Chemical profiling of Croton gratissimus Burch

Croton gratissimus is widely used in traditional medicine to treat a range of conditions, including hypertension, diabetes, arthritis, malaria and urinary tract infections. The aim of this study was to isolate and identify chemical markers for this species and to determine their concentrations in different populations.

Aerial parts of C. gratissimus (n =72) were collected in the Gauteng, Limpopo and Mpumalanga provinces of South Africa. Liquid chromatography coulped to mass spectrometry (LC-MS) method was developped and three major compounds were targetted as chemical markers. Preparative high performance liquid chromatography (prep-HPLC) system was used to isolate marker compounds (major peaks). Method development and validation was carried out using Waters Xevo G2-XS QTof quadrupole Time-of-Flight mass spectrometry. High performance thin layer chromatography (HPTLC) profiling was carried out using a CAMAG HPTLC instrument.

Three flavonoids were isolated and identified using nuclear magnetic resonance (NMR) spectroscopy as iso-orientin [1], trans-tiliroside [2] and 6ʹ-O-(4ʹ’-methoxy-trans-cinnamoyl)-kaempferol-3-β-D-glucopyranoside [3]. The coefficients of determination (R2) were above 0.999. The limits of detection varied from 0.18-0.48 μg/g, the limit of quantification from 0.16-0.53 μg/g) and an intraday precision of 0.6-2.2% was obtained. The concentrations of the three compounds in the extracts ranged from 0.90-2.27mg/g dry mass [1], 1.68-4.11 (mg/g) for [2] and 0.08-0.39 mg/g [3] which indicates significant variation. The HPTLC fingerprint revealed the presence of the three biomarkers in all the samples investigated.

The methods developed contributes significantly towards the quality control of C. gratissimus samples.