Antimicrobial and Antibiofilm Potential of Flourensia retinophylla against Staphylococcus aureus.

Staphylococcus aureus is a Gram-positive bacteria with the greatest impact in the clinical area, due to the high rate of infections and deaths reaching every year. A previous scenario is associated with the bacteria's ability to develop resistance against conventional antibiotic therapies as well as biofilm formation. The above situation exhibits the necessity to reach new effective strategies against this pathogen. Flourensia retinophylla is a medicinal plant commonly used for bacterial infections treatments and has demonstrated antimicrobial effect, although its effect against S. aureus and bacterial biofilms has not been investigated. The purpose of this work was to analyze the antimicrobial and antibiofilm potential of F. retinophylla against S. aureus. The antimicrobial effect was determined using an ethanolic extract of F. retinophylla. The surface charge of the bacterial membrane, the K+ leakage and the effect on motility were determined. The ability to prevent and remove bacterial biofilms was analyzed in terms of bacterial biomass, metabolic activity and viability. The results showed that F. retinophylla presents inhibitory (MIC: 250 µg/mL) and bactericidal (MBC: 500 µg/mL) activity against S. aureus. The MIC extract increased the bacterial surface charge by 1.4 times and the K+ concentration in the extracellular medium by 60%. The MIC extract inhibited the motility process by 100%, 61% and 40% after 24, 48 and 72 h, respectively. The MIC extract prevented the formation of biofilms by more than 80% in terms of biomass production and metabolic activity. An extract at 10 × MIC reduced the metabolic activity by 82% and the viability by ≈50% in preformed biofilms. The results suggest that F. retinophylla affects S. areus membrane and the process of biofilm formation and removal. This effect could set a precedent to use this plant as alternative for antimicrobial and disinfectant therapies to control infections caused by this pathogen. In addition, this shrub could be considered for carrying out a purification process in order to identify the compounds responsible for the antimicrobial and antibiofilm effect.

Mechanisms and Applications of Citral's Antimicrobial Properties in Food Preservation and Pharmaceuticals Formulations.

Citral is a monoterpene constituted by two isomers known as neral and geranial. It is present in different plant sources and recognized as safe (GRAS) by the Food and Drug Administration (FDA). In recent years, investigations have demonstrated that this compound exhibited several biological activities, such as antibacterial, antifungal, antibiofilm, antiparasitic, antiproliferative, anti-inflammatory, and antioxidant properties, by in vitro and in vivo assays. Additionally, when incorporated into different food matrices, citral can reduce the microbial load of pathogenic microorganisms and extend the shelf life. This compound has acceptable drug-likeness properties and does not present any violations of Lipinski's rules, which could be used for drug development. The above shows that citral could be a compound of interest for developing food additives to extend the shelf life of animal and vegetable origin foods and develop pharmaceutical products.

Biological Activity of Ganoderma Species (Agaricomycetes) from Sonoran Desert, Mexico.

Ganoderma species have been used in folk medicine against different illnesses and are characterized by producing a diversity of bioactive metabolites (triterpenoids, polysaccharides, flavonoids, and phenols) with numerous medicinal effects (anti-proliferative, antioxidant, anti-inflammatory, and antibacterial). This work aims to evaluate ethanolic extracts of fruiting bodies of Ganoderma oerstedii, G. weberianum, and G. subincrustatum strains from the Sonoran Desert in the anti-proliferative activity by the MTT assay on cancer cell lines; anti-inflammatory effect by quantifying nitric oxide (NO) production; antioxidant activity by DPPH, ABTS, and FRAP assays; total phenolic and flavonoid content by Folin-Ciocalteu and AlCl3 method, respectively; antibacterial activity by the broth microdilution method against Escherichia coli and Staphylococcus aureus. Extracts showed anti-proliferative activity with IC50 < 100 µg/mL on the cancer cell lines MDA-MB-231, A549, and HeLa, except G. subincrustatum extract with an IC50 > 100 µg/mL; anti-proliferative activity was not selective, being affected non-cancerous cell line ARPE-19. Extracts showed significant inhibition of NO release in cells stimulated by LPS, up to 60% with G. subincrustatum and G. oerstedii, and 47% with G. weberianum. All tested assays showed moderate antioxidant potential; the most active was G. lucium (control strain) with IC50 of 69 and 30 µg/mL by DPPH and ABTS respectively; and 271 µg Trolox equivalents/g by FRAP. Total phenols and flavonoids ranged from 38 to 56 mg GAE/g and 0.53 to 0.93 mg QE/g, respectively. A significant correlation was found between the antioxidant activities revealed by DPPH, ABTS, and FRAP with total phenol and flavonoid contents. Antibacterial activity was weak against S. aureus (MIC50 > 10 mg/mL). These results demonstrate that tested Ganoderma mushrooms have medicinal potential such as anti-inflammatory and anti-proliferative.

Effect of Citral on the Thermal Inactivation of Escherichia coli O104:H4 in Ground Beef.

ABSTRACT: The objective of the present study was to analyze the combined effect of heat treatment (55 to 62.5°C) and citral (0 to 3%) on the heat resistance of Escherichia coli O104:H4 inoculated into ground beef. Inoculated meat packages were immersed in a circulating water bath stabilized at 55, 57.5, 60, or 62.5°C for various times. The surviving microbial cells were counted after culture on tryptic soy agar. A factorial design (4 × 4) was used to analyze the effects and interaction of heat treatment and citral. Heat and citral promoted E. coli O104:H4 thermal inactivation, suggesting a synergistic effect. At 55°C, the incorporation of citral at 1, 2, and 3% decreased D-values (control = 42.75 min) by 85, 89, and 91%, respectively (P < 0.05). A citral concentration-dependent effect (P < 0.05) also was noted at other evaluated temperatures. These findings could be of value to the food industry for designing a safe thermal process for inactivating E. coli O104:H4 in ground beef under similar thermal inactivation conditions.

Quantitative analysis of cucurbitane-type triterpenes in Ibervillea sonorae extracts: Relationship study with their antiproliferative activity.

Ibervillea sonorae (Cucurbitaceae) is a Mexican plant commonly used by local population for its hypoglycaemic activity. Root extracts showed also other different biological activities, including antimicrobial, antifungal, antioxidant and anti-inflammatory activity. Main components of this plant are cucurbitacins, steroid-like triterpenes that possess, among others, antiproliferative activity. In previous studies, kinoin A and cucurbitacin IIb extracted from I. sonorae showed antiproliferative and apoptotic effects against different cancer cell lines. Based on all the above, a RP-HPLC method was developed and validated for the quantitative analysis of these two compounds in I. sonorae root extracts obtained with different extraction conditions. In the present study, the quantitative analysis of kinoin B diglycoside in all the extracts was performed as well. As a result, no direct correlation was found between the antiproliferative activity (IC50) against human cervical cancer cell line (HeLa) and the composition of the above three compounds. Only a slight statically significant negative correlation was observed between IC50s and the content of kinoin A (r = 0.29, p = 0.12), meaning that, at least in part, this is the main compound among the three, contributing to the antiproliferative activity on the real samples. Accordingly, a synergistic effect by the phytocomplex components can account for the observed antiproliferative activity of the methanolic extracts towards HeLa cells.

Antioxidant and antimicrobial activity of Agave angustifolia extract on overall quality and shelf life of pork patties stored under refrigeration.

Agave plants contain different bioactive compounds that are related to different biological activities; however, the application of Agave as a food additive has rarely been evaluated. The objective of this study was to evaluate the antioxidant and antimicrobial potential of Agave angustifolia extract (AAE) on pork patties stored at 4 °C during 10 days. According to the spectrophotometric analysis, AAE contained phenolic compounds and saponins. In addition, AAE exhibited antioxidant activity based on DPPH, ABTS and FRAP assays (94.2, 239.1 and 148.8 µmol ET/g, respectively). Likewise, AAE showed bactericidal activity against Staphylococcus epidermidis (60 mg/mL) and Escherichia coli (60 mg/mL). AAE demonstrated a protective effect against oxidative processes (TBARS and metmyoglobin) in patties compared to the control group. Mesophilic and psychotropic counts showed that AAE exhibited a weak antimicrobial effect. AAE showed a protective effect on redness and lightness (at 3 and 10 days of storage, respectively). Sensory evaluation found that AAE had no effect on the analyzed parameters. AAE exhibited antioxidant activity that preserve quality and extended the shelf life of pork patties.

Seasonal Effect on the Biological Activities of Litsea glaucescens Kunth Extracts.

This study shows the seasonal effect on the antioxidant, antiproliferative, and antimicrobial activities of L. glaucescens Kunth (LG) leaves extracts. Their antioxidant activity was evaluated through the DPPH, FRAP, and ORAC assays. Their phenolic content (PC) was determined by means of the Folin-Ciocalteu method, and the main phenolic compounds were identified through a HPLC-DAD analysis. Antiproliferative activity was determined by MTT assay against HeLa, LS 180, M12.C3.F6, and ARPE cell lines. Antimicrobial potential was evaluated against Staphylococcus aureus and Escherichia coli using a microdilution method. All the LG extracts presented high antioxidant activity and PC, with quercitrin and epicatechin being the most abundant. Antioxidant activity and PC were affected by the season; particularly autumn (ALGE) and summer (SULGE) extracts exhibited the highest values (p < 0.05). All extracts presented moderate antiproliferative activity against the cell lines evaluated, HeLa being the most susceptible of them. However, ALGE and SULGE were the most active too. About antimicrobial activity, SULGE (MIC90 < 800 µg/mL; MIC50 < 400 µg/mL), and SLGE (MIC50 < 1000 µg/mL) showed a moderate inhibitory effect against S. aureus. These findings provide new information about the seasonal effect on the PC and biological properties of LG extracts. Clearly, antioxidant activity was the most important with respect to the other two.

Effects and interactions of gallic acid, eugenol and temperature on thermal inactivation of Salmonella spp. in ground chicken.

The combined effects of heating temperature (55 to 65°C), gallic acid (0 to 2.0%), and eugenol (0 to 2.0%) on thermal inactivation of Salmonella in ground chicken were assessed. Thermal death times were determined in bags submerged in a heated water bath maintained at various set temperatures, following a central composite design. The recovery medium was tryptic soy agar supplemented with 0.6% yeast extract and 1% sodium pyruvate. D-values were analyzed by second-order response surface regression for temperature, gallic acid, and eugenol. The observed D-values for chicken with no gallic acid or eugenol at 55, 57.5, 60, 62.5, and 65°C were 21.85, 5.43, 2.83, 0.58, and 0.26min, respectively. A second-order polynomial model developed to inactivate Salmonella was found to be significant (p<0.0001) with a R2=0.95 and a no significant lack of fit (p>0.1073). Efficacy of the additives in increasing the sensitivity of the pathogen to heat was concentration dependent. The model developed in this study can be used by processors to design appropriate thermal process to inactivate Salmonella in chicken products used in the study and thereby, ensuring an adequate degree of protection against risks associated with the pathogen.

Biological activities of Agave by-products and their possible applications in food and pharmaceuticals.

Agave leaves are considered a by-product of alcoholic beverage production (tequila, mezcal and bacanora) because they are discarded during the production process, despite accounting for approximately 50% of the total plant weight. These by-products constitute a potential source of Agave extracts rich in bioactive compounds, such as saponins, phenolic compounds and terpenes, and possess different biological effects, as demonstrated by in vitro and in vivo tests (e.g. antimicrobial, antifungal, antioxidant, anti-inflammatory, antihypertensive, immunomodulatory, antiparasitic and anticancer activity). Despite their positive results in biological assays, Agave extracts have not been widely evaluated in food systems and pharmaceutical areas, and these fields represent a potential route to improve the usage of Agave plants as food additives and agents for treating medical diseases. © 2017 Society of Chemical Industry.

Antibacterial Effects and Mode of Action of Selected Essential Oils Components against Escherichia coli and Staphylococcus aureus.

Bacterial resistance has been increasingly reported worldwide and is one of the major causes of failure in the treatment of infectious diseases. Natural-based products, including plant secondary metabolites (phytochemicals), may be used to surpass or reduce this problem. The objective of this study was to determine the antibacterial effect and mode of action of selected essential oils (EOs) components: carveol, carvone, citronellol, and citronellal, against Escherichia coli and Staphylococcus aureus. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were assessed for the selected EOs components. Moreover, physicochemical bacterial surface characterization, bacterial surface charge, membrane integrity, and K (+) leakage assays were carried out to investigate the antimicrobial mode of action of EOs components. Citronellol was the most effective molecule against both pathogens, followed by citronellal, carveol, and carvone. Changes in the hydrophobicity, surface charge, and membrane integrity with the subsequent K (+) leakage from E. coli and S. aureus were observed after exposure to EOs. This study demonstrates that the selected EOs have significant antimicrobial activity against the bacteria tested, acting on the cell surface and causing the disruption of the bacterial membrane. Moreover, these molecules are interesting alternatives to conventional antimicrobials for the control of microbial infections.

Modeling the effects of temperature, sodium chloride, and green tea and their interactions on the thermal inactivation of Listeria monocytogenes in turkey.

The interactive effects of heating temperature (55 to 65°C), sodium chloride (NaCl; 0 to 2%), and green tea 60% polyphenol extract (GTPE; 0 to 3%) on the heat resistance of a five-strain mixture of Listeria monocytogenes in ground turkey were determined. Thermal death times were quantified in bags that were submerged in a circulating water bath set at 55, 57, 60, 63, and 65°C. The recovery medium was tryptic soy agar supplemented with 0.6% yeast extract and 1% sodium pyruvate. D-values were analyzed by second-order response surface regression for temperature, NaCl, and GTPE. The data indicated that all three factors interacted to affect the inactivation of the pathogen. The D-values for turkey with no NaCl or GTPE at 55, 57, 60, 63, and 65°C were 36.3, 20.8, 13.2, 4.1, and 2.9 min, respectively. Although NaCl exhibited a concentration-dependent protective effect against heat lethality on L. monocytogenes in turkey, addition of GTPE rendered the pathogen more sensitive to the lethal effect of heat. GTPE levels up to 1.5% interacted with NaCl and reduced the protective effect of NaCl on heat resistance of the pathogen. Food processors can use the predictive model to design an appropriate heat treatment that would inactivate L. monocytogenes in cooked turkey products without adversely affecting the quality of the product.