Long pepper has long been used in medicine and is an important culinary spice throughout the Indian subcontinent, Sri Lanka, Middle Eastern countries and the Americas. It became opular in Europe, northern and eastern Mrica, where it was introduced by traders from India, and it is said that the Roman emperors valued it even more highly than black pepper.
It is considered a native of South Asia and is found both wild as well as cultivated, throughout the hotter parts of India from central to the north-eastern Himalayas. The herb also grows wild in Malaysia, Singapore, Bhutan, Myanmar and elsewhere.
A slender, aromatic, perennial climber, with woody roots and numerous wide ovate, cordate leaves (Plate 45). The inflorescence is a cylindrical, pedunculate spike, the female flower is up to 2.5 em long and 4-5 mm in diameter, the male flowers being larger and more slender. The fruits are small, ovoid berries, shiny blackish green, embedded in fleshy spikes.
Immature spikes, roots.
The dried fruit spikes are extensively used for flavouring a variety of foods. They are considered to have stimulant, carminative, laxative and stomachic properties. The berries are also given with honey for asthma, coughs and sore throats. The root is a stimulant and is also used in gout, rheumatism and lumbago. The whole plant is considered by tribal people in India to be useful in splenic disorders, cholera, dysentery, asthma, cough and bronchitis.
A decoction of the roots is given for swellings of the joints of cattle in the north-western Himalayan regions.
The fruit contains a large number of alkaloids and related compounds, the most abundant of which is piperine, together with methyl piperine, pipernonaline, piperettine, asarinine, pellitorine, piperundecalidine, piperlongumine, piperlonguminine, retrofractamide A, pergumidiene, brachystamide-B, a dimer of desmethoxypiplartine, N -isobutyl?decadienamide, brachyamide- A, brachystine, pipercide, piperderidine, longamide, dehydropipernonaline piperidine and tetra hydro piperine. Piperine, piperlongumine, tetrahydropiperlongumine, trimethoxy cinnamyol-piperidine and piperlonguminine have been found in the root.
Sesamin, pulviatilol, fargesin and others have been isolated from the fruits.
The fruits contain tridecyl-dihydro-p?coumarate, eicosanyl-(E)-p-coumarate and Z-12-octadecenoic-glycerol-monoester.
The essential oil of the fruit is a complex mixture, the three major components of which are (excluding the volatile piperine) caryophyllene and pentadecane (both about 17.8%) and bisaboline (11 %). Others include thujine, terpinoline, zingiberine, p-cymene, p-methoxyacetophenone and dihydrocarveol.
Immunomodulatory activity: Tests such as haemagglutination titre (HA), macrophage migration index (MMI) and phagocytic indeJ (PI) in mice have demonstrated the immunostimulatory action of Piper longum fruits to be both specific and non-specific. The effect was more prominent at lower doses (225 mg/kg) and was marginally reduced when the dose was increased," In another study, it was found to offer protection against externally induced stress,' A famous Ayurvedic preparation containing long pepper, Pippali Rasayana, was tested in mice infected with Giardia lamblia and found to produce significant activation of macro phages, as shown by an increased MMI and phagocytic activity.
Stimulant effects: Isolated piperine showed a central stimulant action in frogs, mice, rats and dogs and increased the hypnotic response in mice. It antagonised respiratory depression induced by morphine or pentobarbitone in anaesthetised dogs anda petroleum ether extract of the fruits antagonised morphine-induced respiratory depression in mice, A comparative study conducted with piperine and nalorphine,for effects against morphine-induced respiratory depression and analgesia, found that both reversed respiratory depression but, unlike nalorphine, piperine did not antagonise morphine-induced analgesia in rats,
Antiasthmatic activity: Studies have been carried out to validate the traditional claims of Ayurveda for antiasthmatic activity of Piper longum. An extract of the fruits in milk reduced passive cutaneous anaphylaxis in rats and protected guinea pigs against antigen-induced bronchospasm.
Bio-availability enhancement: Piperine has been shown to enhance the bio-availability of structurally and therapeutically diverse drugs, possibly by modulating membrane dynamics, due to its easy partitioning and increasing permeability.The effect of Trikatu', a compound Ayurvedic preparation containing Piper longum as one of the major ingredients, was tested in combination with other drugs. The study reported that Trikatu' increased their bio-availability either by promoting rapid absorption from the gastrointestinal tract or by protecting the drug from being metabolised during its first passage through the liver after being absorbed, or by combination of both mechanisms.
Hepatoprotective activity: Piperine was evaluated and found to exert significant protection against tertiary butyl hydroperoxide and carbon tetrachloride?induced hepatotoxicity, by reducing both in vitro and in vivo lipid peroxidation. A fruit extract was assessed in rodents for its hepatoprotective action against CCL,?induced acute, chronic and reversible damage and chronic irreversible damage, using morphological, biochemical and histopathological assessment parameters. The extract improves the regeneration process by restricting fibrosis, but offered no protection against acute damage or against cirrhotic changes.
Hypocholesterolaemic activity: Methyl piperine significantly inhibited the elevation of total serum cholesterol, and the total cholesterol to HDL-cholesterol ratio, in rats fed with a high cholesterol diet. The unsaponifiable fraction of the oil of Piper longum also significantly decreased total serum cholesterol and hepatic cholesterol in hypercholesterolaemic mice.
Antiinflammatory activity: A marked antiinflammatory activity of a decoction of P. longum fruits has been reported using carrageenan-induced rat oedema.
Antiamoebic activity: The fruits were tested for their efficacy against Entamoeba histolytica in vitro and experimental caecal amoebiasis in vivo. Both the ethanolic extract and isolated piperine produced an improvement of 90% and 40% respectively, in rats with caecal amoebiasis.
Antibacterial activity: The essential oil of P. longum showed antibacterial action against a number of bacterial strains32,33 although a 50% ethanolic extract of the fruits did not show any effect.3' Piperlonguminine was found to have potent activity against Bacillus subtilis while piperine was more effective against Staphylococcus aureus.
Since it is so widely used in cooking and traditional medicine, it is generally assumed to be safe in moderate doses. However, as the fruits are reported to have contraceptive activity in experimental models, its use during pregnancy and lactation should be avoided. Piperine may interfere with enzymatic drug biotransformations, resulting in the inhibition of hepatic arylhydrocarbon hydroxylase (AHH) and UDP?glucuronyltransferase, and alter the pharmacokinetic parameters of barbiturates and phenytoin. A single oral dose of 3 g/kg body weight in experimental animals, and chronic toxicity studies with 100 mg/kg body weight for 90 days, revealed no untoward effects. Studies of isolated constituents in mice gave LDso values for piperine, piperlongumine and piperlonguminine as 56.2:t 3.0, 110.1 :t 7.8 and 115.3:t 9.5 mg/kg body weight respectively.39 In the evaluation of antifertility activity, long pepper at a dose of 1 g/kg body weight was found to be an effective contraceptive agent without toxic or teratogenic effects.