Abstract:
Skin aging is associated with the degradation of the extracellular matrix through increased activity of enzymes such as elastase, collagenase and hyaluronidase. The aim of this study was to investigate the ability of a South African wetland plant, Elegia tectorum to reduce the formation of wrinkles on the skin through the inhibition of elastase and KIAA1199 protein. Elastase inhibition assay was used to screen the plant extracts of E.tectorum made from ethanol, hexane, dichloromethane, ethyl acetate, water, acetone and methanol. The methanolic and ethanolic extracts showed highest anti-elastase activity with an inhibitory concentration (IC50) of 10.93±4.98 and 13.495±1.53 µg/ml respectively. The ethanolic extract, which is a suitable solvent in product development, was selected for further testing. In vitro cytotoxicity was investigated on human colorectal adenocarcinoma cell line (HT-29), the ethanolic extract was found to be not toxic at the highest tested concentration (IC50>400 µg/ml). Furthermore, at non-toxic concentrations (15, 60, and 240 µg/ml), E.tectorum was able to significantly inhibit the KIAA1199 protein. The mutagenic potential of the extract was investigated using Salmonella typhimurium TA98, and was found to be a non-mutagen. Molecular docking was conducted to predict the binding affinity and binding mode of the compounds, identified through GC-MS, to the active site of elastase. Five compounds had the closest docking score to the reference ligand which had a score of -11.64, octadecanoic acid, 9,12,15-octadecatrienoic acid (Z,Z,Z), n-hexanoic acid, 3-(5-methylfuryl)-n-furamidopropionamide, and hexanedioic acid bis(2-ethylhexyl) ester. The docking scores were -6.92, -6.39, -6.20, -5.21, -5.02 respectively. Bio-assay guided fractionation column chromatography was conducted and none of the six pooled fractions were able inhibit elastase, indicating a potential-synergistic activity with two or more compounds within the crude extract. Stability testing of the formulation containing the extract and extract was conducted and parameters such as odour, colour, pH, and viscosity were investigated. The results indicated that the product is stable for a period of two years when stored at temperatures below 40 ºC and away from direct sunlight. In vivo irritancy studies revealed that the plant extract, when applied neat, showed mild irritancy. Elegia tectorum was able to inhibit elastase enzyme and KIAA1199 protein. It is a good candidate as an anti-wrinkle product as it is a non-mutagen, is stable and is a mild irritant. Therefore, this plant has a potential to result in an antiaging product.
