Adulteration in commercial buchu dietary supplements: Analyses of commercial and authentic buchu samples and comparative studies of Agathosma betulina and Agathosma crenulata by microscopy and HPTLC

Abstract

Buchu is a popular medicinal plant known for its beneficial properties such as diuretic, urinary tract antiseptic, stimulant and tonic. It has traditionally been used to treat urinary tract infections and stomach troubles. It is widely marketed in the USA in various forms as dietary supplements. Buchu used in commerce is mainly derived from Agathosma betulina known as round-leaf or short buchu. However, leaves of Agathosma crenulata, which may contain high levels of pulegone in the essential oil, and other closely related species are often marketed as or used to adulterate buchu thus making the product potentially unsafe for human consumption. In the present work, 43 samples of authentic and commercial buchu were assessed by microscopy and high performance thin layer chromatography methods. Adulterations or contaminations with senna, grass and various other extraneous materials were observed in some of the buchu products. HPTLC fingerprinting showed that the profiles of 11 samples were not comparable to those of authentic and botanically verified buchu samples. Detailed morphology and anatomy of the leaves of A. betulina and A. crenulata by light and scanning electron microscopy are illustrated and discussed. Minute prismatic crystals of calcium oxalate were observed for the first time in A. betulina.