids (blue fluorescent spots) as major compounds especially for vegetables and herbal teas (**Figure 3**). Cassava flours, mushrooms and yams contain mainly phenolic acids. Flavonoids identified were derivatives of quercetin (rutin, hyperoside, isoquercitrin, quercitrin) and kaempferol (Kaempferol 3-O-glucoside, kaempferol 3-O-rutinoside). Phenolic acids were caffeic acid and its derivatives such chlorogenic acid ferulic acid and

accessible for the majority of Kahemba's population.

ent chemical structures (hydrophilic or lipophilic).

eases, and cancer [12].

122 Antioxidants in Foods and Its Applications

**4.1. Phytochemicals**

verbascoside.

**4. Traditional foods as functional foods and nutraceuticals**

**Figure 3.** TLC chromatogram of methanolic extracts from *M.esculenta* (varieties: *Chamusuku, Disanka, Kamonji, Mwambu, Tshibombi, TEM 419*), *M. glaziovii* with astragalin (ast), caffeic acid (caf), chlorogenic acid (chl), ferulic acid (fer), luteolin(lut), quercitrin(que) and rutin (rut) as standards; developed with ethyl acetate/formic acid/methanol/water (20:0.5:2.5:2; v/v/v/v) and visualized at 365 nm with natural products-PEG reagent. Flavonoids are detected as yelloworange fluorescent spots and phenolic acids as blue fluorescent spots.

Leaves of *Manihot esculenta* and *Manihot glaziovii* contained amentoflavone, quercetin, quercetin-3-rutinoside, quercetin-3-glucoside, and kaempferol 3-rutinoside as flavonoids and caffeic acid, ferulic acid, gallic acid as phenolic acids. Cassava roots, cossettes and cassava flours contained phenolic acids, such as ferulic acid, as major compounds [8]. *Hibiscus acetosella* contained 2-O-trans-caffeoyl-hydroxycitric acid as major phenolic compounds and flavonoids such as quercetin-3-galactoside. *Hibiscus cannabinus and Hibiscus sabdariffa* contained neochlorogenic acid as major phenolic compounds and flavonoids such as quercetin-3-rutinoside, quercetin-3-glucoside and kaempferol 3-rutinoside (**Figure 4**) [16].

**Figure 4.** Structures of phytochemicals (a) quercetin-3-O-rutinoside, (b) caffeic acid, (c) Caffeoyl-hydroxycitrique, and (d) verbascoside.

Verbascoside is found to be abundant in herbal teas [17] and we first report here its presence in leaves of *Sesamum angustifolium*. Chlorogenic acid is the main phenolic acid found in extracts of *Raphia sese, Solanum aethiopicum* and *Solanum gilo.* Rosmarinic acid was found to be a major compound of Ocimum species of DRC [18]. Phytochemical screening of mushrooms and yams showed that phenolic acids are their major compounds. Phytochemicals derived from various sources target inflammatory and oxidative stress pathways and retard or delay the onset of neurological diseases.

Protective effects of phenolic compounds have often been ascribed to their direct antioxidant effect and/or to their anti-inflammatory action [12].

#### **4.2. Antioxidant properties**

Oxidative stress is recognized as an important factor in a variety of neurodegenerative diseases, as a mediator of the adverse effects of a number of neurotoxicants, and as a mechanism for age related degenerative processes [12]. Finding alternative and complementary ways to reduce the redox processes might have a beneficial interest in the context of developing countries.

Traditional foods contained a considerable amount of phenolic compounds expressed as total polyphenol contents as described in **Tables 1**–**3**. Total polyphenol contents of Kahemba's ethnic foods varied significantly between the samples of each group of foods. *Lippia multiflora* had the highest total polyphenol content among herb-teas, *Manihot glaziovii* among vegetables, *Cantharellus rufopunctatus* among mushrooms and *Dioscorea alata* among yams. Antioxidant activities significantly varied also between the samples of each group of foods (p < 0.05). All methanolic extracts had significant radical scavenging effects with increasing concentrations in the range of 1–40 μg/mL for herb teas, 10–80 μg/mL for spices and vegetables, and 10–250 μg/mL for mushrooms. This antiradical activity is connected to their ability to scavenge free radicals according to their IC50 values (**Tables 1–3**). IC50 values ranged from 7.56 ± 0.87 μg/mL (*L. multiflora*) to 653.13 ± 51.25 μg/mL (*D. cayenensis*) for the ABTS assay and from 10.44 ± 1.13 μg/mL (*L. multiflora*) to 17179.09 ± 1150.25 μg/mL (*Cantharellus* sp.) for the DPPH assay. Cassava flours also exhibited a good scavenging activity with IC50 values ranging from 99.54 ± 9.60 to 974.99 ± 94.01 μg/mL.

Beside conventional cell-free antioxidant assays, it can be pertinent to evaluate the anti- oxidant and anti-catalytic potential of plant extracts in cellular models involved in ROS production and inflammatory responses [16, 19]. The addition of extract solutions at increasing concentrations resulted in a dose dependent decrease of the ROS-induced lucigenin-amplified chemiluminescence. All tested extracts induced a significant inhibition (p < 0.0001) of the ROS production by neutrophils compared to controls at the concentration range of 0.05–10 μg/mL for herbal teas and vegetables; of 5–20 μg/mL for mushrooms (**Figure 5**).

For the antioxidant activity, *L*. *multiflora* is the most active for herbal teas, *M. glaziovii* for vegetables and *A. delicata* for mushrooms related to their hydrophilic and lipophilic compounds [20]. The vegetable *D. praehensilis* exhibited higher cellular antioxidant activity than *I. batatas* and *S. gilo* (leaves) whereas these showed a superior activity to *D. praehensilis* for radical scavenging activity. López-Alarcón and Denicola showed that a good antioxidant is not just

*Sesamum angustifolium*, one of banned vegetables for konzo households by local traditional medicine [2], is the most

**Table 1.** Total phenolic content (TPC) of vegetables, expressed in mg of gallic acid equivalent (GAE) per g of dried matter

According to the scientific data, our study is the first to evaluate the antioxidant capacity of local traditional foods in an area severely affected by konzo disease in order to establish scien-

Eight species of edible mushrooms used in this study showed an interesting antioxidant activity compared to results reported in previous studies [22, 23]. There are few reports regarding the antioxidant activities of the studied mushrooms. *A. delicata* exhibited the highest antioxidant activity in comparison to other vegetables. However, Kabuyi et al. (2017) assessed

tific basis of their use in the prevention of chronic cassava cyanogenic poisoning.

**Vegetables TPC AOX IC50 (μg/mL)**

*Abelmoschus esculentus* Linn 32.94 ± 0.93 86.27 ± 9.2 nd

*Manihot esculenta* Crantz var. Chamusuku 41.51 ± 0.26 23.28 ± 1.11 nd *Manihot esculenta* Crantz var. Kamonji 45.18 ± 0.79 17.65 ± 1.13 nd

active (antioxidant activity) among the vegetables after *Manihot* species. nd = not determined.

and IC50 (μg/mL) values of organic extracts in ABTS and DPPH assays (means ± SD, n = 6).

*Manihot esculenta* Crantz var. Mwambo 86.4 ± 2.99 15.10 ± 1.13 20.15 ± 1.07 *Manihot esculenta* Crantz var. Tshibombi 57.56 ± 6.19 19.45 ± 1.11 40.93 ± 1.91 *Manihot esculenta* Crantz var. TEM 419 36.70 ± 4.16 23.07 ± 1.11 37.93 ± 2.25 *Manihot glaziovii* Mûll. Arg 107.71 ± 7.80 12.42 ± 2.08 20.5 ± 1.06 *Megaphrynium macrostachum* 32.69 ± 3.65 79.25 ± 10.29 503.5 ± 10.29 *Sesamum angustifolium* auct\* 63.76 ± 3.76 31.19 ± 1.07 48.3 ± 1.02 *Solanum aethiopicum* L 32.24 ± 4.13 123.89 ± 16.15 282.49 ± 27.81 *Solanum gilo* Raddi (leaves) 72.04 ± 1.70 29.51 ± 0.94 163.68 ± 30.41 *Solanum gilo* Raddi (fruits) 24.19 ± 0.37 81.97 ± 5.17 349.95 ± 19.03

*Abelmoschus moshatus* Medik 36.32 ± 1.05 52.36 ± 2.1 71.45 ± 14.44 *Amaranthus viridis* L. 23.31 ± 0.92 88.9 ± 11.1 762.08 ± 155.34 *Dioscorea praehensilis* 34.09 ± 4.46 106.44 ± 17.36 230.14 ± 31.07 *Hibiscus cannabinus* L. 89.05 ± 11.92 44.98 ± 0.87 73.79 ± 17.20 *Hibiscus sabdarifa* L. 82.97 ± 3.27 64.72 ± 6.17 86.04 ± 4.32 *Ipomea batatas* L. 76.78 ± 3.20 47.76 ± 3.25 233.35 ± 63.53

**ABTS DPPH**

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Traditional Foods as Putative Sources of Antioxidants with Health Benefits in Konzo

a good radical scavenger [21].

\*

Aqueous and methanolic extracts of Herbal teas showed also the best cellular antioxidant activity using DCFH- DA on HL-60 monocytes assay at 1–20 μg/mL [17]. The lucigenindependent chemiluminescence (CL) and the intracellular fluorescent probe DCFH-DA were used to evaluate the extra- and intracellular ROS production resulting mainly from NADPH oxidase activity by stimulated neutrophil and HL-60 cells [16].


Verbascoside is found to be abundant in herbal teas [17] and we first report here its presence in leaves of *Sesamum angustifolium*. Chlorogenic acid is the main phenolic acid found in extracts of *Raphia sese, Solanum aethiopicum* and *Solanum gilo.* Rosmarinic acid was found to be a major compound of Ocimum species of DRC [18]. Phytochemical screening of mushrooms and yams showed that phenolic acids are their major compounds. Phytochemicals derived from various sources target inflammatory and oxidative stress pathways and retard or delay

Protective effects of phenolic compounds have often been ascribed to their direct antioxidant

Oxidative stress is recognized as an important factor in a variety of neurodegenerative diseases, as a mediator of the adverse effects of a number of neurotoxicants, and as a mechanism for age related degenerative processes [12]. Finding alternative and complementary ways to reduce the redox processes might have a beneficial interest in the context of developing

Traditional foods contained a considerable amount of phenolic compounds expressed as total polyphenol contents as described in **Tables 1**–**3**. Total polyphenol contents of Kahemba's ethnic foods varied significantly between the samples of each group of foods. *Lippia multiflora* had the highest total polyphenol content among herb-teas, *Manihot glaziovii* among vegetables, *Cantharellus rufopunctatus* among mushrooms and *Dioscorea alata* among yams. Antioxidant activities significantly varied also between the samples of each group of foods (p < 0.05). All methanolic extracts had significant radical scavenging effects with increasing concentrations in the range of 1–40 μg/mL for herb teas, 10–80 μg/mL for spices and vegetables, and 10–250 μg/mL for mushrooms. This antiradical activity is connected to their ability to scavenge free radicals according to their IC50 values (**Tables 1–3**). IC50 values ranged from 7.56 ± 0.87 μg/mL (*L. multiflora*) to 653.13 ± 51.25 μg/mL (*D. cayenensis*) for the ABTS assay and from 10.44 ± 1.13 μg/mL (*L. multiflora*) to 17179.09 ± 1150.25 μg/mL (*Cantharellus* sp.) for the DPPH assay. Cassava flours also exhibited a good scavenging activity with IC50 values rang-

Beside conventional cell-free antioxidant assays, it can be pertinent to evaluate the anti- oxidant and anti-catalytic potential of plant extracts in cellular models involved in ROS production and inflammatory responses [16, 19]. The addition of extract solutions at increasing concentrations resulted in a dose dependent decrease of the ROS-induced lucigenin-amplified chemiluminescence. All tested extracts induced a significant inhibition (p < 0.0001) of the ROS production by neutrophils compared to controls at the concentration range of 0.05–10 μg/mL for herbal teas

Aqueous and methanolic extracts of Herbal teas showed also the best cellular antioxidant activity using DCFH- DA on HL-60 monocytes assay at 1–20 μg/mL [17]. The lucigenindependent chemiluminescence (CL) and the intracellular fluorescent probe DCFH-DA were used to evaluate the extra- and intracellular ROS production resulting mainly from NADPH

the onset of neurological diseases.

**4.2. Antioxidant properties**

124 Antioxidants in Foods and Its Applications

countries.

effect and/or to their anti-inflammatory action [12].

ing from 99.54 ± 9.60 to 974.99 ± 94.01 μg/mL.

and vegetables; of 5–20 μg/mL for mushrooms (**Figure 5**).

oxidase activity by stimulated neutrophil and HL-60 cells [16].

\* *Sesamum angustifolium*, one of banned vegetables for konzo households by local traditional medicine [2], is the most active (antioxidant activity) among the vegetables after *Manihot* species. nd = not determined.

**Table 1.** Total phenolic content (TPC) of vegetables, expressed in mg of gallic acid equivalent (GAE) per g of dried matter and IC50 (μg/mL) values of organic extracts in ABTS and DPPH assays (means ± SD, n = 6).

For the antioxidant activity, *L*. *multiflora* is the most active for herbal teas, *M. glaziovii* for vegetables and *A. delicata* for mushrooms related to their hydrophilic and lipophilic compounds [20]. The vegetable *D. praehensilis* exhibited higher cellular antioxidant activity than *I. batatas* and *S. gilo* (leaves) whereas these showed a superior activity to *D. praehensilis* for radical scavenging activity. López-Alarcón and Denicola showed that a good antioxidant is not just a good radical scavenger [21].

According to the scientific data, our study is the first to evaluate the antioxidant capacity of local traditional foods in an area severely affected by konzo disease in order to establish scientific basis of their use in the prevention of chronic cassava cyanogenic poisoning.

Eight species of edible mushrooms used in this study showed an interesting antioxidant activity compared to results reported in previous studies [22, 23]. There are few reports regarding the antioxidant activities of the studied mushrooms. *A. delicata* exhibited the highest antioxidant activity in comparison to other vegetables. However, Kabuyi et al. (2017) assessed


**Table 2.** Total phenolic content (TPC) of mushrooms, expressed in mg of gallic acid equivalent (GAE) per g of dried matter and IC50 (μg/ mL) values of organic extracts on ABTS and DPPH assays (means ± SD, n = 6).


activities of different varieties of *M. esculenta* (P < 0.05). Few reports exist on the antioxidant activity of leaves of *M. esculenta* and *M. glaziovii*. However, to the best of our knowledge, leaves of *M. glaziovii* are only consumed in the west of Democratic Republic of Congo. This species is particularly used elsewhere as biomass for bioethanol and bio-gas production [25]. The antioxidant activity of the other vegetables is also considerable and comparable to results reported in similar studies on ethnic foods from Kwango. *Entada gigas* (L.) Fawc. & Rendle, *Psophocarpus scandens* (Endl.) Verdc, *Salacia pynaertii* De Wild, and *Tetrorchidium congolense* J. Léonard, four unconventional green leafy vegetables with high nutritive value consumed to Kenge, showed important antioxidant activities [26]. Interestingly, these vegetables have high protein content specially *S. pynaertii* that constitute the richest vegetable in methionine and cysteine [13]. Methionine and cysteine are sulfur amino acids, essential for the detoxification

**Figure 5.** Effects of gallic acid and organic extracts of mushrooms on the CL response produced by PMA activated equine neutrophils (means ± SD, n = 6). The intensity of CL results from the reaction between lucigenin and the ROS produced by the non-activated (NAEN) and activated equine neutrophils (AEN). The chemiluminescence response observed in the presence of solvent (DMSO), used to solubilize the extracts, and was defined as 100%. For non-activated

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*S. angustifolium* showed a remarkable antioxidant activity which can be attributed to the presence of verbascoside, which is also responsible for high antioxidant activity of herbal teas. Herbal teas exhibited antioxidant activity according to the order *Lippia multiflora > Ocimum gratissimum > Lantana montevidensis > Ocimum basilicum*. Herbal tea is a commonly consumed beverage prepared from different parts of plant species other than *Camellia sinensis*. Particularly, extracts of *L. multiflora* are known to have an excellent antioxidant activity

Antioxidant activity of studied yams was considerable and *Dioscorea alata* was the most active. Bukatuka et al. studied *Dioscorea alata, Dioscorea bulbifera, Dioscorea dumetorum, Dioscorea burkilliana* and *Dioscorea praehensilis* from Kenge, known to be relevant in traditional medicine for diabetes mellitus treatment. These authors reported that they displayed highest radical-scavenging activities and a good antihyperglycemic activity related to their appreciable

of cyanogen glycosides implicated in the occurrence of konzo [27].

(NAEN) cells, 10 μL of PBS was added to the cell suspension instead of PMA.

related to their abundance of phenylpropanoids such as verbascoside [17, 28].

**Table 3.** Total phenolic content (TPC) of herb-teas and spices, expressed in mg of gallic acid equivalent (GAE) per g of dried matter and IC50 (μg/mL) values of organic extracts in ABTS and DPPH assays (means ± SD, n = 6).

the selenium content and the antioxidant capacity of wild edible mushrooms from Kenge, another rural area of Kwango (DRC) with a high prevalence of malnutrition. They reported that *Auricularia delicata, Lentinus cf. cladopus, Pleurotus tuberregium, Marasmius buzungolo* and *Schizophillum commune* showed the interest antioxidant activity and moderate quantity of selenium, and *L. cf. cladodus* had the highest concentration [24]. The radical scavenging activity of mushrooms found by ABTS assay is significantly higher than that obtained with the DPPH assay. This great difference could be explained by synergistic effects of mushroom hydrophilic and lipophilic compounds on the ABTS•+ chromogen [16].

Tested vegetables showed high antioxidant activity and leaves of *Manihot* species exhibited a strong radical scavenging capacity. A significant difference was found between antioxidant

**Figure 5.** Effects of gallic acid and organic extracts of mushrooms on the CL response produced by PMA activated equine neutrophils (means ± SD, n = 6). The intensity of CL results from the reaction between lucigenin and the ROS produced by the non-activated (NAEN) and activated equine neutrophils (AEN). The chemiluminescence response observed in the presence of solvent (DMSO), used to solubilize the extracts, and was defined as 100%. For non-activated (NAEN) cells, 10 μL of PBS was added to the cell suspension instead of PMA.

activities of different varieties of *M. esculenta* (P < 0.05). Few reports exist on the antioxidant activity of leaves of *M. esculenta* and *M. glaziovii*. However, to the best of our knowledge, leaves of *M. glaziovii* are only consumed in the west of Democratic Republic of Congo. This species is particularly used elsewhere as biomass for bioethanol and bio-gas production [25]. The antioxidant activity of the other vegetables is also considerable and comparable to results reported in similar studies on ethnic foods from Kwango. *Entada gigas* (L.) Fawc. & Rendle, *Psophocarpus scandens* (Endl.) Verdc, *Salacia pynaertii* De Wild, and *Tetrorchidium congolense* J. Léonard, four unconventional green leafy vegetables with high nutritive value consumed to Kenge, showed important antioxidant activities [26]. Interestingly, these vegetables have high protein content specially *S. pynaertii* that constitute the richest vegetable in methionine and cysteine [13]. Methionine and cysteine are sulfur amino acids, essential for the detoxification of cyanogen glycosides implicated in the occurrence of konzo [27].

*S. angustifolium* showed a remarkable antioxidant activity which can be attributed to the presence of verbascoside, which is also responsible for high antioxidant activity of herbal teas. Herbal teas exhibited antioxidant activity according to the order *Lippia multiflora > Ocimum gratissimum > Lantana montevidensis > Ocimum basilicum*. Herbal tea is a commonly consumed beverage prepared from different parts of plant species other than *Camellia sinensis*. Particularly, extracts of *L. multiflora* are known to have an excellent antioxidant activity related to their abundance of phenylpropanoids such as verbascoside [17, 28].

the selenium content and the antioxidant capacity of wild edible mushrooms from Kenge, another rural area of Kwango (DRC) with a high prevalence of malnutrition. They reported that *Auricularia delicata, Lentinus cf. cladopus, Pleurotus tuberregium, Marasmius buzungolo* and *Schizophillum commune* showed the interest antioxidant activity and moderate quantity of selenium, and *L. cf. cladodus* had the highest concentration [24]. The radical scavenging activity of mushrooms found by ABTS assay is significantly higher than that obtained with the DPPH assay. This great difference could be explained by synergistic effects of mushroom

**Table 3.** Total phenolic content (TPC) of herb-teas and spices, expressed in mg of gallic acid equivalent (GAE) per g of

**ABTS DPPH**

**ABTS DPPH**

Tested vegetables showed high antioxidant activity and leaves of *Manihot* species exhibited a strong radical scavenging capacity. A significant difference was found between antioxidant

hydrophilic and lipophilic compounds on the ABTS•+ chromogen [16].

**Herb-teas TPC AOX IC50 (μg/mL)**

matter and IC50 (μg/ mL) values of organic extracts on ABTS and DPPH assays (means ± SD, n = 6).

**Mushrooms TPC AOX IC50 (μg/mL)**

126 Antioxidants in Foods and Its Applications

*Amanita loosii* 8.82 ± 0.01 45.65 ± 1.00 1862.1 ± 425 *Auricularia delicata* 9.53 ± 0.12 39.31 ± 1.04 252.4 ± 15.5 *Cantharellus* sp. 4.73 ± 0.02 220.3 ± 17.40 1717.09 ± 522 *Cantharellus symoensii* 6.4 ± 0.02 144.9 ± 21.80 1367.73 ± 364 *Cantharellus rufopunctatus* 10.32 ± 1.09 41.1 ± 1.02 1815.52 ± 418 *Lactarius tenellus* 5.96 ± 1.47 43.51 ± 1.04 1603.25 ± 294 *Lactifluus edulis* 5.12 ± 0.11 262.4 ± 20.74 1318.3 ± 259 *Schizophyllum commune* 9.77 ± 0.40 169.8 ± 23.80 307.61 ± 25.05

**Spices**

*Lantana montevidensis (Spreng.)* 87.74 ± 1.66 21.11 ± 1.68 27.15 ± 3.50 *Lippia multiflora Moldenke* 110.35 ± 3.89 7.56 ± 0.87 10.44 ± 1.13 *Ocimum gratissimum* L. 71.88 ± 1.16 12.07 ± 0.84 21.76 ± 2.92

Mushrooms exhibited a relatively interesting activity similar to some vegetables despite their low total phenol content.

**Table 2.** Total phenolic content (TPC) of mushrooms, expressed in mg of gallic acid equivalent (GAE) per g of dried

*Ocimum basilicum* 6.52 ± 0.18 38.37 ± 3.13 136.77 ± 15.64 *Raphia sese* De Wild 10.08 ± 0.51 40.71 ± 1.05 518.8 ± 95.16

dried matter and IC50 (μg/mL) values of organic extracts in ABTS and DPPH assays (means ± SD, n = 6).

*Aeollanthus suaveolens* 26.30 ± 3.72 41.82 ± 3.99 nd

nd = not determined. Herbal teas exhibited considerable antioxidant activity.

Antioxidant activity of studied yams was considerable and *Dioscorea alata* was the most active. Bukatuka et al. studied *Dioscorea alata, Dioscorea bulbifera, Dioscorea dumetorum, Dioscorea burkilliana* and *Dioscorea praehensilis* from Kenge, known to be relevant in traditional medicine for diabetes mellitus treatment. These authors reported that they displayed highest radical-scavenging activities and a good antihyperglycemic activity related to their appreciable amount of total phenolic contents [29]. Interestingly, cassava flours exhibited higher antioxidant activity than cassava roots. This could be explained by possible chemical modifications during processing before cassava flour is traded. Nevertheless, it is probable that the antioxidant capacity of cassava flours is not sufficient to counteract oxidative damage induced by cyanogenic glycosides. In this context, the mixture of cassava flours with maize, proposed to reduce the ingestion of cyanogenic glycosides from cassava and to improve amino acid intake, could be interesting to promote [8].

and antimalarial activities [33]. Biflavonoids are compounds with therapeutic potential against

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129

Verbascoside is well known for its numerous biological activities including anti-oxidative, anti-apoptosis and anti-inflammatory effects. The *in vivo* effects of verbascoside could also be assigned to its metabolites such as caffeic and ferulic acids [34]. Verbascoside is able to reverse some of the cognitive impairment and to prevent the neuronal apoptosis due to oxidative stress. For this, previous results support the use of traditional medicinal herbs containing

Typical preparation methods applied to these food items before consumption include a strong heating process to prepare different sauces with spices and palm oil, which are consumed together with a maize or cassava preparation. Our results are limited to non-cooked traditional foods. The literature reports controversial effects of heat treatment on the antioxidant capacity depending on the analyzed plant and the applied heat treatment. Tsumbu et al. reported that the moderate heat treatment of the green vegetables did not modify their antioxidant and anti-inflammatory capacities [36]. Cooking could lead to the loss of phenolic compounds due to their good solubility in water [37]. However, Ola *et al.* (2009) demonstrated that almost all the phenolic constituents of *M. esculenta* leaves are stable even after heating processes such as boiling [38]. Abdullah *et al.* (2012), reported that selected culinary-medicinal mushrooms extracted by boiling in water for 30 min, showed a good antioxidant activity related to synergistic effects of entire water-soluble fractions [39]. Nevertheless, this aspect

Motor and cognitive performance continues to be significantly impaired in konzo are associated in part with exposure to poorly processed cassava as measured by urinary thiocyanate [11].

in the bodily fluids of konzo subjects is a consequence of dietary exposure to cyanide. Besides chloride, myeloperoxidase (MPO) also uses the thiocyanate as a major physiological substrate.

by MPO [40, 41] and leading to carbamoylation of proteins [42]. Cassava consumption is associated with increased protein carbamyolation and neurological complications. Prevention of carbamoylation may protect against the neuropathic effects of cyanate [43, 44]. MPO generates a battery of highly diffusible reactive oxidants such as hypochlorite, tyrosyl radicals and aldehydes, which instigate oxidative damage in the host tissues at the inflammatory sites exacerbating tissue damage. In some acute and chronic pathologies, the uncontrolled stimulation of neutrophils could contribute to amplify or maintain the inflammatory response with the release of MPO, a pro-oxidant enzyme involved in secondary cell damage and considered as a marker of inflammation [19]. Indeed, recent investigations have increasingly revealed the cause-effect relationship between MPO and the development of diverse inflammatory diseases supporting MPO and its metabolites as a promising biomarkers not only for infectious diseases but also for a wide array of non-infectious and neurodegenerative disorders [45]. Malle et al. (2007), suggested that the inhibitots of MPO activity are promising therapeutic agents [46].

concentration is a powerful driver of the extent of thiol proteins oxidation in induced

), the major metabolite of cyanide,

AD and other neurodegenerative diseases [12].

acteoside for neuroprotection [35].

should be examined in further studies.

Presence of very high concentrations of thiocyanate (SCN−

**4.3. Anti-inflammatory activity**

The SCN−

Altogether, the antioxidant activities measured with cell-based assays were in good accordance to radical-scavenging capacities. Mushrooms exhibited a considerable cell-based antioxidant activity comparable to certain vegetables. To the best of our knowledge this is the first report regarding the potential inhibitory effect on intracellular ROS production by inflammatory cells of the studied mushrooms and some vegetables such as *D*. *praehensilis, M*. *glaziovii,* and *S*. *angustifolium*. Globally, herbal teas showed the highest antioxidant and radical scavenging capacities, followed by vegetables, yams, mushrooms, spices and cassava flours. TLC and HPLC fingerprints of extracts of investigated foods revealed that they contain a diversity of phenolic compounds (Flavonoids, phenolic acids…) [8].

Flavonoids are a group of phenolic compounds or secondary metabolites that are widely distributed in higher plants and are part of our daily diet. It has been reported that flavonoids exhibit a wide variety of biological effects, including anti-inflammatory, anti oxidant, antiviral, antibacterial, anticarcinogenic, antituberculosis, vasodilatory, and antiallergic activities [12]. They are also cytoprotective in various organs and promote intracellular signals that enhance cell survival, among other benefits. However, interest in flavonoids stems mainly from their antioxidant activities, resulting from the catechol group in the B ring, which confers free radical-scavenging activity. Additionally, they act as electron donors or chelators of metal ions (e.g., iron, copper), inhibiting the oxidation of low-density lipoproteins (LDLs). Flavonoids have thus become key compounds. When ingested in the diet, they may prevent and combat neurodegenerative diseases such as Alzheimer disease (AD). Studies have reported that the oral administration of some flavonoids (apigenin, rutin, myricetin…) to mice prevents the development of Alzheimer disease [12]. Rivadeneyra-Domínguez et al. reported that *G. biloba* extract exert a protective effect against behavioral and neuronal damage associated with consumption of cassava juice in the rat and these effects are possibly related with flavonoids [30].

Traditional foods studied contained glycosylated flavonoids mainly the derivatives of quercetin. Quercetin is the major flavonoid in our daily diet and its estimated daily intake is between 5 and 40 mg. After absorption, quercetin is mainly metabolized in the intestine and liver. The plasma concentration of quercetin is normally in the nanomolar range, but it can reach the micromolar range after consumption of quercetin- rich foods [12]. Quercetin is the most extensively studied flavonoid that has been shown to exhibit antioxidant, antiviral, antibacte- rial, anti-inflammatory, and anticarcinogenic properties. Quercetin modulate several cellular signaling pathways involved in regulating the antioxidant response, cell survival, apoptosis, and inflammation [12, 31, 32]. Others compounds such as some biflavonoids founded in the seeds as *Garcinia kola* largely consumed to Kahemba, may have anticancer, antimicrobial, anti-inflammatory, antiviral, and antimalarial activities [33]. Biflavonoids are compounds with therapeutic potential against AD and other neurodegenerative diseases [12].

Verbascoside is well known for its numerous biological activities including anti-oxidative, anti-apoptosis and anti-inflammatory effects. The *in vivo* effects of verbascoside could also be assigned to its metabolites such as caffeic and ferulic acids [34]. Verbascoside is able to reverse some of the cognitive impairment and to prevent the neuronal apoptosis due to oxidative stress. For this, previous results support the use of traditional medicinal herbs containing acteoside for neuroprotection [35].

Typical preparation methods applied to these food items before consumption include a strong heating process to prepare different sauces with spices and palm oil, which are consumed together with a maize or cassava preparation. Our results are limited to non-cooked traditional foods. The literature reports controversial effects of heat treatment on the antioxidant capacity depending on the analyzed plant and the applied heat treatment. Tsumbu et al. reported that the moderate heat treatment of the green vegetables did not modify their antioxidant and anti-inflammatory capacities [36]. Cooking could lead to the loss of phenolic compounds due to their good solubility in water [37]. However, Ola *et al.* (2009) demonstrated that almost all the phenolic constituents of *M. esculenta* leaves are stable even after heating processes such as boiling [38]. Abdullah *et al.* (2012), reported that selected culinary-medicinal mushrooms extracted by boiling in water for 30 min, showed a good antioxidant activity related to synergistic effects of entire water-soluble fractions [39]. Nevertheless, this aspect should be examined in further studies.

#### **4.3. Anti-inflammatory activity**

amount of total phenolic contents [29]. Interestingly, cassava flours exhibited higher antioxidant activity than cassava roots. This could be explained by possible chemical modifications during processing before cassava flour is traded. Nevertheless, it is probable that the antioxidant capacity of cassava flours is not sufficient to counteract oxidative damage induced by cyanogenic glycosides. In this context, the mixture of cassava flours with maize, proposed to reduce the ingestion of cyanogenic glycosides from cassava and to improve amino acid

Altogether, the antioxidant activities measured with cell-based assays were in good accordance to radical-scavenging capacities. Mushrooms exhibited a considerable cell-based antioxidant activity comparable to certain vegetables. To the best of our knowledge this is the first report regarding the potential inhibitory effect on intracellular ROS production by inflammatory cells of the studied mushrooms and some vegetables such as *D*. *praehensilis, M*. *glaziovii,* and *S*. *angustifolium*. Globally, herbal teas showed the highest antioxidant and radical scavenging capacities, followed by vegetables, yams, mushrooms, spices and cassava flours. TLC and HPLC fingerprints of extracts of investigated foods revealed that they contain a diversity

Flavonoids are a group of phenolic compounds or secondary metabolites that are widely distributed in higher plants and are part of our daily diet. It has been reported that flavonoids exhibit a wide variety of biological effects, including anti-inflammatory, anti oxidant, antiviral, antibacterial, anticarcinogenic, antituberculosis, vasodilatory, and antiallergic activities [12]. They are also cytoprotective in various organs and promote intracellular signals that enhance cell survival, among other benefits. However, interest in flavonoids stems mainly from their antioxidant activities, resulting from the catechol group in the B ring, which confers free radical-scavenging activity. Additionally, they act as electron donors or chelators of metal ions (e.g., iron, copper), inhibiting the oxidation of low-density lipoproteins (LDLs). Flavonoids have thus become key compounds. When ingested in the diet, they may prevent and combat neurodegenerative diseases such as Alzheimer disease (AD). Studies have reported that the oral administration of some flavonoids (apigenin, rutin, myricetin…) to mice prevents the development of Alzheimer disease [12]. Rivadeneyra-Domínguez et al. reported that *G. biloba* extract exert a protective effect against behavioral and neuronal damage associated with consumption of cassava juice in the rat and these effects are possibly

Traditional foods studied contained glycosylated flavonoids mainly the derivatives of quercetin. Quercetin is the major flavonoid in our daily diet and its estimated daily intake is between 5 and 40 mg. After absorption, quercetin is mainly metabolized in the intestine and liver. The plasma concentration of quercetin is normally in the nanomolar range, but it can reach the micromolar range after consumption of quercetin- rich foods [12]. Quercetin is the most extensively studied flavonoid that has been shown to exhibit antioxidant, antiviral, antibacte- rial, anti-inflammatory, and anticarcinogenic properties. Quercetin modulate several cellular signaling pathways involved in regulating the antioxidant response, cell survival, apoptosis, and inflammation [12, 31, 32]. Others compounds such as some biflavonoids founded in the seeds as *Garcinia kola* largely consumed to Kahemba, may have anticancer, antimicrobial, anti-inflammatory, antiviral,

intake, could be interesting to promote [8].

128 Antioxidants in Foods and Its Applications

related with flavonoids [30].

of phenolic compounds (Flavonoids, phenolic acids…) [8].

Motor and cognitive performance continues to be significantly impaired in konzo are associated in part with exposure to poorly processed cassava as measured by urinary thiocyanate [11]. Presence of very high concentrations of thiocyanate (SCN− ), the major metabolite of cyanide, in the bodily fluids of konzo subjects is a consequence of dietary exposure to cyanide. Besides chloride, myeloperoxidase (MPO) also uses the thiocyanate as a major physiological substrate. The SCN− concentration is a powerful driver of the extent of thiol proteins oxidation in induced by MPO [40, 41] and leading to carbamoylation of proteins [42]. Cassava consumption is associated with increased protein carbamyolation and neurological complications. Prevention of carbamoylation may protect against the neuropathic effects of cyanate [43, 44]. MPO generates a battery of highly diffusible reactive oxidants such as hypochlorite, tyrosyl radicals and aldehydes, which instigate oxidative damage in the host tissues at the inflammatory sites exacerbating tissue damage. In some acute and chronic pathologies, the uncontrolled stimulation of neutrophils could contribute to amplify or maintain the inflammatory response with the release of MPO, a pro-oxidant enzyme involved in secondary cell damage and considered as a marker of inflammation [19]. Indeed, recent investigations have increasingly revealed the cause-effect relationship between MPO and the development of diverse inflammatory diseases supporting MPO and its metabolites as a promising biomarkers not only for infectious diseases but also for a wide array of non-infectious and neurodegenerative disorders [45]. Malle et al. (2007), suggested that the inhibitots of MPO activity are promising therapeutic agents [46].

All plant extracts tested and isolated phenolic acids exhibited a dose-dependent inhibitory effect on MPO activity performed with SIEFED (**S**pecific **I**mmunological **E**xtraction **F**ollowed by **E**nzymatic **D**etection) technic. The SIEFED method used to measure MPO activity allowed the detection of compounds that have a direct interaction with the MPO. For the Hibiscus, dichloromethane extracts showed a stronger inhibition of MPO in comparison to methanolic extracts in the following order: *H. cannabinus* > *H. acetosella* > *H. sabdariffa*. The dichloromethane allowing a better extraction of lipophilic molecules may allow a better interaction of these molecules with the hydrophobic pocket at the entrance of the active site of MPO [16]. Tsumbu et al. evaluated the antioxidant, anti-radical, anti-inflammatory, and modulating properties of in "inflammation like" conditions of green vegetables from Bas Congo in DRC [36]. These authors showed that *Abelmoschus esculentus*, *Hibiscus acetosella*, *Manihot esculenta* and *Pteridium aquilinum* were active to inhibit MPO activity and the best effects were observed for *Pteridium* which contains the highest amount of total polyphenols and tannins, and *Manihot*, which has a high content of flavonoids [36]. Caffeoylhydroxycitric acid and neochlorogenic acid isolated from Hibiscus species, are less efficient MPO inhibitors in comparison to gallic acid compared to gallic acid, caffeoyl-hydroxycitric acid and neochlorogenic acid are larger molecules that cannot enter easily into the active site of MPO and thus inhibit the enzyme [16]. Gallic acid and caffeic acid were less active than quercetin. Quercetin shown the best activity than his glycosylated flavonoids [8].

considerable potential for antioxidants. However, *in vitro* findings, such as the antioxidant activities we have measured, are of uncertain relevance to the *in vivo* situation in healthy humans. Further studies are needed to evaluate the *in vivo* activity of these traditional foods and particularly in their cooked forms. This could lead to the valorization of traditional foods as functional foods or nutraceuticals with high antioxidant, anti-inflammatory capacities and high quality protein. This may provide benefits to protect the population of Kahemba against

Traditional Foods as Putative Sources of Antioxidants with Health Benefits in Konzo

http://dx.doi.org/10.5772/intechopen.74523

131

The authors thank Dr. Pieter Stofelen and Mrs. Bibiche Mato of the National Botanical Garden of Meise, Belgium, and Professor Dibaluka and Mr. Anthony Kikufi of the Biology Department of University of Kinshasa for identification of specimens. They thank the community of Kahemba and nurse Dieudonné Kasenia (Kwango Province, DRC) for their participation. They thank also the Center for Oxygen, Research and Development (C.O.R.D.) for her scientific and

\*, Désiré Tshala-Katumbay2,3, Dieudonné Mumba<sup>4</sup>

1 Centre d'Etudes des Substances Naturelles d'Origine Végétale (CESNOV), Faculty of Pharmaceutical Sciences, University of Kinshasa, Democratic Republic of Congo

2 Department of Neurology, Faculty of Medicine, University of Kinshasa, Democratic

5 Laboratory of Pharmacognosy, Center for Interdisciplinary Research on Medicines

6 Laboratoire d'Analyses et de Recherche sur l'Alimentation et la Nutrition (LARAN), Department of Biology, Faculty of Science, University of Kinshasa, Kinshasa, Democratic

4 Department of Tropical Medicine, Faculty of Medicine, University of Kinshasa, Democratic

3 Department of Neurology, Oregon Health and Science University, USA

and Nadege Kabamba Ngombe<sup>1</sup>

,

oxidative damage under different conditions, including konzo.

The authors declare that they have no conflict of interest.

, Théophile Mbemba<sup>6</sup>

\*Address all correspondence to: garaphmutwal@yahoo.fr

(CIRM), University of Liege, Liege, Belgium

**Acknowledgements**

technical supports.

**Author details**

Michel Frédérich5

Republic of Congo

Republic of Congo

Republic of the Congo

Paulin Mutwale Kapepula1

**Conflict of interest**

Although many phytochemicals present in plant foods are poorly absorbed and undergo rapid excretion, they exert anti-inflammatory, antioxidant, and anticarcinogenic effects at realistic doses. Consumption of phytochemicals may also mediate neurohormetic response through the modulation of adaptive stress-resistance genes, which are responsible for encoding protein chaperones that favor resistance to cellular stress and modulate immune function. Thus, regular consumption of phytochemicals from childhood to adulthood may reduce the risk of age related neurological disorders [32].

Polyphenols are promising neuroprotective agents for the treatment of neurodegenerative diseases and act by different mechanism including a potential to protect neurons against injury induced by neurotoxins, an ability to suppress neuroinflammation, and the potential to promote memory, learning and cognitive function. Evidence for neuroprotection has been provided by *in vitro* studies showing that various polyphenols protect neuronal cells from damage due to oxidative stress, and by *in vivo* animal studies that have shown their ability to protect neurons against oxidative insults [12].

Traditional foods are good source of essential amino acids and minerals especially for children who are exposed to many diseases. The high nutritive value of these traditional vegetables associated with their important antioxidant activities could contribute to a diversification of the diet in konzo's population, and could then provide benefits leading to a protection against oxidative damage under different conditions including konzo.
