Thin layer chromatography-direct bioautography guided isolation of ß-sitosterol from the leaves of Capparis fascicularis.

The aim of the study was to isolate and characterise antimicrobial agents from the leaves of Capparis fascicularis using thin-layer chromatography-direct bioautography (TLC-DB). Capparis fascicularis is a medicinal plant used traditionally to treat various ailments. Previous studies have shown that species of the genus Capparis, contain several classes of secondary metabolites, including sterols. In this study, the leaves of C. fascicularis were extracted with 80% aqueous methanol, and the extract's fractions were screened for antimicrobial activity against Staphylococcus aureus ATCC 25923 using a broth micro-dilution assay. The hexane fraction was the most active, with a minimum inhibitory concentration (MIC) of 512 µg/mL. TLC-DB and flash column chromatography of the hexane fraction resulted in the isolation of ß-Sitosterol for the first time from C. fascicularis. The compound was characterised using NMR and HRMS.

Constituents of Two Dioscorea Species That Potentiate Antibiotic Activity against MRSA.

The isolation of two diarylnonanoids from Dioscorea cotinifolia possessing antibiotic-potentiating activity against resistant strains of S. aureus are reported. The diarylnonanoids are a class of natural products similar in structure to the diarylheptanoids, which have a wide spectrum of reported biological activities. One of the diarylnonanoids (1) isolated possesses a chiral center, and to deduce its configuration, the modified Mosher ester method was used. Using both 1D and 2D NMR data, as many protons as possible were assigned to both the R- and S-MTPA esters, and the configuration of the chiral center in 1 was determined to be R. Both the chiral and achiral diarylnonanoid (2) exhibited potent antibiotic-potentiating activity with the chiral natural product showing a greater tetracycline-potentiating activity than 2. Interestingly, 2 gave a higher norfloxacin-potentiating activity with a resultant higher efflux pump inhibitory activity. Manipulation of the structure of the diarylnonanoids through synthesis could lead to improved biological activity.

The anti-diarrhoeal properties of Breonadia salicina, Syzygium cordatum and Ozoroa sphaerocarpa when used in combination in Swazi traditional medicine.

AIM OF THE STUDY: The aim of the study was to determine in vitro activity of the bark of Ozoroa sphaerocarpa R. Fern & A. Fern (Anacardiaceae), Breonadia salicina (Vahl) Hepper & J.I.R. Wood (Rubiaceae) and Syzygium cordatum Hochst ex C Krauss (Myrtaceae) against a diarrhoea-causing pathogen, Escherichia coli; as well as the pharmacological interactions present in their combination. MATERIALS AND METHODS: In consultation with traditional healers, the plants were collected from the wild, dried and extracted with dichloromethane:methanol (1:1). Thereafter, antimicrobial activity of the individual plants and their different combinations was tested using a common diarrhoea pathogen, Escherichia coli by employing the minimum inhibitory concentration assay. RESULTS: Ozoroa sphaerocarpa was the most potent inhibitor of antimicrobial growth (MIC value of 1.2 mg/ml), followed by Syzygium cordatum (MIC value of 1.44 mgl/ml) and lastly Breonadia salicina (MIC value of 10.89 mg/ml). The combination between Syzygium cordatum and Ozoroa sphaerocarpa gave the strongest synergistic interaction (MIC value of 0.33 mg/ml); whilst that between Syzygium cordatum and Breonadia salicina was mildly synergistic (MIC value of 1.00 mg/ml). The triple combination (1:1:1) was also very effective in inhibiting microbial growth (MIC value of 0.44 mg/ml). The combined effect of these plants on toxicity was predominantly synergistic except for the combination of Ozoroa sphaerocarpa and Syzygium cordatum which was predominantly antagonistic (ΣFIC value of 1.48 ± 0.25). The triple combination had a favourable toxicity profile with an IC(50) value of 155.76 ± 11.86 µg/ml. CONCLUSION: This study supports the rationale by traditional healers to use the bark of Syzygium cordatum, Breonadia salicina and Ozoroa sphaerocarpa in combination for the treatment of diarrhoea.