TOTAL POLYPHENOL CONTENT AND ANTIOXIDANT AND CYTOTOXIC ACTIVITIES OF THE SRI LANKAN ENDEMIC PLANT GENUS SCHUMACHERIA

Objective: Schumacheria is a genus endemic to Sri Lanka distributed in lowland rain forests and mountain rain forests. The total polyphenol content and antioxidant and cytotoxic activities of hexane, dichloromethane and methanol extracts of stem-bark, root-bark, leaves and flowers of the three representative plant species S. castaneifolia , S. alnifolia and S. angustifolia belonging to the endemic genus Schumacheria are reported . Methods: Antioxidant activity was determined using the DPPH (1,1-diphenyl-2-picrylhydrazine) radical scavenging assay. The total polyphenol content, expressed as the gallic acid equivalent, was determined using theFolin-Ciocaltue method and the cytotoxic activity was determined using the brine shrimp ( Artemiasalina ) assay. Results: The methanol extract of S. castaneifolia flowers (IC 50 = 6.8 ± 0.1 ppm)and the methanol extracts of S. alnifolia stem-bark (IC 50 =7.1 ± 0.4 ppm) and leaves (IC 50 =8.3 ± 0.3 ppm) showed antioxidant activity higher than that of α-tocopherol(IC 50 = 10.9 ± 4.3 ppm). The methanol extracts of S. alnifolia stem-bark (69.3 ± 6.9 mg g -1 ) and leaf (57.7 ± 0.0 mg g -1 ) extracts showed the highest polyphenol content closely followed by the methanol extracts of S. castaneifolia flowers (71.2 ± 0.6 mg g -1 ) . The highest cytotoxic activity was exhibited by the methanol extract of S. castaneifolia flowers (LC 50 = 1.3 ± 0.7 ppm), and all the other extracts showed comparatively less cytotoxic activity. Conclusion: S. castaneifolia and S. alnifolia exhibit potent bioactivitiesvalidating the ethnomedical claims where the former has been used for oral aphthous.