ARKA (Stem Bark)
Arka consists of dried stem bark of Calotropis procera (Ait.) R. Br. (Fam. Asclepiadaceae); an erect shrub exuding milky white latex from cut parts, found wild more or less throughout India.
SYNONYMS –
Sansk. : Surya
Assam. : Akand, Akan
Beng. : Akanda, Akone
Eng. : Maddar
Guj. : Aakado
Hindi. : Aak, Madar, Akavana
Kan. : Ekka, Ekkagida
Kash. : —
Mal. : Errikku
Mar. : Rui
Ori. : Arakku
Punj. : Akk
Tam. : Vellerukku, Erukku
Tel. : Jilledu
Urdu. : Madar, Aak
DESCRIPTION –
a) Macroscopic:
Drug occurs in channelled, quilled and fibrous pieces, upto 0.1 – 0.5 cm thick, external surface yellowish brown having longitudinal cracks, internal surface greenish, smooth, with an occasional wood tissue attached; fracture, fibrous; odour and taste not distinct.
b) Microscopic:
Stem bark shows exfoliated cork, consisting of 6-8 layers of tangentially elongated, thick-walled cells; where cork has not developed, epidermis present consisting of a single layered rectangular cells covered externally with striated cuticle; secondary cortex composed of tangentially elongated, oval, rounded or rectangular thinwalled, parenchymatous cells having intercellular spaces, some cells contain rosette crystals of calcium oxalate, a number of rounded, oval to elongated, single or groups of stone cells and latex cells also found scattered in this region; pericyclic fibres numerous, lignified; secondary phloem composed of sieve elements, phloem parenchyma, phloem fibres and phloem rays; phloem parenchyma rectangular to polygonal in shape having rosette crystals of calcium oxalate, latex cells and stone cells similar to those found in secondary cortex; phloem fibres aseptate with bordered pits; phloem rays mostly uniseriate and run straight.
Powder – Light yellowish-green; shows fibres, stone cells, rosette crystals of calcium oxalate and latex cells.
IDENTITY, PURITY AND STRENGTH –
Foreign matter Not more than 2 Per cent, Appendix 2.2.2
Total ash Not more than 12 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 7 Per cent, Appendix 2.2.6
Water-soluble extractive Not less than 15 Per cent, Appendix 2.2.7
T.L.C. –
T.L.C. of the alcoholic extract on Silica gel ‘G’ plate using Chloroform :
Methanol (1: 1) shows under UV (366 nm) four fluorescent zones at Rf. 0.63, 0.71, 0.81 and 0.87 (all blue). On spraying with Dragendorff reagent followed by 5% Methanolic Sulphuric acid reagent one spot appears at Rf. 0.08 (orange).
CONSTITUENTS – α – and β- Calotropeols, β-Amyrin, Giganteol, a Colourless wax, small amount of Tetracyclic Terpenes and Traces of Sterols.
PROPERTIES AND ACTION –
Rasa : Katu, Tikta
Guna : Laghu, Ruksa, Sara, Tiksna
Virya : Usna
Vipaka : Katu
Karma : Dipana, Vatahara, Sodhana, Virecan, Lekhan, Ropana.
IMPORTANT FORMULATIONS – Abhaya Lavana, Arka Lavana
THERAPEUTIC USES – Udararoga, Kustha, Kandu, Vrana, Pliharoga, Gulma, Arsa, Krmiroga.
DOSE – 0.5-1 g. in powder form.
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