A colorless amorphous, mp 197-201°(decomp),[α]^<20>_D -9.4°(H_2O), C_<60>H_<102>O_<29>・2H_2O, was isolated as sweet principle from Fructus Momordicae (fruit of Momordica grosvenori Swingle, Cucurbitaceae), a crude drug of Kwangsi, China. The compound was considered to be an unknown triterpene glycoside. So it was named "S-5", temporary. The aglycone of S-5, mp 118-119°,[α]^<17>_D+70.0°(MeOH), C_<30>H_<52>O_4, was obtained by enzymatic hydrolysis. The structure of aglycone(S-O_1) has been elucidated to be 13 on the basis of chemical and physicochemical evidence. Final evidence for the chemical structure of S-5(1) was obtained by methanolysis of permethylates, NMR spectroscopy and molecular optical rotation of S-5 and its parcial hydrolysates.
