Source, Etc

The capsicum fruit official in the British Pharmacopoeia is derived from Capsicum minimum, Roxburgh (N.O. Solanaceoe), a small erect shrub with spreading branches, producing oblong-conical fruits commercially known as chillies, the fruits of G. annuum being termed capsicums. It is apparently a native of Southern India but is cultivated in Eastern and Western Africa, in South America, etc. The plant shows a great disposition to vary and the chillies and capsicums of commerce vary exceedingly in their size shape, and pungency. In Hungary G. tetragonum, Miller, and G. annuum, var. Szegedinense are widely grown, and produce the large fruits with a short peduncle and conspicuous green calyx known as paprika. In Italy and Spain G. grossum, Linne (C. annuum, Linne, var. grossum) is cultivated, but in tropical countries G. minimum and G. frutescens, Linne, are most largely cultivated; these yield smaller and more pungent fruits, those of C. minimum being alone official.

The fruits are collected when ripe, and dried.

Description

The fruits of G. minimum have, when fresh, a scarlet colour which changes on drying to a dull orange red. They are oblong-conical in shape, and obtuse at the apex; they vary usually from 12 to 20 mm. in length, and do not exceed 7 mm. in diameter. They are superior, and not unfrequently remain attached to a small, inconspicuous, five-toothed, inferior calyx, and straight, slender peduncle, which is as long as, or rather longer than, the fruit itself. The pericarp is somewhat flattened, shrunken, and shrivelled. It is quite glabrous and shining, thin and leathery in texture, and more or less translucent.

Cut transversely, the fruit is seen to consist of two cells separated by a thin, reddish, membranous dissepiment. Each cell contains from five to ten small, flat, nearly circular, whitish seeds with a characteristic, thickened margin; they were originally attached to the dissepiment, but are frequently found loose in the cavity.

Capsicum fruits have a characteristic but not powerful odour, and an extremely fiery pungent taste. The latter resides principally in the membranous dissepiment that divides the fruit into two cells.

The student should observe

(a) The shape and size of fruit and peduncle,

(b) The dissepiment and its pungent taste,

(c) The shape of the seeds.

Constituents

The most important constituent of capsicum fruit is the pungent principle, capsaicin (0'02 per cent.), first isolated by Thresh (1876) in colourless, odourless crystals. It also contains a minute quantity of a liquid alkaloid which is not pungent, a fixed oil, and red colouring matter; the seeds may contain traces of starch.

Constituents 100Constituents 101Constituents 102Fig. 68.   a, Zanzibar; b, Sierra Leone; c, Japanese chillies; d, Bombay capsicums. Natural size. (Chemist and Druggist.)

Fig. 68. - a, Zanzibar; b, Sierra Leone; c, Japanese chillies; d, Bombay capsicums. Natural size. (Chemist and Druggist).

Capsicum fruits yield about 5 (not over 7) per cent, of ash and from 20 to 25 per cent, of alcoholic extract, known in commerce as capsicin; the same name has also been applied to an ethereal extract as well as to a soft red substance extracted by ether from an alcoholic extract. All of these contain capsaicin associated with fixed oil, colouring matter, etc.

Capsaicin (capsacutin) is secreted by the epidermis of the dissepiments of the fruit, between the outer cell wall and the cuticle.

Thresh assigned to it the formula C9H1802, which has been corrected to C18H17N03. The crystals melt at 65° and at higher temperatures are volatile, the vapour being extremely irritating; they are phenolic in character, dissolving in dilute solution of potassium hydroxide, but being reprecipitated by a current of carbon dioxide. The pungency is not affected by the alkali but is destroyed by oxidation with potassium bichromate or permanganate. Much interest is attached to this substance, as it is one of the very few pungent principles that have been isolated in a crystalline form, most of them being obtainable only in the state of oily liquids.

Microscopical Characters

For the complete identification of the fruit of C. minimum the following histological characters are necessary in addition to the macroscopical characters detailed above. The outer epidermis of the pericarp consists of rectangular cells with a delicately striated cuticle and straight, thick, yellow, sparsely pitted walls abutting on parenchymatous tissue, the cells of which contain droplets of red oil and have thin cellulose walls. The inner epidermis of the pericarp exhibits groups of sclerenchymatous cells alternating with bands of thin-walled parenchyma, the whole forming a very characteristic tissue. The epidermis of the seed is composed of very large sinuous cells with thin outer walls, but strongly thickened and pitted radial and inner walls.

Varieties

Sierra Leone: these are regarded as the most pungent of all. They have the macroscopical and microscopical characters detailed above. The pod is rather slender, bright in colour, with the stalk occasionally attached.

Nyassaland closely resemble Sierra Leone, but are rather brighter and more free from stalk.

Zanzibar are usually duller in colour, more stalky, and the pod rather shorter and broader.

Japanese: these are distinguished by their very bright, reddish colour and freedom from stalk; the cells of the epidermis of the pericarp have a smooth (not striated) cuticle, strongly thickened walls and radiate lumen; the cells of the single-layered hypoderma have rather thick, pitted, cuticularised walls. These fruits are less pungent than the African, but are valued for their very bright colour. According to Holmes the small Japanese chillies of commerce are probably derived from C. frutescens, Linne; the larger from a form of G. minimum, Roxburgh.

Fig. 69.   Capsicum an nuum, fruit. Natural size. (Bentley and Trimen.)

Fig. 69. - Capsicum an-nuum, fruit. Natural size. (Bentley and Trimen).

Fig. 70.   Natal capsicum fruit. Natural size. (Chemist and Druggist.)

Fig. 70. - Natal capsicum fruit. Natural size. (Chemist and Druggist).

Bombay capsicums, the fruits of C. annuum, Linne. They vary-considerably in size and shape from nearly globular to oblong; they are larger than the fruits of C. minimum, and have a less pungent taste. The stalk is usually bent, the calyx larger, the pericarp more leathery, and the dissepiment does not extend throughout the entire length of the fruit. The cells of the epidermis are polygonal, larger than those of C. minimum and with numerous pits, while the hypo-derma consists of several layers of cuticularised collenchymatous cells.

Natal capsicums: these are much larger, averaging about 8 cm. in length, and are distinguished by their beautiful, transparent red pericarp.

Paprika, which is largely grown and used in Hungary, is derived from C. tetragonum, Miller, or from C. annuum, var. Szegedinense; the fruits are large and usually more or less distinctly tetragonal in shape.

Bird Pepper, the powder of which is given to canaries to improve the colour of their plumage is derived from C. annuum, var. grossum, Sendtn. (Spanish) or C. annuum, var. Szegedinense (Hungarian); it is free from pungency.

Uses

Cayenne pepper is applied externally as a stimulant and counter-irritant; internally it is used as a pungent stomachic carminative and stimulant, to dispel flatulence and rouse the appetite.