Antioxidant Properties of Fungal Endophytes Associated with the Three Medicinal Plants Gliricidia sepium, Canna indica and Gardenia jasminoides

Abstract

Fungal endophytes live within tissues of living plants without causing any disease. These fungi are recognized sources of natural, bioactive compound with potential applications in agriculture, medicine, and food. Aims: This research study aimed to isolate and produce bioactive metabolites from fungal endophytes isolated from three Philippine medicinal plants and assess their antioxidant activities. Study Design: The study used exploratory research where medicinal plants were selected because these were considered to contain a wide range of endophytes which could have varied secondary metabolites that exhibit biological activities. Place and Duration of Study: Research Center for the Natural and Applied Sciences at the University of Santo Tomas, Manila and Center for Natural Sciences at Saint Mary’s University, Bayombong, Nueva Vizcaya during June 2011 to October 2012. Methodology: Medicinal plant leaf endophytes (MPLE) were isolated through surface sterilization of healthy leaves of Gliricidia sepium, Canna indica and Gardenia jasminoides. Selected MPLE were grown in vitro and extracted for their secondary metabolites. Assay of antioxidant activities was done using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) while total phenolics content was through the Folin-Ciocalteu method. The number of metabolites present was detected using thin layer chromatography. Results: A total of 73 fungal strains belonging to 23 different morphospecies endophytes were isolated from the three host plants. G. sepium had the highest number of morphospecies (32) among the three medicinal plants studied. These fungal endophytes were identified as belonging to the genera Botrytis. Curvularia, Aspergillus, Trichoderma, Penicillium, and Gliocladium. Many MPLE were identified only as mycelia sterile The MPLE crude cultures showed antioxidant activities (75-90%RSA) and total phenolic content of 134 AAE/g. There were a maximum of 11 secondary metabolites present in the crude culture extracts belonging to the class of flavonoids, terpenoids, phenolics, fatty acids and coumarins. Conclusion: Fungal endophytes are rich in tropical regions and the three Philippine medicinal plants studied are good hosts of fungal endophytes which showed antioxidant activities and secondary metabolites which can be harnessed as sources of pharmaceuticals and nutraceuticals.