Synergistic Antimycobacterial Actions ofKnowltonia vesicatoria(L.f) Sims

Euclea natalensisA.DC.,Knowltonia vesicatoria(L.f) Sims, andPelargonium sidoidesDC. are South African plants traditionally used to treat tuberculosis. Extracts from these plants were used in combination with isoniazid (INH) to investigate the possibility of synergy with respect to antimycobacterial activity. The ethanol extract ofK. vesicatoriawas subjected to fractionation to identify the active compounds. The activity of theKnowltoniaextract remained superior to the fractions with a minimum inhibitory concentration (MIC) of 625.0 μg/mL againstMycobacterium smegmatisand an MIC of 50.00 μg/mL againstM. tuberculosis. TheK. vesicatoriaextract was tested against two different drug-resistant strains ofM. tuberculosis, which resulted in an MIC of 50.00 μg/mL on both strains. The combination ofK. vesicatoriawith INH exhibited the best synergistic antimycobacterial activity with a fractional inhibitory concentration index of 0.25 (a combined concentration of 6.28 μg/mL). A fifty percent inhibitory concentration of this combination against U937 cells was 121.0 μg/mL. Two compounds, stigmasta-5,23-dien-3-ol (1) and 5-(hydroxymethyl)furan-2(5H)-one (2), were isolated fromK. vesicatoriaas the first report of isolation for both compounds from this plant and the first report of antimycobacterial activity. Compound (1) was active against drug-sensitiveM. tuberculosiswith an MIC of 50.00 μg/mL.

Evaluation of an Experimental Gel ContainingEuclea natalensis: AnIn VitroStudy

Objective. To evaluate the effect of an experimental gel containingEuclea natalensisextract on dentin permeability.Methods. Thirty-six dentin discs, 1-mm-thick. The discs were prepared from the coronal dentin of extracted human third molars that were divided into 3 groups (). The dentin discs in each group were treated with the groups following experimental materials: (FG): 1.23% fluoride gel, pH 4.1; (EG):Euclea natalensisextract gel, pH 4.1; (CG): control gel, pH 4.1. The gels were applied to the occlusal slide of the dentin under the following conditions: after 37% phosphoric acid and before 6% citric acid. The hydraulic conductance (HC) of each condition was determined four times using a fluid flow apparatus (Flodec). The data were analyzed using Two-way ANOVA and Tukey's test ().Results. The greatest mean reduction in HC was produced in group EG dentin discs (61.2%; ). Even after acid challenge with 6% citric acid the great reduction occurred in group EG (66.0%; ) than other groups (CG-77.1%, FG-90.8%).Conclusion.E. natalensisgel not only reduced dentin permeability, but also resisted posttreatment citric acid challenge without changing its permeability. Further research has to confirm this promising result in the clinical situation.