Chapter 63 - Antifungal and Lipid Transfer Proteins from Ginkgo (Ginkgo biloba) Seeds

Abstract

This chapter discusses the medicinal properties of ginkgo seeds. The tree produces a variety of secondary metabolites, among which the terpene trilactones, ginkgolides, and bilobalide are the most characteristic. Ginkgolides are diterpenes that have been detected both in roots and leaves, and the Sesquiterpene bilobalide is the major terpene trilactone in leaves and a minor component in roots. Extracts from the ginkgo leaf are the most widely sold as phytomedicines to treat early-stage Alzheimer's disease, vascular dementia, and so on. On the other hand, the nuts have been used as traditional Chinese herbal remedies for frequent urination, enuresis, asthmatic response, and lung tuberculosis. A protein from the seeds exerts potent antifungal activity, moderate antibacterial activity, inhibitory activity toward HIV-1 reverse transcriptase and the proliferation of murine splenocytes. Recently, we characterized an antifungal protein and the other bioactive proteins in ginkgo nuts, in order to shed light on the relationship between these proteins and the pharmaceutical properties of the nuts. Seed germination of plants begins in an environment rich in pathogens; therefore, many plant seeds contain antifungal and antibacterial proteins. Gb-nsLTP1 exhibits binding activity toward cis-unsaturated fatty acids and inhibits the aspartic protease pepsin. This inhibitor would suppress the proteinase activity secreted by pathogens and reduce the resulting inflammation. Ginkgo seeds and their external seed coat contain some toxic compounds, including ginkgotoxin and ginkgolic acids. The toxic mechanisms of these compounds have been elucidated in detail at the molecular level.