Manjeet Kumar

Present study relates to the effect of valproic acid, an epigenetic modifier on the metabolic profile of Aspergillus fumigatus (GA-L7), an endophytic fungus isolated from Grewia asiatica L. Seven secondary metabolites were isolated from A. fumigatus (GA-L7) which were identified as: pseurotin A, pseurotin D, pseurotin F2, fumagillin, tryprostatin C, gliotoxin and bis(methylthio)gliotoxin. Addition of valproic acid in the growth medium resulted in the alteration of secondary metabolic profile with an enhanced production of a metabolite, fumiquinazoline C by tenfolds. In order to assess the effect of valproic acid on the biosynthetic pathway of fumiquinazoline C, we studied the expression of the genes involved in its biosynthesis, both in the valproic acid treated and untreated control culture. The results revealed that all the genes i.e. Afua_6g 12040, Afua_6g 12050, Afua_6g 12060, Afua_6g 12070 and Afua_6g 12080, involved in the biosynthesis of fumiquinazoline C were overexpressed significantly by 7.5, 8.8, 3.4, 5.6 and 2.1 folds respectively, resulting in overall enhancement of fumiquinazoline C production by about tenfolds.

Enol acetates have enjoyed unique importance as intermediates in organic synthesis with a wide range of applications. [ ¹ ] The enol acetates are mainly employed in the transesterification of alcohols to synthesise chiral alcohols and acetates in high enantiomeric excess catalyzed by biocatalysts, such as lipases, [ ² ] as well as the catalysts, such as iodine, [ ³ ] Cp₂Sm(thf)₂, [ 4 ] diethylzinc, [ 5 ] etc. They also find applications in the synthesis of biologically active intermediates like 1-acetyladamantane, [ 6 ] used as the starting material in the efficient preparation of the anti-influenza drug rimanadine and natural products, such as sapon­aceolides, [ 7 ] briarellin J, [ 8 ] etc. Enol acetates are commercially accessible. Acetates of cyclic ketones can be easily prepared using perchloric acid and acetic anhydride. [ 9 ] Isopropenyl acetate is prepared on commercial scale by a sulfuric acid catalyzed reaction of acetone and ketene. [ ¹0 ] Whereas, the vinyl ester can be obtained by the reaction of ethylene and acetic acid with oxygen in the presence of palladium catalyst. [ ¹¹ ] Besides, chiral enol acetates have also been synthesized from racemic enol acetates or ketones through multistep reactions catalyzed by lipase and a ruthenium complex. [ ¹² ]