Biotransformation of organic compounds in vivo using larvae of beetles (Allomyrina dichotoma) as biocatalysts

The biotransformation of organic compounds using the larvae of the Japanese rhinoceros beetle (Allomyrina dichotoma) as a biocatalyst is described. When phenyl alkanediones were administered by mouth (p.o) or subcutaneous injection (s.c) to the beetle, asymmetric reduction occurred to yield the corresponding diols in varying optical yields: 1-phenyl-1,2-propandione or 1-phenyl-1,3-butanedione reduced to (1R,2S)- and (1S,2S)-1,2-phenylpropanediols in high optical yields or (1R,3S)- and (1R,3R)-1-phenyl-1,3-butanediols in low to high optical yields, respectively. By administrating 1-phenyl-1-propanone, 1-phenyl-1-butanone or 4-phenyl-2-butanone, redox reactions occurred to give 1-phenyl-1,2-propanediols or 1-phenyl-1,3-butanediols in lower optical yields. The administrations of β-ionone and cinnamyl chloride resulted in regioselective allylic oxidations producing enone and cinnamic acid, respectively. However, when (R)-(-)-carvone was administered, regiospecific dihydroxylation at the isopropenyl group occurred to give (4R,8R)- and (4R,8S)-8,9-dihydroxy-8,9-dihydrocarvone as diastereoisomers. These results appear to demonstrate similar reaction tendency with the case of a microorganism. It is possible that these reactions were due in part to bacteria in the intestine of the larva: however, regio- and stereoselectivities of the reactions were sometimes unique. Thus, it is supposed that these biotransformations were accomplished by the ensemble of the larva's own enzymes with several bacteria. The results obtained in this study might show the possibility of using such enzymes derived from insects, including beetle larvae, as a biocatalyst.