The Effects Of Gamma Irradiation On Microbiological Safety, Biological Activities And Gallic Acid Content Of Euodia Malayana, Gnetum Gnemon And Khaya Senegalensis
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Date
2018-01
Authors
Khawory, Muhammad Hidhir
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Publisher
Universiti Sains Malaysia
Abstract
Medicinal plants such as herbs and spices are often contaminated with high levels of bacteria, fungus and yeasts. Therefore, medicinal plants can be decontaminated using gamma irradiation to sterilize the microorganisms effectively. The aim of this study is to evaluate the effects of gamma radiation treatment on three medicinal plants, namely Euodia malayana, Gnetum gnemon and Khaya senegalensis at two different forms; methanol leaf extracts and dried leaves respectively. The microbial limit test studies indicated the suitable dosage of minimum and maximum gamma irradiation was 6-12 kGy for leaf extracts and 9-13 kGy for dried leaves of all the medicinal plants. The stability studies demonstrated that there was no microbial contamination one year after gamma radiation treatment when the plants were stored under controlled temperature and humidity. For the chemical constituent analysis, qualitative analysis using High Performance Liquid Chromatography (HPLC) revealed the presence of gallic acid compound at retention time of 2.173 minutes in each plant. Quantitative analysis showed that the percentage of gallic acid concentration in each plant increased significantly from 0.024%-0.053% before treatment to 0.03%-0.064% after treatment with gamma radiation. This result was confirmed by total phenolic content (TPC) analysis based on calorimetric measurements determined using the Folin-Ciocalteu reagent with gallic acid used as the reference. DPPH (2,2-diphenyl-1-picryl-hydrazyl) assay was conducted by using vitamin C and gallic acid as the positive controls to determine the antioxidant property of each plant. Effective concentration (EC50) values of Khaya senegalensis plant reduced significantly (P≤0.005) from 44.510 μg/ml before treatment to 24.691 μg/ml after treatment with gamma radiation, which indicate an increase of free radical scavenging activity. In vitro cytotoxicity assay by using fibroblast (L929) cell lines was performed on each plant to determine the toxicity effect.
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Keywords
Medicinal plants such as herbs and spices , often contaminated with high levels of bacteria, fungus and yeasts