Antitumor and immunomodulatory effects of Justicia spicigera Schltdl (Acanthaceae)

Abstract

Ethnopharmacological relevance: Medicinal plants are an important source of antitumor compounds. This study evaluated the acute toxicity in vitro and in vivo, as well as the cytotoxic, antitumor and immunomodulatory effects of ethanolic extracts of Justicia spicigera leaves (JSE).

Materials and methods: The in vitro and in vivo toxicity of JSE was evaluated with comet assay in peripheral blood mononuclear cells (PBMC) and acute toxicity in mice, according to the Lorke procedure, respectively. The apoptotic effect of JSE on human cancer cells and human noncancerous cells was evaluated using flow cytometry with annexin-Alexa 488/propidium iodide. Also, different doses of JSE were injected intraperitoneally daily into athymic mice bearing tumors of HeLa cells during 18 days. The growth and weight of tumors were measured. The in vitro immunomodulatory effects of JSE were evaluated estimating the effects of JSE on the phagocytosis of the yeast Saccharomyces cerevisiae, NO production and H(2)O(2) release in macrophages, as well as the proliferation of splenocytes and NK activity.

Results: The comet assay showed that only JSE tested at 200 and 1000 μg/ml induced a significantly DNA damage in PBMC, compared to untreated cells, whereas the LD(50) was >5000 mg/kg by intraperitoneal route (i.p.) and by oral route. JSE showed pro-apoptotic (Annexin/PI) effects by 35% against HeLa cells, but lack toxic effects against human normal cells. JSE administrated at 10, 50 and 100 mg/kg i.p. inhibited the tumor growth by 28%, 41% and 53%, respectively, in mice bearing HeLa tumor. JSE stimulated, in a concentration dependent manner, the phagocytosis of Saccharomyces cerevisiae yeasts, the NO production and H(2)O(2) release by human differentiated macrophages. In addition, JSE stimulated the proliferation of murine splenocytes and induced the NK cell activity.

Conclusion: Justicia spicigera shows low toxic effects in vitro and in vivo, exerts apoptotic effects on HeLa cells, has antitumor effects in mice bearing HeLa tumor and induces immunomodulatory activities in vitro.