Detection of Adulteration in Rubia cordifolia – A Chromatographic Approach

Abstract

According to traditional medicinal texts as well as modern research, Rubia cordifolia (Desi Manjistha) stem cure various diseases of blood, skin diseases, inflammations, kidney stones, fever and various Kapha disorders. However, stems of Rubia cordifolia (Desi Manjistha) are often adulterated with stems of Rubia tinctorum (Irani Manjistha) due to morphological similarity. This adulteration is extremely harmful as R. tinctorum has Lucidin as one of the chemical constituents, which has severe genotoxic effects. The present work focuses on developing a comparative HPTLC fingerprint and GC-MS analysis of R. cordifolia and R. tinctorum, so as to detect the adulteration by R. tinctorum in R. cordifolia raw material form and in formulations. Methanol extracts of the individually powdered stems were used to develop a suitable mobile phase, such that a clear spot was obtained in TLC of R. tinctorum but not in TLC of R. cordifolia using the same mobile phase. This mobile phase was further used to develop a comparative HPTLC fingerprint of the two species. Methanol extracts of R. cordifolia and R. tinctorum were used for investigation of phytoconstituents by GC-MS analysis. The mobile phase n-butanol: ethanol (6:4) was the one which gave a clear single spot at Rf 0.89 in TLC of methanol extract of R. tinctorum but not in TLC of methanol extract of R. cordifolia, at 254nm and 366nm. Further, HPTLC analysis gave results clearly differentiating the two species using the same mobile phase. Further, GC-MS analysis of R. cordioflia revealed the presence of 9 phytoconstituents while R. tinctorum revealed the presence of 6 phytoconstituents, which are different from each other. Thus, these simple yet sophisticated techniques will be very useful for herbal industry in standardization and detection of adulteration of R. tinctorum in R. cordifolia formulations, thereby benefitting the patients who consume Manjistha formulations.