IN VITRO TOXICITY STUDIES ON THE EXTRACT OF MEDICINAL PLANT EVOLVULUS NUMMULARIUS AS A POTENT MICROBICIDAL CANDIDATE

Abstract

The herb Evolvulus nummularius (L). L generally grown as an ornamental plant. This herb has found many applications in traditional folk medicine. There was however insufficient scientific data to back its safety to be used on humans. Methanolic extract of E. nummularius was used to check for its safety as a vaginal microbicide through various safety tests such as cell viability using MTT assay on three female genital tract epithelial cell lines, vaginal (VK2/E6E7), endocervical (End1/E6E7) and endometrial (HEC-1-A). Quantification of hemolytic activity was done on human red blood cells (RBCs). Determination of cellular integrity was checked by transepithelial electrical resistance (TER) assay and permeability by fluorescent microsphere assay. At 24 hours, application of the extract for cell viability assay showed extensive cell death with cell disruption. IC₅₀ of VK2/E6E7 and HEC-1-A cells were found to be 2 mg/ml, IC₅₀of End1/E6E7 was 1 mg/ml. For hemolytic assay, with treatment of the extract for one hour did not show hemolysis till the concentration of 2.5mg/ml. In TER and microsphere permeability assays, polarized HEC-1-A monolayer 24 hours post treatment had significant drop in TER and enhanced fluorescence from passage of microspheres implying disruption of the epithelial monolayer. The study revealed the crude methanolic extract appeared to be toxic towards human RBCs and female genital tract epithelial cells. Due to its toxic nature, its direct applications to the human vaginal tissue in vivo should be done with caution.

Keywords: Medicinal plants; Microbicide; Evolvulus nummularius (L). L; MTT assay; Transepithelial electrical resistance; Fluorescent microsphere assay.