Botanical name: Azadirachta indica, Melia azadirachta, Meliaceae
Other names: Nim, Nimb (H), Vempu, Veppu (T), Neem, Margosa (E)
Botany: Nimba is a medium to large evergreen tree, attaining a height of between 15 and 20 meters, with a straight bole, widely spreading branches, and grayish tubercled bark. The leaves are alternate and imparipinately compound, with 7-17 leaflets arranged in pairs, often with a terminal leaflet, ovate to lanceolate, sickle-shaped with an uneven base and serrate margins, 6-8 cm long, 1-3 cm wide. The flowers are cream to yellow in color, borne in axillary panicles, giving rise to a single seeded ellipsoid drupe that is greenish-yellow when ripe. Nimba is widely cultivated in tropical and subtropical regions all over the world, and is thought to be native to the subcontinent (Kirtikar & Basu 1935, Warrier et al 1994).
Part used: Bark, leaves (Nimbapatra), seeds (Nimbaphala).
• Rasa: kaṣāya, tikta
• Vipāka: kaṭu
• Vīrya: śīta
• Karma: dīpanapācana, vamana, purīṣasangrahaṇīya, kṛmighna, jvaraghna, chedana, dāhapraśamana, raktaprasādana, kuṣṭhaghna, mūtravirecana, mūtraviśodhana, saṃdhānīya, viṣaghna, pittakaphahara (Srikanthamurthy 2001, Warrier et al 1994).
Constituents: Nimba is a fairly well researched medicinal plant, and as a result a number of constituents have been isolated from it. Among these are bitter-tasting terpenes called limonoids, including azadirachtin, nimbanal, nimbidiol, margocin, margocinin and related compounds, as well as a variety of other terpenoids including isoazadirolide, nimbocinolide, gedunin, margosinone and nimbonone. More recently, researchers have isolated a series of tetranortriterpenoids including azadirachtol, 1alpha,2alpha-epoxy-17beta-hydroxyazadiradione, 1alpha,2alpha-epoxynimolicinol, and 7-deacetylnimolicinol. Other constituents include the flavonoids kaempferol, quercetin, quercitrin, rutin, and myricetin, as well as b-sitosterol, a tannin, a gum, and a series of polysaccharides named CSP-II and -III, CSSP-I, -II, and -III, etc. (Duke 2003, Hallur et al 2002, Kapoor 1990, Luo et al 2000, Malathi et al 2002, Williamson 2002).
• In vitro: negatively ionotropic/chronotropic (Kholsa et al 2002); hypotensive (Chattopadhyay 1997); antiviral (Badam et al 1999, Parida et al 2002); antifungal (Fabry et al 1996); antibacterial (Almas 1999, Alzoreky and Nakahara 2003)
• In vivo: hepatoprotective (Arivazhagan et al 2000, Bhanwra et al 2000); anti-ulcerogenic (Bandyopadhyay et al 2002); hypoglycemic (Kholsa et al 2000) hypotensive (Koley and Lal 1994); immunostimulant (Mukherjee et al 1999, Njiro and Kofi-Tsekpo 1999, Upadhyay et al 1992); anti-inflammatory (Chattopadhyay et al 1998); antitumor (Kumar et al 2002, Tepsuwan et al 2002); anxiolytic (Jaiswal et al 1994), antifertility (Kasturi et al 2002, Mukherjee et al 1999; Parshad et al 1994); antiviral (Parida et al 2002)
Human trials: a lyophilised powder of Nimba extract administered over 10 days, 30-60 mg twice daily, caused a significant decrease in gastric acid secretion and pepsin activity, and when taken between 6-10 weeks almost completely healed lesions in patients suffering duodenal, gastric and esophageal ulcers (Bandyopadhyay et al 2004); an extract of Nimba was found to lower total serum cholesterol and LDL-cholesterol levels in non-malaria patients, while increasing triacylglycerol and HDL-cholesterol malarial patients (Njoku et al 2001); a Nimba mouth rinse was found to be active against Streptococcus mutans and reversed incipient carious lesions (Vanka et al 2001); a dental gel containing Nimba leaf extract (25 mg/g) was found to significantly reduced the plaque index and bacterial count compared to chlorhexidine gluconate (0.2% w/v) mouthwash (Pai et al 2004) ; a paste prepared from Nimba and Haridrā was found to promote a 97% cure rate in scabies within 3 to 15 days of treatment, with no toxic or adverse reactions (Charles and Charles 1992); a 2% Nimba oil mixed in coconut oil applied to the exposed body parts of human volunteers provided complete protection from mosquito bites over a 12 hour period (Sharma et al 1993).
Toxicity: A cumulative oral dose of the crude bark extract of Nimba, of 1 to 9 g/kg in mice over a 15 day period, was well tolerated and below the LD50 (Bandyopadhyay et al 2002). The seed oil of Nimba was determined to have a 24 hour oral LD50 of 14 ml/kg in rats and 24 ml/kg in rabbits. The lungs and central nervous system appeared to be the target organs of toxicity. In comparison, a mustard seed oil was determined to have an oral LD50 of 80 ml/kg (Gandhi et al 1988). Chewing sticks made from Azadirachta indica was observed to be susceptible to post-harvest spoilage and are not advisable for oral hygiene measures if not fresh (Etebu et al 2003).
Indications: Dyspepsia, ulcers, intestinal parasites, hemorrhoids, liver diseases, fever, malarial fever, cough, bronchitis, asthma, tuberculosis, skin diseases, inflammatory joint disease, cystitis, amenorrhea, diabetes, tumors, conjunctivitis and ophthalmic disorders generally.
Medicinal uses: Nimba is a widely used remedy in India, cultivated in villages, gardens and parks for its beauty as well as for its medicinal properties, as a culinary spice, as a chewing stick, and for firewood. The name Nimba is an ancient name, derived from the Sanskrit phrase “nimbati svāsthyamdadāti,” meaning ‘bestower of good health.’ Nimba is a sacred tree in India, associated with Lakṣmī, the goddess of abundance and good fortune, and Surya, the sun. It has a bitter taste and a cooling energy, acting to remove congestion and reduce inflammation, and is thus reserved for afflictions of pitta and kapha. Although one study indicates an anxiolytic effect, the Bhāvaprakāśa states specifically that it is “bad for the heart,” and “unpleasant for the mind” (Srikanthamurthy 2001). Nimba is an important herb in fever, used in simple formulations such as a soup prepared with Paṭola (Sharma 2002). It is also used in more complex formulations such as Nimbādi kvātha, used in the treatment of masūrikā, or chicken pox, comprised of equal parts Nimba, Harītakī, Kaṭuka, Vāsaka, Uśīra, Āmalakī, Candana, Parpaṭa, Durālabhā, Paṭola, and Raktacandana (Sharma 2002). In the treatment of jaundice the Cakradatta recommends a buffalo milk decoction of Nimba, Haridrā, Pippalī, Balā and Yaṣṭimadhu (Sharma 2002). In the treatment of acid reflux and vomiting associated with gastritis, as well as colic and fever, the Cakradatta recommends a decoction of Nimba, Guḍūcī, Triphalā and Paṭola, taken cool with honey (Sharma 2002). In the treatment of unmāda (‘psychosis’) Nimba leaves are reduced to a powder with Vacā, Hiṅgu, Sarṣapa seed and the discarded skin of a snake, and burned as an incense (Sharma 2002). In the treatment of gout and eczema Nimba is mixed with equal parts Triphalā, Mañjiṣṭhā, Vacā, Kaṭuka, Guḍūcī and Dāruharidrā, taken as a cūrṇa or kvātha (Sharma 2002). In combination with Punarnavā, Kaṭuka, Guḍūcī, Devadāru, Harītakī, Paṭola, and Śūṇṭhī, Nimba is stated to be an effective treatment for intestinal parasites associated with anemia and dyspnea (Sharma 2002). Mixed with Haridrā, Nimba has been shown to be an effective remedy in the treatment of scabies, and similar formulations can be used in Udvartana abhyaṅga in the treatment of obesity and edema. Nimba is also used in premature aging and grayness associated with anger and physical strain, used as a simple medicated taila in nasya therapy for a period of one month (Sharma 2002). Nimba flowers are traditionally used in Tamil cookery, stir-fried with pepper, mustard seed, and Hiṅgu in ghṛta, after which water, tamarind paste, curry leaves and salt are added, as the base of a spicy, flavourable dīpanapācana soup. Nimba has recently undergone much investigation for its insecticidal properties against disease-carrying insects such as mosquitoes and common agricultural pests such as flies, beetles, worms, cockroaches and moths, but appears to cause little harm to beneficial insects such as wasps, butterflies, bees, spiders and earthworms (Vietmeyer 1992). Organic farmers can thus take advantage of Nimba’s insecticidal properties to good advantage, and people can apply the diluted oil (2%) to ward off mosquitos, without fear of harm. Some studies suggest that Nimba may act as a contraceptive, but this application is still in the experimental stage.
• Cūrṇa: bark, leaf, 1-2 g b.i.d.-t.i.d.
• Svarasa: leaf, 6-12 mL b.i.d.-t.i.d.
• Hima: leaf, 30-90 mL bi.d.-t.i.d.
• Kvātha: bark, 30-60 mL
• Seed oil: topically only, 2-50% v/v in a carrier oil