Antifungal and phytochemical studies of Acalypha indica linn. extracts and its skin sensitization test

Abstract

Acalypha indica is a plant that has been extensively used in the traditional medicine to treat a number of illnesses. It has been used as an expectorant, to treat skin ailments, headaches and asthma. As such, this research sought to investigate the antifungal activity and active phytochemicals of A. indica extracts and its skin sensitivity reaction. Phytochemical screening undertaken have shown that the plant contain saponins, flavonoids, steroids, terpernoids, tannins, phenolics and alkaloids. A Kirby-Bauer disc diffusion assay was undertaken for the screening of antifungal activity against Candida albicans, Microsporum gypseum and Tricophyton mentagrophytes. Both chloroform and methanol extracts have shown to inhibit the growth of C. albicans but not T. mentagrophytes and M. gypseum. Chloroform extract produced inhibition zone against C. albicans at the concentration of 50 to 200 mg/mL, whereas methanol extract produced inhibition zones at all the concentration used which was 25 to 200 mg/mL. However, the petroleum ether extract did not produce any inhibition zones against all the pathogens tested. In order to obtain the minimum inhibitory concentration (MIC) value, broth microdilution test was undertaken. The result that was achieved produced MIC value against C. albicans for both chloroform and methanol extracts at 1.56 and 0.39 mg/mL, respectively. From the result obtained, the most active extract of A. indica was continued to the skin sensitivity study. The test was conducted via Organization for Economic Co-operation and Development (OECD) guideline #406 using Buehler method and erythema readings were taken via Dermalab Combo. Guinea pigs in this study were divided into four groups which were negative control, positive control, lower dose and higher dose group. It was observed that during the challenge phase, when compared to the positive control (7.21), the erythema indices of treated groups were lower (4.11 and 4.54) which were closer towards the negative control group (3.46). Both results for week 3 of induction phase and challenge were considered significant according to the p value obtained. Active extracts of A. indica were then undertaken for fractionation and isolation via column chromatography and chromatotron. Identification of the compounds was done via the use of gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR) study. Identified compounds in the A. indica extracts are essential oils components such as nonacosane, and pentacosane, as well as ethyl ester (ethyl palmitate, ethyl stearate), squalene, phytol and phytosterols. The major components were the phytosterols which were the combination of three major compounds of campesterol, stigmasterol and sitosterol. The compounds discovered in this extract have been reported to possess antifungal activity against C. albicans, thus corroborating the result obtained during the antimicrobial study. Apart from that, the compounds were also found to possess other attributes such as antioxidant and also as an emollient.