Potential of neuroprotective antioxidant-based therapeutics from Peltophorum africanum Sond. (Fabaceae)

There is ample scientific and empirical evidence supporting the use of plant-derived antioxidants for the control of neurodegenerative disorders. Antioxidants may have neuroprotective (preventing apoptosis) and neuroregenerative roles, by reducing or reversing cellular damage and by slowing progression of neuronal cell loss. Although demand for phytotherapeutic agents is growing, there is need for their scientific validation before plant-derived extracts gain wider acceptance and use. We have evaluated antioxidant potential of Peltophorum africanum (weeping wattle), a plant widespread in the tropics and traditionally used, inter alia, for the relief of acute and chronic pain, anxiety and depression. The dried leaves, bark and root of P. africanum were extracted with acetone. Thin layer chromatograms were sprayed with 0.2% 2,2-diphenyl-1-picryl hydrazyl (DPPH) in methanol for screening for antioxidants. Quantification of antioxidant activity was assessed against 6-hydroxy-2, 5,7,8-tetramethylchromane-2-carboxylic acid (Trolox) and L-ascorbic acid (both standard antioxidants), using two free radicals, 2,2'-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) and DPPH, respectively. Results of our study show that the bark and root extracts had higher antioxidant activity than L-ascorbic acid and Trolox, a synthetic vitamin-E analogue. The respective TEAC (Trolox Equivalent Antioxidant Capacity) values for the bark and root extracts, and Trolox were 1.08, 1.28 and 1.0. EC(50) values for L-ascorbic acid (5.04 microg/mL) was more active than the leaf 6.54 (microg/mL), but much less active than the bark (4.37 microg/mL) and root (3.82 microg/mL) extracts. Continued work on P. africanum, and other plants rich in antioxidants, may avail neuroscientists with potent neuroprotective antioxidant therapeutics.