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.
Sansk. : Shurya
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
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.
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.
CONSTITUENTS – s – and s- Calotropeols, s-Amyrin, Giganteol, a Colourless wax, small amount of Tetracyclic Terpenes and Traces of Sterols.
PROPERTIES AND ACTION –
Rasa : Katu, Tikta
Guna : Laghu, Ruksha, Sara, Tikshna
Virya : Ushna
Vipaka : Katu
Karma : Dipana, Vatahara, sodhana, Virecan, Lekhan, Ropana.
IMPORTANT FORMULATIONS – Abhaya Lavana, Arka Lavana
THERAPEUTIC USES – Udararoga, Kushtha, Kandu, Vrana, Pliharoga, Gulma, Arsa, Krimiroga.
DOSE – 0.5-1 g. in powder form.