A comprehensive study of the potential phytomedicinal use and toxicity of invasive Tithonia species in South Africa

Abstract

BackgroundTithonia diversifolia and T. rotundifolia belong to the Asteraceae family and are native to Mexico and Central America. These plants have become invasive in parts of tropical Africa and Asia where they have become an ecological, agricultural and economic burden. Tithonia diversifolia is exploited by locals in its native and most parts of its invasive range as a source of medicines; however, T. rotundifolia is only used for medicinal purposes in one country in the native range (Venezuela) and none in the invasive range. Although T. diversifolia has been studied for different biological activities, little or no attention has been given to T. rotundifolia. This study compared the antimicrobial activity, phytochemistry, identification of bioactive compound(s) and toxicity levels of different leaf extracts and fractions of T. diversifolia and T. rotundifolia.MethodsAntimicrobial activity was evaluated against seven pathogenic bacteria, four non-pathogenic Mycobacterium species and three fungal species using serial microdilution assays. Phytochemical contents were determined through standard methods of analysis. UPLC/MS was used to analyse the fractions to identify possible bioactive compounds that may be responsible for bioactivity, while toxicity tests were carried out using the colorimetric MTT assay and the Ames test.ResultsBoth species had a range of antimicrobial activity against bacterial, mycobacterial and fungal species. However, T. rotundifolia displayed better activity against most of the strains tested with minimum inhibitory concentration values ranging between 0.01 and 0.07 mg/ml. Both species were rich in phenolics, flavonoids and tannins. Tagitinin A was identified as the main compound present in both species, and this compound may be responsible for the antimicrobial activity displayed. Toxicity tests showed that T. diversifolia was cytotoxic at concentrations used in this study, while T. rotundifolia was not. Both species did not show any mutagenic/genotoxic effects.ConclusionThe above results suggest that both species may be further developed as a source of antimicrobials for the treatment of infections caused by opportunistic pathogens. They may also serve as alternatives to highly exploited plant species with the same medicinal properties. However, T. diversifolia should be used with caution as it may be toxic.

In Vitro Cytotoxicity of Aspilia Pluriseta Schweinf. Extract Fractions

“…We chose the Vero cell line as an ideal in vitro model for the study because of its sensitivity to toxicity, ease to culture and readily available in our test facility. Additionally, it is recommended as a model to detect basal cytotoxicity (1,23,24). In this study, we set a threshold of the cytotoxic concentration (CC 50 ) below 20 µg/mL to be toxic, and above 20 µg/mL to be non-toxic as previously reported (1,21,22).…”

LC-MS Analysis, 15-Lipoxygenase Inhibition, Cytotoxicity, and Genotoxicity of Dissotis multiflora (Sm) Triana (Melastomataceae) and Paullinia pinnata Linn (Sapindaceae)

“…e assay was performed spectrophotometrically based on the formation of the complex Fe 3+ /xylenol orange according to Pinto et al [27] as previously described by Motlhatlego et al [28]. [29] as described by Omokhua et al [30]. From the previously reported MIC values [10,19] and lethal concentration 50 (LC 50 ) values obtained in the current study, the selectivity index (SI) values were calculated using the following formula: SI � LC 50 /MIC.…”

“…e genotoxicity evaluation of plant samples was done in the histidine-deficient growth medium using the Salmonella microsome assay according to Maron and Ames [31] as described by Omokhua et al [30].…”

Ethnopharmacological Potential of Tithonia diversifolia (Hemsl) A. Gray

“…On the other hand, T. diversifolia stands out as the most studied species, due to its widespread use in folk medicine. Several compounds of pharmacological and nutritional interest have been identified (Omokhua, Abdalla, van Staden, & McGaw, 2018).…”

“…Although pharmacological activities associated with phytochemicals of T. diversifolia have in general been attributed to sesquiterpene lactones and, in some cases, to chlorogenic acid derivatives present in leaves, recent studies have shown that saponins and leaf flavonoids of T. diversifolia have potential pharmacological properties. However, future studies should be performed to substantiate such effects (Ajao & Moteetee, 2017;Omokhua et al, 2018). Research, Society and Development, v. 9, n. 10, e2339108370, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i10.8370…”