An Investigation Into The Phytochemistry And Biological Activity Of Pappea Capensis Used Against Cancer

Abstract

ascertain the medical benefits and safety of the woody part of this plant. The sensitivity testing of the plants plays a critical role in ascertaining the safety use of the plant extracts. In this study, antimicrobial screening showed that different extraction methods isolated the active compound which the solvent type depended on. The ethanoic and methanolic extracts were showed to have active compounds against Gram positive and Gram-negative organisms. Both extracts (ethanoic and methanolic) indicated that potential antimicrobial compounds were in the high polarity fraction. Water was found to be the only solvent mostly used by Sangomas and traditional healers to make medicinal mixtures for their patients. Then antimicrobial activity was extended by including other organisms. The Staphylococcus aureus and Klebsiella pneumoniae were found to be susceptible to ethanoic and methanolic extracts. However, in chapter 5 methanolic extract showed broad antimicrobial activity against two organisms known as part of the normal flora (Staphylococcus epidermidis and Enterococcus faecalis) which are both Gram positives. The water extract showed antimicrobial activity against Klebsiella pneumoniae, although no antimicrobial activity was observed against all Gram-positive organism. The Pappea capensis plants extract were screened for cytotoxity against the three cell lines (vero cells, MCF7 and PC). Upon comparing the used control and the only extract showing slight toxicity, it’s conclusive to say the high dose of methanolic extract is physiologically inappropriate. All extracts that are not active (cytotoxic) enough to suggest Pappea capensis can be taken into further anticancer testing. The extracts were further screened for genotoxicity. Two extracts were considered none genotoxic and the ethanoic extract could be considered genotoxic. The micronucleated cells of 30% were determined at the high concentration (200ug/ml) of ethanoic extract. A further test should be done to predict what mechanism is affected by compounds in ethanoic extract. The results indicate the potential use of this plant against cancer, despite the moderate genotoxicity at 200ug/ml. The in vitro screening results for anti- and pro-inflammatory assays are shown in fig 8.1 (A and B) for the analysis of NO production and the cell viability analysis on LPS-activated macrophages treated with the different extracts concentrations. There was an increased NO production which correlated with each extract cytotoxicity in LPS- activated macrophages (fig 8.1 B). Resveratrol, a known inhibitor of iNOS expression served as a positive control to the regime. In fig 8.2 there was macrophage activation observed which was extracts concentrations depended. This response to treatment with different concentrations of Pappea capensis extracts corresponded with NO production in fig 8.2 and a similar trend was observed with the analysis of cell viability (fig 8.2 A and B) which predicts the corresponding cytotoxicity of all extracts. However, there was a high NO production and observable macrophage activation in the presence of water extract no. 7 (fig 8.2). A confirmatory test was done to ascertain if this effect is owed to plant constituents or due to endotoxin contamination. Then, NO production was analysed in the presence and absence of polymyxin B (PMB) as shown in fig 8.3. It can be concluded that PMB counteracts the pro-inflammatory effect suggesting that this activity is possibly a result of endotoxins in this part of the plant. The determination of endotoxin as a cofactor perpetrating pro-inflammatory activity tested with polymyxin B was used and indicated the presence of a toxin in water extract. The low anti-inflammatory effect seen in the three extracts at 200ug/ml are not physiologically active. The GC-MS revealed the presence of 41 compounds which included 4-ethylbenzaldehyde, 2, 4-di-ter-butyl phenol, acetic acid and butanoic acid have the role in antioxidant, antimicrobial, antitumor, antifungal effects. The identified alkanes and aldehydes are possible poisonous compounds identified in fig 8.2A. Then it can be concluded the pro-inflammatory activity was indeed caused by toxin or poisonous compounds from the plant itself. Furthermore, seven (7) unknown bioactive chemical compounds were revealed regardless of their amounts, their existence could be having a positive impact on therapeutic agents and a source of the biological activities claimed for between traditional healers. Furthermore, many diverse chemical compounds identified and some quantified make it a holistic plant for use in traditional medicine and for aesthetic value between the local communities in Limpopo. More scientific tests are needed to carry out bioassay guided fractionation of the three extracts to determine the purified compounds and identify the ones that are biologically active. Medicinal plants, being the only sources that healers and Sangomas rely on for treatment of their patients have received tremendous attention in drug therapy, discovery and development. In conclusion, this study has shown that the Pappea capensis may serve as a new possible source of remedies due to the presence of these phytochemicals, bioactive compounds and antimicrobial activities.