In the
adipocere, which is one of the
postmortem changes, some specific
fatty acids possessing higher melting points, together with
soap, play an important role in the formation of
adipocere. These
fatty acids were shown to be mainly 10-hydroxystearic and 10-hydroxypalmitic
acids. Moreover, slight amounts of 10-oxostearic and 10-oxopalmitic
acids, which have higher melting points than those of hydroxy
fatty acids, exist in the
adipocere as well. The substantial
adipocere is formed and stabilized by these specific
fatty acids together with the
soap. The hydroxy
fatty acid (OHFA) and oxo
fatty acid (OXOFA) are biosynthesized by some bacterial
enzymes. Various aerobic and anaerobic bacteria are involved in the formation of
adipocere. For example, microbial conversion of various
unsaturated fatty acids to 10-OHFA by Micrococcus luteus was investigated. It turned out that 10-OHFA was synthesized only from
fatty acids possessing cis-9-unsaturation. It was also shown that 10-OHFAs were converted to the corresponding 10-OXOFAs but the 10-OXO compounds were inactive as substrates. Furthermore, it was found that the
enzyme preparations from Flavobacterium meningosepticum solubilized by sonication catalyzed not only hydration of
oleic acid to produce
10-hydroxystearic acid, but also dehydrogenation of this product in the presence of
deuterium. On the other hand, we found out that there was
10-hydroxy-12-octadecenoic acid (10-OHODA) from
linoleic acid in some kinds of
adipocere. Recently, 10-epoxy-12-octadecenoic
acid (
leukotoxin, LTx), which is one of the
lipid peroxides, was found not only in rice plants but in polymorphonuclear leukocytes. Since LTx was found in leukocytes related to inflammatory response, interest has been focused on its involvement, not only in the basic mechanism of
biological defense, but also on the mechanism of
shock as a vasoactive substance. A
postmortem change itself is only remotely associated with a phenomenon in a living body. However, 10-OHODA found in
adipocere seemed to exist also in polymorphonuclear leukocytes, suggesting that this compound might be closely related to a
biological reaction.