Chapter 66 - Gastroprotective Activity of Grapefruit (Citrus paridisi) Seed Extract Against Acute Gastric Lesions

Abstract

This chapter provides an outline of the antibacterial, antiviral, and antiparasitic activities of grapefruit seeds. Grapefruit seed extract (GSE) is a product of the grapefruit seed and pulps, and has been found to exert antibacterial, antiviral, and antiparasitic activities. Previous studies documented that grapefruit seeds are the major depositories for limonoids. Grapefruit also contains many flavonoid glycosides, naringenin, quercetin, kaempferol, hesperidin, and apigenin being the most abundant among their aglycones. Grapefruit seed extracts (GSEs), containing flavonoids, have been shown to possess antibacterial, antiviral, and antifungal properties. Furthermore, grapefruit-containing flavonoids such as naringenin were also recently implicated in cytoprotection against injury induced by algal toxins in isolated hepatocytes. The antimicrobiological properties of GSE against a wide range of gram-negative and gram-positive organisms were attributed to the disruption it caused to the bacterial membrane and the subsequent liberation by this extract of the bacterial cytoplasmic contents within a relatively short time. The underlying mechanism of the therapeutic efficacy of citrus seed extracts such as from grapefruits and red grapes seems to depend upon the presence of different classes of polyphenolic flavonoids, which were shown to inhibit platelet aggregation, thus decreasing the risk of coronary thrombosis and myocardial infarction. The mechanism of the gastroprotective activity of GSE appears to be dependent on endogenous PG and the functional activity of sensory nerves releasing CGRP. The major mechanism of protection against gastric mucosal damage involves enhancement of the gastric microcirculation mediated by increased generation of endogenous prostaglandins (PGs) and nitric oxide (NO) and activity of sensory neuropeptides such as CGRP. Interestingly, GSE in a formulation of Citricidal was demonstrated to be effective against more than 800 bacterial and viral strains, 100 strains of fungus, and a large number of single- or multi-celled parasites.