Bufogarlides A-C, three new bufadienolides with Δ 14,15 double bond from the skins of Bufo bufo gargarizans

Three new bufadienolides with a Δ^14,15 double bond, named bufogarlides A-C (1-3), together with three known analogs (4-6), were isolated from the skins of Bufo bufo gargarizans. Their structures were identified by analyses of spectroscopic data (1 D and 2 D NMR, HR-ESIMS), and comparison with the literature data. All the isolates were evaluated for their cytotoxic activities against ovarian carcinoma cell lines A2780 and SKOV3. Among them, compound 5 showed the highest potential for the growth inhibition of cancerous cells A2780 and SKOV3 with the IC₅₀ values of 21.09 and 67.08 nM, respectively.