betulonal and betulin

Several novel alkylidene branched lupane derivatives have been prepared. Many of these compounds showed a significant cytotoxicity. The most active compound, 2-methylene-betulonic acid, showed IC(50) values between 0.2 and 0.6 μM for 15 different human cancer cell lines. Cytotoxicity can be improved by encapsulation in liposomes. These compounds act by triggering apoptotic cell death as shown by DNA-laddering experiments and acridine orange/ethidium bromide staining.

Topics: Alkenes; Antineoplastic Agents; Cell Line, Tumor; Chemistry Techniques, Synthetic; Humans; Hydroxides; Inhibitory Concentration 50; Oxidation-Reduction; Triterpenes

In a study to investigate the relationship between the chemical structure and the differentiation-inducing activity of pentacyclic triterpenes, several lupane, oleanane, and ursane triterpenes were prepared and their effects on B16 2F2 melanoma cell differentiation and growth were examined. Eleven lupane triterpenes used in this study acted on the melanoma cells as a melanogen, but no induction of melanogenesis of B16 2F2 cells by oleanane and ursane was detected. The differences at C-17 of the lupane series and acetylation of the OH group at C-3 did not markedly influence their activities. However, the ED(50) value for up-regulation of melanin biosynthesis was markedly decreased by the oxidation of the OH group at C-3 of lupeol (1). Betulinic acid (11), its methyl ester (12), lup-28-al-20(29)-ene-3beta-ol (9), and lup-28-al-20(29)-en-3-one (10) inhibited B16 2F2 cell proliferation by induction of apoptosis. These findings suggested that the carbonyl group at C-17 might be essential for the apoptotic effects of these compounds on B16 2F2 cells.

Topics: Animals; Apoptosis; Betulinic Acid; Cell Differentiation; Inhibitory Concentration 50; Magnetic Resonance Spectroscopy; Melanoma, Experimental; Mice; Molecular Structure; Oxidation-Reduction; Pentacyclic Triterpenes; Pyridinium Compounds; Spectroscopy, Fourier Transform Infrared; Structure-Activity Relationship; Triterpenes; Tumor Cells, Cultured

Succinyl and 3'-substituted glutaryl betulin derivatives showed stronger anti-HIV activity and higher therapeutic index (TI) values than their dihydrobetulin counterparts, with ratios of 1.2:1 to 15:1 (cf. 7 and 15, 9 and 17, 10 and 18, 11 and 19, and 12 and 20). For various 3'-substituted glutaryl compounds, the order of anti-HIV effects, from strong to weak inhibition, was 3',3'-dimethyl, 3'-methyl, 3'-ethyl-3'-methyl, followed by 3',3'-tetramethylene glutaryl derivatives (10 > 9 > 11 > 12, 18 > 17 > 19 > 20). The most potent compound, 10, has two 3',3'-dimethylglutaryl groups and displays significant anti-HIV potency with an EC50 value of 0.000 66 microM and a TI of 21 515. Results for compounds (22 and 23) without a C-3 acyl group confirmed the importance of the C-3 acyl group to the anti-HIV effect. With 3',3'-tetramethylene glutaryl derivatives, triacyl 29 showed stronger inhibition than diacyl 12; in contrast, 3',3'-dimethylglutaryl compounds displayed opposite results. 3-Keto compounds (35 and 36) and 2,3-dihydro compounds (39 and 40) had EC50 values in the range of 4.3-10.0 microM, suggesting that A ring modification led to decreased potency. The reduced activity of amide (33 and 34), ester (41), and oxime (42) analogues suggested that the orientation and linkage of the C-3 acyl side chain play crucial roles in the potent anti-HIV activity. Finally, replacing the C-28 acyl group with a bulky non-carboxylic group produced a less potent compound (44). In the study of mechanism of action, our results indicated that fusion is not the primary target for the anti-HIV activity of 10. It appears to inhibit HIV replication at a late stage of the viral life cycle, i.e., after viral protein synthesis.

Topics: Acquired Immunodeficiency Syndrome; Animals; Anti-HIV Agents; Cell Fusion; Cell Line; Glutarates; HeLa Cells; HIV-1; Humans; Lymphocytes; Mice; Structure-Activity Relationship; Triterpenes; Virus Replication