... cac dti' kien pho va tham khao tai lieu [4] cho phep xac dinh cau true ctia chat nay la axit betulinic, mpt tritecpen khung lupan. Day la mpt hpp chat co hoat tinh chong ung thu, ch6ng ... 47,7 (C-9); 55,3 (C-5); 59,1 (C-18); 81,0 (C-3); 124,3 (C-12); 139,6 (C-13); 170,9 (C=0). Axit betulinic (2): Chit rin mau tring, ESI-MS (m/z): 457[M+H]^ 'H-NMR (CDCI3, 500 MHz)...