Procedure

(a) Extraction of embelin from Tamarindus indica / Embelia ribes

Dried Embelia ribes / Tamarind (5gm) + Ethanol (100 ml)
Sonicated for 8 hrs
Solvent extract
Filter
Filtrate
Rota vapour (Distillation under reduced pressure)
Crude extracts

(b) Qualitative and quantitative analysis of embelin

• A stock solution of embelin was prepared by dissolving embelin (5 mg) in chloroform (5 ml) in a volumetric flask. The solution was sonicated for 10 minutes over an ultrasonic bath, to obtain a homogenous solution.
• Embelin samples (tamarind, false black pepper, 5gm) were mixed with ethanol and sonicated for 6 hrs for proper mixing.
• The solution was filtered through Whatman No. 41 filter paper and filtrate was used as sample solution.
• A 20cm × 10cm aluminium backed HPTLC plate coated with silica gel 60 F 254 (E. Merck, Darmstadt, Germany) was used for analysis.
• The samples were applied at 10 mm from the base of HPTLC plate by means of a Camag (Switzerland) Linomat V sample applicator using a syringe (100µL, Hamilton, Bonaduz, Switzerland).
• A linear calibration curve was obtained on applying the increasing concentration of standard embelin in the range (200-1400 ng).
• HPTLC analysis was performed on a computerized densitometer scanner 3, controlled by winCATS planar chromatography manager version 1.4.4. (CAMAG, Switzerland)..
• Plate was developed to a distance of 80 mm, in a Camag twin-trough chamber with mobile phase [n-propanol: n-butanol: ammonia:: 7:1:4(v/v)].
• Plates were evaluated by densitometry at 200 nm with a Camag Scanner 3 for quantification.

Observation

Use of pre-coated silica gel HPTLC plates with n propanol :n butanol : ammonia :: ,7: 1: 4 ,resulted in good separation of the embelin at 333nm (Rf = 0.68). The absence of additional peaks in chromatogram indicates non- interference of the common excipients used. Regression analysis of the calibration data for caffeine showed that the dependent variable (peak area) and the independent variable (concentration) were represented by the equations Y = – 191.213 + 2.518 x for embelin in Embelia ribes and tamarind. The correlation of coefficient (r2) obtained was 0.99971 shows a good linear relationship.

Results