HPTLC-Based Quantitative Analysis of Scopoletin and In vitro Antioxidant and Antimicrobial Evaluation of Hymenodictyon orixense Roxb. Bark

Hymenodictyon orixense Roxb. is a medically valuable evergreen tree that has been traditionally used worldwide to treat conditions such as inflammation, infection, wounds, and chronic diseases. This study was conducted to evaluate the phytochemical analysis, in vitro antioxidant properties, antimicrobial activity, and HPTLC characterization of the ethanol extracts from the bark of H. orixense . Roxb. by using scopoletin as a standard. The bark of H. orixense Roxb. was collected and identified as a medicinally valuable evergreen tree. This was dried under shade and Soxhlet-extracted using ethanol as the solvent. The preliminary phytochemical study of the ethanol bark extracts of H. orixense Roxb. identified the presence of alkaloids, flavonoids, phenols, tannins, saponins, steroids, glycosides, and fixed oils. The total content of the antioxidant compounds, like total phenols (249.3 ± 1.25µg GAE/mg), total flavonoid content (81.29 ± 0.56µg RE/mg), total tannin content (47.85 ± 0.44µg TAE/mg), and total alkaloid content (0.4% w/w) of the ethanol bark extracts of H. orixense Roxb. was determined. This study evaluated the antioxidant activity of ethanol extracts of H. orixense Roxb. using various in vitro assays, including the DPPH, ABTS, CUPRAC, superoxide scavenging, hydroxyl scavenging, and nitric oxide scavenging assays. The ethanol extracts of H. orixense Roxb. possessed key antioxidant activity in all the in vitro antioxidant assays. The studies revealed high DPPH scavenging activity and the least in ABTS scavenging activity, indicating higher electron donation and stronger scavenging of free radicals. The ethanol extracts of H. orixense Roxb. showed appreciable inhibition of S.aureus and E. coli with IC ₅₀ comparable to the standard chloramphenicol in disc diffusion methods.