**4. Discussion**

136 Macro to Nano Spectroscopy

The results of the colorimetric analysis of total phenolics expressed as Gallic Acid Equivalents (GAE) and those of total flavonoids expressed as Catechine Equivalents (CE)

*A. leiocarpus* L 223.1 ± 0.2 38.9 ± 1.7

*C. populnea* RB 76.4 ± 1.1 27.6 ± 1.2 *M. inermis* TB 19.5 ± 0.7 11.1 ± 1.3 *T. macroptera* TB 48.5 ± 1.3 14.2 ±1.4

*V. heterophylla* L 51.5 ± 0.5 9.3 ± 0.9 *Z. mucronata* L 52.2 ± 0.5 14.4 ± 0.8

L= leaves; TB= trunk barks; RB= root bark.Total phenolics expressed as gallic acid equivalent (GAE),

The total phenolic compounds which are present in plant materials were ranged from 19.3 ± 0.6 to 223.1 ± 0.2 mg GAE /g dry weight and the total amount of flavonoids varied from 9 ± 1.6 to 38.9 ± 1.7 mg CE

ABTS and DPPH tests were conducted to evaluate the antioxidant properties of plant part extract on their stable free radicals in comparison to the antioxidant activity of vitamin C,

The antioxidant activity using ABTS varied from 39 mg to 468 mg VCE per g dry weight. The overall antioxidant capacity of plant parts in VCEAC, which was evaluated by ABTS assay, was in the following order: *T. macroptera* root bark > *A. leiocarpus* leaves > *T. macroptera* trunk bark > *C. populnea* root bark > *A. leiocarpus* trunk bark > *Z. mucronata* leaves

The antioxidant activity using DPPH ranged from 21 mg to 361 mg VCE per g dry weight. The overall antioxidant capacity of plant parts in VCEAC which was evaluated by DPPH assay decreased in the following order: *T*. *macroptera* root bark > *A. leiocarpus* leaves >*T. macroptera* trunk bark > *C. populnea* root bark > *Z. mucronata* leaves ≈ *A. leiocarpus* trunk bark

(mg GAE)

TB 26.5 ± 0.4 10.3 ± 0.3

RB 219.6 ± 0.4 33.1 ± 1.3

RB 19.3 ± 0.6 9 ± 1.6

Total Flavonoids (mg CE)

Plants name Plant parts Total phenolics

**3. Results** 

/ g dry weight.

are given in the table 2.

**3.1 Total phenolics and total flavonoids** 

total flavonoids expressed as catechin equivalent (CE).

**3.2 ABTS and DPPH radical-scavenging activity** 

the corresponding results were collected in the figure 2.

Values are means of triplicate determination ± standard deviation.

Table 2. Total phenolic and total flavonoid contents of the plant parts

> *V. heterophylla* leaves > *M. inermis* trunk bark > *Z. mucronata* root bark.

> *Z. mucronata* root bark > *V. heterophylla* leaves >*M. inermis* trunk bark.

The leaves of *A. leiocarpus* had the highest total phenolic contents, which was 4- fold higher than those of the leaves of *V. heterophylla.* The lowest total phenolic and total flavonoid contents were found in the leaves of *V. heterophylla*. In the trunk barks of *T. macroptera*, the total phenolics and the total flavonoids were ranked first, followed by *A*. *leiocarpus* and then the *M. inermis* ones*.* The phenolic and flavonoid compounds were found in highest concentration first in the root barks of *T. macroptera* followed by the root barks of *C. populnea.* In contrast, it appeared that the lowest amount of flavonoids was found for the root barks of *Z. mucronata*. The total phenolic and the total flavonoid contents of the root barks of *T. macroptera* were respectively 11-fold and 4-fold greater than those of *Z. mucronata*.

Identification, Quantitative Determination, and Antioxidant Properties

of isovitexin in the leaves of *V. heterophylla* was identified and quantified.

at the origin of the antioxidant activity in the studied plant parts.

French embassy in Mali for its financial support.

Technology, Vol. 11, pp. 419–421

Ethnopharmacology, Vol. 87, pp. 73–83

2nd Ed. CIRAD –UICN

Kew, London

et al., 2006).

**5. Conclusion** 

**6. Acknowledgement** 

**7. References** 

of Polyphenols of Some Malian Medicinal Plant Parts Used in Folk Medicine 139

inflammatory, antithrombotic, immune modulating and anti-atherogenic effects (Djeridane

The results of HPLC analysis were in accordance with those previously reported in the literature. The phytochemical investigations of the different parts of *T. macroptera* led to the isolation of several *C*- and *O*-glycosyl flavones, chlorogenic acid, quercetin, gallic acid (Silva et al., 2000). Chyau et *al.*, (2006) identified 3,4-dihydroxybenzoic acid (protocatechuic acid), *p*-coumaric acid, gallic acid from the leaves of *T. catappa*. Moreover, gallic acid was also present in the trunk barks of *A. latifolia* (Govindarajan et al., 2004). Protocatechuic acid (3,4 dihydroxybenzoic acid) was found in *Mitragyna rotundifolia* (Kang & Hao, 2006). Ojekale et *al.*, (2006) have reported the presence of flavonoids in *C. populnea*. In this study, the presence

This study permits to evaluate the amount of phenolics, flavonoids and their total antioxidant activity linked to six traditional medicinal plants. Antioxidant activity varied greatly among the different plant parts and was highly correlated with the polyphenolic contents. We take an interest in the leaves of *A.Leocarpus* and in the root barks of *T.Macroptera*, since they exhibited important antioxidant activities and could be attractive sources of natural antioxidants. Moreover, this comparative study permits to identify and determine by RP-HPLC, five individual phenolic acids and two flavonoids that are mainly

The authors are thankful to the Service de Cooperation d'Actions Culturelles (SCAC) of the

Arbonnier M. (2002). Arbres, arbustes et lianes des zones sèches d'Afrique de l'Ouest. Paris:

Arnao MB. (2000). some methodological problems in the determination of antioxidant

Bouayed J, Rammal H, Dicko A, Younos C, Soulimani R. (2007). Chlorogenic acid, a

antioxidant effects. Journal of the Neurological Sciences, Vol. 262, pp. 77–84 Burkill HM. (2000).Useful plants of West Tropical Africa, second ed. Royal Botanic Gardens,

Cakir A, Mavi A, Yldrm A, Duru ME, Harmandar M, Kazaz C. (2003).Isolation and

activity using chromogen radicals: a practical case. Trends in Food Science &

polyphenol from *Prunus domestica* (Mirabelle), with coupled anxiolytic and

characterization of antioxidant phenolic compounds from the aerial parts of Hypericum hyssopifolium L. by activity-guided fractionation. Journal of


L= leaves; TB= trunk barks; RB= root barks; nd= not detected.

Table 3. Concentrations of flavonoids and phenolic acids in the medicinal traditional plant parts (mg / 100g of dry material)

The results obtained by ABTS and DPPH tests show that the antioxidant activity order for these different plant parts was approximately similar in both assays. However, the antioxidant capacity using DPPH compared to the one obtained by ABTS essay was underestimated about 33%. Arnao, (2000) and Delgado-Andrade et *al*., (2005) report the same occurrence and they explain that the DPPH is only dissolved in alcoholic media. In contrast, the ABTS radicals being solubilised in aqueous and in organic media the antioxidant activity measured is due to the hydrophilic and lipophilic nature of the compounds. In addition, at 515 nm near the visible region where the antioxidant activity is measured, interferences occur with the DPPH coloration.

In this study, we found that phenolic compounds are the major contributors to the antioxidant activity, since total phenolics and antioxidant activity showed a good correlation with a correlation coefficient of R2=0.9208. However, we note that the trunk barks of *A. leiocarpus* exhibit a high antioxidant activity and a low level of total phenol antioxidant. The value of correlation coefficient between total flavonoids and antioxidant activity was R2 = 0.752 only.

These results showing good antioxidant activity of these plant parts are particularly interesting since the antioxidant agents would induce analgesic, anticarcinogenic, antiinflammatory, antithrombotic, immune modulating and anti-atherogenic effects (Djeridane et al., 2006).

The results of HPLC analysis were in accordance with those previously reported in the literature. The phytochemical investigations of the different parts of *T. macroptera* led to the isolation of several *C*- and *O*-glycosyl flavones, chlorogenic acid, quercetin, gallic acid (Silva et al., 2000). Chyau et *al.*, (2006) identified 3,4-dihydroxybenzoic acid (protocatechuic acid), *p*-coumaric acid, gallic acid from the leaves of *T. catappa*. Moreover, gallic acid was also present in the trunk barks of *A. latifolia* (Govindarajan et al., 2004). Protocatechuic acid (3,4 dihydroxybenzoic acid) was found in *Mitragyna rotundifolia* (Kang & Hao, 2006). Ojekale et *al.*, (2006) have reported the presence of flavonoids in *C. populnea*. In this study, the presence of isovitexin in the leaves of *V. heterophylla* was identified and quantified.
