Antibacterial potential of essential oils against planktonic and sessile cells of Escherichia coli isolated from diarrhea cases in swine

Escherichia coli is a pathogen associated with infections in piglets in the post-weaning phase, its pathogenicity is related to the animal's susceptibility to bacterial enterotoxins. The objective of the present study was to determine the EOs activity against E. coli strain, in the form planktonic and sessile. Although the Disc-Diffusion tests to determine the Minimum Inhibitory Concentration, do not fully corroborate with the other analyzes of this study, it was noticed bacteria inhibition. The EOs were prepared at 0.4%, 0.8% and 1.0% for tests. The tested EOs were effective against E. coli planktonic cells (p<0.05). As for the sessile cells, the most significant result was inhibition and 100% sessile cells at the concentration of 1.0% of Cymbopogon citratus EO. Although there was resistance in some treatments, the tested EOs demonstrated inhibition capacity, constituting promising alternatives for the control of E. coli, especially of planktonic cells.

Mushroom Bioactive Compounds

Mushrooms are widely utilized as a nutritional and functional food, and they are also appreciated for their medicinal as well as therapeutic applications. Bioactive compounds are isolated from mushrooms possess medicinal properties such as anti-inflammatory, antimicrobial, antitumor, immunomodulatory, and antioxidant. Mushroom bioactive compounds having antibacterial potential and can be used in medical sectors for the cure of several pathogenic disease. Nanoemulsions are one such example of nano-technique that has a very promising application in various fields. The use of nanoemulsion in encapsulation for food-grade ingredients in their compounds such as vitamins, lipids, antioxidants, and antimicrobial agents is a new technique. Bioactive compounds from mushrooms can be a good alternative source for antibacterial nanoemulsions development. This chapter discusses all bioactive compounds and the production and purification of these bioactive compounds. Another hand discusses the nanoemulsion formation by bioactive compounds and nanoemulsion used as antimicrobial agents.

Chemical profile and antioxidant, antibacterial, and cytotoxic activities on Artemia salina from the essential oil of leaves and xylopodium of Cochlospermum regium

Cochlospermum regium is a shrub plant species from the Cerrado domain used in traditional medicine. This study aimed to evaluate the chemical profile and antioxidant, antibacterial and cytotoxic activities on Artemia salina from the essential oil of fresh leaves and xylopodium. Fresch leaves and xylopodium of C. regium were collected in an area of ​​Cerrado domain in Goiás State, Brazil, 2021. The essential oil was obtained by hydrodistillation, the yield was quantified and the chemical profile determined by gas chromatography with mass spectrometry (GC-MS). Physicochemical analyzes were carried out for organoleptic analysis (color and appearance), solubility, relative density (g mL-1), refractive index, optical rotation (αD), antioxidant activity in DPPH radical reduction (IC50 µL mL-1), antibacterial activity on Escherichia coli, Staphylococcus aureus, Enterococcus faecalis, Salmonella serovar Enteritidis and Salmonella serovar Thyphymurium by the disc method (mm), and cytotoxicity bioassay on Artemia salina (LC50 µg mL-1). The major compounds for the essential oil of fresh leaves were viridiflorol 10.21%, Copaen-4-α-ol <β>, longiborneol 9.07 and β-bisabolene 11.48%, and for the essential oil of xylopodium β-selinene 26.17%, aromadendrene 8.66 % and thujopsene 8.09%. The yield was 0.58 and 0.33%, color slightly yellow and yellow for fresh leaves and xylopodium, respectively. Positive solubility, refractive index of 1.3468 and 1.3347, optical rotation +48.8 and +21.5, relative density 0.932 and 0.936 g mL-1, antioxidant activity IC50 = 47.65 and 111.16 µL mL-1 for fresh leaves essential oil and xylopodium, respectively. The essential oil from fresh leaves showed high antibacterial potential for all strains, as well as for cytotoxic activity on A. salina with LC50 = 90.17 and 625.08 µg mL-1, respectively.

Drug Resistance Reversal Potential of Nanoparticles/Nanocomposites via Antibiotic’s Potentiation in Multi Drug Resistant P. aeruginosa

Bacteria employ numerous resistance mechanisms against structurally distinct drugs by the process of multidrug resistance. A study was planned to discover the antibacterial potential of a graphene oxide nanosheet (GO), a graphene oxide–zinc oxide nanocomposite (GO/ZnO), a graphene oxide-chitosan nanocomposite (GO–CS), a zinc oxide decorated graphene oxide–chitosan nanocomposite (GO–CS/ZnO), and zinc oxide nanoparticles (ZnO) alone and in a blend with antibiotics against a PS-2 isolate of Pseudomonas aeruginosa. These nanocomposites reduced the MIC of tetracycline (TET) from 16 folds to 64 folds against a multidrug-resistant clinical isolate. Efflux pumps were interfered, as evident by an ethidium bromide synergy study with nanocomposites, as well as inhibiting biofilm synthesis. These nanoparticles/nanocomposites also decreased the mutant prevention concentration (MPC) of TET. To the best of our knowledge, this is the first report on nanomaterials as a synergistic agent via inhibition of efflux and biofilm synthesis.

A Comparison of Antibacterial Potential of Different Soil Actinomycetes from Pokhara

Actinomycetes are widely distributed in the environment and used for the production of several important secondary metabolites like antibiotics, immunosuppressive agents, enzymes and antitumor agents. Therefore, the main objective of this study is to isolate and assess antibacterial potential of different actinomycetes obtained from different soil samples. This study was conducted in the microbiology laboratories of Prithvi Narayan Campus and Lambda Food Lab Pvt Ltd, Pokhara. A total of nine soil samples were collected from different places of Pokhara (forest land, agriculture land and lake bank) and processed. Isolated actinomycetes were screened by primary and secondary screening for antibiotic producers against test organisms like Staphylococcus aureus (ATCC 25923), Pseudomonas aeruginosa (ATCC 27853) and Bacillus spp, E coli (ATCC 25922). This study isolated 27 actinomycetes in total, using the soil samples through spread plating on Starch Casein Agar (SCA) and by serial dilution. After incubation, actinomycetes colonies (rough, chalky) were selected for gram staining to observe thin thread-like mycelial and hyphal structures. The highest number of actinomycetes isolates were obtained from agricultural land’s soil samples (14 out of 27 isolates i.e. 51.85%) whereas only 3 isolates were obtained from the lake soil. Primary screening was performed on Nutrient agar where test bacteria were streaked perpendicular to the isolated actinomycetes to observe antagonism. This showed 12 actinomycetes as active isolates inhibiting at least one test bacteria. The antibacterial compounds were extracted by ethyl acetate method and used in secondary screening. Secondary screening in Mueller Hinton agar (MHA) further revealed five isolates showed promising inhibitory capacity. In both screening methods higher sensitivity was observed towards Gram-positive bacteria especially S aureus (ATCC 25923), and the least sensitivity towards Gram-negative bacteria especially Pseudomonas aeruginosa (ATCC 27853). Agricultural land was shown to harbor more actinomycetes than forest land and lake bank soil. Though variations were observed in primary and secondary screening, actinomycetes obtained from agricultural land demonstrated an inhibitory action against the Gram-positive and Gram-negative test organisms. As compared to Gram-negative bacteria, the Gram-positive had higher effects. These findings showed that soil of different locations of Pokhara valley found many actinomycetes strains, preventing the growth of pathogenic bacteria of certain kinds. The study suggested that further investigations need to be done that helped obtain new antimicrobial agents from actinomycetes, using various other sources.

Exploring the DPP-IV Inhibitory, Antioxidant and Antibacterial Potential of Ovine “Scotta” Hydrolysates

The aim of this work was to valorize the by-product derived from the ricotta cheese process (scotta). In this study, ovine scotta was concentrated by ultrafiltration and then subjected to enzymatic hydrolyses using proteases of both vegetable (4% E:S, 4 h, 50 °C) and animal origin (4% E:S, 4 h, 40 °C). The DPP-IV inhibitory, antioxidant, and antibacterial activities of hydrolysates from bromelain (BSPH) and pancreatin (PSPH) were measured in vitro. Both the obtained hydrolysates showed a significantly higher DPP-IV inhibitory activity compared to the control. In particular, BSPH proved to be more effective than PSPH (IC50 8.5 ± 0.2 vs. 13 ± 1 mg mL−1). Moreover, BSPH showed the best antioxidant power, while PSPH was more able to produce low-MW peptides. BSPH and PSPH hydrolysates showed a variable but slightly inhibitory effect depending on the species or strain of bacteria tested. BSPH and PSPH samples were separated by gel permeation chromatography (GPC). LC-MS/MS analysis of selected GPC fractions allowed identification of differential peptides. Among the peptides 388 were more abundant in BSPH than in the CTRL groups, 667 were more abundant in the PSPH group compared to CTRL, and 97 and 75 of them contained sequences with a reported biological activity, respectively.

Isolation and evaluation of in vitro antibacterial potential of endophytic fungi from the leaves of Psidium guajava (Guava)

No Abstract.

Chemical and Bioactive Characterization of the Essential Oils Obtained from Three Mediterranean Plants

Cupressus sempervirens L., Juniperus communis L. and Cistus ladanifer L. are Mediterranean arboreal and shrub species that possess essential oils (EO) in their leaves and branches. This study aimed at characterizing the EOs obtained by steam distillation from the three species collected in different locations from Spain (Almazán, Andévalo, Barriomartín, Cerezal, Ermitas and Huéscar). For this purpose, volatiles composition was determined by GC-MS, and different bioactivities were evaluated. The highest content in terpenes was observed in C. sempervirens (Huéscar origin) followed by J. communis (Almazán origin), corresponding to 92% and 91.9% of total compounds, respectively. With exception of C. ladanifer from Cerezal that presented viridiflorol as the most abundant compound, all the three species presented in common the α-pinene as the major compound. The EOs from C. ladanifer showed high antibacterial potential, presenting MIC values from 0.3 to 1.25 mg/mL. Concerning other bioactivities, C. ladanifer EO revealed an oxidation inhibition of 83%, while J. communis showed cytotoxicity in the MCF-7 cell line, and C. sempervirens and C. ladanifer EOs exhibited the highest potential on NCI-H460 cell lines. Nevertheless, some EOs revealed toxicity against non-tumoral cells but generally presented a GI50 value higher than that of the tumor cell lines.

Chemical Profile of Ruta graveolens, Evaluation of the Antioxidant and Antibacterial Potential of Its Essential Oil, and Molecular Docking Simulations

The research aimed to investigate the chemical composition and antioxidant and antibacterial potential of the essential oil (EO) isolated from the aerial parts (flowers, leaves, and stems) of Ruta graveolens L., growing in western Romania. Ruta graveolens L. essential oil (RGEO) was isolated by steam distillation (0.29% v/w), and the content was assessed by gas chromatography-mass spectrometry (GC-MS). Findings revealed that 2-Undecanone (76.19%) and 2-Nonanone (7.83%) followed by 2-Undecanol (1.85%) and 2-Tridecanone (1.42%) are the main detected compounds of the oil. The RGEO exerted broad-spectrum antibacterial and antifungal effects, S. pyogenes, S. aureus, and S. mutans being the most susceptible tested strains. The antioxidant activity of RGEO was assessed by peroxide and thiobarbituric acid value, 1,1-diphenyl-2-picrylhydrazyl radical (DPPH), and β-carotene/linoleic acid bleaching testing. The results indicated moderate radical scavenging and relative antioxidative activity in DPPH and β-carotene bleaching tests. However, between the 8th and 16th days of the incubation period, the inhibition of primary oxidation compounds induced by the RGEO was significantly stronger (p < 0.001) than butylated hydroxyanisole (BHA). Molecular docking analysis highlighted that a potential antimicrobial mechanism of the RGEO could be exerted through the inhibition of D-Alanine-d-alanine ligase (DDl) by several RGEO components. Docking analysis also revealed that a high number RGEO components could exert a potential in vitro protein-targeted antioxidant effect through xanthine oxidase and lipoxygenase inhibition. Consequently, RGEO could be a new natural source of antiseptics and antioxidants, representing an option for the use of synthetic additives in the food and pharmaceutical industry.