Antibiofilm activity of cashew juice pulp against Staphylococcus aureus, high performance liquid chromatography/diode array detection and gas chromatography-mass spectrometry analyses, and interference on antimicrobial drugs

Effect of clarification on physicochemical properties and nutrient retention of pressed and blended cashew apple juice

The cashew apple is a nutritious pseudofruit of the cashew tree, after the nut. It is highly perishable and has an astringent taste, which hinder its utilization in the food sector. This study was designed to optimize clarification of cashew apple juice (CAJ) using gelatine, and assess the effect of clarification on physicochemical properties (titratable acidity, total soluble solids, and pH), nutrient retention, and sensory quality of pressed and blended CAJ. CAJ was treated with gelatine concentrations (0, 0.025, 0.05, 0.1, 0.2, 0.3, and 0.4 g/L) at room temperature (24-26°C) for 1, 2, 4, 6, 8, 10, and 12 h. Both clarified and unclarified juice were analyzed for tannin, total phenol, β-carotene, vitamin C, sugar, minerals, antioxidant activity, and physicochemical and sensory qualities. The results showed that tannin in pressed CAJ was optimally reduced from 217.6 mg/100 ml TAE to 24.6 mg/100 ml TAE, and from 258.0 mg/100 ml TAE to 55.0 mg/100 ml TAE in blended CAJ, using 0.2 g of gelatine in a liter of juice, for 2 h at room temperature. Both CAJ with and without clarification showed no significant difference in pH, total soluble solids, and titratable acidity (p < .05). However, blended CAJ had higher contents of total phenol, tannin, β-carotene, vitamin C, sugar, minerals, and antioxidant activity (p < .05). The use of a low concentration (0.2 g/L) of gelatine in a liter of either blended or pressed CAJ yielded sweet and less astringent CAJ with high-intensity yellow color. The technologies performed well at room temperature and therefore provide the basis for potential business investment.

Susceptibility of bacterial species isolated from mares to ozonated sunflower oil

Sunflower oil is known for its therapeutic properties and culinary use. It is an important alimentary source of tocopherol and unsaturated fatty acids, and is used especially for wound healing. Studies on its antimicrobial potential, however, are lacking. The ozonation of oils of vegetable sources has been explored to enhance their therapeutic properties; however, studies that provide evidence of such benefits are still lacking. In the field of veterinary medicine, such data are even more scarce. In this study, the antimicrobial activity of ozonated sunflower oil was compared to that of non-ozonated oil, in an in vitro system, against strains of Staphylococcus aureus and Escherichia coli, isolated from intrauterine lavages of mares with endometritis. Tests were conducted using the minimum inhibitory concentration method. The ozonated oil was effective against S. aureus, whereas it was not against E. coli isolates. Our data open doors for discussion on the use of sunflower oil, with or without ozone treatment, for therapeutic purposes in veterinary medicine.

GC, GC/MS Analysis, and Biological Effects of Essential Oils from Thymus mastchina and Elettaria cardamomum

Spanish marjoram (Thymus mastichina) and cardamom (Elettaria cardamomum) are traditional aromatic plants with which several pharmacological properties have been associated. In this study, the volatile composition, antioxidative and antimigratory effects on human breast cancer (MDA-MB-468 cell line), antimicrobial activity, and antibiofilm effect were evaluated. Results obtained via treatment of human breast cancer cells generally indicated an inhibitory effect of both essential oils (EOs) on cell viability (after long-term treatment) and antioxidative potential, as well as the reduction of nitric oxide levels. Antimigratory effects were revealed, suggesting that these EOs could possess significant antimetastatic properties and stop tumor progression and growth. The antimicrobial activities of both EOs were determined using the disc diffusion method and minimal inhibition concentration, while antibiofilm activity was evaluated by means of mass spectrometry. The best antimicrobial effects of T. mastichina EO were found against the yeast Candida glabrata and the G⁺ bacterium Listeria monocytogenes using the disc diffusion and minimal inhibitory concentration methods. E. cardamomum EO was found to be most effective against Pseudomas fluorescens biofilm using both methods. Similarly, better effects of this oil were observed on G^- compared to G⁺ bacterial strains. Our study confirms that T. mastichina and E. cardamomum EOs act to change the protein structure of older P. fluorescens biofilms. The results underline the potential use of these EOs in manufactured products, such as foodstuffs, cosmetics, and pharmaceuticals.

Antibiofilm potential of Psidium guajava and Passiflora edulis pulp extracts against Staphylococcus aureus, cytotoxicity, and interference on the activity of antimicrobial drugs

Background

Pathogenic strains of Staphylococcus aureus can cause several diseases including septicemia and endocarditis, in spite of being a commensal species of the human microbiota. The current drug resistance of S. aureus raises the need for new antimicrobials, and natural products represent a feasible source for prospection of such compounds, due to features including the diversity of structures and mechanisms of action. Here, we provide evidence of the antimicrobial activity of methanolic of Psidium guajava and Passiflora edulis pulps against planktonic cells and biofilms of clinical isolates of S. aureus.

Results

The extracts were effective against the strains in concentrations up to 7.81 and 250 μg/mL for planktonic cells and biofilms, respectively. Antagonistic interactions of the extracts to antimicrobial drugs were observed. The pulps caused no cytotoxic effects on BGM cells. GC-MS analysis found relevant molecules, and UPLC analysis suggested the presence of flavonoids. To the best of our knowledge, this is the first antibiofilm evidence of such extracts.

Conclusion

The extracts seem to be safe and effective enough for more studies aiming at exploring isolated antimicrobial molecules using in vivo models for the treatment of staphylococcal diseases.

Antimicrobial Capacity of Plant Polyphenols against Gram-positive Bacteria: A Comprehensive Review

BACKGROUND

Multi-drug-resistant bacteria such as Methicillin-Resistant Staphylococcus aureus (MRSA) disseminate rapidly amongst patients in healthcare facilities and suppose an increasingly important cause of community-associated infections and associated mortality. The development of effective therapeutic options against resistant bacteria is a public health priority. Plant polyphenols are structurally diverse compounds that have been used for centuries for medicinal purposes, including infections treatment and possess, not only antimicrobial activity, but also antioxidant, anti-inflammatory and anticancer activities among others. Based on the existing evidence on the polyphenols' antibacterial capacity, polyphenols may be postulated as an alternative or complementary therapy for infectious diseases.

OBJECTIVE

To review the antimicrobial activity of plant polyphenols against Gram-positive bacteria, especially against S. aureus and its resistant strains. Determine the main bacterial molecular targets of polyphenols and their potential mechanism of action.

METHODOLOGY

The most relevant reports on plant polyphenols' antibacterial activity and their putative molecular targets were studied. We also performed virtual screening of thousand different polyphenols against proteins involved in the peptidoglycan biosynthesis to find potential valuable bioactive compounds. The bibliographic information used in this review was obtained from MEDLINE via PubMed.

RESULTS

Several polyphenols: phenolic acids, flavonoids (especially flavonols), tannins, lignans, stilbenes and combinations of these in botanical mixtures, have exhibited significant antibacterial activity against resistant and non-resistant Gram-positive bacteria at low μg/mL range MIC values. Their mechanism of action is quite diverse, targeting cell wall, lipid membrane, membrane receptors and ion channels, bacteria metabolites and biofilm formation. Synergic effects were also demonstrated for some combinations of polyphenols and antibiotics.

CONCLUSION

Plant polyphenols mean a promising source of antibacterial agents, either alone or in combination with existing antibiotics, for the development of new antibiotic therapies.

Antioxidant, Antimicrobial, and Anticancer Effects of Anacardium Plants: An Ethnopharmacological Perspective

Anacardium plants have received increasing recognition due to its nutritional and biological properties. A number of secondary metabolites are present in its leaves, fruits, and other parts of the plant. Among the diverse Anacardium plants' bioactive effects, their antioxidant, antimicrobial, and anticancer activities comprise those that have gained more attention. Thus, the present article aims to review the Anacardium plants' biological effects. A special emphasis is also given to their pharmacological and clinical efficacy, which may trigger further studies on their therapeutic properties with clinical trials.

Dexamethasone abrogates the antimicrobial and antibiofilm activities of different drugs against clinical isolates of Staphylococcus aureus and Pseudomonas aeruginosa

Staphylococcus aureus and Pseudomonas aeruginosa are part of the human microbiota and are also important bacterial pathogens, for which therapeutic options are lacking nowadays. The combined administration of corticosteroids and antimicrobials is commonly used in the treatment of infectious diseases to control inflammatory processes and to minimize potential toxicity of antimicrobials, avoiding sequelae. Although different pharmaceutical dosage forms of antimicrobials combined to corticosteroids are available, studies on the interference of corticosteroids on the pharmacological activity of antimicrobials are scarce and controversial. Here, we provide evidence of the interference of dexamethasone on the pharmacological activity of clinically important antimicrobial drugs against biofilms and planktonic cells of S. aureus and P. aeruginosa. Broth microdilution assays of minimal inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum biofilm eradication concentration (MBEC) of gentamicin, chloramphenicol, oxacillin, ceftriaxone and meropenem were conducted with and without the addition of dexamethasone. The effect of all drugs was abrogated by dexamethasone in their MIC, MBC, and MBEC, except gentamicin and meropenem, for which the MBC was not affected in some strains. The present study opens doors for more investigations on in vitro and in vivo effects and safety of the combination of antimicrobials and glucocorticoids.