Phytochemical Profiling, Structural Characterization, And Cytotoxic Evaluation Of Bioactive Constituents from Padina Tetrastromatica

Abstract

Padina tetrastromatica, a brown marine macroalga, is a rich source of bioactive metabolites with potential pharmaceutical applications. The present study aimed to investigate the phytochemical profile, structural characteristics, and in vitro cytotoxic potential of the hydroethanolic extract and chromatographic fractions of P. tetrastromatica. Preliminary phytochemical screening confirmed the presence of flavonoids, phenolics, steroids, terpenoids, and carbohydrates. Column chromatography yielded five fractions (F1–F5), which were further characterized using HPTLC, FTIR, Mass Spectrometry, and ¹H NMR analyses. Brine shrimp lethality assay demonstrated significant concentration-dependent cytotoxic activity in Fractions 3 and 4, with LC₅₀ values of 90 µg/mL and 65 µg/mL, respectively. HPTLC fingerprinting and spectroscopic analyses indicated the presence of sterol glycosides and flavonoid glycosides in the bioactive fractions. Structural elucidation identified Fraction 3 as Fucosterol-3-O-β-D-glucoside and Fraction 4 as Quercetin-3-O-β-D-glucoside (Isoquercitrin). MTT assay against MCF-7 human breast cancer cells revealed significant cytotoxic effects, with IC₅₀ values of 63.4 µg/mL and 91.7 µg/mL for Fractions 3 and 4, respectively. These findings demonstrate that P. tetrastromatica possesses notable cytotoxic potential and represents a promising source of marine-derived bioactive compounds for anticancer research.