UNEXPECTED PRODUCTION OF CHAETOGLOBOSINS FROM MAIZE INCUBATED BY PHOMOPSIS-LEPTOSTROMIFORMIS .1. ISOLATION AND OPTIMIZATION OF THE PRODUCTION IN LIQUID-MEDIA BY LC MONITORING

Attempts to obtain the toxin phomopsin A, usually isolated from Phomop sis leptostromiformis fungus, failed when infesting maize with the str ain MRC2654 of this fungus. However, taking into account the acute tox icity for rats of the crude methanol extract, mycotoxins less polar th an phomopsins were searched for by checking other separation procedure s. Preparative thin layer chromatography on silica (TLC) entailed the localisation of the toxicity in the fraction soluble in isopropylic et her. Finally, the preparative high performance liquid chromatography ( HPLC) on silica allowed the purification of two toxins, which are demo nstrated to belong to the chaetoglobosin series, as described elsewher e. An LC method for the direct monitoring of these toxins' production in liquid media resulted in a first optimization of the culture condit ions. It appeared that the yields of these toxins can be approximately increased four-fold by reducing the culture of Phomopsis leptostromif ormis in darkness from a 28-day period to 10 days.