RESUMEN
\ \ \ \ \ \ \ Acanthus ebracteatus Vahl. (family Acanthaceae) is a Thai medicinal plant, traditionally used to treat skin diseases and various types of cancer, and for health promotion and longevity. Previous studies reported that the aqueous extract of the Acanthus plant had non-cytotoxic effects on various cancer cells, and possessed antitumor activity in mice without chronic toxicity. The extract contains many different polysaccharides; various polysaccharides have been shown to exhibit immunomodulatory effects. In this study, an aqueous extract of A. ebracteatus (AE) root was evaluated in vitro for immunomodulatory effects on macrophage and NK cell function. Activated murine macrophage-like cells (J774A.1) with various concentrations of AE (31.25 to 500 mg/ml) on nitric oxide (NO) production and expression of inducible nitric oxide synthase (iNOS), were assessed using Griess reaction assay and RT-PCR, respectively. In addition, its effect on NK cell activation using PBMCs as an effector, and Ramos as target cells, was analyzed by flow cytometry. The results showed that the aqueous extract of A. ebracteatus root significantly stimulated NO production in J774A.1 cells in a dose-dependent manner. Correspondingly, AE extract increased the mRNA expression of iNOS, which is involved in NO production. However, it had no effect on antibody-dependent cellular cytotoxicity (ADCC) of natural killer (NK) cells against target cells. Our findings show that the aqueous extract of A. ebracteatus root may activate macrophage function, which plays essential roles in both innate and specific immune responses, suggesting that further research into this plant may lead to the development of an immunomodulating drug for treatment and/or health promotion. (Thai Cancer J 2010;30:55-67)
RESUMEN
The chemopreventive potential of Rhinacanthus nasutus Kurz. (family Acanthaceae), traditionally used in Thai folk medicine for cancer treatment, on 7, 12-Dimethylbenz[a] anthracene (DMBA)-induced mammary gland carcinogenesis in female Sprague-Dawley rats was investigated. Seventy-five rats were randomly divided into seven groups consisting of one control group (15 animals) and six treated groups (10 animals for each group). The control group received 0.3% carboxymethylcellulose in normal saline and each treated group received the aqueous extracts of roots and stems (500 mg/kg body weight/day), chloroform extract and rhinacanthin C from roots (25 and 50 mg/kg body weight/day) intragastrically everyday two weeks prior to the administration of a single oral dose of DMBA (30 mg/kg body weight) in corn oil and continuously for 9 weeks. Rats were weighed and monitored twice weekly for tumor development after DMBA administration. At the end of experiment, all rats were sacrificed and the tumor volume, number of tumor per rat, tumor incidence, histopathological and blood biochemical parameters were evaluated. The results revealed that all extracts and rhinacanthin C isolated from R. nasutus Kurz. at the given doses had no affects in the growth rate between the treated and control groups. Oral administration of aqueous extracts of roots and stems (500 mg/kg/day) and chloroform extract (25 mg/kg/day) in tumor-bearing rats significantly suppressed the growth of mammary gland carcinogenesis (p \< 0.01). Moreover, rhinacanthin C (25 and 50 mg/kg/day) suppressed the tumor growth in dose-dependently (p \< 0.001), whereas the high dose of chloroform extract (50 mg/kg/day) had no effect when compared with the control group. The aqueous extract of roots (500 mg/kg/day), chloroform extract and rhinacanthin C (25 mg/kg/day) markedly reduced the number of tumors per rat at 4.2±0.5, 4.37±0.4 and 4.89±0.2, respectively whereas the aqueous extract of stems and high doses of chloroform extract and rhinacanthin C (50 mg/kg/day) had slightly effect when compared with the control group (7.25±0.8). Likewise, rats receiving the aqueous extract of roots (500 mg/kg/day), chloroform extract and rhinacanthin C (25 mg/kg/day) had lower tumor incidence (72.41%, 60.34% and 75.86%) than the control group (100%). For the biochemical analysis, no significant difference of the biochemical parameters was occurred in rats receiving both of aqueous extracts of roots and stems (500 mg/kg/day). In contrast, the levels of blood urea nitrogen (BUN), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) in rats receiving the high dose of chloroform extract (50 mg/kg/day) were markedly increased. Tumor-bearing rats treated with rhinacanthin C (25 mg/kg/day) also had increasing levels of AST and ALT, but with no significant difference when compared with the control group. Based on these available data, our findings first demonstrate that the aqueous extracts of roots and stems, chloroform extract and rhinacanthin C isolated from roots R. nasutus Kurz. markedly suppress tumor growth, number of tumor per rat and tumor incidence of the mammary gland carcinogenesis in the experimental rats induced by 7, 12-dimethylbenz[a] anthracene (DMBA). Interestingly, aqueous extracts of both roots and stems, traditionally usage forms for the treatment of various cancers, provided significantly effective results. Therefore, Rhinacanthus nasutus Kurz. may be a useful Thai medicinal plant for preventing the mammary carcinogenesis, however, prolonged use and overdoses of chloroform extract and rhinacanthin C should be avoided to prevent hepatoxic and nephrotoxic effects of the drugs.