Estimation of Levodopa in the Unani Drug Mucuna pruriens Bak. and Its Marketed Formulation by High-Performance Thin-Layer Chromatographic Technique.

Abstract

Mucuna pruriens Bak. Syn. Mucuna prurita Hook. seed is the rich source of levodopa (L-dopa) and has been used in traditional medicines to treat diseases resembling Parkinson's disease. In the present study, a new HPTLC method was developed and validated for estimation of L-dopa from M. pruriens (black- and white-colored seeds) collected from two different locations in India. TLC aluminum plates precoated with silica gel were used as the stationary phase. The plates were developed to a distance of 60 mm at a temperature of 22 ± 4°C in a twin glass chamber saturated with ethyl acetate-methanol-formic acid-water (15+3+3+4.5, v/v/v/v), as the mobile phase. The Rf value of L-dopa was found to be 0.45. L-dopa was quantified at 282 nm, the wavelength of maximum absorbance by a densitometric scanner. The TLC plate was derivatized by ninhydrin reagent and photodocumented. L-dopa showed a good linearity in the concentration range 400-1000 ng/spot. The linear regression analysis of calibration plot showed good linear relationship between peak area and peak height (r2 = 0.997). The method was validated for precision, repeatability, and accuracy. Recovery was determined by spiking L-dopa with samples and was found to be 96.10%. L-dopa was found to be present at concentration 3.02-4.72% in samples and its formulation.