Interactions Between The Solanum Glycoalkaloids In Relation To Inhibition Of Fungul Growth

Glycoalkaloids are secondary metabolism of plants and distributed mainly in Solanaceae and Liliaceae. These molecules have an oligosaccharide chain attached at the C3 position of the nitrogenous steroidal alkaloid backbone.the sugar chain are uaually trisaccharide or tetrasaccharide. Some investigation have indicated that glycoalkaloids must have been evolved in nature to protect plants against bacteria, fungi, insects, and animals. They are toxic to a wide range of organisms and are generally considered to be defensive allelochmicals.The biological activity of glycoalkaloids is largely due to their membrane-disruptive effects.They complex with sterols in membranes, ultimately to form aggregates and cause loss of membrane integrity.The study about the untifungal activity of glycoalkaloids is an important moiety in the ecology and exploitation of plant resources.But much less information is available on these compounds in china. In addition, in many solanaceous species, the major glycoalkaloids present are pairs of structurally related compounds which share a common aglycone and differ only in their carbohydrate moiety. Interestingly, some of these naturally'paired'glycoalkaloids share the carbohydrate moieties of solanine (solatriose)and chaconine (chacotriose) differing only in aglycone structure, e.g. solamargine and solasonine. With regard to membrane-disruptive activity,chacotriose-based glycoalkaloids are normally highly active whereas solatriose-based compounds show lower or no activity.There is evidence too that such"paired"glycoalkaloids may interact synergistically.So it is valuable for us to understand and study the biological activity of glycoalkaloids their mixtures to pathogenic fungi in china. In this paper with two phytopathogenic fungi Cercosporella brassicae Hoehnel and Alternaria porri Cif as texted strain,the characteristics of antifungal activity of solamargine, solasonine, chaconine, solanine and their mixtrue were examined by means of inhibition of mycelial growth.The main results obtained from this work are as follows:1. The glycoalkaloids show a pronounced concentration dependency in their inhibition of pathgenic fungal growth. Chaconine was the most inhibitory and solanine was the least inhibitory of the four compounds..2. The mixtures of solamargine and chaconine/solasonine and solanineproduced additive effects and didn't produce synergistic effects on antifungal activity. the inhibition caused by the glycoalkaloid mixture were equivalent with the expected values(based on summing the individual activities).