Conformational Preference of Two Toad Poison Bufadienolides, Bufarenogin and y-Bufarenogin

The solution state conformations of two toad poison bufadienolides, -~p bufarenogin and q-bufarenog~n, which are the epimers at C-12, were analyzed b) using NOE expcnment?and molecular dynamics simulation study.The C-ring of bufarenogin with 12b-hydroxy function mas shown to take a chair form, whereas that of v-bufarenogin with lla-hydrosy function, a boat form.The Chinese drug Ch'an Su, called "Senso" in Japan, is a product of the skin gland of toad BNfo b1,fo grrrgr~ricmrs, and related specles, and has bccn used tndillonally as a wrdiotonic, diuretic, anodyne and