Differentiation of Tarchonanthus camphoratus L. and Tarchonanthus parvicapitulatus P.P.J. Herman (Asteraceae) using electron microscopy, and comparison of their biological activities

• Published in: Journal of ethnopharmacology 2021-03, Vol.267, p.113620, Article 113620
• Main Authors: Aro, A.O., Famuyide, I.M., Elisha, I.L., Kabongo-Kayoka, P.N., McGaw, L.J., Kahler-Venter, C.P.
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - metabolism; Animals; Asteraceae - chemistry; Asteraceae - classification; Asteraceae - ultrastructure; Asthma; ATP production; Bronchodilator Agents - isolation & purification; Bronchodilator Agents - pharmacology; Bronchodilatory; Electron microscopy; Free Radical Scavengers - isolation & purification; Free Radical Scavengers - pharmacology; Guinea Pigs; Humans; In Vitro Techniques; Male; Microscopy, Electron, Scanning; Muscle Contraction - drug effects; Neutrophils - drug effects; Neutrophils - metabolism; Oxidative Stress - drug effects; Plant Extracts - isolation & purification; Plant Extracts - pharmacology; Plant Leaves - chemistry; Plant Leaves - ultrastructure; Superoxide production; Superoxides - metabolism; Tarchonanthus camphoratus; Tarchonanthus parvicapitulatus; Taxonomy; Trachea - drug effects
• ISSN: 0378-8741; 1872-7573
• DOI: 10.1016/j.jep.2020.113620

Tarchonanthus camphoratus L. complex has numerous medicinal uses amongst the sub-Saharan African populace, including treatment for bronchospasm. This study focused on providing scientific rationale for the traditional use of the extracts of T. camphoratus and T. parvicapitulatus. T. camphoratus L. complex has been published under diverse names by various taxonomists. Tarchonanthus parvicapitulatus was one of the newly described taxa, leaving Tarchonanthus camphoratus L. sens. strict. as a homogenous taxon. However, some of the morphological characters used tend to overlap, making it difficult to identify the different taxa. The aim of this study was to evaluate the bronchodilatory, antioxidant and toxicological properties of the leaves of T. camphoratus L. and T. parvicapitulatus. This study also aimed to use scanning electron microscopy (SEM) to assess the differences between T. camphoratus L. and T. parvicapitulatus. Thin layer chromatography (TLC) with vanillin as visualizing agent was used to qualitatively compare the phytoconstituents of the plant acetone extracts. The free radical scavenging antioxidant qualitative assay was done by spraying TLC plates with DPPH free radical. The bronchodilatory effects of the aqueous extracts were assessed using pre-contracted guinea pig trachea. The effects of the extracts of T. camphoratus L. and T. parvicapitulatus on superoxide and ATP production was also investigated on isolated human neutrophils. A micromorphology study was done using scanning electron microscopy to study the leaves. Different compounds were visualized on the TLC plates with more than 40 compounds of intermediate polarity. The TLC plates sprayed with DPPH revealed the presence of 20 and 23 antioxidant compounds for T. camphoratus and T. parvicapitulatus respectively. Upon pre-contraction of the tracheal smooth muscles, the aqueous extracts of T. parvicapitulatus significantly relaxed the trachea while the relaxation observed for T. camphoratus was not significant. All the tested concentrations had a dose dependent inhibitory effect on superoxide production. The crude extract of T. parvicapitulatus at the highest concentration (10 mg/ml) significantly decreased ATP production while a non-significant increase in ATP production was observed for T. camphoratus at the highest concentration (10 mg/ml) when compared with the control. The micromorphology study was useful in revealing the presence of trichomes on the upper leaf surface of the studied t