Membrane disruption and anti-quorum sensing effects of synergistic interaction between Lavandula angustifolia (lavender oil) in combination with antibiotic against plasmid-conferred multi-drug-resistant Escherichia coli.

AIM: The aim of this study was to investigate the mode of action of the lavender essential oil (LV) on antimicrobial activity against multi-drug-resistant Escherichia coli J53 R1 when used singly and in combination with piperacillin. METHOD AND RESULTS: In the time-kill analysis, a complete killing of bacteria was observed based on colony counts within 4 h when LV was combined with piperacillin during exposure at determined FIC concentrations. Analysis of the membrane permeabilizing effects of LV on treated cultures through their stability against sodium dodecyl sulphate revealed that the LV played a role in disrupting the bacterial cell membrane. The finding is further supported by scanning electron microscopy analysis and zeta potential measurement. In addition, reduction in light production expression of E. coli [pSB1075] by the LV showed the presence of potential quorum sensing (QS) inhibitors. CONCLUSIONS: These results indicated that the LV has the potential to reverse bacterial resistance to piperacillin in E. coli J53 R1. It may operate via two mechanisms: alteration of outer membrane permeability and inhibition of bacterial QS. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings offer a novel approach to develop a new option of phytopharmaceuticals against multi-drug-resistant E. coli.

Genomic DNA extraction from medicinal plants available in Malaysia using a TriOmic(TM) improved extraction kit.

DNA extraction was carried out on 32 medicinal plant samples available in Malaysia using the TriOmic(TM) extraction kit. Amounts of 0.1 g flowers or young leaves were ground with liquid nitrogen, lysed at 65°C in RY1(plus) buffer and followed by RNAse treatment. Then, RY2 buffer was added to the samples and mixed completely by vortexing before removal of cell debris by centrifugation. Supernatants were transferred to fresh microcentrifuge tubes and 0.1 volume RY3 buffer was added to each of the transferred supernatant. The mixtures were applied to spin columns followed by a centrifugation step to remove buffers and other residues. Washing step was carried out twice by applying 70% ethanol to the spin columns. Genomic DNA of the samples was recovered by applying 50 µL TE buffer to the membrane of each spin column, followed by a centrifugation step at room temperature. A modification of the TriOmic(TM) extraction procedure was carried out by adding chloroform:isoamyl alcohol (24:1) steps in the extraction procedure. The genomic DNA extracted from most of the 32 samples showed an increase of total yield when chloroform:isoamyl alcohol (24:1) steps were applied in the TriOmicTM extraction procedure. This preliminary study is very important for molecular studies of medicinal plants available in Malaysia since the DNA extraction can be completed in a shorter period of time (within 1 h) compared to manual extraction, which entails applying phenol, chloroform and ethanol precipitation, and requires 1-2 days to complete.

In vitro modulation of naturally occurring flavonoids on cytochrome P450 2A6 (CYP2A6) activity.

1. The effect of flavonoids on coumarin 7-hydroxylation, an activity marker of an important human liver cytochrome P450 isoform, cytochrome P450 2A6 (CYP2A6), was investigated in this study. 2. Coumarin 7-hydroxylase activity was measured fluorometrically in reaction mixtures containing cDNA-expressed CYP2A6, nicotinamide adenine dinucleotide phosphate generating system and 10 uM coumarin, at various concentrations of flavonoids. 3. Among the 23 compounds tested, most of the active members were from flavonol group of hydroxylated flavonoids, with myricetin being the most potent inhibitor followed by quercetin, galangin, and kaempferol. 4. Further exploration of the inhibition mechanism of these compounds revealed that myricetin, galangin, and kaempferol exhibited mixed-type of inhibition pattern while quercetin was observed to exhibit competitive mode of inhibition. 5. Structure-function analyses revealed that degree of inhibition was closely related to the number and location of hydroxyl groups, glycosylation of the free hydroxyl groups, degree of saturation of the flavane nucleus as well as the presence of the alkoxylated function.