Emmanuel Amukohe Shikanga

A Novel Approach in Herbal Quality Control Using Hyperspectral Imaging: Discriminating Between Sceletium tortuosum and Sceletium crassicaule

INTRODUCTION Sceletium tortuosum is the most sought after species of the genus Sceletium and is commonly included in commercial products for the treatment of psychiatric conditions and neurodegenerative diseases. However, this species exhibits several morphological and phytochemical similarities to S. crassicaule. OBJECTIVES The aim of this investigation was to use ultrahigh-performance liquid chromatography (UPLC) and hyperspectral imaging, in combination with chemometrics, to distinguish between S. tortuosum and S. crassicaule, and to accurately predict the identity of specimens of both species. METHODS Chromatographic profiles of S. tortuosum and S. crassicaule specimens were obtained using UPLC with photodiode array detection. A SisuChema near infrared hyperspectral imaging camera was used for acquiring images of the specimens and the data was processed using chemometric computations. RESULTS Chromatographic data for the specimens revealed that both species produce the psychoactive alkaloids that are used as quality control biomarkers. Principal component analysis of the hyperspectral image of reference specimens for the two species yielded two distinct clusters, the one representing S. tortuosum and the other representing S. crassicaule. A partial least squares discriminant analysis model correctly predicted the identity of an external dataset consisting of S. tortuosum or S. crassicaule samples with high accuracy (>94%). CONCLUSIONS A combination of hyperspectral imaging and chemometrics offers several advantages over conventional chromatographic profiling when used to distinguish S. tortuosum from S. crassicaule. In addition, the constructed chemometric model can reliably predict the identity of samples of both species from an external dataset.

In vitro permeation of Mesembrine alkaloids from Sceletium tortuosum across porcine buccal, sublingual, and intestinal mucosa

Sceletium tortuosum is an indigenous South African plant that has traditionally been used for its mood-enhancing properties. Recently, products containing S. tortuosum have become increasingly popular and are commonly administered as tablets, capsules, teas, decoctions, or tinctures, while traditionally the dried plant material has been masticated. This study evaluated the in vitro permeability of the four major S. tortuosum alkaloids (i.e., mesembrine, mesembrenone, mesembrenol, and mesembranol) across porcine intestinal, sublingual, and buccal tissues in their pure form and in the form of three different crude plant extracts, namely water, methanol, and an acid-base alkaloid-enriched extract. The permeability of mesembrine across intestinal tissue was higher than that of the highly permeable reference compound caffeine (which served as a positive control for membrane permeability) both in its pure form, as well as in the form of crude extracts. The intestinal permeability of mesembranol was similar to that of caffeine, while those of mesembrenol and mesembrenone were lower than that of caffeine, but much higher than that of the poorly permeable reference compound atenolol (which served as a negative control for membrane permeability). In general, the permeabilities of the alkaloids were lower across the sublingual and the buccal tissues than across the intestinal tissue. However, comparing the transport of the alkaloids with that of the reference compounds, there are indications that transport across the membranes of the oral cavity may contribute considerably to the overall bioavailability of the alkaloids, depending on pre-systemic metabolism, when the plant material is chewed and kept in the mouth for prolonged periods. The results from this study confirmed the ability of the alkaloids of S. tortuosum in purified or crude extract form to permeate across intestinal, buccal, and sublingual mucosal tissues.

An HPTLC-densitometry method for the quantification of pharmacologically active alkaloids in Sceletium tortuosum raw material and products

Mesembrine-type alkaloids are reported to be responsible for the psychoactive properties of Sceletium tortuosum. The aim of the study was to develop a simple, rapid, and precise high-performance thin-layer chromatography densitometric method for the simultaneous determination of mesembrenol, mesembranol, mesembrine, and mesebrenone in S. tortuosum raw materials and commercial products. Silica gel 60 F254 pre-coated glass plates were used with a mobile phase of dichloromethane-MeOH-10% NH3 (90:10:0.1, v/v). Densitometric quantification was performed in absorbance mode at 280 nm, and good separation was obtained using a single mobile phase. Regression analyses of the calibration data showed good linear relationships with regression coefficient (r2) values ranging from 0.994 to 0.999. The method was validated for linearity, accuracy, limit of detection, limit of quantification, and precision (repeatability). The results showed good correlation with data obtained from gas chromatography/mass spectrometry analysis (reference method). The method proved to be specific, with potential application for rapid quantitative analyses of pharmacologically active alkaloids in S. tortuosum raw materials and commercial products.