Antibacterial Evaluation Research Articles

Identification of novel 4-thiazolidinones as new TcaR inhibitors: Design, synthesis, molecular docking, MD simulation, ADMET and in vitro antibacterial evaluation

Novel morpholine and piperazine-containing 4-thiazolidinone derivatives (6a-6e) and (7a-7e) were designed and synthesized utilizing a multi-component reaction (MCR) to develop lead compounds with excellent antibacterial potency. The synthesized compounds were characterized using various analytical techniques, including 1H NMR, 13C NMR, IR and HR-MS. Additionally, the docking studies against microbial transcriptional regulators (TcaR) protein offered a comprehensive understanding of the binding interactions between potential molecules and the 3KP3 protein of the Staphylococcus epidermidis (RP62A) organism. These docking studies enabled the prediction of the binding affinity and the identification of key molecular interactions between the compounds and the target protein. Derivatives 6b and 6d showed excellent in vitro inhibitory action at par with ampicillin against S. pyogenes and E. coli, respectively. In general, piperazine-containing compounds showed greater affinity to bind with target protein than the morpholine-containing compounds. The probable reason being, the salt bridge is formed using a terminal nitrogen of the piperazine substituent with the target protein. Furthermore, to assess the dynamic behavior and stability of the most promising compound 6b in complex with the target protein, molecular dynamics simulations were conducted. Protein Cα atoms' RMSD figure reveals that the complex was stable throughout the simulation since the deviation was not more than 2.7 Å at any one time. The simulations revealed that the compound maintained its favorable binding conformation throughout the trajectory, indicating a strong and persistent interaction with the target protein. The in silico ADMET studies of synthesized compounds suggest all compounds are nontoxic and non-carcinogenic in the biological systems.

Synthesis and Antibacterial Evaluation of Novel Vancomycin Derivatives Containing Quaternary Ammonium Moieties.

A series of novel vancomycin analogues with quaternary ammonium moieties have been designed and synthesized for fighting with clinically isolated drug-resistant bacteria. Partial target molecules exhibited potent activity against the tested strains. Among all of the compounds, a triazole quaternary ammonium vancomycin (QAV) derivative QAV-a1 exerted the best antibacterial activities. QAV-a1 was found to be 4- to 32-fold more efficacious than vancomycin against MRSA. Meanwhile, QAV-a1 showed a good pharmacokinetic profile with a half-life of 5.19 ± 0.10 h, which is longer than that of vancomycin (4.3 ± 1.9 h). These results provided guidance for the further exploitation of vancomycin derivatives against drug-resistant bacteria.

Fractionation and Antibacterial Evaluation of the Surface Compounds from the Leaves of Combretum zeyheri on Selected Pathogenic Bacteria.

Combretum zeyheri is traditionally used for the treatment of many infections, including bacterial infections. The aim of this study was to fractionate and evaluate antibacterial activity of the crude extract of C. zeyheri, as well as the surface compounds from the leaves of C. zeyheri, in two pathogenic bacteria, Staphylococcus aureus and Pseudomonas aeruginosa. The antibacterial activities of fractions obtained from chromatographic separations were determined using broth microdilution assay on the laboratory and clinical strains of S. aureus and P. aeruginosa. The fractionation of the compounds on the leaf surface yielded 262 fractions. The fractionated compounds with similar TLC profiles were pooled together to yield 47 pools. The extract and pooled fractions CZSC151154, CZSC155160, and CZSC209213 showed significant antibacterial activity with MIC values ranging from 12.5 μg/ml to 100 μg/ml. The clinical strain of S. aureus had MIC greater than 100 μg/ml for CZSC151154 and CZSC155160. The minimum bactericidal concentration values for these fractions were also in the range of 12.5 μg/ml to 100 μg/ml. The extract and fractions CZSC151154, CZSC155160, and CZSC209213 showed a concentration-dependent inhibition of growth in S. aureus. Analyses of the CZSC209213 pool by LC-MS showed the presence of nine compounds which are (3R,7R)-1,3,7-octanetriol, (-)-tortuosamine, 11-aminoundecanoic acid, 1-piperidinecarboxaldehyde, 3-hydroxy-4-isopropylbenzyl alcohol 3-glucoside, hydroxy-isocaproic acid, oleamide, palmitic amide, phytospingosine, and sphinganine. In conclusion, C. zeyheri leaf surface compounds exhibited antibacterial activity. The crude extract and the pooled fractions showed concentration-dependent inhibition of growth on S. aureus. Results from this study indicate the potential of C. zeyheri as a source of lead compounds that may be further developed into antibacterial drugs.

Characterization, antibacterial and antibiofilm evaluation of biosynthesized silver nanoparticles from Pseudomonas aeruginosa against drug resistant Acinetobacter baumannii

Antimicrobial resistance is regarded as one of the top three terrible events threatening the worldwide existence of humans Here of, Acinetobacter baumannii evolved as the most challenging pathogen threatening to initiate the post-antibiotic era.
 Their ability to withstand antibiotics is attributed to a set of virulence determinants in particular biofilms which are known to enhance pathogenesis and drug resistance potency. Studies regarding green silver nanoparticles (AgNP)s as an alternative treatment modality to antibiotics increased over recent years. Considering these facts, we aimed to explore the antibiofilm effect of AgNPs in the multi-drug-resistant Acinetobacter baumannii. AgNPs were bio-fabricated by Pseudomonas aeruginosa and characterized via FTIR, UV-Vis, XRD, EDS, and SEM. Well-diffusion was used to screen the antimicrobial effects of AgNPs. Minimal-inhibitory concentrations of AgNPs were determined to study their antibiofilm effect at sub-inhibitory concentrations (SIC). Results showed that all isolates were biofilm producers and portrayed high resistance to the tested antibiotics. Characterization results supported the successful fabrication of crystalline nanoparticles. Exposure of the isolates to the bacteriogenic AgNPs resulted in pronounced inhibition zones and reduced biofilms at SICs values. These results indicate that Pseudomonas aeruginosa can be employed to produce AgNPs with an aptitude to disrupt biofilm development and growth in the multi-drug resistant Acinetobacter ­­­­­baumannii.

The Enhanced Durability of AgCu Nanoparticle Coatings for Antibacterial Nonwoven Air Conditioner Filters.

Antibacterial nonwoven fabrics, incorporated with Ag, have been applied as masks and air conditioner filters to prevent the spread of disease from airborne respiratory pathogens. In this work, we present a comparison study of Ag ions: Ag and AgCu nanoparticles (NPs) coated onto nonwoven fabrics intended for use as air conditioner antibacterial filters. We illustrate their color changes and durability running in air conditioners using antibacterial activity testing and X-ray Photoelectron Spectroscopic (XPS) analysis. We found that AgCu NPs showed the best antibacterial efficacy and durability. XPS analysis indicated that the Ag concentration, on both the AgCu and Ag- NP-coated fibers, changed little. On the contrary, the Ag concentration on Ag ion-coated fibers decreased by ~30%, and the coated NPs aggregated over time. The color change in AgCu NP-coated fabric, from yellow to white, is caused by oxide shell formation over the NPs, with nearly 46% oxidized silver. Our results, both from antibacterial evaluation and wind blowing tests, indicate that AgCu NP-coated fibers have higher durability, while Ag ion-coated fibers have little durability in such applications. The enhanced durability of the AgCu NP-coated antibacterial fabrics can be attributed to stronger NP-fiber interactions and greater ion release.

Green synthesis of selenium/attapulgite nanocomposites and antibacterial activities evaluation

Se nanoparticles (NPs) with smaller size often exhibit higher antibacterial activity, thus size control of Se NPs is important to develop its application in the antibacterial field. In this study, Se NPs loaded attapulgite (APT) nanocomposites (Se/APT) were successfully prepared by a one-pot green method mediated by Aloe vera leaf extract, for which APT acts as a support to anchor Se NPs leading to the formation of small-sized and dispersed Se NPs. Structure characterization showed that the well-crystalline Se NPs with a size range of 1 ∼ 3 nm were uniformly distributed on the surface of APT nanorods. Antibacterial activities of the Se/APT nanocomposites were examined against S. aureus, and the result showed that the higher the Se loadings, the better the antibacterial activities of the nanocomposites, and the minimum inhibitory concentration of Se/APT-40% nanocomposite was up to 0.5 mg/mL. In addition, the green-synthesized nanocomposites have little cytotoxicity on mouse fibroblast cell L-929, and conversely promoted the growth and proliferation of the cells. The nanocomposites are expected to be candidates used in various antibacterial fields for preventing infections induced by S. aureus, such as suppuration of the wound.

Novel fluoroquinolones analogues bearing 4-(arylcarbamoyl)benzyl: design, synthesis, and antibacterial evaluation.

Bacterial resistance to fluoroquinolone has been increasing at an alarming rate worldwide. In an attempt to find more potent anti-bacterial agents, an efficient, straightforward protocol was performed to obtain a large substrate scope of novel ciprofloxacin and sarafloxacin analogues conjugated with 4-(arylcarbamoyl)benzyl 7a-ab. All prepared compounds were evaluated for their anti-bacterial activities against three gram-positive strains (Methicillin resistant staphylococcus aureus (MRSA), Staphylococcus aureus, and Enterococcus faecalis) as well as three gram-negative strains (Pseudomonas aeruginosa, Klebsiella pneumonia, and Escherichia coli) through three standard methods including broth microdilution, agar-disc diffusion, and agar-well diffusion assays. Most of the compounds exhibited great to excellent anti-bacterial potencies against MRSA and S. aureus. Among the targeted compounds, derivative 7n exhibited great antibacterial potency, which was noticeably more potent than parent ciprofloxacin. Subsequently, a molecular docking study was performed for this compound to find out its probable binding mode with the active site of S. aureus DNA gyrase (PDB ID: 2XCT).

Serendipitous discovery of a regioselective synthesis of novel benzoyloxy substituted phenyl/benzyl-sulfanyl/selenylbisesters, 3-benzoyloxy-3-(phenylsulfanyl)-β-lactams and their antimicrobial evaluation

The regioselective benzoyloxylation process involves stirring a mixture of phenyl/benzyl-sulfanyl/selenylethanoate 1a-c with appropriate oxidant [benzoyl peroxide (BPO) 2a/ m-chloroperbenzoic acid (m-CPBA) 2b /bis(p-methoxybenzoyl peroxide) (BPM-BPO) 2c] under catalysis of hydrated copper acetate in toluene at 60 °C/RT. Regioselective C–H functionalization of esters 1a-c leads to benzoyloxy substituted phenyl/benzyl-sulfanyl/selenylbisesters 3a-g in good to excellent yields (80–95%). Variably substituted trans-3-phenylsulfanyl-β-lactams 4 employed for C3-H functionalization with BPO 2a generates diastereoisomeric mixture of trans- and cis-3-benzoyloxy-3-(phenylsulfanyl)-β-lactams 5 and 6 as major and minor isomers after efficient column chromatographic purification. The structural confirmation was done using IR, 1H NMR, 13C NMR, DEPT-90 NMR spectroscopic analysis and CHNS elemental analysis. In vitro antibacterial and antifungal evaluations on bisesters suggest benzylselenyl-bisester 3c as potent antimicrobial agent. Out of trans- and cis-3-benzoyloxy-β-lactams 5a and 6a, the trans isomer 5a was active against all microbial strains whereas the cis isomer 6a was completely inactive.

Antibacterial evaluation of electroless Ni–P coating with ZnO nanoparticles on 3D printed ABS

Acrylonitrile butadiene styrene (ABS) is one of the most widely used polymers in the manufacture of different parts in engineering applications. This polymer is sometimes subjected to metallizing processes that seek to modify the surface properties of the accessories. These processes often require the use of chromium and palladium. Some of the accessories in which ABS is used are subjected during their day-to-day use to environments in which they are prone to colonization of bacteria, generating multiple problems that affect both human health and the useful life of different equipment and devices. Recently, there have been great developments of nanoparticles with antibacterial properties, such as zinc oxides. However, these nanoparticles have not yet been incorporated and evaluated in metal coatings on ABS substrates with a view to conferring such properties on the polymer. This work implements the use of an electroless antibacterial Ni-P coating, modified with zinc oxide nanoparticles through processes free of chromium and palladium, on ABS substrates. The results showed that the addition of zinc oxide nanoparticles in quantities of 0.5 g/L and above in the electroless bath confer antibacterial characteristics on the surface for S. aureus under JIS Z 2801 standard. Through the methodology developed, the future development of 3D printed parts with metallized coating is possible, implementing processes chrome and palladium free, expanding the applications and uses of these.

Enhanced synthesis of novel multisubstituted isoxazolidines as potential antimicrobial and antioxidant agents using zinc (II) catalyst, and in silico studies

In the effort of our endeavour to synthesize new heterocyclic bioactive agents, we succeed the synthesis of a new series of Multisubstituted isoxazolidines (3-(4- substituted)-5-(1H-imidazol-1-yl)-2-methyl-1,2-oxazolidine derivatives (3a–l) by 1,3-dipolar cycloaddition between chiral nitrone (1a–l) and 1-vinylimidazole. The spectral data was utilized to verify and elucidate the structures and mechanistic routes of all the products. By utilizing zinc chloride as a catalyst, the reaction rate was significantly enhanced, resulting in a reduction of the reaction time by over 100-fold. After the synthesis process, our objective was to examine the effectiveness of the synthesized compounds as antimicrobial agents against a range of bacterial and fungal species. The antimicrobial properties of the compounds were assessed using the macro double broth dilution method. with some exhibiting higher potency than established antibiotics and antifungals. Additionally, the compounds exhibited good antioxidant activity by in vitro assay, with 3c, 3g, and 3l showing higher activity than ascorbic acid. The study also evaluated the drug-likeness of the synthesized compounds and found that they followed Lipinski's rule of five, making them suitable for oral drug development. Molecular docking studies further supported the in vitro antibacterial evaluation The synthesized compounds demonstrated an excellent binding mode with the target 1QFG protein, some outperformed a standard drug.

Determination of Phytochemicals and Anti-Bacterial Properties Evaluation of the Leaves Extracts of Psidium guajava (L) Myrtaceae

The current study sought to assess the phytochemicals and antimicrobial activities of Psidium guajava Linnaeus leaves extracts. The contents of healthy free fresh leaves of Psidium guajava Linnaeus were analyzed for antibacterial efficacy using dichloromethane (DCM), palm wine, and n-hexane solvents. The presence of several chemical components was revealed by phytochemical analysis of the extracts. The Agar disc diffusion method was used to assess antibacterial activity against five clinically significant organisms. The extract's zone of inhibition against each organism was measured. The presence of phytochemicals such as tannins, terpenoids, flavonoids, alkaloids, and phenol were discovered. Saponin was not found in all of the solvents tested. The antibacterial results showed that the n-hexane fraction had 44mm as zone inhibition against Bacillus subtilis at 25 mg/ml, followed by 42 mm in Escherichia coli at the same concentration, which was significantly higher than the standard amoxicillin at 25 ug. The highest zone of inhibition for DCM fraction was at 25 mg/ml (35 mm) and 10 mg/ml (25 mm) against Pseudomonas aeruginosa and E. coli, respectively, with similar zones of inhibition to the standard. Finally, resistance was observed in P. aeruginosa, but significant inhibition was observed against B. subtilis (30mm), E. coli (15 mm), and S. aureus (15 mm) at 15%. As a result, Psidium guajava leaf extracts contain phytochemicals as well as significant antibacterial properties, particularly against B. subtilis and E. coli, and can be used to obtain useful lead compounds for the eventual synthesis of medicinally significant antioxidant and antibacterial agents.

Antibacterial Evaluation of some traditionally used medicinal plants and their Formulations for treatment of Gastro Intestinal Disorders

Even though modern medicinal system is well developed and easily accessible, the rural people still continues to depend upon traditional medicinal system for curing various ailments. Several cases of fast recovery and many cases of death due to wrong treatment was observed during the year 2018-19 in rural villages of Nagaon district of Assam, India. The objective of this study was to evaluate the efficacy of some medicinal plants and their formulations used by traditional healer for treatment of gastrointestinal disorders. The information was collected by interaction with the traditional healers and altogether 14 plant species were documented for preparation of six different formulations. Antibacterial evaluation against E. coli, P. aeruginosa and S. aureus revealed that formulation prepared from freshly prepared plant materials showed better efficacy than formulations obtained from traditional healers. Again, organic solvents extracts showed greater antibacterial activity than the aqueous extracts. Amongst the solvents, the polar organic solvent methanol showed greater inhibitory effect as compared to other non polar organic solvents, ethanol and hexane. GC-MS analysis of the potent plant extracts showed presence of several bioactive compounds like tumerone, curlone, hexadecanoic acid, oleic acid, eicosanoic acid, erucic acid and isopimaric acid which have earlier reports of having significant antibacterial activities.

Sono-assembly of folate-decorated curcumins/alginate core-shell microcomplex and its targeted delivery and pH/reduction dual-triggered release

In this study, sodium alginate (SA), a non-toxic natural polysaccharide with good biocompatibility and biodegradability, was developed for targeted delivery of curcumin (CUR) in tumor therapy. The strategy is to sulfhydrylate the folic acid (FA) modified SA, and the CUR dissolved in ethyl acetate (EAC) phase is coated in microcapsules by a quick, efficient and environment-friendly sonochemical method. The EAC in the microcapsule core is volatile, which can be recycled and reused to reduce cost. The prepared microcapsules (FA-RSMCs@CUR) exhibited similar toxicity to free curcumin in anti-tumour evaluation in vitro. FA-RSMCs@CUR also exhibited effective antibacterial properties in the antibacterial evaluation in vitro. It is expected to become a low-cost tumor targeting vector in the future, and has the potential to be promoted in clinical application.

Bio‐fabrication of Silver Nanoparticles Using Alysicarpus vaginalis Extract: Preparation, Characterization and Comparative in vitro Antibacterial Evaluations

AbstractGreen synthesis of silver nanoparticles (AgNPs) using the Alysicarpus vaginalis alcoholic extract as a reducing agent and a capping ligand was carried out. Notable peaks of λmax 442–602 nm indicated the reduction of silver ions to elemental AgNPs. Particle size (Zavg) was in the range of 32.3±0.76 to 252.3±0.342 nm). The negative Zeta potential (ZP, −2.9±0.31 to −21.7±0.13 mV) and low polydispersity index (PDI, 0.181±0.02 to 0.635±0.02) supported the homogeneous nature of AgNPs. Further, crystalline spherical nature of AgNPs with a smooth surface was confirmed by high‐resolution transmission electron microscopy (HRTEM) studies. The AgNPs showed 1.2 to 1.4‐fold enhanced antibacterial activity than extract (6–10 mm zone of inhibition) against Staphylococcus aureus, Pseudomonas aeruginosa, Listeria monocytogenes, and Salmonella enterica ser. Typhi by disc diffusion assay. The AgNP formulation F9 showed equal (against Gram‐positive L. monocytogenes) or even better (against Gram‐negative S. enterica Typhi) antimicrobial activity than the positive control, ciprofloxacin. Further investigations on F9 are suggested in order to develop a broad‐spectrum, cost‐effective antibacterial formulation of natural origin. This study represents a significant step forward in the field of bio‐fabrication and presents a promising alternative to traditional chemical synthesis methods for the production of antimicrobial AgNPs.

Hantzsch‐like reaction of isoquinoline‐1‐acetonitrile in synthesis of 4H‐pyrido[2,1‐a]isoquinolines with antibacterial evaluation

AbstractThe in vitro antibacterial activity of brand‐new fused pyrido[2,1‐a]isoquinoline compounds was investigated. The desired pyrido[2,1‐a]isoquinoline derivatives 5, 9, and 10 were obtained by heating 2‐(6,7‐dimethoxy‐3,4‐dihydroisoquinolin‐1‐yl)acetonitrile 1 with ethylacetate derivatives 2, 6, and 7 in refluxing acetonitrile, while piperidine was present as a catalytic quantity. Under the same conditions, compound 1 was refluxed with compounds 11a–f to give the corresponding compounds 12a–f.

Long-Term and Stable Dental Therapies via an In Situ Spontaneous Medicine Delivery System.

Chronic oral diseases are boring, long-term, and discomfort intense diseases, which endanger the physical and mental health of patients constantly. Traditional therapeutic methods based on medicines (including swallowing drugs, applying ointment, or injection in situ) bring much inconvenience and discomfort. A new method possessing accurate, long-term, stable, convenient, and comfortable features is in great need. In this study, we demonstrated a development of one spontaneous administration for the prevention and therapy on a series of oral diseases. By uniting dental resin and medicine-loaded mesoporous molecular sieve, nanoporous medical composite resin (NMCR) was synthesized by a simple physical mixing and light curing method. Physicochemical investigations of XRD, SEM, TEM, UV-vis, N2 adsorption, and biochemical experiments of antibacterial and pharmacodynamic evaluation on periodontitis treatment of SD rats were carried on to characterize an NMCR spontaneous medicine delivery system. Compared to existing pharmacotherapy and in situ treatments, NMCR can keep a quite long time of stable in situ medicine release during the whole therapeutic period. Taking the periodontitis treatment as an instance, the probing pocket depth value in a half-treatment time of 0.69 from NMCR@MINO was much lower than that of 1.34 from the present commercial Periocline ointment, showing an over two times effect.

Synthesis and Sonodynamic Antibacterial Activity Evaluation of Three Novel Fluoroquinolone Compounds

Three ciprofloxacin derivatives (CPDs) were synthesized. Also, their sonodynamic antibacterial activities and possible mechanism under ultrasound (US) irradiation were preliminarily investigated. Staphylococcus aureus and Escherichia coli were selected as the research objects. The sonodynamic antibacterial effects of three CPDs and their structure-effective relationship were explored by the inhibition rate. The reactive oxygen species (ROS) produced under US irradiation were detected by oxidative extraction spectrophotometry and used to analyze the sonodynamic antibacterial mechanism of three CPDs. Research indicated that three CPDs, named compound 1 (C1), compound 2 (C2) and compound 3 (C3), separately all had strong sonodynamic antibacterial activities. In addition, C3 had the strongest effect relative to the other CPDs. The study also found that CPDs' concentration, US irradiation time, US solution temperature and US medium could disturb their sonodynamic antimicrobial effects. Moreover, 1O2 and ·OH were the main types of ROS produced by C1 and C3; the ROS produced by C2 included 1O2, among other types. Results showed that all three CPDs could be activated to produce ROS after US irradiation. Among them, C3 displayed the highest ROS production and the utmost activity, which may be related to the introduction of the electron-giving group at the C-3 position of the quinoline backbone.

Isolation, identification, and antibacterial evaluation of endophytic fungi from Gannan navel orange.

Gannan navel orange is a famous brand in China but the isolation of its endophytic fungi was rarely reported. In this study, a total of 54 strains of endophytic fungi were successfully isolated from the pulp, peel, twig, and leaf of Gannan navel orange; they were successfully identified to belong to 17 species of 12 genera. All these strains were fermented using potato-dextrose agar (PDA) medium, and their secondary metabolites were then extracted with ethyl acetate (EtOAc). The antibacterial assays of Escherichia coli (E. coli), methicillin-resistant Staphylococcus aureus (MRSA), and Xanthomonas citri subsp. citri (Xcc) were also performed for the EtOAc extracts of these strains. As a result, the extracts of both Geotrichum sp. (gc-1-127-30) and Diaporthe biconispora (gc-1-128-79) demonstrated significant antibacterial activities against Xcc, and the MIC value for the extract of Colletotrichum gloeosporioides against MRSA was low to 62.5 μg/mL. Moreover, the chemical components of the extracts of Colletotrichum sp., Diaporthe biconispora, and Annulohypoxylon atroroseum were primarily investigated, and they successfully led to the isolation of 24 compounds involving a new botryane sesquiterpene. Among the isolated products, compound 2 showed significant inhibitory activities toward SA, MRSA, E. coli, and Xcc with MIC values of 12.5, 3.1, 125, and 12.5 μg/mL, respectively. This study revealed that the endophytic fungi of Gannan navel orange showed high potency to produce secondary metabolites with significant antibacterial effects.

Development of biohybrid Ag2CrO4/rGO based nanocomposites with stable flotation properties as enhanced Photocatalyst for sewage treatment and antibiotic-conjugated for antibacterial evaluation

The proposed research outlines a facile method to synthesize Silver Chromate/reduced graphene oxide nanocomposites (Ag2CrO4/rGO NCs) with a narrow dissemination size for the ecological treatment of hazardous organic dyes. The photodegradation performance toward the decontamination of model artificial methylene blue dye was assessed under solar light irradiation. The crystallinity, particle size, recombination of photogenerated charge carriers, energy gap and surface morphologies of synthesized nanocomposites were determined. The experiment objective is to use rGO nanocomposites to increase Ag2CrO4 photocatalytic efficiency in the solar spectrum. Tauc plots of ultraviolet-visible (UV–vis) spectrum were used to calculate the optical bandgap energy of the produced nanocomposites ∼1.52 eV, which resulted in a good photodegradation percentage of ∼92 % after 60 min irradiation of Solar light. At the same time, pure Ag2CrO4 and rGO nanomaterials showed ∼46 % and ∼ 30 %, respectively. The ideal circumstances were discovered by investigating the effects of several parameters, including catalyst loading and different pH levels, on the degradation of dyes. However, the final composites maintain their ability to degrade for up to five cycles. According to the investigations, Ag2CrO4/rGO NCs are an effective photocatalyst and can be used as the ideal material to prevent water pollution. Furthermore, antibacterial efficacy for the hydrothermally synthesized nanocomposite was tested against gram-positive (+ve) bacteria viz. Staphylococcus aureus and gram-negative (−ve) bacteria viz. Escherichia coli. The maximum zone of inhibition for S. aureus and E. coli were 18.5 and 17 mm, respectively.

Fermentation, bioactivity and molecular identification of endophytic fungi isolated from mangrove Ceriops tagal

Abstract. Putra IPYA, Utami KS, Hardini J, Wirasuta IMAG, Ujam NT, Ariantari NP. 2023. Fermentation, bioactivity and molecular identification of endophytic fungi isolated from mangrove Ceriops tagal. Biodiversitas 24: 3091-3098. Mangrove-associated-endophytic fungi are recognized as a considerable source of bioactive compounds in drug discovery. This study evaluated the antimicrobial activity and toxicity of endophytic fungi isolated from Ceriops tagal. Four endophytic fungal isolates, documented as SU-1-4, were obtained. In addition, isolate SU-3 was further identified as Hypoxylon mangrovei according to the comparison of the internal transcribed spacer region. Each fungal isolate was fermented on a solid rice medium, then extracted with ethyl acetate at the end of fermentation. After that, the crude ethyl acetate extracts were partitioned between aqueous methanol and n-hexane, and the methanolic phases were subjected to phytochemical screening and antimicrobial and toxicity assays. Preliminary phytochemical identification suggested the presence of alkaloids, triterpenoids, and steroids in all fungal methanolic extracts. Among them, H. mangrovei SU-3 extract showed the most pronounced antimicrobial effects with minimum inhibitory concentration (MIC) values of 125 and 250 µg.mL-1 towards Staphylococcus aureus ATCC 6538 and Staphylococcus epidermidis ATCC 12228. Meanwhile, the toxicity assay employing the brine shrimp lethality test revealed that all fungal methanolic extracts were toxic, with LC50 values ranging from 173.09 to 227.76 µg.mL-1. Isolation of antibacterial compounds and evaluation of their cytotoxicity on human cancer cells will be promising for further studies.