Effect of glucosinolates on clinical isolates of staphylococcus aureus

Abstract

Brassica vegetables, including cabbage, radish, broccoli, kohlrabi and cauliflower play a unique nutritional and sensory role in human diets around the world. Their characteristic flavors come from the breakdown products of glucosinolates. Glucosinolates are plant secondary metabolites involved in the defense response of plants. This biological activity is in fact mediated by glucosinolate degradation products, which are released by the action of an enzyme called myrosinase. These include nitriles, isothiocyanates, epithionitriles, thiocyanates and oxalidine-2-thiones. Glucosinolate hydrolysis products are known to suppress pathogens, nematodes, pests, and weeds. They are also known for their ability to prevent cancer by inducing phase I and phase II detoxification enzymes, which inhibit cell proliferation and modulate apoptosis in cancer cells. However, despite the well-established strong effect of these compounds on pathogens and on cancer cells, little is known about their effect against bacteria. The present work was, therefore, undertaken to shed light on this aspect of glucosinolate metabolism. Intact glucosinolates and their hydrolysis products were tested on different Staphylococcus aureus strains isolated from stools of enteritis patients. Using the serial dilution method, the effect of intact and myrosinase-degraded glucosinolates, extracted from three different members of Brassicaceae (broccoli, cabbage and radish) were tested for their effect on bacterial growth. Results surprisingly showed that only intact glucosinolates, and not their hydrolysis products, had significant antibacterial potential. However, the inhibitory concentrations varied for the different strains and between the plants tested.