Synthesis of Some O-Substituted Derivatives of Natural 6-hydroxymethyl-4-methoxy-2H-pyran-2-one (opuntiol)

This manuscript reports the synthesis of a series of new O-substituted derivatives of opuntiol (1) which is a naturally occurring compound isolated from a plant Opuntia dillenii Haw belonging to family Cactaceae. These derivatives 3a-t, were characterized by FAB-MS, IR, and H-1-NMR and then screened against acetylcholinesterase, butyrylcholinesterase, lipoxygenase and square-chymotrypsin enzymes. The screening results revealed that 6-(acetyloxy) methyl- 4-methoxy-2H-pyran-2-one (3b) and N-(2,5-dimethylphenyl)-2-[(4-methoxy-6-oxo-2H-pyran-2-yl)methoxy]acetamide (3p) were found to be the inhibitor of butyrylcholinesterase while 6-(acetyloxy)methyl- 4-methoxy-2H-pyran-2-one (3b), 6-(ethoxymethyl)-4-methoxy-2H-pyran-2-one (3c), 4-methoxy-6-[(phenylmethoxy)methyl]-2H-pyran-2-one (3g), 6-[(2-bromoethyloxy)methyl]-4-methoxy-2H-pyran-2-one (3j), N-(5-chloro-2-ethoxyphenyl)-2-[(4-methoxy-6-oxo-2H-pyran-2yl)methoxy]acetamide (3r), N-(3,4-dimethylphenyl)-2-[(4-methoxy-6-oxo-2H-pyran-2yl) methoxy] acetamide (3s) N-(3,5-dimethylphenyl)-2-[(4-methoxy-6-oxo-2H-pyran-2yl) methoxy] acetamide (3t) were found to be active against a-chymotrypsin and among these 3s was the good inhibitor of this enzyme having IC50 value of 142.71 +/- 0.22 mu moles/L.