Abstract

Alstonia scholaris (Linn.) leaves extracted in aqueous, dichloromethane (DCM), methanolic and ethanolic solvents were assessed for different polyphenolic constituents endowed with antioxidant/antiradical activity. Total phenolic, flavonoids and tannin contents were significantly (P<0.05) higher in ethanolic extract as compared to other extracts. The antiradical activity and efficiency was significantly (P<0.05) higher in ethanolic extract followed by methanolic, DCM and aqueous extracts. The ethanolic extract as compared to other extracts also exhibited high total antioxidant capacity, superoxide and nitric oxide anion scavenging activity. However, aqueous extract has shown high hydroxyl radicals scavenging activity as compared to other extracts. Total phenolic content of the ethanolic extract of A. scholaris was positively correlated with total antioxidant capacity (r = 0.901), antiradical activity (r = 0.948) and antiradical efficiency (r = 0.891). Therefore, ethanolic extract showed maximum, contents endowed with high total antioxidant capacity, superoxide and nitric oxide radicals scavenging activity as compared to other solvents. Thus, the dietary supplementation of ethanolic extract may provide protection in preventing the free radicals induced damage besides improve the food quality by retarding oxidative degeneration of food lipids.

Key words: Total phenolics, antioxidant potential, free radicals, Alstonia scholaris.

Abbreviation

TAC, Total antioxidant capacity; PVPP, polyvinyl-polypirrolidone; GAE, gallic acid equivalents; DCM, dichloromethane; AEAS, aqueous extracts of A. scholaris; DCMEAS, dichloromethane extracts of A. scholaris;  MEAS methanolic extracts of A. scholaris; EEAS, ethanolic extracts of A. scholaris;  NBT, nitroblue tetrazolium; PMS, phenazine methosulfate.