NIMBA (Stem Bark)
Nimba (stem bark) consists of stem bark of Azadirachta indica A. Juss. Syn. Melia azadirachta Linn. (Fam. Meliacem); a moderate sized to fairly large, evergreen tree, attaining a height of 12-15 m with stout trunk and spreading branches, occurring throughout the country upto an elevation of 900 m.
SYNONYMS
Sanskrit : Arista, Picumarda
Assamese : Mahanim
Bengali : Nim, Nimgacha
English : Margosa Trees
Gujrati : Kadvo Limbdo
Hindi : Nim, Nimb
Kannada : Bevu, Kahibevu, Nimba, Oilevevu
Kashmiri : —
Malayalam : Veppu, Aruveppu
Marathi : Balantanimba, Kadunimb, Limba
Oriya : Nimba
Punjabi : Nim, Nimba, Bakam
Tamil : Veppai, Vembu
Telugu : Vemu, Vepa
Urdu : Neem
DESCRIPTION
a) Macroscopic
Bark varies much in thickness according to age and parts of tree from where it is taken; extemal surface rough, fissured and rusty-grey; laminated inner surface yellowish and foliaceous, fracture, fibrous; odour, characteristic; taste, bitter
b) Microscopic
Stem Bark -Shows outer exfoliating pieces hard, woody, considerably thick in older barks; almost entirely dead elements of secondary phloem, alternating with discontinuous tangential bands of compressed cork tissue, former composed of several layers of stone cells occurring in regularly arranged groups together with collapsed phloem elements filled with brown contents; in between the successive zones of cork tissue 3-5 layers of fibre groups with intervening thin-walled and often collapsed phloem elements present; each zone of cork tissue consists of several layers of regular, thinwalled cells occasionally with a few compressed rows of thick-walled cells towards outer surface; within exfoliating portion a number of layers of newly formed cork composed of thin walled, rectangular cells and one or two layers of cork cambium, below which a wide zone of secondary phloem present; secondary cortex absent in most cases; secondary phloem commonly composed of well-developed fibre bundles traversed by 2-4 seriate phloem rays and transversely separated by bands of parenchymatous tissue of phloem; phloem elements of outer bark mostly collapsed; a few fairly large secretory cavities also occur in phloem; most of phloem parenchyma contain starch grains and prismatic crystals of calcium oxalate; starch grains, simple, round with central hilum,measuring 2.75-5 n structure of bark varies considerably according to gradual formation of secondary cork bands.
Powder – Reddish-brown; shows numerous prismatic crystals of calcium oxalate, phloem fibres with narrow lumen and pointed ends; cork cells, stone cells mostly in groups, lignified rectangular to polygonal, having wide lumen and distinct striations, simple starch grains, measuring 2.75-5 n in diameter.
IDENTITY, PURITY AND STRENGTH
Foreign matter Not more than 2 per cent, Appendix 2.2.2.
Total Ash Not more than 7 per cent, Appendix 2.2.3.
Acid-insoluble ash Not more than 1.5 per cent, Appendix 2.2.4.
Alcohol-soluble extractive Not less than 6 per cent, Appendix 2.2.6.
Water-soluble extractive Not less than 5 per cent, Appendix 2.2.7.
T.L.C.
T.L.C. of alcoholic extract of the drug on Silica gel ‘G’ plate using Chloroform :
Ethylacetate; Formic acid (5:4: I:) shows under U.V. (366nm) three fluorescent zones at Rf. 0.72 (blue), 0.86 (blue), and 0.90 (green). On spraying with 5% Methanolic Phosphomolybdic acid reagent and heating the plate for about ten minutes at 105°C four spots appear at Rf. 0.20, 0.45, 0.63 and 0.90 (all blue).
CONSTITUENTS – Bitter principles Nimbin and Nimbiol
PROPERTIES AND ACTION
Rasa : Tikta
Guna : Laghu, Ruksa
Virya : Sita
Vipaka : Katu
Karma : Kandughna, Kaphahara, Pittahara, Visaghna, Vranasodhanakara, Hrdayavidahasantikara
IMPORTANT FORMULATIONS – Sudarsana Curna., Nimbadi Kvatha Curna, Nimbadi Curna, Pancanimba Curna, Pancatikta Guggulu Ghrta, Pathyadi Kvatha (Sadanga) Curna
THERAPEUTIC USES – Daha, Jvara, Krmiroga, Kandu, Kustha, Prameha, Rakta Pitta, Vrana
DOSE – 2-4 g. of the drug in powder form.
Decoction should be used externally.
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