In vitro antibacterial-antibiofilm effect of Hypericum atomarium Boiss and chemical composition

Abstract Treatment with plant is considered an effective option against increased antibiotic resistance. In this study antibiofilm activity of methanol (CH3OH), chloroform (CHCl3), ethyl acetate (EtOAc) and water (H2O) extracts of Hypericum atomarium Boiss. which is member of Hypericum genus was evaluated in Pseudomonas aeruginosa PAO1 and antibacterial performance against Gram (+) and Gram (-) strains and also bioactive compounds of extract were analysed using by HPLC and GC-MS. According to antibacterial activity test results the extracts were effective all Gram (+) bacteria and Gram (-) Chromobacterium violaceum (MICs ranging from 0.42 µg/ml to 4.3 mg). Inhibition effect of biofilm formation was found to be different rate in extracts (methanol-63%, chloroform-52%). The major flavonoids were detected (−)-epicatechin (2388.93 µg/ml) and (+)-catechin (788.94 µg/ml). The main phenolic acids were appeared as caffeic acid 277.34 µg/ml and chlorogenic acid 261.79 µg/ml. And according to GC results α-pinene was found main compound for three solvent extracts methanol, chloroform and ethyl acetate 67.05, 62.69, 49.28% rate respectively

Anti-quorum sensing activity in Pseudomonas aeruginosa PA01 of benzimidazolium salts: electronic, spectral and structural investigations as theoretical approach.

Quorum sensing (QS) is a system used in the expression of virulence factors by many pathogenic bacteria, and blockage of the system is seen as a new and effective strategy in combating with resistant bacteria. The inhibition effects of two benzimidazolium salts, namely 1-(2-methylbenzonitrile)-3-benzylbenzimidazolium bromide (2) and 1-(N-methylphthalimide)-3-(4-methylbenzyl)benzimidazolium bromide (3), on quorum sensing-related virulence factors such as pyocyanin, elastase, biofilm formation and swarming motility, which is an opportunistic pathogen Pseudomonas aeruginosa PA01, were investigated in this study. The results show that the compound 3 has a significant inhibition on biofilm formation with 94%. Furthermore, the compounds 2 and 3 reduced swarming motility by 64-69% as well as pyocyanin production by 49-64% in P. aeruginosa PA01 without preventing bacterial growth in the tested concentrations. HF, B3LYP and M06-2X methods were used with 3-21 g, 6-31 g, sdd basis sets to compare the chemical activity of the compounds. Theoretically, 1H NMR, 13C NMR and Infrared spectra of the compounds were calculated in the HF/6-31++g basis set. The biological activities of the relative compounds were theoretically studied against cancer proteins. Crystal structure of the BRCT repeat region from the breast cancer associated protein, ID: 1JNX, crystal structure of liver cancer protein, ID: 3WZE and crystal structure of lung cancer protein, ID: 5ZMA, were compared. In the docking studies, the best result was obtained with compound 2 against the lung cancer cell with a docking score parameter of -5.85.Communicated by Ramaswamy H. Sarma.

In Vitro and in Silico Assessment of the Potential of Niaouli Essential Oil as a Quorum Sensing Inhibitor of Biofilm Formation and its Effects on Fibroblast Cell Viability

Abstract Essential oils (EO), as new bioactive compounds, have been used for pharmaceutical applications. In this study, EO of Niaouli was found to have a high content in 1,8-cineole (58.53%). Furthermore, pinene, α-terpineol, nerolidol and ledene were found to be its components with an abundance of above 2%. Niaouli EO also had effects as inhibitor of Pseudomonas aeruginosa PAO1 biofilm formation (p<0.05). In the molecular docking study, this effect was explored. The natural ligand OdDHL, the bound ligand TP-1 (Triphenyl-1), the major component 1,8-cineole and the other components with significant abundance were docked against the binding region of the LasR protein. The docking study exhibited that 1,8-cineole together with the other components investigated could inhibit LasR competitively. Its effect on cell viability was also analyzed by MTT assay. Although dose-dependent cell viability effect was observed for all hours (p<0.05), IC50 value was above 100 μg/mL. Therefore, Niaouli can be assessed safely for dermatological applications because of its low toxicity on fibroblast cells and may be considered as potential quorum sensing inhibitor because of its inhibition effect on biofilm formation.