Originally from south? estern India, P. nigrum is highly regarded as a condiment as well as a medicine, especially in Ayurveda and Unani. It is an important constituent of the Ayurvedic preparation Trikatu,l and historically was important to the Romans, Africans and Europeans. White pepper comes from the same plant but the fruits are ripe and peeled; it has a more pungent taste.
The plant grows wild in tropical par!s of India and is widely cultivated there and in many other countries including Sri Lanka, China and parts of Africa.
Pepper is a climbing perennial shrub cultivated on posts or wire and growing up to a height of 6 m (Plate 46). The branches are stout, trailing and rooting at the nodes. The glossy pale green leaves are entire, 8-18 cm in length and 5-10 cm in breadth, with an acute base, rounded or equally or unequally cordate. The flowers occur in minute spikes and are dioecious. The female bears two anthers and the male a single pistil. Fruiting spikes usually vary in length. Fruits are globular or oblong, 4-6 mm in diameter, and externally are bright red when ripe and blackish-brown when dried, with protruding reticulate wrinkles and a single seed. Seeds are white, hollow, globose with a thin testa and hard albumin. They are aromatic and strongly pungent.
Dried unripe fruits, oleoresin and volatile oil.
Black pepper is used particularly for stomach and digestive disorders and colds and bronchitis. It also finds use in conditions like neuralgia and scabies. External application helps to relieve pain due to cold and neuralgia, piles and various skin diseases. In Indian medicine it is used as an aromatic stimulant in cholera, weakness following fevers and vertigo, as an antiperiodic in malaria and for arthritic disease; Trikatu is used to enhance the bio-availability and efficacy of other medicines. In Chinese medicine it is used to improve the appetite and in the treatment of cold, influenza, pains of the upper abdomen, diarrhoea and epilepsy.
The dried fruits contain 1.2-2.6% of volatile oil mainly composed of sabinene (15-25%), caryophyllene, a-pinene, ?-pinene, ?ocimene, 8-guaiene, farnesol, 8-cadinol, guaiacol, 1-phellandrene, 1,8 cineole, p?cymene, carvone, citronellol, a-thujene, a-terpinene, bisabolene, dl-limonene, dihydrocarveol, camphene and piperonal.
These are the main pungent principles and include piperine, piperylin, piperolein A and B, cumaperine, piperanine, piperamides, pipericide, guineensine and sarmentine. Other alkaloids include chavicine, piperidine and piperettine, methyl caffeic acid, piperidide, ?-methyl pyrroline, and a series of vinyl homologues of piperine and their stereoisomers.
The dried fruits are rich in ?-alanine, arginine, serine, threonine, histidine, lysine, cystine, asparagine and glutamic acid in combination with y-aminobutyric acid and pipecolic acid.
Ascorbic acid, carotenes, thiamine, riboflavin and nicotinic acid are present and minerals including potassium, sodium, calcium, magnesium, iron, phosphorus, copper and zinc.
Antimicrobial activity: Black pepper extracts inhibited aflatoxin production, via the p?glucuronidase reporter gene under the control of the aflatoxin biosynthesis gene promoter in the fungus Aspergillus parasiticus.ll Using the agar diffusion method, both the ethanol and aqueous extracts of the dried fruits were found to have significant activity against a penicillin G-resistant strain of Staphylococcus aureus. An extract was toxic to the culture of Escherichia coli, Staphylococcus faecalis, Staph. aureus, Staph. albus, Corynebacterium diphtheriae, Salmonella dysenteriae and S. sonnei. The volatile oil also exhibited a high degree of antimicrobial activity against various types of organisms including animal pathogens, organisms involved in food poisoning and other spoilage bacteria and fungi.
Effect on the gastrointestinal trad: An aqueous extract of black pepper perfused into pentobarbitone-anaesthetised rats increased acid secretion. This was mainly due to cholinergic activity but may involve other mechanisms also. Piperine has the capability to increase absorption from the intestine by enhancing permeability of intestinal cells. This is thought to be due to stimulation of y-glutamyl trans peptidase enzyme activity and increased lipid peroxidation.
Melanocyte proliferating activity: An aqueous extract enhanced cell multiplication in a mouse melanocyte culture (melan-a), which was inhibited by protein kinase C, suggesting the involvement of PKC signalling.
Thermogenic activity: Oxygen uptake by the perfused rat hind limb was increased by piperine, in association with vascular resistance which was blocked by glyceryl nitrate. This implies piperine may act as a thermogenic agent.
Hepatic enzyme induction: Administration of black pepper to experimental animals resulted in a significant elevation of glutathione S-transferase (GST), cytochrome bS, cytochrome P4S0, acid-soluble sulfhydryl (-SH) content and malondialdehyde (MDA) levels in a dose-dependent manner. This shows it induces various detoxification enzymes, which suggests a possible role as a chemopreventive. Piperine protected the liver against the toxic effects of tert - butyl hydroperoxide and carbon tetrachloride by a reduction in lipid peroxidation, prevention of enzymatic leakage of GPT and AP, and by the inhibition of GSH depletion and total thiols.
Anticancer activity: Increased activities of ?glucuronidase in the distal colon, and levels of mucinase in the colon and faeces in experimental colon cancer, were brought down to almost normal by the ingestion of black pepper. This may prevent the hydrolysis of glucuronide conjugates, which liberate toxins, and the degradation of mucinase, which would prevent the hydrolysis of protective mucins in the colon.
Antiinflammatory activity: Piperine exhibited activity by depressing both the acute inflammatory process and chronic granulative changes using carrageenan?induced rat paw oedema, cotton pellet and croton oil-induced granuloma pouch models. It was thought to act partially through the stimulation of the pituitary adrenal axis.
Antioxidant effects: Pepper is rich in phenolic amides and possesses antioxidant effects that are more potent than a-tocopherol and equivalent to the synthetic antioxidants butylated hydroyanisole (BHA) and butylated hydroxytoluene (BHT).
Anticonvulsant effects: In a recent study piperine and derivatives antagonised convulsions in animals induced by both physical and chemical methods.22 In another experiment, convulsions produced by an intracerebroventricular injection of kainite was blocked by piperine, possibly due to activity at different aminoacid receptor subtypes.
Pepper is widely used and considered safe at the usual therapeutic doses and as a flavouring. Use during pregnancy has not been properly evaluated and excessive intake is not encouraged in nursing mothers as metabolites are excreted into human milk. As it is known as an enzyme inducer it may reduce blood levels of concurrent medication if taken in large doses over a period of time.