Asoka
Ashoka, Saraca asoca
Asoka consists of dried stem bark of Saraca asoca Roxb. (Fam. Caesalpinaceae)
Asoka contains not less than 0.4 per cent w/w of total β-sitosterol.
Category: Antimenorrhafic, antioxytoxic, Kasaya.
Description: The dried stem bark occurs in pieces of variable size and thickness, surface rough. It is externally
brown in colour with no characteristic odour.
Identification:
A. Macroscopic – Stem bark externally brown and elongated, with circular lenticels and transversely ridged,
cracked; internally reddish-brown with fine longitudinal strands and fibres. Texture rough; fracture splinting
exposing striated surface, a thin whitish and continuous layer is seen beneath the cork layer.
B. Microscopic – Wide layer of cork, secondary cortex wide with one or two continuous layers of stone cells
with many patches of sclereids, parenchymatous tissue containing yellow masses. Secondary phloem consists of
phloem parenchyma, sieve tubes, fibres, with medullary rays, with companion cells and phloem fibres occurring
in groups.
C. Determine by thin layer chromatography (2.4.17), coating the plate with silica gel GF254.
Mobile phase. A mixture of 60 volumes of toluene, 15 volumes of ethyl acetate and 1 volume of glacial acetic
acid.
Test solution. Macerate about 1 g of the coarsely powdered substance under examination with 50 ml of
methanol for 48 hours, cool and filter.
Reference solution. Macerate about 1 g of the coarsely powdered Asoka RS under examination with 50 ml of
methanol separately for 48 hours, cool and filter.
Apply to the plate 10 µl each solution as bands of 10 mm by 2 mm. Allow the mobile phase to rise to 8 cm. Dry
the plate in air and examine in ultraviolet light at 254 nm and 365 nm. Spray the plate with 10 per cent
methanolic sulphuric acid reagent. Heat the plate at 100º for 10 minutes. Examine the plate in day light. The
chromatographic profile of the test solution is similar to that of the reference solution.
Tests
Foreign organic matter (2.6.1). Not more than 2.0 per cent
Ethanol-soluble extractive (2.6.2). Not less than 15.0 per cent
Water-soluble extractive (2.6.3). Not less than 11.0 per cent.
Total Ash (2.3.19). Not more than 11.0 per cent
Acid-insoluble ash (2.3.19). Not more than 1.0 per cent.
Heavy Metals (2.3.13). 1.0 g complies with the limit test for heavy metals, Method B (20ppm).
Loss on Drying (2.4.19). Not more than 5.0 per cent.
Microbial contamination (2.2.9) Complies with the microbial contamination tests.
Assay. Determine by thin layer chromatography (2.4.17), coating the plate with silica gel GF254.
Mobile phase. A mixture of 60 volumes of toluene, 15 volumes of ethyl acetate and 1 volume of glacial acetic
acid.
Test solution. Macerate about 1 g of the coarsely powdered substance under examination with 50 ml of hexane
and methanol separately for 48 hours, cool and filter.
Reference solution. A 0.0025w/v solution of β-sitosterol in methanol.
Apply to the plate, 10 µl of test and reference solution as bands 10 mm by 2 mm. Allow the mobile phase to rise
8 cm. Dry the plate in air and scan the plate in absorbance mode at 366nm. Record the chromatograms and
measure the responses for the analyte peak.
Calculate the content of β-sitosterol.
Storage. Store protected from heat, moisture and against attack by insects and rodents.
Asoka
RS
TEST
(Under UV light at
254 nm)
RS
TEST
(Under UV light at
365 nm)
TLC Chromatogram of Asoka
RS
TEST
(After spray methanolic
sulphuric acid reagent)
Asoka
HPTLC Chromatogram of β-sitosterol
HPTLC Chromatogram of Asoka