GC-MS ANALYSIS, PHYTOCHEMICALS AND IN-VITRO ANTIOXIDANT PROPERTIES OF ROOT EXTRACTS OF PHLOGACANTHUS THYRSIFLORUS NEES., WESTERN ASSAM, INDIA

The Phlogacanthus thyrsiflorus roots have been used by the tribal population of western Assam to treat the hepatic disorder. The present study focuses on phytochemical screening, GC-MS analysis and in-vitro antioxidant activities using different extracts. Plant total phenolics, flavonoids, reducing power assay and antioxidant activity was evaluated. DPPH, FRAP, ABTS, Metal chelating activity, and H₂O₂ free radical scavenging activity were studied. The screening from extracts showed the presence of phenols, flavonoids, tannins, resins, terpenoids, alkaloids, glycosides, cardiac glycosides, steroids. The highest concentration of total phenolics, flavonoids, reducing power and total antioxidant activity was found in the hydro-alcoholic extract of RoPt. The results of the radical scavenging activity in 70% ethanolic extract showed better IC₅₀ value in DPPH (265.87 ± 17.58), ABTS (17.89 ± 1.18) and H₂O₂ (17.89 ± 1.05) µg/ml respectively. EC₅₀ value of 535.16 ± 34.82 was found in 70% ethanolic against 1471.32 ± 19.77 µg/ml of acetone extract whereas the FRAP showed high FeSO₄.7H₂O concentration in acetone extract with 820 ± 9.1 µM/ml. The major chemical constituents that were identified in GC-MS analysis were 2R-Acetoxymethyl-1,3,3-Trimethyl-4T-(3-Methyl-2-Buten-1-YL)-1T- Cyclohexanol (71.243%) and 2,4,4-Trimethyl-3-Hydroxymethyl -5A-(3-Methyl-But-2-Enyl)- Cyclohexene (88.107%) in hydro-alcoholic and acetone extracts respectively. The study showed an enhanced phenolic and flavonoid concentration and radical scavenging activity in the 70% ethanol extracts of RoPt which are the good source of antioxidants showing potential in preventing much free radical-mediated disorder.