Screening of Indian aphrodisiac ayurvedic/herbal healthcare products for adulteration with sildenafil, tadalafil and/or vardenafil using LC/PDA and extracted ion LC–MS/TOF

Ayurvedic/herbal healthcare products are considered safe under the impression that they are derived from natural products. But recently, there have been several reports worldwide on the adulteration of synthetic PDE-5 inhibitors in aphrodisiac herbal formulations. Therefore, the objective of the present study was to explore the presence of synthetic PDE-5 inhibitors (sildenafil, tadalafil and/or vardenafil) in ayurvedic/herbal healthcare products sold in Indian market for aphrodisiac/related uses. In total, 85 herbal formulations (HFs) were included in the study. The formulations were extracted with methanol and subjected to centrifugation. The supernatant was analysed by HPLC and LC–MS/TOF. Early detection of the presence of sildenafil, tadalafil and vardenafil in the herbal samples was done by the study of extracted ion mass chromatograms at the m/z values of respective parent ions, and two prominent fragments of each. In case of sildenafil and tadalafil, adulteration was also detected by comparing the relative retention times (RRT) and UV spectra. Further substantiation was done through comparison of accurate mass spectra with those of the two available standards. Of the 85 HFs tested, only one was eventually found to be adulterated with sildenafil. The extent of adulterant in this sample was determined to the therapeutic dose in the formulation. The study thus indicates emergence of the problem of adulteration of Indian herbal products with PDE-5 inhibitors.