Phytochemical and Antioxidant Potential of Four Traditional Malaysian Medicinal Plants

Abstract

Phytochemicals and antioxidants can be found at different levels in medicinal plants that are associated with the use in chronic diseases treatment. The objective of the present study was to investigate the phytochemical and antioxidant properties of Albizia myriophylla, Garcinia opaca var. dumosa, Oxalis barrelieri and Tacca cristata, traditional medicinal plants used in healthcare by aborigines or 'Orang Asli' from Kelantan, Malaysia. The total antioxidant capacity was estimated by ABTS (2,2’ azinobis-(3-ethybenzthiazoline-6-sulfonic acid)), DPPH (1,1-diphenyl-2-picrylhydrazyl radical) and FRAP assay. The results showed that the four selected plants had significant differences in their total phenolic content (ranging from 45.92 ± 2.01 to 613.37 ± 8.92 mg GAE/g dry weight), in their total flavonoid content (ranging from 6.03 ± 1.03 to 19.29 ± 2.90 mg CE/g dry weight), in their tannins (ranging from 28.23 ± 7.39 to 64.99 ± 7.27 mg TAE/g dry weight), in their alkaloids (ranging from 0.40 to 3.27%) and in their saponins (ranging from 4.31 to 13.15%). The TEAC values of the extracts ranged from 112.12 ± 3.16 to 237.20 ± 1.55 µmol Trolox/g dry weight, from 8.38 ± 2.09 to 219.36 ± 23.48 µmol Trolox/g dry weight and from 136.83 ± 5.24 to 220.93 ± 48.71 µmol Trolox/g dry weight, for ABTS, DPPH and FRAP respectively. TEAC values determined by ABTS, DPPH and FRAP were well correlated with phenolics, flavonoids and tannins contents. Garcinia opaca demonstrated the highest total phenolics and tannins while Oxalis barrelieri showed the highest total flavonoid and alkaloid compared to other plants studied. Garcinia opaca also had shown the highest antioxidant potential, followed by Oxalis barrelieri. This study had shown that Garcinia opaca var. dumosa and Oxalis barrelieri can be promoted as the source of phenolics antioxidant and radical scavengers.