Antitumor effect of laticifer proteins of Himatanthus drasticus (Mart.) Plumel - Apocynaceae.

ETHNOPHARMACOLOGICAL RELEVANCE: Himatanthus drasticus (Mart.) Plumel - Apocynaceae is a medicinal plant popularly known as Janaguba. Its bark and latex have been used by the public for cancer treatment, among other medicinal uses. However, there is almost no scientific research report on its medicinal properties. AIM OF THE STUDY: The aim of this study was to investigate the antitumor effects of Himatanthus drasticus latex proteins (HdLP) in experimental models. MATERIALS AND METHODS: The in vitro cytotoxic activity of the HdLP was determined on cultured tumor cells. HdLP was also tested for its ability to induce lysis of mouse erythrocytes. In vivo antitumor activity was assessed in two experimental models, Sarcoma 180 and Walker 256 carcinosarcoma. Additionally, its effects on the immunological system were also investigated. RESULTS: HdLP did not show any significant in vitro cytotoxic effect at experimental exposure levels. When intraperitoneally administered, HdLP was active against both in vivo experimental tumors. However, it was inactive by oral administration. The histopathological analysis indicates that the liver and kidney were only weakly affected by HdLP treatment. It was also demonstrated that HdLP acts as an immunomodulatory agent, increasing the production of OVA-specific antibodies. Additionally, it increased relative spleen weight and the incidence of megakaryocyte colonies. CONCLUSION: In summary, HdLP has some interesting anticancer activity that could be associated with its immunostimulating properties.

In vitro and in vivo antitumor effects of (4-methoxyphenyl)(3,4,5-trimethoxyphenyl)methanone.

PURPOSE: (4-Methoxyphenyl)(3,4,5-trimethoxyphenyl)methanone (PHT) is a phenstatin analog compound. PHT is a known tubulin inhibitor that has potent cytotoxic activity. In the present study, PHT was synthesized and its antitumor activity was determined using in vitro and in vivo experimental models. METHODS: The in vitro cytotoxic activity of the PHT was determined by the MTT assay. The antimitotic and hemolytic effects were determined based on the inhibition of sea urchin embryo development and lysis of mouse erythrocytes, respectively. In vivo antitumor activity was assessed in mice inoculated with sarcoma 180 cells. RESULTS: In vitro, PHT displayed cytotoxicity in tumor cell lines, showing IC(50) values in the nanomolar range. In addition, it inhibited sea urchin embryo development during all phases examined, first and third cleavage and blastula stage. However, PHT did not induce hemolysis using mouse erythrocytes, suggesting that the cytotoxicity of PHT does not involve membrane damage. The in vivo study demonstrated tumor inhibition rates of 30.9 and 48.2% for PHT at doses of 20 and 40 mg/kg, respectively. In addition, PHT was also able to increase the response elicited by 5-fluorouracil (5-FU) from 33.3 to 55.7%. The histopathological analysis of liver, kidney, and spleen showed that they were just moderately affected by PHT treatment. Neither enzymatic activity of transaminases nor urea levels were significantly affected. Hematological analysis showed leukopenia after 5-FU treatment, but this effect was prevented when 5-FU was combined with PHT. CONCLUSIONS: In conclusion, PHT exhibited in vitro and in vivo antitumor effects without substantial toxicity.