Résumé
Bioassay-guided fractionation of an ethanolic extract of Ochrosia borbonica led to the isolation of two known pyridocarbazole alkaloids, ellipticine (1) and 9-methoxyellipticine (2), and six known monoterpenoid indole alkaloids (3-8). Lipid-lowering assay in 3T3-L1 cell model revealed that 1 and 2 could significantly inhibit the lipid droplet formation (EC = 0.41 and 0.92 μmol·L, respectively) and lower triglyceride levels by 50%-60% at the concentration of 1 μmol·L, being more potent than the positive drug luteolin (EC = 2.63 μmol·L). A mechanistic study indicated that 1 and 2 could intercalate into supercoiled DNA, which consequently inhibited the mitotic clonal expansion of 3T3-L1 cells at the early differentiation phase, leading to the retardance of following adipogenesis and lipogenesis. These findings suggest that 1 and 2 may serve as promising leads for further development of anti-obesity drugs.
Résumé
<p><b>AIM</b>To study the synthesis and antitumour activities of some aryl-substituted pteridines.</p><p><b>METHODS</b>A series of aryl-substituted pteridines were synthesized from 4, 6-diamino-5-nitrosopyrimidines by cyclization with 4-aminophenylacetonitriles. The antitumour activities were tested by MTT method.</p><p><b>RESULTS</b>Nine new compounds (I-III) were synthesized and their structures were characterized by EA, IR, 1HNMR and MS spectra. Compounds I-III showed antitumour activities in vitro.</p><p><b>CONCLUSION</b>Compounds I-III showed remarkable antitumour activities in vitro. No interaction was determined between the title compounds and calf thymus DNA. It indicated that these compounds possibly inhibit dihydrofolate reductase (DHFR) or other enzymes on which folic acid depends.</p>