No abstract

The aim of the present study was to (i) evaluate the in vitro action of rifampicin (RIF), ethambutol or isoniazid with efflux pumps inhibitors (EPIs) in Mycobacterium tuberculosis (Mtb) H37Rv and (ii) evaluate the morphological and efflux pumps (EPs) transcriptional changes by the action of rifampicin + verapamil combination (RIF + VP). The minimal inhibitory concentration and synergic effect of drug combinations were determined by Resazurin Microtiter Plate Assay and Resazurin Drugs Combination Microtiter Assay, respectively. VP showed greater capacity of ethidium bromide accumulation and RIF + VP had the lower fractional inhibitory concentration index. The RIF + VP exerted a similar reduction of viable cell counts to RIF by time-kill curve, but decreases in the expression of EPs genes were observed by Real time PCR at 72 h of RIF + VP exposure. Accumulative morphological changes (wrinkled and rounding) caused by each drug were observed by scanning electron microscopy after RIF + VP exposure. The downexpression of EPs related genes exposed to RIF + VP, suggest an effective inhibitory activity of VP in Mtb H37Rv. The role of EPs and the use of EPIs open up a powerful approach and the RIF + VP combination should be studied in Mtb more thoroughly.

These results revealed that TrEO isolated from leaves of T. riparia and the pure compound 6,7-dehydroroyleanone display good activity against M. tuberculosis clinical isolates, including MDR isolates, with low cytotoxicity to murine macrophages. The 6,7-dehydroroyleanone compound is a potential candidate for anti-TB drug.

Tetradenia riparia (Lamiaceae) is native to Central Africa popularly known as myrrh, used in folk medicine to treat various diseases like malaria, gastroenteritis, and tropical skin disease. This research was to evaluate the antioxidant and antibacterial activities of the crude extract (CE) and fractions (FR) of the T. riparia by classical chromatography. The CE of T. riparia leaves was submitted to column chromatographic fractionation to obtain four fractions of the interest, which were identified by nuclear magnetic resonance and gas chromatograph coupled to mass spectrum: FR-I (abieta-7,9(11)-dien-13-β-ol), FR-II (Ibozol), FR-III (8 (14), 15-sandaracopimaradiene-2α, 18-diol and 8 (14), 15-sandaracopimaradiene-7α, 18-diol), and FR-IV (Astragalin, Boronolide and Luteolin). Total phenol content of CE and FR were measured, and antioxidant action by methods of DPPH (2,2-diphenyl-1-picrylhydrazyl), β-carotene/linoleic acid system, and ferric reducing/antioxidant power (FRAP) and the antibacterial activity was evaluated by the broth microdilution method with the determination of the minimum inhibitory concentration (MIC). The FR-IV presented antioxidant potential with 181.67 μg gallic acid/mg, IC of 0.61 μg/mL by DPPH method, 55.61% oxidation protection by β-carotene/linoleic acid system and 4.59 µM ferrous sulfate/mg of sample by FRAP, and the FR-I showed higher antibacterial potential on the strain Staphylococcus aureus with MIC 0.98 μg/mL, Enterococcus faecalis and Bacillus cereus with MIC 31.2 μg/mL. Thus, the fractionation of CE was extremely important to detect fractions with potential activities, and investigations are necessary regarding the mechanism of action and action in vivo.

In this study we investigated the antidiabetic and hypolipidemic potential of dried powdered leaves of Gymnema sylvestre (GS). The acute effect of GS administered by oral gavage on glucose blood level of and lipids in nondiabetic and alloxan-diabetic rats were investigated in the following conditions: a) after a balanced meal; b) after the ingestion of 1000 mg/kg amylose or 1000 mg/kg glucose; c) after the ingestion of a mixture of 12 mL/kg soybean oil + 1% cholesterol (SOC). In addition, the effect of the treatment with GS during two (sub-acute)