Evaluation of antifungal spectrum for utilization of gallic acid derivatives, the main components of Eucalyptus saligna leaves
2018
Inagaki, R. (The University of Tokyo (Japan). Graduate School of Agricultural and Life Sciences, Department of Biomaterial Scienecs) | Terada, T. | Inoue, H. | Kamoda, S. | Samejima, M.
Eucalyptus saligna is a fast-growing tree and is expected to be used as a raw material in Japan in the future. We examined the use of gallic acids, one of the ingredients of the E. saligna leaves, in order to explore the possibility of the utilization of waste leaves. Using the aqueous extract of E. saligna leaves, gallic acid (GA) and methyl gallate (MG), we investigated the antibacterial spectrum against the damping-off fungi Fusarium oxysporum, Fusarium solani, Rhizoctonia solani, Pythium sylvaticum, Pythium ultimum, rice blast causative fungus Magnaporthe oryzae, and dark snow-blight fungi. Aqueous extracts in which most of the GA and MG are present as glycosides showed some antifungal activity against Pythium spp., but showed little antifungal activity against other fungi. GA completely inhibited the growth of M. oryzae and P. sylvaticum at 2000 ppm and MG completely suppressed the growth of P. sylvaticum and P. ultimum at 800 ppm. We concluded that in order to utilize the extract of E. saligna leaves for antifungal purposes, it is appropriate to use them after hydrolysis treatment. Furthermore, a germination test was carried out on Picea jezoensis and Picea glehnii, the spruces usually attacked by fungi causing blight and dark snow-blight diseases. Since the effects of GA on the germination and growth of plants were hardly observed, it is expected that GAs can actually be of use as an antibacterial agent.
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