Evaluation of Athrixia bush tea for cytotoxicity, antioxidant activity, caffeine content and presence of pyrrolizidine alkaloids

Abstract

In South Africa, Athrixia phylicoides DC. (bush tea) is widely used as a beverage, cough remedy and purgative. The commercialization of this tea in a similar vein to rooibos (Aspalathus linearis), is being considered. Traditional infusions and decoctions, as well as water and ethanol extracts, were prepared and screened. A related species, Athrixia elata Sond. (daisy tea), was included in many of the assays as a comparison. Extracts of Athrixia phylicoides and Athrixia elata were tested for toxic effects to brine shrimp larvae and the Vero kidney cell line. In both assays, the traditional preparations and aqueous extracts had little effect, but the ethanol extracts were relatively toxic. Antioxidant activity comparable to that found in rooibos was established. No detectable levels of caffeine were present in the Athrixia extracts following analysis using TLC and I/HCl spray reagent. Neither screening using spectrophotometry nor confirmation using gas chromatography-mass spectrometry analyses showed evidence of pyrrolizidine alkaloids in Athrixia phylicoides. Although a wider range of studies needs to be conducted prior to commercialization, these results support the development of bush tea as a healthy alternative to caffeine-containing beverages.Abbreviations: ABTS, 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid); DPPH, 1,1-diphenyl-2-picryl-hydrazyl; GC-MS, gas chromatography-mass spectrometry; I/HCl, iodine hydrochloric acid; MEM, minimal essential medium; MTT,[3][4]]-2,5-diphenyltetrazolium bromide; PA, pyrrolizidine alkaloid; TEAC, trolox equivalent antioxidant capacity; TLC, thin layer chromatography; Trolox, 6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid Article Outline

Anthelmintic and cytotoxic activities of extracts of Markhamia obtusifolia Sprague (Bignoniaceae)

“…Berberine is an alkaloid with well-studied pharmacological and cytotoxic effects, derived from plants of the families Berberidaceae and Ranunculaceae (Bahar et al, 2011). The purified compound is inexpensive and readily available commercially, and published LC 50 values for its activity against Vero cells are available (McGaw et al, 2007;Chin et al, 2010). The Vero cell line was selected for cytotoxicity evaluation as it is widely available, easy to culture and has been adopted by many laboratories as a model for screening plant extracts and other compounds for cytotoxicity (Mahapatra et al, 2007;McGaw et al, 2007;Liao et al, 2010;de Toledo et al, 2011).…”

“…The purified compound is inexpensive and readily available commercially, and published LC 50 values for its activity against Vero cells are available (McGaw et al, 2007;Chin et al, 2010). The Vero cell line was selected for cytotoxicity evaluation as it is widely available, easy to culture and has been adopted by many laboratories as a model for screening plant extracts and other compounds for cytotoxicity (Mahapatra et al, 2007;McGaw et al, 2007;Liao et al, 2010;de Toledo et al, 2011). Using this cell line provided an indication of cellular toxicity of the M. obtusifolia plant extract which is easily comparable with published cytotoxicity data of other plant extracts.…”

“…Tannins have been linked to a case of poisoning in avian species (Kinde, 1988). Methods such as cell line cytotoxicity assays are widely used for determining toxic effects of plant extract in vitro (McGaw et al, 2007).…”

Acaricidal activity of the organic extracts of thirteen South African plants against Rhipicephalus (Boophilus) decoloratus (Acari: Ixodidae)

“…The plant extracts were therefore screened against these cells using the tetrazolium-based (MTT) colorimetric assay to determine the cell viability (Mosmann, 1983;McGaw et al, 2007). Each of the plant extracts were redissolved in their extracting solvents (acetone or ethanol) and tested at a concentration range of 1 to 0.001 mg/ml.…”

Quantitative capillary electrophoresis and its application in analysis of alkaloids in tea, coffee, coca cola, and theophylline tablets

“…The amount of these compounds needs to be controlled strictly due to their stimulative effects. Several chromatography methods such as HPLC [10], TLC [11], and CE [12,13] have been reported for the determination of these alkaloids. Among these methods, RP-HPLC is one of the most commonly used technologies.…”