Salvianolic acid A (1) is one of the active components from Salvia miltiorrhiza, which was found to suppress the growth of mouse tumors. S-3-1 (a 2-allyl-3,4-dihydroxybenzaldehyde, 2) is a synthetic intermediate of a salvianolic acid A derivative with strong inhibitory effects on the growth of cancer cells in vitro. The inhibitory effects of 2 on tumor growth and its molecular targets were studied. 2 significantly suppressed the growth of mouse Lewis lung carcinoma, S180 sarcoma and H22 hepatic carcinoma in a dose-dependent manner. With a simple scrape-loading dye transfer method, 20 microg/ml of 2 was found to significantly enhance gap junction intercellular communication (GJIC) in human pancreatic adenocarcinoma PaCa Cells, human lung epithelial carcinoma W1-38 cells and human lung adenocarcinoma A549 cells, but 2 had no marked effect on GJIC in human colon cancer CACO2 cells. With Northern blot analysis, 2 was found to inhibit the expression of c-myc gene in A549 cells and have no marked effect on H-ras oncogene expression, and increase the cellular P53 mRNA contents, though it did not affect the expression of RB tumor suppressor gene. 2 also suppressed the P46 (JNK/SAPK) expression in A549 cells. Western blot analysis was applied to visualize the P21ras protein. Results shows that 2 at concentrations ranging from 10 to 20 microg/ml decreases the contents of the membranous P21ras and total P21ras and increases the contents of cytosolic P21ras protein in a time-dependent manner. However, 2 had no significant effects on farnesyl protein transferase activities at the concentrations that could efficiently decrease the membranous P21ras content. This suggested that 2 might suppress tumor growth partly through enhancement of GJIC and reversion of the transformed phenotypes. The other mechanisms may be that 2 can suppress the overexpression of c-myc oncogene, inhibit the function of Ras oncoprotein, increase the expression of P53 tumor suppressor gene and interrupt P46-associated mitogen-activated pathway other than farnesylation of Ras protein.

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Salvia miltiorrhiza is a traditional Chinese medicine which has been well documented for its anti-cancer effects. Based on the structure of danshinone, one of the active compounds derived from Salvia miltiorrhiza, we synthesized a simplified phenolic analog, S-3-1, and tried to explore its possible actions in preventing the development of cancer. With the Ames test, S-3-1 was found to efficiently suppress the mutagenicity of benzo[alpha]pyrene. This result is consistent with the inhibitory effect of S-3-1 on the activation of benzo[alpha]pyrene by hepatic microsomal enzymes. Besides the anti-initiation effects, S-3-1 could significantly inhibit the croton oil-induced increase of mouse skin epithermal ornithine decarboxylase activity. Moreover, S-3-1 quenched both superoxide and hydroxyl free radicals whereas it inhibited lipid peroxidation in the in vitro model. These results suggest that S-3-1 might act as anti-initiation and anti-promotion agents through reversing the biochemical alterations induced by carcinogen during carcinogenesis. Therefore, we further investigated the effects of S-3-1 on carcinogenesis. In vitro, S-3-1 inhibited the benzo[alpha]pyrene-induced transformation of V79 Chinese hamster lung fibroblasts. At 10-40 mg/kg, S-3-1 was found to inhibit the development of DMBA/croton oil-induced skin papilloma in mice through decreasing the incidence of papilloma, prolonging the latent period of tumor occurrence and reducing tumor number per mouse in a dose-dependent manner. We concluded from this study that S-3-1 might be developed as a new chemopreventive drug.

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A novel C31 sterol, 25-methylxestosterol, resulting from quadruple biomethylation in the side chain has been isolated as a trace constituent of the sterol fraction from a Caribbean sponge (Xestospongia sp.). Its structure (1, 24-methylene-25,26,27-trimethylcholesterol) has been elucidated by spectroscopic methods and confirmed by partial synthesis. A biosynthetic route leading to 1 is proposed that is consistent with the hypothesis of stepwise biomethylations and with earlier discoveries of "extended" side chains among marine sterols.