The biochemical basis for the antimicrobial effect of the carrot phytoalexin 6-methoxymellein (6-MM) was examined. At fungistatic concentrations 6-MM retarded the ability of Candida albicans to incorporate radioactive thymidine, uridine and leucine into biopolymers. When C. albicans was incubated with 6-MM, 260-nm-absorbing materials and 3H-labelled compounds leaked from the cells. The inhibitory effects of 6-MM on cell growth and membrane functions were, however, reduced as the concentration of divalent metal cations added to the medium was increased. 6-MM interacted with multilamellar liposomes constituted from phosphatidylcholine, cholesterol and dicetyl phosphate, or from phosphatidylcholine only, resulting in the release of glucose trapped in these liposomes. These results suggest that 6-MM exerts its toxic effects on susceptible cells as a result of its interaction with their membranes and disturbance of membrane-associated functions.
BanghamA.D.,
StandishM.W.,
WatkinsJ.C.1965; Diffusion of univalent ions across the lamellae of swollen phospholipid. Journal of Molecular Biology 13:238–252
BoydstonR.,
PaxtonJ.D.,
KoeppeD.E.1983; Glyceollin, a site-specific inhibitor of electron transport in isolated soybean mitochondria. Plant Physiology 72:151–155
CoxonD.T.,
CurtisF.R.,
PriceK.R.,
LevettG.1973; Abnormal metabolites produced by Daucus carota roots under conditions of stress. Phytochemistry 12:1881–1885
HsuchenC.-C.,
FeingoldD.S.1973; Polyene antibiotic action on lecithin liposomes. Effect of cholesterol and fatty acyl chains. Biochemical and Biophysical Research Communications 51:972–978
ImaiM.,
InoueK.,
NojimaA.1975; Effect of polymyxin B on liposomal membranes derived from Escherichia coli lipids. Biochimica et biophysicaacta 375:130–137
KaplanD.T.,
KeenN.T.,
ThomasonI.J.1980; Studies on the mode of action of glyceollin in soybean. Incompatibility to root knot nematode Meloidogyne incognita
. Physiological Plant Pathology 16:319–325
KotaniH.,
ShinmyoA.,
EnatsuT.1977; Killer toxin for sake yeast: properties and effects of adenosine 5′-diphosphate and calcium ion on killing action. Journal of Bacteriology 129:640–650
KurosakiF.,
NishiA.1983; Isolation and antimicrobial activity of the phytoalexin 6-methoxy-mellein from cultured carrot cells. Phytochemistry 22:669–672
OkuN.,
NojimaS.,
InoueK.1980; Selective release of non-electrolytes from liposomes upon perturbation of bilayers by temperature change or polyene antibiotics. Biochimica et biophysica acta 595:277–290
SwamyK.H.,
SirsiM.,
RaoG.R.1974; Studies on the mechanism of action of miconazole: effect of miconazole on respiration and cell permeability of Candida albicans. Antimicrobial Agents and Chemotherapy 5:420–425
WeinsteinL.I.,
AlbersheimP.1983; Host-pathogen interactions. XXIII. The mechanism of the antibacterial action of glycinol, a pterocarpan phytoalexin synthesized by soybeans. Plant Physiology 72:557–563