Polyphenolic Profiles and Antioxidant Potential of Selected Indian Dioscorea Species

Abstract

Dioscorea tubers are widely valued in India as both food materials and ethnomedicinal resources, yet direct comparisons of their polyphenolic profile and antioxidant behaviour remain limited. This study compared total phenolic content (TPC), total flavonoid content (TFC), total proanthocyanidin content (TPAC), ferric reducing antioxidant power (FRAP), and nitric oxide (NO) scavenging activity in ten Indian Dioscorea species. Methanolic tuber extracts were assessed by Folin–Ciocalteu, aluminium chloride, acidified vanillin, FRAP, and sodium nitroprusside–Griess procedures. Data were reported as mean ± SD. TPC varied from 2.36 ± 0.05 to 9.68 ± 0.08 mg GAE/g DW, with D. bulbifera giving the highest value. TFC ranged between 0.34 ± 0.02 and 0.84 ± 0.03 mg QE/g DW and was greatest in D. hamiltonii. TPAC extended from 3.02 ± 0.07 to 6.60 ± 0.06 mg CE/g DW, and D. bulbifera again ranked first. FRAP values ranged from 0.067 ± 0.006 to 1.06 ± 0.04, with the strongest reducing capacity observed in D. bulbifera and D. alata. NO scavenging IC50 values ranged from 47.31 ± 0.78 to 683.33 ± 10.41 µg/mL; D. bulbifera showed the strongest activity, followed by D. pubera and D. pentaphylla. Higher TPC and TPAC were associated with lower NO IC50 values and showed moderate positive relationships with FRAP. Marked differences in antioxidant behaviour were evident among the species. Overall, D. bulbifera was the most consistently active and should be prioritized for development of nutrition supplement and safety assessment.