Neem: An Overview

Abstract

Neem (Azadirachta indica) belonging to the Meliaceae family is popular tree. In Traditional System of Medicine, bark, leaf, flower, seed, oil and other parts are used for number of aliments. Number of patents has been filed for neem for pharmacological uses. This review provides a detailed view on Pharmacognosy, phytochemistry and pharmacological activity reported so far.

Keywords: Neem; Azadirachta indica; Pharmacognosy; Phytochemistry; Pharmacological activity; Review

Introduction

Azadirachta indica is an adaptable medicinal tree belonging to Meliaceae family. Every part of neem has some beneficial effects on human ailments and hence it has gained worldwide importance. 4000 years existence plant in India is Azadirachta indica [1].

A.indica also known as Margosa tree, as ‘arista’ or ‘nimba’ and ‘nimbati swasthyamdadati in Sanskrit meaning ‘to give good health’. The biological benefits of neem are enlisted in ‘Charak-Samhita’ and ‘Susruta-Samhita’, which forms the basis of Ayurvedic system of treatment. ‘Azad- Darakth- E- Hind’ means ‘Free tree of India’ in Persian. Neem is considered genetic diverse plant. In India, Neem was used for chicken pox and small pox from antiquity. It has been used for environment protection such as soil erosion, soil fertility, insecticide, pesticide etc [2].

Habitat

Although the exact native region of Neem tree is not known, it is thought to be originating naturally in south Asia and it grows in natural forests with drier-climatic condition of southern India and Burma. For many millennia, neem has been cultivated in India, Pakistan, Sri Lanka, Bangladesh, Myanmar, Thailand, Southern Malaysia, and the drier Indonesian islands from Java eastward. Neem was introduced to Fiji and Mauritius during early 19^th century [3].

Climate

It is a drought resistant tree and the mean annual temperature ranges from 21 to 32°C for its growth. In India, neem grows at temperatures between 0 to 49°C and annual rainfall of less than 600 mm. The plant is also used in afforestation programmes in arid and semi-arid regions [4].

Propagation and Cultivation

It is a hard tree, grows well in saline soils and drought conditions. Growth is slow in water-logged conditions. Propagated from seeds, which should be sown immediately after ripening, as their viability is very short. Seeds germinate within three weeks time. Root suckers and stem cuttings are also used for planting. It can be grown in all types of soil, but black-loam soil is more suitable. Within one year, the seedlings grow up to a height of 120 cm. Rapid multiplication through leaf culture has been found successful. Tissue culture techniques have been reported for the production of azadirachtin from cultures of leaves and flowers. 20 weeks old callus of leaves is reported to yield maximum concentration of azadirachtin upto 2.68 % and the 12 weeks old flower callus 2.46 % of azadirachtin on dry weight basis [5,6].

Scientific Classification of Neem

Kingdom: Plantae

Division: Magnoliophyte

Class: Magnoliopsida

Order: Sapindales

Family: Meliaceae

Genus: Azadirachta

Species: indica

Scientific name: Azadirachta indica

Vernacular Names

¾Hindi – Nim, Nimb

¾English – Margosa, Neem, Indian Lilac

¾Konkani – Beva-rooku

¾Bengali – Nim,Nimgach

¾Marathi – Kadunimb

¾Gujarathi – Limba

¾Tamil – Veppamaram, Vempu, Veppam

¾Punjabi – Nimb

¾Malayalam – Veepu, Aryaveppu, Aruveppu, Kaippan, Veppu, Vepa

¾Oriya – Nimo

¾Telugu –Vepa, Yapachettu

¾Kannada – Bevinmar, Kahibevu [7]

Botanical Description

Macroscopical Characteristics

A large evergreen tree, 12 to 18m high with bitter in taste.

Bark: Dark brown to grayish, thick hard woody, external rough surface, scaly, oblique furrows, bitter taste, characteristic odor, straight trunk.

Leaved: Leaves are dark green coloured, compound, ovate- lanceolate, attenuate, opposite, imparipinnate (5-15 leaflets), serrated edges, short petioles, 3-8 cm long, with typical odor.

Fruits: Glabrous, olive like drupe, oval to roundish, green, edible and thin skinned.

Flowers: Flowers are white, fragrant, arranged in axillary panicles, protandrous, bisexual flowering.

Seed: One seeded only, dirty brown in color, with gritty touch and oily.

Microscopical Characteristics

The transverse section showed outer dark reddish brown rhytidoma consisting of 10 to 15 rows of outer most dark brown colored cells of cork, and a narrow band of stone cells lying underneath this followed by outer few rows of parenchyma and inner wide 20 to 25 rows of dark orange brown colored phloem tissue; very narrow band of phelloderm with tangentially running tannin cells and very wide phloem with discontinuous groups of crystal fibers alternating with medullary rays. Prismatic crystals of calcium oxalate traversed throughout the parenchymatous cells.

Powder Characteristics

It shows abundant fragments of rhytidoma embedded with stone cells, isolated or groups of fibres; few oval to rectangular sclerides associated with idioblast containing prismatic crystals of calcium oxalate, few simple, oval to spherical starch grains and parenchymatous cell filled tannin contents [8-10].

Traditional Actions and Uses

Bark: It is urinary astringent, acrid, pectoral, tonic, hyperdipsia, leprosy, skin diseases, eczema, leucoderma, pruritis, malaria, burning sensation, tumor, dyspepsia, intestinal worms, hepatopathy, cough, bronchitis, urine incontinence, diabetes, inflammation, wound healing, ulcer, amenorrhea, lumbago, hemorrhoids, otalgia, syphilis and fatigue.

Leaves: It is anthelmintic, insecticidal, demulcent, refrigerant, skin diseases, leucoderma, in burning sensation, leprosy, pruritus, antiseptic, ophthalmic, ophthalmopathy, intestinal worms, dyspepsia, ulcer, tuberculosis, boils, eczema,malarial and intermittent fevers.

Flowers: It is used as a refrigerant, ophthalmic, stomachic, anthelmintic, tonic, burning sensation, ophthalmopathy, colic, dyspepsia, intestinal worms and general debility.

Seeds: It is used as acrid, thermogenic, purgative, emollient, anodyne, anthelmintic, depurative, vulnerary, uterine stimulant, urinary astringent, tumors, leprosy, skin diseases, odontalgia, intestinal worms, wounds, ulcers and diabetes.

Oil: It is anthelmintic, anodyne, depurative, chronic skin diseases, syphilitic sores, ulcer, ringworm, scabies, worms, fever and leprosy [1,2,4,7].

Ayurvedic Properties

Rasa: Tikta, Kashaya

Guna: Laghu

Veerya: Sheeta

Vipaka: Katu

Doshaghnata: Kaphapitashamaka

Rogaghnata: Vidradhi, Granthi, Amavata, Vamana, Kaphapaittika etc.

Karma: Vranapachana, Vranashodhana, Ampachana, Juaraghna, Vishamapwara pratibandhaka, Chakshushya etc.

Doses

Bark powder: 2 to 4 gm

Leaf juice: 10 to 20 ml;

Powder: 2-4 g.

Oil- 5 to 10 drops [11].

Chemical Constituents

More than 100 compounds, mostly triterpenoids of protolimonoids (proto-meliacin), Limonoids (or meliacins or tetranortriterpenoids), tetranortriterpenoid-γ hydroxy butenolides, pentanortriterpenoids. Hexanortriterpenoid apart from a few nontriterpenoid constituents have been reported from various parts as detailed below.

Leaves: Azadirachtin, azadirachtol, azadirachnol, deacetyl-azadirachtinol (-3- tigloylazadirachtol), azadiradione, an isomer of epoxyszadiradione, 17 epi and 17-hydroxyazadiradione, gedunin, 7-hydroxygedunin, melianone, bol nimboeinol (7-acetoxy-7-hydroxy azadiradione), nimocin, 7-deacetoxy- nimolicinol, nimolinone, nimbochalcin and nimbocetin, 21,23 24,25- diepoxytirucall-7-en-21-ol salannin, azadirachtanin, azadirone, azadiradione,epoxyazadiradione, isoazadirolide, nimbandiol nimbinene desacetylnimbinene, nimbin, nimbocinolide, isonimbocinolide, nimbolide, nimocinolide, isonimocinolide, nimocinone, 2',3'-dehydrosalannol kaempferol-3-0-8-glucoside, myricetin, 3-L-arabinoside (mellictrin), 3-0-L-ehanmonide and 3-0-rutinoside, quercetin, its 3-galactoside, 3-0-L- thanoside and 3-0-runinoside, nimbaflavones, scopoletin, β-sitosterol and its β-D-glucoside, amino acids, β-carotene, carbohydrates, n-hexacosanol, nomacommol, protein and vitamins.

Fruits and Seeds: Kernels yield about 400-48.9% of the oil and contain high amount of tocopherol, arachidic, linoleic, margosic, myristic, oleic, palmitic and stearic acids, azadirone azadiradione, epoxyazadiradione (nimbinin), gedunin, meldenin, meliatriol, nimbine, mbinene 6-desacetyl nimbinene, nimbidin, nimbidiol, 6-O-acetylnimbandiol, nimbidic acid, salannin, 3-desacetylsalannin, salannol and its acetate, salannolide, vepinine, vilasinin 1,3-diacetylvilasinin, 1-tigloyl-3-acetyl-vilasinin, and tiglic acid (seed oil), in addition, azadirachtin, 22,23-dihydro-23-8-methorey- azadirachtin (vepaol) and its C-23 epimer (isovepaol), 7-desacetyl-7-benzoyl derivatives of azadirone, azadiradione, epoxyazadiradione, 2-dihydro- epoxyazadiradione, 18.28-diepoxyazadiradione, 7-desacetyl-7-benzoyl-geduni acetylneotrichilenone, nimbidin, nimbidinin, salannic (nimbidic) acid (seeds).

Flowers: Benzyl alcohol, β-sitosterol, thioamyl alcohol, arachidic, behenic, colic, oleic, palmitic and stearic acids, kaempferol and its 3-glucoside, quercetin -3- galactoside and myricetin-3-L-arabinoside, azadirachtin and margosene. flowerine, flowerone, O‐ methylazadironolide and diepoxyazadirol. Other known constituents present in flowers are triterpenoid (trichilenone acetate), flavanones, nimbaflavone, 3′‐prenylnaringenin and 4‐(2‐hydroxyethyl) phenol.

Heartwood: Tannin, β-sitosterol and its glucoside, 24-methylene-cycloartenol, 4,14,α-dimethyl-3-α-ergosta-8, 24(28)- d-38-ol 4-methyl-Sa-ergosta-8, 24(28)-dien-38-ol, nimatone, nimbinene, 6-desacetyl nimbinene, nimbolins A and B.

Stem bark: Vanilic acid, catechol, campesterol stigmasterol, sitosterol, β-amyrin, lupeol, nimbin, nimbidin, nimbinin supiol kulinone, kulactone, kulolactone methyl kulonate, 60- hydroxy-4-stigmasten-3-one and 68-hydroxy-4-campesten-3-one.

Wood: Gedunin, 7-deacetoxy-7-axogedunin, fraxinellone, nimbolin A gydoeucalemone, melanin A and B.

Twigs: Margosinolide, isomargosinolide, desacetyl nimbinolide and desacetyl isonimbinolide.

Wood Oil: Cycloeucalenol, 24- methylene cycloartenol and β-sitosterol.

Trunk bark: Nimbiol, sugiol and bosterol nimbolins A and B (trunk wood),

Root: 24-methylene- cycloartenol, 24-methylene-cycloartanone, cycloeucalenol, cycloeucalenone, 4- campesten-3-one, 4-stigmasten-3-one, trans-cinnamic and vanillic acids, nimbin and nimbidin.

Besides aesculetin, campesterol, 6-hydroxy- 7-methoxy-coumarin, 4α, 6α-dihydroxy-A-homoazadirone, isomeldenin, meldenindiol, 17-acetoxy-meliacin, 6-0-acetylnimbandiol, desacetylnimbin, nimocinol, isonimolicinolide and nimolinolic acid have been isolated from various parts of tree [12-17].

Identification by TLC

Stationery phase: Silica Gel GF254 precoated plates

Mobile phase: Toluene: ethyl acetate: glacial acetic acid: 5:5:1

Standard preparation: 10 mg of epicatechin is dissolved in 5 ml of methanol

Sample preparation: Reflux 5 g of drug with methanol for 8 hrs [2 times]. Filter and remove the solvent. Dissolve in 10 ml of methanol.

Spray reagent: Spray with 10% ethanol potassium hydroxide solution and observe under UV 365 nm.

Detection: Rf 0.29 corresponding to epicatechin is seen in both standard and test.

Estimation by HPTLC

Method is followed as per identification method except plate after drying is scanned at 424 nm

Content present in the sample is determined from the peak area under the curve.

Quantitative Standards

Foreign matter: Not more than 0.3 % w/w

Ash: Not more than 3.0 % w/w

Acid insoluble ash: Not more than 0.25 % w/w

Alcohol soluble extractive: Not less than 4.5 % w/w

Water soluble extractive: Not less than 5.0 % w/w [11,18]

Therapeutic Properties

The pharmacological activities of phytoconstituents reported so far from this plant is given below in the Table [13-15].

Pharmacological Activities

To understand the pharmacological activity it is given in form of Table below

Formulations and Preparations

Shankhapushpi taila, Jwarasamhara rasa, Mahamarichyadi taila, Pathyadi kvatha, Mahamanjishthadyarishta, Punarnavadi kvatha, Mahasudarshana churna, Raktashodhaka vati, Nimbaharidra khanda, Nimbarishta, Mahagandhaka vati, Nimbadi churna, Panchaguna taila, Madhyam narayana taila, Guduchyadighana kvatha [11].

Safety Aspects

The drug used traditionally in prescribed doses may be considered safe.

Conclusion

We can say neem as one plant for treatment of number of ailments. Scientifically it has be proven to be antioxidant, wound healing, antipyretic, antiallergic, antiasthmatic, anti-inflammatory,hepatoprotective, nueroprotective, nephroprotective, immunomodulatory, antifertility, dental hygiene, antidiabetic, cardioprotective, antimicrobial, anticancer, pesticide etc. This review gives the details of chemicals isolated and pharmacological activity of the isolated compounds as well as extract. An extensive research and development work should be undertaken on neem and its products for their better economic and therapeutic utilization.

Author Statements

Acknowledgement

The authors would like to thank Dr S.N.V.L Narasimha Raju, Chairman, The Oxford Group of Institutions and The Oxford College of Pharmacy for their kind support for the project work. Articles taken for this publication from different source is also acknowledged.

Conflicts of Interest

There are no conflicts of interest.

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