Context: Terminalia macroptera Guill. & Perr. (Combretaceae), a tree that grows in West Africa, has been used in traditional medicine against a variety of diseases such as hepatitis, gonorrhea, skin diseases, and diabetes. Objective: To investigate enzyme inhibitory activity against a-glucosidase and 15-lipoxygenase (15-LO) and toxicity against brine shrimp of extracts and compounds from T. macroptera leaves. Materials and methods: Methanol extract, ethyl acetate, and butanol extracts obtained from the methanol extract, six isolated polyphenols (chebulagic acid, chebulic acid trimethyl ester, corilagin, methyl gallate, narcissin, and rutin), and shikimic acid were evaluated for enzyme inhibition and toxicity. Results: In enzyme inhibition assays, all extracts showed high or very high activity. Chebulagic acid showed an IC 50 value of 0.05 mM towards a-glucosidase and 24.9 ± 0.4 mM towards 15-LO, in contrast to positive controls (acarbose: IC 50 201 ± 28 mM towards a-glucosidase, quercetin: 93 ± 3 mM towards 15-LO). Corilagin and narcissin were good 15-LO and a-glucosidase inhibitors, as well, while shikimic acid, methyl gallate, and chebulic acid trimethyl ester were less active or inactive. Rutin was a good a-glucosidase inhibitor (IC 50 ca. 3 mM), but less active towards 15-LO. None of the extracts or the isolated compounds seemed to be very toxic in the brine shrimp assay compared with the positive control podophyllotoxin. Conclusion: Inhibition of a-glucosidase in the gastrointestinal tract may be a rationale for the medicinal use of T. macroptera leaves against diabetes in traditional medicine in Mali. The plant extracts and its constituents show strong inhibition of the peroxidative enzyme 15-LO.

From a methanol extract of the leaves of the Malian medicinal tree Terminalia macroptera, cis-polyisoprene (1), chebulic acid trimethyl ester (2), methyl gallate (3), shikimic acid (4), corilagin (5), rutin (6), narcissin (7), chebulagic acid (8) and chebulinic acid (9), were isolated. Cispolyisoprene (1) was the major non-polar constituent. The novel compound 2 showed high radical scavenging activity (IC 50 4.7 μg/mL), but was inactive as xanthine oxidase inhibitor. The major substituent of the crude extract, substance 5, showed a high radical scavenger effect (IC 50 2.7 μg/mL) and weak xanthine oxidase inhibition (IC 50 ca 105 μg/mL). The antioxidant and radical scavenging effects of some of the substances identified in this study may to some extent explain the medical use of this tree in West Africa.

The tree Terminalia macroptera (Combretaceae) is widespread in Western Africa, and in this area, different parts have been utilized in the treatment of various diseases. In this article, we report on the medicinal use of T. macroptera in three different districts in Mali (Siby, Dioïla and Dogonland), based on interviews with 78 healers in these districts. Roots, root bark, stem bark, leaves and fruits have all been employed by healers, as has parasitic Loranthus species growing on the tree. Major areas of use comprise treatment of wounds and sores, infections, pain, cough, tuberculosis and hepatitis. Some of the medicinal uses of T. macroptera appear to be rationally explained by its chemical constituents.

Abstract:Three flavone-C-glycosides-cassiaoccidentalin A (1), isovitexin (2) and isoorientin (3)-were isolated from the ethyl acetate (EtOAc) soluble fraction of the methanol crude extract of the African medicinal plant Biophytum umbraculum, This is the first report of these compounds in this plant. All compounds were identified by spectroscopic analysis and comparison with published data. Isoorientin (3) and the EtOAc extract showed the greatest antioxidant activity in the DPPH assay as well as the strongest inhibition of xanthine oxidase (XO) and 15-lipoxygenase (15-LO). From these results, the extract of B. umbraculum might be a valuable source of flavone C-glycosides.

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