Graphical abstractPhenolic-enriched extracts of four Combretum species namely Combretum bracteosum, Combretum padoides, Combretum vendae and Combretum woodii used in South African traditional medicine to treat various ranges diseases were evaluated against some diarrhoeal aetiologies. All the crude extracts and their fractions of varied polarities had good antimicrobial (non-polar fractions) or good antioxidant (polar fractions) activity. The crude extract of all the plant species were cytotoxic to Vero cell lines but did not lead to COX enzyme inhibition.
Phenolic-enriched extractsFour Combretum species traditionally used for treating infectious and gastrointestinal complications in southern Africa In vitro assays: antioxidant, anti-inflammation, antimicrobial, cytotoxicity
AbstractEthnopharmacological importance: Infections and gastrointestinal (GIT) disorders such as diarrhoea causes many problems in human health and animal production. Many Combretum species are used in traditional medicine to treat various diseases by rural people in Africa and Asia. Much of the work done to date on some species to validate their ethnopharmacological use was on the non-polar or intermediate polarity components. Many species are yet to be studied against relevant disease parameters using more polar extracts.
Aims:The polar components were extracted and fractionated by solvent-solvent fractionation to yield fractions of different polarities. The activity of these fractions on different parameters that could be involved in infectious and gastrointestinal track (GIT) disorders was investigated. The cytotoxic activities of the extracts were also determined to evaluate the potential of these extracts to combat diarrhoea in production animals.
Materials and Methods:Phenolic-enriched leaf extracts of Combretum bracteosum (Cob), Combretum padoides (Cop), Combretum vendae (Cov) and Combretum woodii (Cow) were obtained by extracting with a mixture of 70% acetone acidified with 1% HCl and n-hexane. The extract was sequentially treated by solvent-solvent fractionation with dichloromethane, ethyl acetate, and butanol to yield fractions with a large variation in polarity. The phenolic constituents of the extracts and fractions were determined using standard procedures. The antioxidant activities were determined using various standard methods. The minimum inhibitory concentrations (MICs) of the crude extracts and fractions against four bacterial and three fungal strains were assessed with a microplate serial dilution method.Cyclooxygenase (COX) and lipoxygenase (LOX) enzyme inhibitory assays and cytotoxicity studies against Vero cells were also carried out.Result: Some of the fractions had much higher antioxidant activity than the positive controls. The average EC 50 values of the extracts for the DPPH and ABTS antioxidant assays were 0.21-12 µg/ml (Cop), 0.25-16 µg/ml (Cov), 0.33-9.41 µg/ml (Cow) and 4.97-85 µg/ml (Cob) respectively while the mean EC 50 values for the positive controls ascorbic acid and trolox were 1.28-1.51 and 1.02-1.19 ...