Amide pungent principles

The chemistry of pepper has long been studied and the pungent principle of black pepper—a piperidine alkaloid, piperine 134—was isolated as early as 1877 (201). Its synthesis from the acid and piperidine was accomplished in 1882. (202). The corresponding pyrrolidine alkaloid trichostachyne (135) was isolated some 100 years later from several Piper species (see below). The cooccurence of piperidine and pyrrolidine alkaloids is a common feature of the chemistry of pepper. In many cases, the crude alkaloid extract is first cleaved with acids or bases and then each alkaloid is reconstituted by selective amidation. For the sake of unity, this chapter will be limited to comments on pyrrolidines, even in cases where they are minor alkaloids. 

It is interesting to discuss the SEE of capsaicin next, directly after the discussion of the SEE of vanillin. Capsaicin is an amide (containing isoprene units) derivative of vanillin. Ten parts per milhon can be detected by tasting. Capsaicin is the compound responsible for the pungency (heat) of Jalapena and other peppers. It is the pungent principle in fruit of various species of Capsicum Solanaceae. 

The pungent principles of the fruits of pepper Capsicum species, Solanaceae) are A-(4-hydroxy-3-methoxybenzyl)al-kyl amides (Fig. 28.6). This plant should not be confused with black pepper. Piper nigrum (Piperaceae) see the discussion of pungent principles of black pepper in Chapter 29). The major and best known of these compounds is capsaicin (12) (Suzuki and Iwai, 1984). Capsaicin and its relatives comprise about 0.5-1.5% of some hot pepper cultivars. Other pepper cultivars have been selected for their very low content of these compounds. Capsaicin is synthesized in the fruit of Capsicum species (Suzuki and Iwai, 1984). 

Capsaicin is the pungent principle derived from fruits of cayenne pepper—Capsicum annum, C. frutescens (Solanaceae). Capsaicin, a phenolic amide, is present in the fruit at a level of only 0.02%, yet its taste is detectable even in minute doses. The compound acts as a local anaesthetic and pain reliever through a complex mechanism (see Chapter 8). 

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