BIOCHEMICAL ACTIVITIES OF BERBERINE, PALMATINE AND SANGUINARINE MEDIATING CHEMICAL DEFENSE AGAINST MICROORGANISMS AND HERBIVORES

The alkaloids berberine, palmatine and sanguinarine are toxic to insec ts and vertebrates and inhibit the multiplication of bacteria, fungi a nd viruses. Biochemical properties which may contribute to these allel ochemical activities were analysed. Acetylcholine esterase, butyrylcho linesterase, choline acetyl transferase, alpha(1)- and alpha(2)-adrene rgic, nicotinergic, muscarinergic and serotonin(2) receptors were subs tantially affected. Sanguinarine appears to be the most effective inhi bitor of choline acetyl-transferase (IC50 284 nM), while the protoberb erines were inactive at this target. Berberine and palmatine were most active at the alpha(2)-receptor (binding with IC50 476 and 956 nM, re spectively). Furthermore, berberine and sanguinarine intercalate DNA, inhibit DNA synthesis and reverse transcriptase. In addition, sanguina rine (but not berberine) affects membrane permeability and berberine p rotein biosynthesis. In consequence, these biochemical activities may mediate chemical defence against microorganisms, viruses and herbivore s in the plants producing these alkaloids. Copyright (C) 1996 Elsevier Science Ltd