Dolastane diterpenes from and their effects in modulation of drug resistance in .

One new diterpene (4,7,14)-4α,7α-diacetoxy-10-one-14α-hydroxydolasta-1(15),8-diene (), and five known compounds (4,7,14)-4α,7α-diacetoxy-14α-hydroxydolasta-1(15),8-diene (), (4,14)-4α,14α-dihydroxydolasta-1(15),8-diene (), (4,9,14)-4α-acetoxy-9β,14α-dihydroxydolasta-1(15),7-diene (), 4-acetoxy-14-hydroxydolasta-1(15),7,9-triene () and isolinearol (), were isolated from . In this study, dolastane diterpenes were isolated from the alga and evaluated as modifiers of antibiotic activity in : SA-1199B, which overexpresses the norA gene RN-4220, which encodes for the protein efflux of macrolides (MRSA), and IS-58 which has the gene encoding the protein TetK. The minimum inhibitory concentrations (MICs) for norfloxacin, tetracycline and erythromycin were determined by the microdilution broth nutrient in the absence and presence of diterpenes at a sub-inhibitory concentration (MIC/4).

The Essential Oil from Origanum vulgare L. and Its Individual Constituents Carvacrol and Thymol Enhance the Effect of Tetracycline against Staphylococcus aureus.

Background: In an ongoing project to evaluate essential oils as modulators of antibiotic resistance, the essential oil from Origanum vulgare L. (OVEO), as well as its individual constituents carvacrol (CAR) and thymol (THY), were investigated using Staphylococcus aureus strains possessing efflux mechanisms of resistance to norfloxacin, erythromycin and tetracycline.

Methods: The minimum inhibitory concentration (MIC) values of the antibiotics were determined by agar dilution method, in the absence and in the presence of subinhibitory concentrations of OVEO, CAR or THY.

Light-mediated antibacterial activity of Lippia origanoides H.B.K. in vitro.

An ethanol extract and different partition fractions obtained from Lippia origanoides H.B.K.