Evaluation of cytotoxic activity of patriscabratine, tetracosane and various flavonoids isolated from the Bangladeshi medicinal plant Acrostichum aureum

Context: Acrostichum aureum L. (Pteridaceae), a mangrove fern, has been used as a Bangladeshi traditional medicine for a variety of diseases including peptic ulcer. Objective: Isolation and structural elucidation of cytotoxic secondary metabolites from the methanol extract of the aerial parts of A. aureum. Materials and methods: Compounds were isolated using HPLC. The compound structures were elucidated by 1D and 2D NMR, MS and other spectroscopic methods using published data. The compounds were tested for their cytotoxic activity against healthy and cancer cells using the MTT assay. Active compounds were further evaluated for apoptosis- and necrosis-inducing potential against gastric cancer cells (AGS) using the FITC Annexin V apoptosis assay. Results and discussion: Seven known compounds, patriscabratine, tetracosane and 5 flavonoids (quercetin-3-O-beta-D-glucoside, quercetin-3-O-beta-D-glucosyl-(6 -> 1)-alpha-L-rhamnoside, quercetin-3-O-alpha-L-rhamnoside, quercetin-3-O-alpha-L- rhamnosyl-7-O-beta-D-glucoside and kaempferol) were isolated. Patriscabratine was found moderately cytotoxic against AGS, MDA-MB-231 and MCF-7 cells with IC50 values ranging from 69.8 to 197.3 mu M. Tetracosane showed some cytotoxic activity against AGS, MDA-MB-231, HT-29 and NIH 3T3 cells with IC50 values ranging from 128.7 to > 250 mu M. Patriscabratine and tetracosane displayed an apoptotic effect (10%) on AGS cells within 24 h which was increased (20%) after 48 h, and was comparable to, if not greater, than the positive control, cycloheximide. Conclusion: Except for quercetin-3-O-beta-D-glucoside and kaempferol; compounds were isolated for the first time from this plant and evaluated for their cytotoxic activity. The results highlight the potential of this plant as a source of bioactive compounds and provide a rationale for its traditional use in peptic ulcer treatment.