Scheme 1
From: Structurally diverse bufadienolides from the skins of Bufo bufo gargarizans and their cytotoxicity

The plausible biosynthetic pathway of 1 (A) and 2 (B).
From: Structurally diverse bufadienolides from the skins of Bufo bufo gargarizans and their cytotoxicity

The plausible biosynthetic pathway of 1 (A) and 2 (B).