Bisradicinin: A Novel Dimer Elicited in Cultures of Alternaria chrysanthemi

Abstract

A s s m c r . A u l t u r e s of Alternaria chysantbtmi are known to produce the a-pyrones radicinin 111 and radicinol 121. During the course of a study to monitor the ability ofA. chyJantbtmi cultures to biotransform foreign substrates it was observed that the addition of foreign substrates stimulated the production of a third a-pyrone. This compound was identified as bisradicinin 131, a dimer of 1. Compound 3 was not produced in cultures of A. chysantknzi grown under identical conditions without added substrate. (Dematiaceae) is the etiological agent of leaf spot disease of Cbtysanthemwm maximum (Ram.) DC. (Compositae) (1). Early phytochemical analyses of A . chrysanthemi have led to the isolation and identification of two phytotoxic compounds, radicinin E17 and radicinol [27 (2,3). To date there have been no reports on the biotransformation of foreign chemical substrates by A . chrysanthemi, although unidentified strains of Alternaria have been reported to catalyze the deacylation of phenoxymethyl penicillin (4) and the reduction of progesterone to l-dehydroprogesterone ( 5 ) . As part of an ongoing study on the ability of A . chrysanthemi to biotransform foreign substrates we have recently identified 3, a novel dimer of radicinin. This compound was produced in all cultures used in biotransformation studies and was not observed in cultures grown under identical conditions but without added substrate. Alternaria cbtysanthemi Simmons and CrosierHplc analysis of EtOAc extracts of the culture medium of A . chrysanthemi (over a 1 1 0 0 2 3

Novel Radicinol Derivatives from Long-Term Cultures of Alternaria chrysanthemi

“…The coupling constant of 3.8 Hz is in keeping with that observed by Nukina et al for 3-epiradicinol, the diastereoisomer of 2 that has a 5S,4R,3S configuration. 3 Based on these data and a comparison with literature values, 4 3 was identified as 3-epiradicinol, previously isolated from cultures of A. chrysanthemi and A. longipipes. 5 The third compound (4) recovered from the growth medium, with the molecular formula C 13 H 16 O 5 , was also an optically active oil.…”

“…(Compositae) . Chemical analyses of A. chrysanthemi have led to the isolation of the phytotoxins radicinin ( 1 ) and radicinol ( 2 ). , The phytotoxic dimer bisradicinin has been isolated from cultures of A. chrysanthemi used in biotransformation studies . During the course of a long-term study into the production of metabolites by Alternaria species, we observed trace compounds in addition to 1 and 2 in cultures of A. chrysanthemi grown on malt-extract broth .…”

“…2,3 The phytotoxic dimer bisradicinin has been isolated from cultures of A. chrysanthemi used in biotransformation studies. 4 During the course of a long-term study into the production of metabolites by Alternaria species, 5 we observed trace compounds in addition to 1 and 2 in cultures of A. chrysanthemi grown on malt-extract broth. 6 The concentration of these compounds was found to increase when cultures were grown for longer than the normal 20 days.…”

“…In previous studies, when A. chrysanthemi was grown on modified Czapek−Dox medium 2 or potato dextrose broth, 1 immediately appeared, followed after 10 days by 2 . The use of malt-extract broth as a long-term growth medium has yielded radicinol ( 2 ), together with the novel metabolites 3-epiradicinol ( 3 ) and its methoxyl derivatives 4 and 5 .…”

(±)-3-Deoxyradicinin Induces Stomata Opening and Chloroplast Oxidative Stress in Tomato (Solanum lycopersicum L.)

“…Its chemical structure was first proposed in 1964 [8] and definitely determined in 1982 by X-ray crystallography [5] and recently by chiroptical spectroscopy [9]. From a biological point of view, radicinin is an interesting metabolite, having several biological effects, including promising herbicidal effects [5,[10][11][12] and antifungal, insecticidal, and plant growth regulatory activities [13][14][15][16], as well as antibiotic activity against Gram-positive bacteria [17]. More recently, the toxin was shown to possess in vitro anticancer activity [18].…”