Isolation and quantification of bioactive Carpaine from Carica papaya L. and its commercial formulation by HPTLC densitometry

Abstract

Carpaine, the major alkaloid present in Carica papaya leaves, have recently been shown to have antiplasmodial activity. Traditionally, water decoctions of papaya leaves (boiling in water) have been used as a malaria preventative. In this paper Carpaine from the shade-dried leaves of C. papaya have been isolated, characterized, and quantified. A rapid, sensitive, and reproducible high-performance thin-layer chromatography (HPTLC) method was developed for the bioactive marker. Chloroform:methanol (70:30, v/v) was used as the mobile phase over pre-coated HPTLC silica gel F254 plates. The plates were developed to a distance of 60 mm at 23 ± 4 °C in a chamber previously saturated for 20 min. Under these conditions, the retention factor (Rf) of Carpaine was 0.59 and it was quantified at 550 nm, its wavelength of maximum absorbance after derivatization with Dragendorff’s reagent. Carpaine showed a linear function of the amount over the range 400–1200 ng per band; the correlation coefficient was 0.99451, indicating a good linear relationship between peak area and amount. The method was validated for precision, repeatability, and accuracy. The recovery percentage of Carpaine was found to be 101.56% w/w. It is found to be present 0.52% (w/w) in shade-dried leaves, 5.02% (w/w) in processed extract and 0.04% (w/w) in the Zandu Papaya tablet (commercial formulation).