Marine Based Natural Products: Exploring the Recent Developments in the Identification of Antimicrobial Agents.

The marine ecosystem is the less explored, biologically diverse, and vastest resource to discover novel antimicrobial agents. In recent decades' antimicrobial drugs are losing their effectiveness due to the growing resistance among pathogens, which causes diseases to have considerable death rates across the globe. Therefore, there is a need for the discovery of new antibacterials that can reach the market. There is a gradual growth of compounds from marine sources which are entering the clinical trials. Thus, the prominence of marine natural products in the field of drug design and discovery across the academia and pharmaceutical industry is gaining attention. Herein, the present review covers nearly 200 marine based antimicrobial agents of 11 structural classes discovered from the year 2010 to 2022. All the discussed compounds have exhibited medium to high antimicrobial activity in inhibiting various microorganisms.

Mechanistic Insights into the Antimicrobial Actions of Metallic Nanoparticles and Their Implications for Multidrug Resistance.

Multiple drug-resistant bacteria are a severe and growing public health concern. Because relatively few antibiotics have been approved over recent years and because of the inability of existing antibiotics to combat bacterial infections fully, demand for unconventional biocides is intense. Metallic nanoparticles (NPs) offer a novel potential means of fighting bacteria. Although metallic NPs exert their effects through membrane protein damage, superoxide radicals and the generation of ions that interfere with the cell granules leading to the formation of condensed particles, their antimicrobial potential, and mechanisms of action are still debated. This article discusses the action of metallic NPs as antibacterial agents, their mechanism of action, and their effect on bacterial drug resistance. Based on encouraging data about the antibacterial effects of NP/antibiotic combinations, we propose that this concept be thoroughly researched to identify means of combating drug-resistant bacteria.

The effect of alkyl chain length of (R)-3-Hydroxybutyric alkyl ester on antibacterial activity and its antibacterial mechanism.

This work describes the relationship between the antibacterial activity and the ester chain length (C1-C8) of (R)-3-Hydroxybutyric ((R)-3-HB) alkyl esters that synthesized from (R)-3-HB acid ((R)-3-HBA) by esterification reaction. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) decrease as the length of the (R)-3-HB alkyl ester chain increases from 1 to 6, but (R)-3-HB-C7 and (R)-3-HB-C8 have their own rules for different microorganisms. Among them, the (R)-3HB-C6 has the relatively best antibacterial and antifungal properties, which MIC were 1.95 mg mL-1 against E. coli and S. aureus; 0.98 mg mL-1 against C. albicans and B. subtilis; 0.49 mg mL-1 against A. niger. Finally, the antimicrobial mechanisms of the (R)-3HB-C6 are revealed, and these include disruption of biofilm and the bacterial wall/membrane, leakage of the intracellular content, and change in the transmembrane potential. These results imply the potential application of (R)-3-HB alkyl ester as new antimicrobial agents; future research can use this as an antibacterial element to synthesize new polymer materials or agents with high-efficiency antibacterial activity.

Quaternized Amphiphilic Block Copolymers as Antimicrobial Agents.

In this study, a novel polystyrene-block-quaternized polyisoprene amphipathic block copolymer (PS-b-PIN) is derived from anionic polymerization. Quaternized polymers are prepared through post-quaternization on a functionalized polymer side chain. Moreover, the antibacterial activity of quaternized polymers without red blood cell (RBCs) hemolysis can be controlled by block composition, side chain length, and polymer morphology. The solvent environment is highly related to the polymer morphology, forming micelles or other structures. The polymersome formation would decrease the hemolysis and increase the electron density or quaternized groups density as previous research and our experiment revealed. Herein, the PS-b-PIN with N,N-dimethyldodecylamine as side chain would form a polymersome structure in the aqueous solution to display the best inhibiting bacterial growth efficiency without hemolytic effect. Therefore, the different single-chain quaternized groups play an important role in the antibacterial action, and act as a controllable factor.

Suspect screening of antimicrobial agents transformation products in environmental samples development of LC-QTrap method running in pseudo MRM transitions.

The aim of the work was to develop a new HPLC-MS/MS method that allows for the simultaneous detection of antimicrobials agents (targeted analysis) and their transformation products (non-targeted analysis), which enabled the elucidation of their transformation pathways in the environment. Targeted analysis was performed for 16 selected antimicrobials agents (AMs) in wastewater collected at different stages of the treatment process and river water from sections before and after wastewater discharge. The samples were collected in the Lyna sewage treatment plant (Olsztyn, Poland) in three measuring periods at different seasons. Analytes were selected from tetracyclines, fluoroquinolones, ß-lactams, macrolides, glycopeptides, lincosamides and synthetic antibiotics. As a part of the targeted analysis, 13 AMs were detected in wastewater samples, and 7 of them in river water samples. However, their presence and concentrations were closely related to the type of the sample and the season in which the sample was taken. The highest concentrations of AMs were detected in samples collected in September (max. 1643.7 ng L-1 TRI), while the lowest AMs concentrations were found in samples collected in June (max. 136.1 ng L-1 CLR). The total content of AMs in untreated wastewater was in the range of 1.42-1644 ng L-1, while in the river water was for upstream 1.22-48.73 ng L-1 and for downstream 2.24-149 ng L-1. In the non-target analysis, 33 degradation products of the selected AMs were identified, and the transformation pathways of their degradation were speculated. In the course of the research, it was found that as a result of the processes taking place in wastewater treatment plant, the parent substances are transformed into a number of stable transformation products. Transformation products resulted from hydroxylation, ring opening, oxidation, methylation or demethylation, carboxylation, or cleavage of the CN bond of the parent AMs.

Characterization of Bioactives and Nutra-Pharmaceutical Potential of Supercritical Fluid and Hydro-Distilled Extracted Coriander Leaves Essential Oil.

The volatiles chemical composition and biological attributes of coriander (Coriandrum sativum L.) leaves essential oil obtained by two extraction techniques namely supercritical fluid extraction and hydro-distillation is appraised. The coriander essential oil yield (.12%) by hydro-distillation was slightly higher than that of supercritical fluid extraction (.09%). The physico-chemical variables of the essential oil obtained from both the techniques varied in significantly (P < .05). GC-MS analysis identified 23 different components in supercritical fluid extracted oil and 18 components in hydro-distilled essential oil having linalool as major component (51.32% and 61.78%, respectively) followed by phytol (12.71%). The oil recovered by supercritical fluid extraction exhibited greater DPPH radical scavenging activity as well as reducing power as compared to the essential oil obtained by hydro-distillation technique along with a stronger biofilm inhibition and least hemolysis. The results of antimicrobial activity revealed that super critical fluid extracted essential oil has potent antifungal and antibacterial activity against P. multocida and A alternata, whereas hydro-distilled essential oil displayed better antimicrobial potential against E coli and A niger. Overall, these results depict that supercritical fluid extraction is superior than hydro-distillation with regard to isolation of better-quality coriander essential oil for nutra-pharmaceutical developments.

The Microbiome: A Reservoir to Discover New Antimicrobials Agents.

Nature offered mankind the first golden era of discovery of novel antimicrobials based on the ability of eukaryotes or micro-organisms to produce such compounds. The microbial world proved to be a huge reservoir of such antimicrobial compounds which play important functional roles in every environment. However, most of those organisms are still uncultivable in a classical way, and therefore, the use of extended culture or DNA based methods (metagenomics) to discover novel compounds promises usefulness. In the past decades, the advances in next-generation sequencing and bioinformatics revealed the enormous diversity of the microbial worlds and the functional repertoire available for studies. Thus, data-mining becomes of particular interest in the context of the increased need for new antibiotics due to antimicrobial resistance and the rush in antimicrobial discovery. In this review, an overview of principles will be presented to discover new natural compounds from the microbiome. We describe culture-based and culture-independent (metagenomic) approaches that have been developed to identify new antimicrobials and the input of those methods in the field as well as their limitations.

Antimicrobianos en neonatología. Parte II: Recomendaciones para la dilución y administración de antimicrobianos utilizados en el recién nacido / Antimicrobials in neonatology. Part II: Recommendations for the dilution and administration of antimicrobials in the newborn

Resumen Los antimicrobianos corresponden al grupo de medicamentos más utilizados en Unidades de Cuidados Intensivos Neonatales; no obstante, su uso ha sido asociado a constantes errores de medicación en la práctica clínica. Paradojalmente, aún no existe consenso en torno a la administración adecuada de estos medicamentos y existen importantes brechas de conocimiento en torno a los procesos de dosificación, administración y manipulación de antimicrobianos en esta población. Con el fin de mejorar el uso de antimicrobianos, disminuir errores y optimizar los resultados clínicos en el recién nacido, la presente revisión tiene por objetivo entregar recomendaciones y servir de guía para la correcta preparación de aquellos antimicrobianos de mayor relevancia en neonatología.

Abstract Antimicrobials are among the most commonly prescribed classes of medications in Neonatal Intensive Care Units; however, its use has been constantly associated with a number of medication errors in clinical practice. In contrast to this situation, there is no common agreement when it comes to determining the right dosing, administration, or handling of antibiotics in this population. In order to help improve the use of antibiotics, decrease the rate of medication errors and optimize clinical results in the newborn, this review aims to provide recommendations to support and guide the correct preparation of some of the most relevant antibiotics used in neonatal wards.

Classification of antimicrobial resistance using artificial neural networks and the relationship of 38 genes associated with the virulence of escherichia coli isolates from broilers

Avian pathogenic Escherichia coli (APEC) is responsible for various pathological processes in birds and is considered as one of the principal causes of morbidity and mortality, associated with economic losses to the poultry industry. The objective of this study was to demonstrate that it is possible to predict antimicrobial resistance of 256 samples (APEC) using 38 different genes responsible for virulence factors, through a computer program of artificial neural networks (ANNs). A second target was to find the relationship between (PI) pathogenicity index and resistance to 14 antibiotics by statistical analysis. The results showed that the RNAs were able to make the correct classification of the behavior of APEC samples with a range from 74.22 to 98.44%, and make it possible to predict antimicrobial resistance. The statistical analysis to assess the relationship between the pathogenic index (PI) and resistance against 14 antibiotics showed that these variables are independent, i.e. peaks in PI can happen without changing the antimicrobial resistance, or the opposite, changing the antimicrobial resistance without a change in PI.

Escherichia coli patogênica (APEC) para as aves é responsável por vários processos patológicos em aves, sendo considerado como uma das principais causas de morbidade e mortalidade, associado com perdas econômicas para a indústria avícola. O objetivo do presente trabalho foi demonstrar que é possível predizer a resistência antimicrobiana de 256 amostras de APEC utilizando 38 genes responsáveis por distintos fatores de virulência, através de um programa computacional de redes neurais artificiais (RNAs). O segundo objetivo foi verificar por análise estatística a relação entre o índice de patogenicidade (IP) e a resistência aos 14 antimicrobianos. Os resultados demostraram que as RNAs foram capazes de realizar a classificação correta do comportamento das amostras APEC com uma amplitude de 74,22 a 98,44%, desta forma tornando possível predizer a resistência antimicrobiana. A análise estatística realizada para verificar a relação entre o IP e a resistência aos antimicrobianos demostrou que estas variáveis são independentes, ou seja, podem haver picos no IP sem alteração na resistência, ou até mesmo o contrário, alteração na resistência antimicrobiana sem mudança no IP.