The known compound linderazulene (1) and two new linderazulenes (2, 3) were isolated from a deep-sea gorgonian Paramuricea sp. The structures of 2 and 3 were determined through spectroscopic methods. Compounds 1-3 show moderate in vitro cytotoxicity against the P388 murine leukemia cell line with IC(50)'s of 18.8, 2.7, and 15.6 microg/mL, respectively. Compound 2 showed moderate activity against the PANC-1 pancreatic cell line with an IC(50) of 18.7 microg/mL.
The carcinogen, 7,12dimethylbenz (a)anthracene (DMBA), induces mammary adenocarcinoma in Sprague-Dawley female rats when administered by stomach tube. Tumor incidence depended on the quantity and type of dietary fat (1-4). Rats maintained on diets containing high levels of polyunsaturated fat were more susceptible to tumor development than rats maintained on diets containing similar levels of saturated fat. Rats maintained on low-fat diets were least susceptible as measured by tumor incidence, latent period, number of tumors per tumor-bearing rat, and rate of tumor growth.Other studies have indicated that tumor incidence can be reduced by treating rats either before or after exposure to DMBA. For example, Takeda et al. (5) observed an increase in the latent period and a reduction in tumor incidence if diets fed after DMBA were supplemented with arginine. Similar results were observed when antioxidants were added to diets (6-8).More recently, Weislow et al. (9) reported that rats were protected against DMBA-induced mammary carcinoma by immunization with a mouse xenotropic type C virus, before exposure to DMBA. The mouse virus used in their studies acted as a nonspecific immunostimulant. Spleen lymphocytes were much more responsive to PHA when taken from immunized rats compared to nonimmunized controls. Furthermore, DMBA-induced lymphocyte anergy was prevented by immunization.The methanol extraction residue (MER) of
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