Isolation and Structural Elucidation of Flavonoids from Aquatic Fern Azolla Microphylla and Evaluation of Free Radical Scavenging Activity

Objective: The present study was designed for isolation of bioactive polyphenolic compounds from methanol extract of Azolla microphylla and their subsequent characterization. Methods: The flavonoid compounds were isolated and characterized by using thin layer chromatography (TLC), purified by preparative thin layer chromatography (PTLC) and were identified using High performance chromatography (HPLC). Their structures and chemical bonds were analyzed using Ultraviolet-Visible spectrophotomery (UV spec), Fourier Transform-Infra Red spectroscopy (FTIR) and Nuclear magnetic resonance NMR (13C and 1H) techniques. Results: Two flavonoids were identified as rutin and quercetin. The isolated compounds showed a potent antioxidant radical scavenging activity, as assessed by non-physiological assays like DPPH (2, 2-diphenyl-1-picrylhydrazyl), ABTS (2, 2’-Azinobis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt) and FRAP (Ferric reducing antioxidant power). Conclusion: For the first time rutin and quercetin have been isolated successfully from the macrophyte aquatic fern Azolla microphylla under the present study. The isolation of the above characterized flavonoids would be useful to prepare plant-based pharmaceutical preparation to treat various complications linked with human diseases.