Antioxidant activity of proanthocyanidins from Adansonia digitata fruit
Besides (-)-epicatechin, epicatechin-(4β-8)-epicatechin (procyanidin B2), epicatechin-(4β-6)-epicatechin (procyanidin B5), epicatechin-(4β-8, 2β-O-7)-epicatechin (proanthocyanidin A2) and epicatechin-(4β-8)-epicatechin-(4β-8)-epicatechin (procyanidin C1), which were isolated before from Adansonia digitata , in this work an A-type proanthocyanidin trimer, i.e. epicatechin-(4β-8)-epicatechin-(4β-8, 2β-O-7)-epicatechin, tetrameric procyanidin D1, i.e. epicatechin-(4β-8)-epicatechin-(4β-8)-epicatechin-(4β-8)-epicatechin and a polymeric compound were isolated from the pericarp (fruit wall) of the fruits for the first time from this plant . The antioxidant activity of different fractions and pure compounds was experimentally evaluated in the DPPH· assay. The ethyl acetate fraction, and most of the isolated compounds displayed a high activity (IC50 2.40–9.60µg/ml) compared with the reference antioxidant  Trolox (IC50 12.18µg/ml) as a standard.
Acknowledgements: University of Antwerp Belgium, Prof. Dr. Pieters L. and Prof. Dr. Apers S. for NMR and MS spectra measurements.
References: 1. Escribano-Bailon, T., et al. (1992)J. Agric. Food Chem. 40: 1794–1799.
2. Esterhuyse, N. et al. (2001) Remarkable Trees of South Africa. Briza Publications, Pretoria.
3. Cos, P. et al. (2002). Free Rad. Res. 36: 711–716.