Experimental and quantum chemical studies of a novel synthetic prenylated chalcone

BACKGROUND: Chalcones are ubiquitous natural compounds with a wide variety of reported biological activities, including antitumoral, antiviral and antimicrobial effects. Furthermore, chalcones are being studied for its potential use in organic electroluminescent devices; therefore the description of their spectroscopic properties is important to elucidate the structure of these molecules. One of the main techniques available for structure elucidation is the use of Nuclear Magnetic Resonance Spectroscopy (NMR). Accordingly, the prediction of the NMR spectra in this kind of molecules is necessary to gather information about the influence of substituents on their spectra. RESULTS: A novel substituted chalcone has been synthetized. In order to identify the functional groups present in the new synthesized compound and confirm its chemical structure, experimental and theoretical (1)H-NMR and (13)C-NMR spectra were analyzed. The theoretical molecular structure and NMR spectra were calculated at both the Hartree-Fock and Density Functional (meta: TPSS; hybrid: B3LYP and PBE1PBE; hybrid meta GGA: M05-2X and M06-2X) levels of theory in combination with a 6-311++G(d,p) basis set. The structural parameters showed that the best method for geometry optimization was DFT:M06-2X/6-311++G(d,p), whereas the calculated bond angles and bond distances match experimental values of similar chalcone derivatives. The NMR calculations were carried out using the Gauge-Independent Atomic Orbital (GIAO) formalism in a DFT:M06-2X/6-311++G(d,p) optimized geometry. CONCLUSION: Considering all HF and DFT methods with GIAO calculations, TPSS and PBE1PBE were the most accurate methods used for calculation of (1)H-NMR and (13)C-NMR chemical shifts, which was almost similar to the B3LYP functional, followed in order by HF, M05-2X and M06-2X methods. All calculations were done using the Gaussian 09 software package. Theoretical calculations can be used to predict and confirm the structure of substituted chalcones with good correlation with the experimental data

Improved method for qualitative screening of lipolytic bacterial strains

Esterases and lipases are lipolytic enzymes that catalyse the hydrolysis of triacylglycerols, Determination of lipolysis on agar plates is a simple approach to determine lipase or esterase action, but visual evaluation of lipolysis is frequently difficult in practice. Therefore, the aim of this work was to improve the efficiency of lipolysis visualization in tributyrin agar (mTBA) by adding calcium and/or magnesium ions in the screening of lipolytic microbial strains. Lipolytic activity was evaluated in mTBA using the well diffusion technique, where a clear zone around the inoculated wells indicated lipid hydrolysis. Results suggest that the addition of 2.5 mM calcium and 5.0 mM magnesium was the best combination of ion addition to TBA. Lipolytic activity increased the clearing zone up to 38% more than without the addition of ions and the clear zone was clearly observed. The mTBA plate was used with culture collection microbial strains, as well as with a collection of soil microorganisms, to identify lipase producers. The addition of calcium and magnesium ions can provide an easier screening procedure for selection of lipolytic bacterial strains. • A modified tributyrin agar for screening of lipolytic bacteria was prepared by adding calcium and magnesium ions. • The modified TBA agar was tested with control bacterial strains, and, based on the results, 2.5 mM Ca and 5.0 mM Mg ions were added in the mTBA. • mTBA was validated with environmental bacterial strains for screening of lipolytic activity. Method name: Improved method for qualitative screening of lipolytic bacterial strains, Keywords: Lipase activity, Calcium ion, Magnesium ion, Bioprospectin

Modeling the Inhibition of Vibrio cholerae Non-01 in Trypticase Soy Broth by Chitosan of Low and High Molecular Weight

Chitosan has proved to have antimicrobial properties, which can be used to protect seafood from contamination and growth of pathogens such as Vibrio cholerae. The aim of this study was to model the inhibition of Vibrio cholerae Non-01 by low and high molecular weight chitosan. Chitosan of low (LMWC) and high (HMWC) molecular weight (150 and 320 KDa respectively) was used at final concentrations of 600 and 1,000 mg/L and antimicrobial assays were carried out at temperatures of 5 and 35°C. Data were fitted to the Weibull distribution and b and n values were used to plot resistance frequency curves. Inhibition curves showed that the four treatments were effective at 5°C, with 5.5 log reduction after 312 h with the highest chitosan concentration tested, while the effect of the 600 mg/L chitosan concentration was bacteriostatic rather than bactericidal (3.5 log reduction at 388 h). The 1,000 mg/L chitosan concentration was bactericidal at 35°C (6 log reduction) at a shorter time (12 h). No differences were observed by the different molecular weight of the chitosan used. Weibull model fit adequately (R2 > 0.8908) with experimental data, the highest cellular damage occurs significantly (p < 0.05) with high chitosan concentrations regardless of molecular weight and treatment temperature. Resistance frequency plots showed a greater resistance of LMWC, with the maximum values of V. cholerae Non-01 resistance presented in the first minutes of the treatments regardless of the temperature

Microbiological Impact of the Use of Reclaimed Wastewater in Recreational Parks

Reclaimed wastewater for irrigation is an opportunity for recovery of this natural resource. In this study, microbial risk from the use of treated wastewater for irrigation of recreational parks in the city of Chihuahua, evaluating the effect of distribution distance, season, and presence of storage tanks, was analyzed. Escherichia coli, Salmonella, and multidrug-resistant bacteria were recovered from samples of reclaimed water and soils at recreational parks in Chihuahua by the membrane filtration method, using selected agars for microbial growth. Samples were taken at three different seasons. No correlation in the presence of microbial indicators and multidrug-resistant bacteria (p > 0.05) was found between the distance from the wastewater treatment plant to the point of use. Presence of storage tanks in parks showed a significant effect (p < 0.05) with a higher level of E. coli. The highest count in wastewater occurred in summer. We isolated 392 multidrug-resistant bacteria from water and soil; cluster analysis showed that the microorganisms at each location were of different origins. Irrigation with reclaimed wastewater did not have a negative effect on the presence of microbial indicators of the quality of soils in the parks. However, the prevalence of multidrug-resistant bacteria still represents a potential risk factor for human health

Total phenolic content, in vitro antioxidant activity and chemical composition of plant extracts from semiarid Mexican region

AbstractObjectiveTo determine the extraction suitable conditions of total phenolic content (TPC) by heat–reflux system, antioxidant activities and HPLC characterization of the aqueous–ethanolic extracts of Jatropha dioica (J. dioica) (Dragon's blood), Flourensia cernua (F. cernua) (Tar bush), Eucalyptus camaldulensis (E. camaldulensis) (Eucalyptus) and Turnera diffusa (T. diffusa) (Damiana).MethodsTPC was evaluated by the well–known colorimetric assay using Folin–Ciocalteu reagent. The antioxidant activities were assayed by three methods based on scavenging of DPPH, ABTS and by lipid oxidation inhibition. The chemical composition of the extracts obtained was subject to HPLC analysis.ResultsTPC in the plant extracts ranged from 2.3 to 14.12 mg gallic acid equivalents/g for J. dioica and E. camaldulensis, respectively. The plant extracts of F. cernua, E. camaldulensis and T. diffusa showed similar strong antioxidant activities on scavenging of DPPH and lipid oxidation inhibition. In contrast, J. dioica extracts had lowest potential antioxidant in three assays used. HPLC assay showed the presence of several phenolic compounds in the extracts used.ConclusionsThe results obtained suggest that F. cernua, E. camaldulensis and T. diffusa are potential sources to obtain bioactive phenolic compounds with high antioxidant properties which can be used in the factories as antioxidant agents or for treatments in diseases

Ataulfo Mango (<i>Mangifera indica</i> L.) Peel Extract as a Potential Natural Antioxidant in Ground Beef

Total phenolic content (TPC), total flavonoid content (TFC), antioxidant and antimicrobial in vitro activity of ethanolic (EE) and hydroethanolic (HE) extracts of mango peel Ataulfo were evaluated. The highest TPC, TFC and antioxidant capacity were as shown in EE. Ethanolic extract was incorporated into ground beef at 1000 (BBEA) and 2000 mg/kg meat (BEEB) concentrations and then compared with 250 mg of sodium ascorbate/kg meat (ASC) along with a control (without antioxidant). The effects of adding EE on instrumental colour, metmyoglobin content, thiobarbituric acid reactive substances (TBARS), pH, microbial load and sensorial analysis of ground beef were evaluated for 11 days at 4 °C. BEEB added in raw ground beef improved colour stability while the lipid oxidation in raw and raw-cooked ground beef was inhibited with a greater antioxidant effect than ASC and a similar overall acceptability score (cooked ground beef). However, incorporating BEEB into ground beef did not show significant antimicrobial activity. Therefore, mango peel extracts could potentially be used as a natural antioxidant in ground beef