In Vitro Antimicrobial Activity and GC-MS Findings of the Gel of Aloe vacillans Forssk. of Abha Region, Saudi Arabia

A great variety of weeds grow in the Abha area, Saudi Arabia, at more than 2700 m above sea level. The aim of this study was to evaluate the antimicrobial activities of various extracts of fresh and dry leaf gel of Aloe vacillans against eight clinical isolates of human pathogens. The chemical compounds present in the gel extract were identified and quantified by gas chromatography-mass spectrometry. Solvent extracts inhibited 62.5% of the examined microbes, whereas the fresh leaf extract was more potent and active against Staphylococcus aureus, Micrococcus luteus, Klebsiella oxytocam, Proteus mirabilis, and Candida albicans compared to the dry leaf extract. No antimicrobial activities were observed against Klebsiella pneumonia, Shigella flexneri, and Pseudomonas aeruginosa. Candida albicans was the most susceptible pathogen based on its zone of inhibition. The maximum inhibitory activities were shown by the fresh gel of the chloroform extract against M. luteus, the methanol extract against S. aureus, the petroleum ether extract against P. mirabilis, C. albicans, and K. pneumoniae, and hot water extracts against K. oxytocam. Gram-positive bacteria and C. albicans were more susceptible than gram-negative bacteria. Compounds were identified and quantified; the major constituents of the gel were 1,3-dimethoxy-2-propanol and glycerol. Acetoglycerides, ethanol, 5-(hydroxymethyl)-2-furaldehyde, palmitic acid, butane, 1,2:3,4-diepoxy-,(..)-, 2-deoxy-d-galactose, butyl acetate, 2,2-dimethoxyethanol, diethyl phthalate, phytol, octadecanoic acid, gamma-linolenic acid, and stearic acid were present in low amounts. Therefore, because of its antimicrobial activities and useful phytochemical composition, A. vacillans leaf gel is a promising pharmaceutical drug for specific microbial infections and for improving health.