**6. Bioactive compounds of doum palm**

#### **6.1. The chemical structure of volatile components**

Doum fruit yielded a yellowish color volatile oil with a fragrant aromatic odor at a yield of 0.5% (fresh wt). Physical constants measured include: specific gravity (0.168) and refractive index (1.383). The result of analysis of essential oil of doum by GC and GC–MS techniques revealed the presence of a total 57 compounds (**Figure 2**). Monoterpenes represented 15.97% including compounds such as sabinene (0.82%), ß-pinene (1.97%), limonene (2.42%), terpinen Biological Activities of the Doum Palm (*Hyphaene thebaica* L.) Extract and Its Bioactive… http://dx.doi.org/10.5772/intechopen.74772 53

**Figure 2.** Chemical structures of doum fruit essential oil.

and hematinic suspensions lipidemic, and hematinic suspensions [17]. The identification of compounds by thin-layer chromatography showed that the doum fruit contains significant amounts of saponins, coumarins, hydroxyl cinnamates, essential oils and flavonoids [18]. It was found that the administration of flavonoid extracts to diabetic rats significantly increased adiponectin levels that stimulate the hypoglycemic action of insulin without altering the concentration of insulin in blood and decrease the weight and volume of contents of granuloma in inflammation [19]. Therefore, this might be its probable mechanism of anti-inflammatory action. Furthermore, the hypoglycemic effect of these herbs may be due to the increased level of serum insulin by increasing the pancreatic secretion of insulin from cells of islets of Langerhans or its release of bound insulin and also may be due to the enhancement of peripheral metabolism of glucose [20]. The decoction of doum fruits is well tolerated and no mortality or morbidity until the dose of 5 g/kg b. wt. Repeated oral administration of doum fruits at 0.5 g/kg b. wt. or 2 g/kg b. wt. was ineffective on the normal reproductive parameters. While the red blood corpuscles, packed cell volume, hemoglobin concentration and percent of phagocytic activity were significantly increased [21]. A significant decrease in blood glucose, cholesterol, triglycerides and total lipid levels was observed after 1 and 2 months of administration of the decoction of doum fruits [21]. The obtained results confirm the value of doum fruits as hematinic potentials, hypolipidemic, improve the hepato-renal functions and

Also, triglycerides were independently related to coronary heart disease and most of the antihypercholesterolemic drugs did not decrease triglycerides levels, but the aqueous extracts of doum fruits lower it significantly [22]. This effect may be related to the increase in endothelium bound lipoprotein lipase which hydrolyzes the triglycerides into fatty acids. Previously, the authors reported that the hypolipidemic properties of the aqueous pulp suspension of doum could be partly due to the presence of glycosides [23]. Saponins have been reported to form complexes with cholesterol and bile in the intestine thereby indirectly reducing the cholesterol level in the blood [24]. In addition, administration of 200, 400 and 800 mg/kg body weight of aqueous extracts of both stem and bark of *H. thebaica* (L) Mart showed no significant (p > 0.05) difference in feed intake, this may be due to the absence of tannin in both the stem and bark extracts. Decrease in feed intake was observed at the highest dose of 800 mg/kg of the methanolic fruit pulp extract of the same plant, this may be due to tannin content of the

Doum fruit yielded a yellowish color volatile oil with a fragrant aromatic odor at a yield of 0.5% (fresh wt). Physical constants measured include: specific gravity (0.168) and refractive index (1.383). The result of analysis of essential oil of doum by GC and GC–MS techniques revealed the presence of a total 57 compounds (**Figure 2**). Monoterpenes represented 15.97% including compounds such as sabinene (0.82%), ß-pinene (1.97%), limonene (2.42%), terpinen

without side effects on the studied reproductive parameters.

52 Antioxidants in Foods and Its Applications

methanolic fruit pulp extract of the plant [25].

**6. Bioactive compounds of doum palm**

**6.1. The chemical structure of volatile components**

4-ol (1.77%), α-terpineol (0.95%), sesquiterpenes (3.2%), diterpenes represent 40.49%, of which incensole (19.81%) and incensole acetate (17.52%) were found to be the main components, non-terpenoidal components amount to 15.21% of which octylacetate (9.38%) was found to be the major and fatty acid (8.55%) with the main component palmitic acid (5.90%). Oxygenated compounds constituted 66.78% of the total compounds identified which indicated the economic value of this oil. Fruit of doum oil was found to contain volatile diterpenes especially cembrene A which showed cytotoxic activity, and this revealed the medical importance of the volatile oil of doum which could be utilized medicinally [26].

#### **6.2. Chemical structure of doum fruit phenolic compounds**

#### *6.2.1. Total soluble phenols content and compounds*

Different total soluble phenols values in doum were published in different studies; it ranged from 45.08 to 64.90 mg GAE/g DW [27]. While it recorded the highest values in pitted doum fruit extracts varied from 116.26 to 139.48 mg GAE/g DW [16]. The bioactive potential of fruits and vegetables attributed to their high content of polyphenols [28].

The most abundant phenolic compounds recorded in doum were metoxicinnamic acid, sinapic acids (hydroxycinnamic acids), chlorogenic acid, catechin, p-hydroxybenzoic acid, vanillic acids, 3,4 di hydroxycinnamic acid, caffeic acid, 2-hydroxycinnamic acid, Epicatechinand cinnamic acid, respectively (**Figure 3**) [29]. Doum pulps exhibited higher caffeic acid contents in comparison to the domestic fruits [30]. The highest four concentrations of phenolic compounds in doum fruit aqueous extracts were found to be 3-OH tyrosol, E-vanillic acid, catechin and chlorogenic acid, while the lowest were of alpha-coumaric acid, cinnamic acid, p-coumaric acid and coumarin [31].

#### *6.2.2. Total flavonoids content and compounds*

The total flavonoids content in different extracts of doum fruit extracts varied widely ranging from 24.04 to 47.17 mg rutin/g DW [16]. Similar results found that the content of flavonoids (mg/g) of fruits of *H. thebaica*, in the quercetin equivalent was 46.28 mg/g DW [27]. HPLC analysis of aqueous doum fruit extracts showed 11 flavonoid compounds (**Figure 4**). The highest concentrations were quercetin, hesperetin, naringin and rutin compounds [18]. Five flavone glycosides were isolated and identified from doum fruits namely, luteolin 7-*O-ß*glucuronoide, apigenin 7-*O-ß*-glucuronoide, luteolin *O-ß*-glycoside, luteolin 7*-O*-rutinoside

and chrysoeriol 7*-O*-rutinoside [32]. Glycosides of luteolin and chryseriol flavones previously isolated from doum fruit were identified. In addition, isoquercetrin and isorhamnetin rutino-

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55

Doum leaves were extracted in 80% ethanol and filtrate. The aqueous ethanolic extract used to scavenge reactive oxygen species (ROS). The phenolic content of doum was determined by using HPLC and recorded the presence of four major compounds correspond to Gallic acid, Quercetin glucoside, Kaempferol rhamnoglucoside, Dimethyoxy quercetin rhamnoglucoside, respectively. An in-depth phytochemical investigation showed the presence of 14 compounds (**Figure 5**): 8*-C-ß-*D-glucopyranosyl-5, 7, 4′-trihydroxyflavone (vitexin), 6*-C-ß*-D-glucopyranosyl-5, 7, 4′-trihydroxyflavone (iso-vitexin) [34, 35]. Quercetin 3-*O-ß*-4C1-D-glucopyranoside, gallic acid [36], quercetin 7-*O-ß-* 4C1-D-glucoside [37], luteolin 7-*O-ß*-4C1- D-glucoside, tricin 5-*O-ß*-4C1-D-glucoside [38], 7, 3′ dimethoxy quercetin 3-O-[6"-O-α-L-rhamnopyranosyl]-*ß-D*-glucopyranoside (rhamnazin 3-O-rutinoside) [39] (kaempferol-3-*O*-[6"-*O-α*-L-rhamnopyranosyl]-*ß*-D-glucopyranoside (nicotiflorin) [40], apigenin, luteolin, tricin, quercetin and kaempferol. All these compounds were isolated and

side are reported for the first time in *H. thebaica* [33].

**Figure 4.** Chemical structures of doum fruit flavonoid compounds.

identified for the first time in doum leaves [41].

*6.2.3. Chemical structure of doum palm leaves phenolic compounds*

**Figure 3.** Chemical structures of doum fruit phenolic compounds.

Biological Activities of the Doum Palm (*Hyphaene thebaica* L.) Extract and Its Bioactive… http://dx.doi.org/10.5772/intechopen.74772 55

**Figure 4.** Chemical structures of doum fruit flavonoid compounds.

The most abundant phenolic compounds recorded in doum were metoxicinnamic acid, sinapic acids (hydroxycinnamic acids), chlorogenic acid, catechin, p-hydroxybenzoic acid, vanillic acids, 3,4 di hydroxycinnamic acid, caffeic acid, 2-hydroxycinnamic acid, Epicatechinand cinnamic acid, respectively (**Figure 3**) [29]. Doum pulps exhibited higher caffeic acid contents in comparison to the domestic fruits [30]. The highest four concentrations of phenolic compounds in doum fruit aqueous extracts were found to be 3-OH tyrosol, E-vanillic acid, catechin and chlorogenic acid, while the lowest were of alpha-coumaric acid, cinnamic acid,

The total flavonoids content in different extracts of doum fruit extracts varied widely ranging from 24.04 to 47.17 mg rutin/g DW [16]. Similar results found that the content of flavonoids (mg/g) of fruits of *H. thebaica*, in the quercetin equivalent was 46.28 mg/g DW [27]. HPLC analysis of aqueous doum fruit extracts showed 11 flavonoid compounds (**Figure 4**). The highest concentrations were quercetin, hesperetin, naringin and rutin compounds [18]. Five flavone glycosides were isolated and identified from doum fruits namely, luteolin 7-*O-ß*glucuronoide, apigenin 7-*O-ß*-glucuronoide, luteolin *O-ß*-glycoside, luteolin 7*-O*-rutinoside

p-coumaric acid and coumarin [31].

54 Antioxidants in Foods and Its Applications

*6.2.2. Total flavonoids content and compounds*

**Figure 3.** Chemical structures of doum fruit phenolic compounds.

and chrysoeriol 7*-O*-rutinoside [32]. Glycosides of luteolin and chryseriol flavones previously isolated from doum fruit were identified. In addition, isoquercetrin and isorhamnetin rutinoside are reported for the first time in *H. thebaica* [33].

#### *6.2.3. Chemical structure of doum palm leaves phenolic compounds*

Doum leaves were extracted in 80% ethanol and filtrate. The aqueous ethanolic extract used to scavenge reactive oxygen species (ROS). The phenolic content of doum was determined by using HPLC and recorded the presence of four major compounds correspond to Gallic acid, Quercetin glucoside, Kaempferol rhamnoglucoside, Dimethyoxy quercetin rhamnoglucoside, respectively. An in-depth phytochemical investigation showed the presence of 14 compounds (**Figure 5**): 8*-C-ß-*D-glucopyranosyl-5, 7, 4′-trihydroxyflavone (vitexin), 6*-C-ß*-D-glucopyranosyl-5, 7, 4′-trihydroxyflavone (iso-vitexin) [34, 35]. Quercetin 3-*O-ß*-4C1-D-glucopyranoside, gallic acid [36], quercetin 7-*O-ß-* 4C1-D-glucoside [37], luteolin 7-*O-ß*-4C1- D-glucoside, tricin 5-*O-ß*-4C1-D-glucoside [38], 7, 3′ dimethoxy quercetin 3-O-[6"-O-α-L-rhamnopyranosyl]-*ß-D*-glucopyranoside (rhamnazin 3-O-rutinoside) [39] (kaempferol-3-*O*-[6"-*O-α*-L-rhamnopyranosyl]-*ß*-D-glucopyranoside (nicotiflorin) [40], apigenin, luteolin, tricin, quercetin and kaempferol. All these compounds were isolated and identified for the first time in doum leaves [41].

**Doum part**

Leaves Superoxide anion radical

**Method used Extract type Antioxidant activity/ IC50**

Fruit DPPH Dichloromethane 343.4 μ moles trolox /g Salih and Yahia [29] Fruit DPPH Hexane 42.67 μ moles trolox /g Salih and Yahia [29] Fruit DPPH Ethanol IC50 = 172.7 μg/ml Aboshora et al. [16] Fruit DPPH Methanol IC50 = 107.6 μg/ml Aboshora et al. [16]

Fruit DPPH Methanol 64.55% Mohamed et al. [27] Bark DPPH Methanol 90.7% Fayad et al. [52] Fruit FRAP Methanol 28.93% Sani et al. [47] Fruit FRAP Distilled water 31.91% Sani et al. [47] Fruit FRAP Methanol 24.3% Mohamed et al. [27] Fruit FRAP Dichloromethane 13.57 μmoles trolox /g Salih and Yahia [29] Fruit FRAP Hexane 7.69 μmoles trolox /g Salih and Yahia [29]

**Figure 6.** The scheme of factors involved in the formation of free radicals and a cellular response to reactive oxygen species (ROS). The red arrow and the text in red emphasize the importance of phenolic compounds, other reactive oxygen species (ROS). The red arrow and the text in red emphasize the importance of phenolic compounds, other antioxidants and the relationship between them. The sun signifies protection of other antioxidants by phenolic compounds.

Fruit DPPH Water 12 h 40.77% Aamer [18]

**Table 1.** Antioxidant activity/ IC50 Inhibition values of doum part by different methods.

**Inhibition values**

Biological Activities of the Doum Palm (*Hyphaene thebaica* L.) Extract and Its Bioactive…

Ethanol IC50 = 1602 μg/ml Eldahshan et al. [41]

**References**

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**Figure 5.** Chemical structures of doum leave phenolic compound.
