The pungency of black pepper has been the subject of chemical investigations since the early nineteenth century. In 1819 Oersted (Guenther 1952) isolated piperine, the most abundant alkaloid in pepper, as a yellow crystalline substance, and its structure was later identified as the trans form of piperoyl piperidine. Later workers
recognising that piperine is not the only pungent principle of pepper continued the isolation work. Bucheim (Govindarajan 1977) obtained a pungent dark oily resin which he named as chavicine after removal of piperine from the oleoresin. This oily substance was claimed to possess a far greater bite on the toungue than crystalline piperine,but later workers demonstrated that piperine in solution is very pungent. The controversey over which compound viz. piperine, its cis-cis isomer chavicine or other possible isomers-isopiperine (cis-trans) and isochavicine (trans-cis)—is more pungent lasted almost a century. Recent investigations have demonstrated, however, that piperine is the major pungent principle and chavicine of the older literature is a mixture of piperine and several minor alkaloids. The presence of chavicine and isopiperine has not been confirmed in pepper extracts while isochavicine is shown to occur as an artefact of photolytic transformation of piperine. Five new minor alkaloids possessing a degree of pungency have been identified in pepper extracts. They are piperettine, piperylin, piperolein A and B and piperanine. Three trace constituents viz peepuloidin, guineesine and pipericide showing insecticidal properties have recently been identified.
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