Screening Of Antibacterial Activity Research Articles

Synthesis, Characterization, in vitro Biological Evaluation of a Series of Benzothiazole Amides as Antibacterial Agents

A series of benzothiazole amides (VH01-06) were synthesized by using modified Schotten-Baumann reaction conditions, all the resultant compounds were obtained in good yields and purity. The molecular structure of the compounds was characterized using physical and spectral methods. The structures of the compounds were consistent with the analytical data obtained for FT-IR, 1H NMR, 13C NMR and HRMS ESI-Mass spectroscopic techniques. Further, compounds were subjected to the in vitro antibacterial activity screening against various strains that includes Gram-positive bacteria (methicillin-resistant Staphylococcus aureus (MRSA) ATCC 3359 and methicillin-sensitive Staphylococcus aureus (MSSA) ATCC 2592) and Gram-negative bacteria (Escherichia coli J53 R1, Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC 10031 and Klebsiella pneumonia BAA-1075). Based on the biological screening results, compounds VH01-06 were found to possesses limited antibacterial properties against selected strains, since the recorded activity was found at 100 µM concentration. While compound VH05 displayed specific activity against E. coli ATCC 25923 at 200 µg/mL.

Exploring actinobacteria isolated from coral originated from Tulamben Bali in inhibiting multidrug resistance bacteria

Increasing bacterial resistance has reduced the effectiveness of most clinical antibiotics. The limited option of antibiotics to treat Multi-Drug Resistance pathogen infections indicates that there is an urgency to explore new antibiotic candidates. Coral is recognized to produce bioactive compounds that have the potential to develop new medicinal materials with antibacterial properties. The use of marine invertebrates for compound production will reduce populations in nature, therefore associated microbes are preferred due to their environmental friendliness. Actinobacteria is one of the coral-associated microbes capable of producing active compounds of secondary metabolites as antibacterials. This study aimed to identify coral and obtain isolates of Actinobacteria associated with coral potential as an antibacterial against MDR bacteria. This research uses an explorative method. The method used is coral identification based on the morphology and shape of the sclerite. Screening of antibacterial activity was carried out using the agar plug method, microscopic observation using Gram staining and molecular identification of potential isolates by PCR. The results showed that the coral genera obtained were Siphonogorgia sp., Menella sp., Echinomuricea sp., Dendronephthya sp., and Epizoanthus sp. The results of antibacterial activity indicated that 19 isolates inhibited the growth of MDR pathogen bacteria. However, only the potential isolates were identified. The microscopic observations showed isolate III.ISP2.10-2.3 and III.ISP2.10-2.6 have Gram-positive coccus and bacillus-shaped, respectively. Potential isolates III.ISP2.10-2.3 (Micrococcus yunnanensis) were found to have antibacterial activity against Acinetobacter baumanii, Pseudomonas aeruginosa, and Bacillus subtilis, while isolate III.ISP2.10-2.6 (Brevibacterium pigmentatum) had the greatest activity against B. subtilis.

Antibacterial activity and phytochemical screening of traditional medicinal plants most preferred for treating infectious diseases in Habru District, North Wollo Zone, Amhara Region, Ethiopia.

Ethiopia's healthcare system relies on traditional medicinal practices that use medicinal plants to treat human and livestock ailments. However, the lack of empirical validation regarding the efficacy of these treatments against specific infectious diseases necessitates rigorous scientific investigations. The objective of this study was to investigate the antibacterial activity and phytochemical screening on five selected medicinal plant species, namely Solanum somalense Franchet., Verbascum sinaiticum Benth., Rumex nervosus Vahl, Withania somnifera (L.) Dunal and Calpurnia aurea (Ait.) Benth. The plants were first identified jointly with local informants and later considering mainly their high informant consensus and fidelity level values for their efficacy in treating infectious diseases in the area. Ethanol and aqueous extracts were prepared from the plant materials, and their antibacterial activities were evaluated against standard bacterial strains, representing both gram-positive and gram-negative types. To assess the antibacterial activity of the extracts, the minimum inhibitory concentration (MIC) was determined using the broth dilution method. Additionally, phytochemical screening was performed using standard qualitative tests to identify various secondary metabolites. The results indicated antibacterial efficacy in the ethanol extracts of S. somalense, W. somnifera, and C. aurea against particular bacterial strains (S. somalense against S. agalactiae with MIC of 1.5 mg/mL; W. somnifera against S. aureus and E. coli, with MIC of 2 mg/mL; C. aurea against E. coli and K. pneumoniae, with MICs of 3 mg/mL and 3.5 mg/mL, respectively). The results of the phytochemical screening indicated the presence of steroids, alkaloids, flavonoids, saponins, and terpenoids. The selected medicinal plants demonstrated promising antibacterial activity against certain bacterial strains. The current findings support the long-standing claim of the traditional medical system of the study area for their continued use of these plants in their treatment of infectious diseases. Further investigation is required to isolate the responsible active compounds and characterize the constituents and description of their antibacterial effect for possible use in areas where these infectious diseases are major health problems.

Antibacterial Activity of Herbal Essential Oils against Gram-positive and Gram-negative Bacteria with a Potential for Multidrug Resistance

Background: In recent years, there has been an extensive and great interest in researching and developing alternative antibacterial agents from various sources to combat bacterial resistance. Therefore, greater attention has been paid to the screening of antibacterial activity. Aims: This study evaluated different types of herbal essential oil to inhibit the growth of selected human pathogenic bacteria with potential multidrug resistance properties. Methodology: The herbal essential oils used include thyme oil, tea tree oil, bergamot oil and lavender oil against Staphylococcus aureus, Escherichia coli and Bacillus subtilis. Antibacterial screening of all the essential oils was done by disk diffusion method. Results: Herbal essential oils have exhibited a broad spectrum of antibacterial activities against the selected microbes: B. subtilis, S. aureus and E. coli. Thyme oil has the most potential antibacterial properties for B. subtilis(40 mm), followed by S. aureus(35 mm) and E. coli(35 mm). Both bergamot and lavender oils showed higher antibacterial effects for E. coli and B. subtilis but have lower efficacy with S. aureus than tea tree oil. Conclusion: The herbal essential oils used in this study can serve as a source of alternative antibacterial agents and may play an important role in the discovery of new drugs for the treatment of a wide range of pathogenic bacteria in the future.

Antibacterial Activity and Cytotoxicity Screening of Acyldepsipeptide-1 Analogues Conjugated to Silver/Indium/Sulphide Quantum Dots.

The continuous rise in bacterial infections and antibiotic resistance is the driving force behind the search for new antibacterial agents with novel modes of action. Antimicrobial peptides (AMPs) have recently gained attention as promising antibiotic agents with the potential to treat drug-resistant infections. Several AMPs have shown a lower propensity towards developing resistance compared to conventional antibiotics. However, these peptides, especially acyldepsipeptides (ADEPs) present with unfavorable pharmacokinetic properties, such as high toxicity and low bioavailability. Different ways to improve these peptides to be drug-like molecules have been explored, and these include using biocompatible nano-carriers. ADEP1 analogues (SC005-8) conjugated to gelatin-capped Silver/Indium/Sulfide (AgInS2) quantum dots (QDs) improved the antibacterial activity against Gram-negative (Escherichia coli and Pseudomonas aeruginosa), and Gram-positive (Bacillus subtilis, Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus) bacteria. The ADEP1 analogues exhibited minimum inhibition concentrations (MIC) between 63 and 500 µM, and minimum bactericidal concentrations (MBC) values between 125 and 750 µM. The AgInS2-ADEP1 analogue conjugates showed enhanced antibacterial activity as evident from the MIC and MBC values, i.e., 1.6-25 µM and 6.3-100 µM, respectively. The AgInS2-ADEP1 analogue conjugates were non-toxic against HEK-293 cells at concentrations that showed antibacterial activity. The findings reported herein could be helpful in the development of antibacterial treatment strategies.

Design, synthesis and antibacterial evaluation of N-substituted indole derivatives containing 1,3,4-thiadiazole and amide moieties

A total of eighteen novel 2-(1H-indol-1-yl)-N-(5-phenyl-1,3,4-thiadiazol-2-yl) acetamide derivatives were synthesized through the condensation reaction of 2-(1H-indol-1-yl) acetic acid and 5-phenyl-1,3,4-thiadiazol-2-amine via fragment-based design strategy. The target compounds were subjected to screening for antibacterial activity against Xanthomonas oryzae pv. Oryzae, Xanthomonas axonopodis pv. Citri and Pseudomonas syringae pv. Actinidiae. The preliminary antibacterial evaluation of the target compounds showed that some target compounds possessed moderate to good activities against Xoo and Xac. Among them, compound 3p exhibited best inhibition effects against Xoo (77.85% and 62.15%, respectively) and Xac (52.51% and 36.48%, respectively) at 100 μg/mL and 50 μg/mL, which were superior to Thiodiazole-copper and Bismerthiazol. To the best of our knowledge, it is the first report on the design, synthesis, and antibacterial evaluation of novel indole-derived compounds containing 1,3,4-thiadiazole and amide moieties.

Antibacterial Activity and Preliminary Phytochemical Screening of Forest Chili Leaf (Piper caninum Bl.) Ethanol Extract against Staphylococcus epidermidis

Forest chili leaves (Piper caninum Bl.) has a potential to become an alternative to conventional antibiotics. This study aims to determine the Minimum Inhibitory Concentration (MIC) of forest chili leaf extract, assess the Lethal Concentration (LC50), and analyze the phytochemical composition of the extract. This study also conducted a Completely Randomized Design (CRD) with four repetitions. The agar well diffusion method is used in this study with various concentrations such as T1 ethanol 96% (negative control), T2 (5% concentration), T3 (10% concentration), T4 (15% concentration), T5 (20% concentration), T6 (25% concentration), and T7 Ciprofloxacin 1% (positive control). Data were subjected to ANOVA at a significance level of 5% and further analyzed using Duncan's test. The results showed that all concentrations of forest chili leaf extract (P. caninum Bl.) exerted a statistically significant effect (P 0.05) against Staphylococcus epidermidis bacteria. The research found that the most effective concentration to inhibits S. epidermidis is at 25%, which generates an inhibitory zone of 25.38 ± 0.52 mm. The estimated MIC value for forest chili leaf extract against S. epidermidis was found to be 0.2%, producing an inhibitory zone of 6.38 ± 0.32 mm. Additionally, the calculated LC50 value was 0.26%. Phytochemical screening revealed the presence of various bioactive compound groups in the forest chili leaf extract, including alkaloids, flavonoids, phenols, tannins, and steroids.

Characterization of Actinobacteria strains in Lebanese soil with an emphasis on investigating their antibacterial activity.

With the alarming rise of drug resistant pathogens, the quest for new bioactive compounds from natural habitats has increased. Actinobacteria are Gram-positive bacteria, considered prominent natural antibiotic synthesizers. This study aimed at isolating Actinobacteria from agricultural soil samples of Tamnine El Tahta and Haddatha, with an emphasis on the physicochemical soil characteristics. It also aimed at screening and identifying the antibacterial-producing Actinobacteria, with a determination of the chemical composition of the extract. Forty-six Actinobacteria were isolated from six soil samples. Actinobacteria load exhibited a positive correlation with moisture content, and a negative correlation with pH, salinity, and organic matter content. Primary screening for antibacterial activity was performed against various Gram-positive and Gram-negative bacteria by cross-streak method. Fourteen Actinobacteria isolates were potent against the test microorganisms, and the most effective isolate (T25) was selected for identification, and extract preparation. The antibacterial activity of the extract was tested using secondary screening, in addition to minimal inhibitory concentration (MIC), and minimal bactericidal concentration (MBC) determination. T25 isolate exhibited a 92% similarity with Micrococcus luteus/lylae. MIC recorded was 12.5mg/ml and the MBC was higher than 100mg/ml against all test microorganisms. Total phenol content was estimated to be 18.5 ± 0.0015mg GAE/g dry weight using Folin-Ciocalteu method, and total flavonoid content recorded 2.3 ± 0.02mg RE/g dry weight using aluminum nitrate colorimetric method. This study revealed that the physicochemical parameters in soils impact the distribution of Actinobacteria. Moreover, it focuses on Micrococcus luteus/lylae strain, considered a promising antibacterial resource for further potential clinical investigations.

Screening for antibacterial and cytotoxic activities of Sri Lankan marine sponges through microfractionation: Isolation of bromopyrrole alkaloids from Stylissa massa.

Sri Lanka is a biodiversity hotspot and one of the richest geographical locations of marine sponges in the Indian ocean. However, the most extensive taxonomical study on Sri Lankan sponge biodiversity dates back ~100 years and only a limited number of studies have been conducted on sponge natural products. In the current study, 35 marine sponge specimens (collected from 16 sponge habitats around Sri Lanka) were identified, microfractionated and evaluated for antibacterial and anticancer assays. In total, 30 species were characterized, of which 19 species gave extracts with antibacterial and/or cytotoxic activities. Microfractionated organic extract of Aciculites orientalis gave the most potent antibacterial activity against Staphylococcus aureus and strongest lymphoma cell toxicity was exhibited by the organic extract of Acanthella sp. Guided by the molecular ion peaks in the bioactive fractions, large-scale extraction of Stylissa massa led to the isolation of three bromopyrrole alkaloids, sceptrin, hymenin and manzacidin A/C. Of these, sceptrin exhibited broad spectrum antibacterial activity against both Escherichia coli and S. aureus (MIC of 62.5 μM against both species). Based on natural product literature, seven promising species were identified as understudied. Their further exploration may lead to the discovery of structurally novel compounds.

The applicability of bioluminescent bacteria for preliminary screening of antibacterial activity: comparative analysis of aqueous and ethanol extracts from plant raw material

The applicability of bioluminescent bacteria for preliminary screening of antibacterial activity: comparative analysis of aqueous and ethanol extracts from plant raw material

Anti-MRSA and cytotoxic activities of different solvent extracts from Artemisia herba-alba grown in Shubak, Jordan.

Globally, resistance to antimicrobial drugs is a major hazard to public health. Infections that were once easily treatable with antibiotics are becoming harder to control, leading to prolonged illnesses, increased mortality rates, and higher healthcare costs. This study intended to assess the antimicrobial, specifically the anti-Methicillin resistant Staphylococcus aureus (MRSA), and anticancer properties of different extracts obtained from A. herba-alba (AHA). The antibacterial tests of AHA were performed on two Gram-negative bacterial strains (Escherichia coli and Klebsiella pneumonia), two Gram-positive bacterial strains (Methicillin-resistant Staphylococcus aureus (MRSA), and Staphylococcus aureus). Initial screening for antibacterial activities was conducted using the well diffusion technique. Subsequently, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined through the broth-dilution assay. The anticancer test was carried out in vitro on a human colorectal carcinoma cell line (HCT-116) using MTT assay. Among all extracts, n-hexane extract of AHA was the most effective against S. aureus with the highest inhibition zone (24.67 mm ± 0.58) compared to standard antibiotic (erythromycin, 24.00 mm) followed by the methanolic extract against MRSA (24.00 mm ± 1.73). The methanol extract of AHA showed the highest antibacterial activity against MRSA. The results of MIC and MBC of the AHA methanol extract against MRSA were 1.17 ± 1.09 and 9.375 ± 0.0 mg/ml, respectively, demonstrating therapeutically significant antibacterial activity. Ethyl acetate extract has no antibacterial activity against E. coli and K. pneumonia. The findings indicated that the methanol extract of AHA exhibited the highest efficacy against the colorectal carcinoma cell line (HCT-116), with an IC50 value of 126.61 ± 13.35 μg/ml. These findings suggest that the methanol extract of AHA could be considered as a potential agent to serve as a source of antibacterial and anticancer compounds.

Morpholine-modified Ru-based agents with multiple antibacterial mechanisms as metalloantibiotic candidates against Staphylococcus aureus infection.

Multidrug-resistant bacteria resulting from the abuse and overuse of antibiotics have become a huge crisis in global public health security. Therefore, it is urgently needed to develop new antibacterial drugs with unique mechanisms of action. As a versatile moiety, morpholine has been widely employed to enhance the potency of numerous bioactive molecules. In this study, a series of ruthenium-based antibacterial agents modified with the morpholine moiety were designed and characterized, aiming to obtain a promising metalloantibiotic with a multitarget mechanism. Antibacterial activity screening demonstrated that the most active complex Ru(ii)-3 exhibited the strongest potency against Staphylococcus aureus (S. aureus) with an MIC value of only 0.78 μg mL-1, which is better than most clinically used antibiotics. Notably, Ru(ii)-3 not only possessed excellent bactericidal efficacy, but could also overcome bacterial resistance. Importantly, Ru(ii)-3 very efficiently removed biofilms produced by bacteria, inhibited the secretion of bacterial exotoxins, and enhanced the activity of many existing antibiotics. The results of mechanism studies confirmed that Ru(ii)-3 could destroy the bacterial membrane and induce ROS production in bacteria. Furthermore, animal infection models confirmed that Ru(ii)-3 showed significant anti-infective activity in vivo. Overall, this work demonstrated that a morpholine-modified ruthenium-based agent is a promising antibiotic candidate in tackling the crisis of drug-resistant bacteria.

Phytochemical Screening of Secondary Metabolites, Antioxidant and Antibacterial Activities of Kalangkala Plant (Litsea Angulata): A Review Article

Litsea angulata, more commonly known as Kalangkala, is a type of plant that belongs to the Lauraceae family. Empirically, the plant has been used traditionally by local people for the treatment of boils, diarrhea, stomachache, dyspepsia, gastroenteritis, diabetes, insect bites, and anti-irritation. This review article aims to find out the results of phytochemical screening of metabolites from parts of Kalangkala plant with various solvents as well as the results of the tests of antioxidant and antibacterial activities that several researchers have carried out. The method used was a literature search on Google Scholar and Pubmed with the keywords kalangkala, Litsea angulata, phytochemical screening, antioxidant, and antibacterial. The results of this review showed that various solvents, such as water, ethanol, methanol, N-hexane, and ethyl acetate in seed, fruit flesh, bark, stem, and leave parts of Kalangakala plant produces different amounts of secondary metabolites. Secondary metabolites such as alkaloids, flavonoids, saponins, and tannins extracted well using etanol as a solvent due to their polarity. The results of the antioxidant activity showed that the part of kalangakala plant such as the bark of the tree, has a very good antioxidant activity of 2.41 ppm when tested using ethyl acetate solvent. Furthermore, the results of the antibacterial activity test show an inhibition of 50 mm on S. mutans bacteria when tested using ethanol solvent. In conclusion, kalangkala plant has secondary metabolites which act as antioxidants and antimicrobials that also potential to developed as traditional medicine.

Antimicrobial activity of plant from educational forest in Universitas Borneo Tarakan

Universitas Borneo Tarakan Educational Forest has a mega biodiversity. There is the potential of plants as raw materials for new medicines or as substitutes for food reserves domesticated. This study aims to identify and explore plant species by screening for antibacterial activity of 25 selected plant species found in the Educational Forest of the Universitas Borneo Tarakan. In this investigation, the agar well method was implemented with a concentration of 5 mg/ml, to determine the antimicrobial activity against five distinct microorganisms. These microorganisms included Streptococcus sobrinus, S. mutans, Candida albicans, Propionibacterium acne, Staphylococcus aureus, and Salmonella typhi. This study resulted in the finding that there were five plants capable of inhibiting the growth of S. sobrinus bacteria, namely, Cytandra sp., Cratoxylum sumatranum, Garcinia sp., Fissistigma sp., and Cyclosorus interruptus, with respective inhibitions of 62%, 54.2%, 49%, 46%, and 45%. Inhibition also occurred in P. acne, namely in Cratoxylum sumatranum, with an inhibition of 46.5%. Cytandra sp. has the strongest inhibition because it can inhibit three bacteria, namely S. aureus, S. sobrinus, and S. thypi, at 71%, 62%, and 50%, respectively. This research needs to be carried out further to identify compounds that play a role in the inhibition mechanism to obtain plant species that play a direct role in disease and can be domesticated.

Comparative Study of Antibacterial Activity of Elephantopus scaber Linn. and Elephantopus mollis Kunth. Extract

Elephantopus scaber Linn. and E. mollis Kunth. are medicinal plant that are traditionally used in Indonesia. This research aimed to determine and compare the antibacterial activity of leaf, stem, and root extracts of the two Elephantopus species against various pathogen bacteria strains. The leaves, stem, and roots of E. scaber Linn. and E. mollis Kunth. were extracted using a Soxhlet apparatus. The disk diffusion method for screening antibacterial activity was conducted with a concentration of 50 mg/mL. The activities of the extracts were determined by Minimum Inhibitory Concentration (MIC) assay using broth microdilution method at a concentration range of 2500 to 1.2 µg/mL against nine human pathogenic bacteria. The results showed that all tested extracts demonstrated antibacterial activitied at varying degrees on all pathogen bacteria strains used in this study. The n-hexane and ethyl acetate extracts from both plants were potent antibacterials with MIC values of 19-156 µg/mL against Staphylococcus aureus ATCC 25923, Streptococcus mutans ATCC 25 175, Vibrio cholerae Inaba, and Pseudomonas aeruginosa ATCC 27853. The present study also revealed that among the bacteria tested, S. mutans ATCC 25175 was the most susceptible to antibacterial properties of E. scaber Linn. and E. mollis Kunth., especially in ethyl acetate fractions (MIC 19 and 39 µg/mL, respectively). The findings suggested that the leaves of both plants hold promise as sustainable bioresources for the development of antibacterial agents. Additionally, ethyl acetate and n-hexane extracts were found to be particularly effective for obtaining natural antibacterial agents from these plants. However, further optimization of the extraction process is needed.

Evaluation of Antimicrobial Activity by Marine Nocardiopsis dassonvillei against Foodborne Listeria monocytogenes and Shiga Toxin-Producing Escherichia coli.

The emergence of multidrug-resistant pathogens creates public health challenges, prompting a continuous search for effective novel antimicrobials. This study aimed to isolate marine actinomycetes from South Africa, evaluate their in vitro antimicrobial activity against Listeria monocytogenes and Shiga toxin-producing Escherichia coli, and characterize their mechanisms of action. Marine actinomycetes were isolated and identified by 16S rRNA sequencing. Gas chromatography-mass spectrometry (GC-MS) was used to identify the chemical constituents of bioactive actinomycetes' secondary metabolites. Antibacterial activity of the secondary metabolites was assessed by the broth microdilution method, and their mode of actions were predicted using computational docking. While five strains showed antibacterial activity during primary screening, only Nocardiopsis dassonvillei strain SOD(B)ST2SA2 exhibited activity during secondary screening for antibacterial activity. GC-MS identified five major bioactive compounds: 1-octadecene, diethyl phthalate, pentadecanoic acid, 6-octadecenoic acid, and trifluoroacetoxy hexadecane. SOD(B)ST2SA2's extract demonstrated minimum inhibitory concentration and minimum bactericidal concentration, ranging from 0.78-25 mg/mL and 3.13 to > 25 mg/mL, respectively. Diethyl phthalate displayed the lowest bacterial protein-binding energies (kcal/mol): -7.2, dihydrofolate reductase; -6.0, DNA gyrase B; and -5.8, D-alanine:D-alanine ligase. Thus, marine N. dassonvillei SOD(B)ST2SA2 is a potentially good source of antibacterial compounds that can be used to control STEC and Listeria monocytogenes.

In vitro antibacterial activity of dinuclear thiolato-bridged ruthenium(II)-arene compounds.

The antibacterial activity of 22 thiolato-bridged dinuclear ruthenium(II)-arene compounds was assessed in vitro against Escherichia coli, Streptococcus pneumoniae, and Staphylococcus aureus. None of the compounds efficiently inhibited the growth of the three E. coli strains tested, and only compound 5 exhibited a medium activity against this bacterium [MIC (minimum inhibitory concentration) of 25 µM]. However, a significant antibacterial activity was observed against S. pneumoniae, with MIC values ranging from 1.3 to 2.6 µM for compounds 1-3, 5, and 6. Similarly, compounds 2, 5-7, and 20-22 had MIC values ranging from 2.5 to 5 µM against S. aureus. The tested diruthenium compounds have a bactericidal effect significantly faster than that of penicillin. Fluorescence microscopy assays performed on S. aureus using the BODIPY-tagged diruthenium complex 15 showed that this type of metal compound enters the bacteria and does not accumulate in the cell wall of gram-positive bacteria. Cellular internalization was further confirmed by inductively coupled plasma mass spectrometry experiments. The nature of the substituents anchored on the bridging thiols and the compounds molecular weight appears to significantly influence the antibacterial activity. Thus, if overall a decrease of the bactericidal effect with the increase of compounds' molecular weight is observed, however, the complexes bearing larger benzo-fused lactam substituents had low MIC values. This first antibacterial activity screening demonstrated that the thiolato-diruthenium compounds exhibit promising activity against S. aureus and S. pneumoniae and deserve to be considered for further studies. IMPORTANCE The in vitro assessment of diruthenium(II)-arene compounds against Escherichia coli, Streptococcus pneumoniae, and Staphylococcus aureus showed a significant antibacterial activity of some compounds against S. pneumoniae, with minimum inhibitory concentration (MIC) values ranging from 1.3 to 2.6 µM, and a medium activity against E. coli, with MIC of 25 µM. The nature of the substituents anchored on the bridging thiols and the compounds molecular weight appear to significantly influence the antibacterial activity. Fluorescence microscopy showed that these ruthenium compounds enter the bacteria and do not accumulate in the cell wall of gram-positive bacteria. These diruthenium(II)-arene compounds exhibit promising activity against S. aureus and S. pneumoniae and deserve to be considered for further studies, especially the compounds bearing larger benzo-fused lactam substituents.

Efficacy of Penicillium limosum Strain AK-7 Derived Bioactive Metabolites on Antimicrobial, Antioxidant, and Anticancer Activity against Human Ovarian Teratocarcinoma (PA-1) Cell Line.

Natural metabolites from beneficial fungi were recognized for their potential to inhibit multidrug-resistant human and plant fungal pathogens. The present study describes the isolation, metabolite profiling, antibacterial, and antifungal, antioxidant, and anticancer activities of soil fungi. Among the 17 isolates, the AK-7 isolate was selected based on the primary screening. Further, the identification of isolate AK-7 was performed by 18S rRNA sequencing and identified as Penicillium limosum (with 99.90% similarity). Additionally, the ethyl acetate extract of the Penicillium limosum strain AK-7 (AK-7 extract) was characterized by Fourier Transform Infrared Spectroscopy (FTIR) and a Gas Chromatography-Mass Spectroscopy (GC-MS) analysis, and the results showed different functional groups and bioactive metabolites. Consequently, a secondary screening of antibacterial activity by the agar well diffusion method showed significant antibacterial activity against Gram-negative and Gram-positive bacterial pathogens. The AK-7 extract exhibited notable antifungal activity by a food poisoning method and showed maximum inhibition of 77.84 ± 1.62%, 56.42 ± 1.27%, and 37.96 ± 1.84% against Cercospora canescens, Fusarium sambucinum and Sclerotium rolfsii phytopathogens. Consequently, the AK-7 extract showed significant antioxidant activity against DPPH and ABTS•+ free radicals with IC50 values of 59.084 μg/mL and 73.36 μg/mL. Further, the anticancer activity of the AK-7 extract against the human ovarian teratocarcinoma (PA-1) cell line was tested by MTT and Annexin V flow cytometry. The results showed a dose-dependent reduction in cell viability and exhibited apoptosis with an IC50 value of 82.04 μg/mL. The study highlights the potential of the Penicillium limosum strain AK-7 as a source of active metabolites and natural antibacterial, antifungal, antioxidant, and anticancer agent, and it could be an excellent alternative for pharmaceutical and agricultural sectors.

Characterization and Antibacterial Activity of Soil Actinomycetes from Diverse Land Use Systems in Meru South, Eastern Kenya

Aim: The increasing emergence and global spread of antibiotic-resistance by microorganisms pose a severe public health threat. Continuous exploration of different environments is required to find new sources of antibacterial compounds. Therefore, the study isolated, characterized and identified potential Actinomycetes candidates with antibacterial activity against bacterial pathogens from diverse land use systems.
 Study Design: Soil samples from land use systems were collected using a cross-sectional survey technique using line transect sampling in order to isolate Actinomycetes. A 30 × 7× 3 factorial experiment with a completely randomized design was used for evaluating Actinomycetes isolates with antibacterial activity.
 Methodology: The in-vitro cultivation of Actinomycetes was evaluated using four selective media. The Actinomycetes isolates were characterized using morphological, biochemical, and molecular markers. The antibacterial activity screening of crude extracts was conducted against six bacterial pathogens using the agar well diffusion method. The antibacterial activity of Actinomycetes isolates were analyzed using Analysis of Variance. The molecular identification was performed using 16S rRNA sequence homology.
 Results: The morphological analysis showed variations in colony morphology, including differences in color, size, and texture. Biochemical tests provided insights into the metabolic capabilities of the isolates, indicating variations in enzymatic activities and substrate utilization. Antagonistic activity of Actinomycetes extracts exhibited significant differences (P =.05) against test bacterial pathogens. Notably, isolate C52 from degraded forest zone showed the highest antibacterial activity against Staphylococcus aureus (12.21 mm), isolate L6 (16.23 mm) against Listeria monocytogenes and isolate C50 (15.5 mm) against Raoutella planticola. Streptomyces celluloflavus, S. griseobrunneus, S. pratensis, S. crystallinus, and S. eurocidicus were identified in the study.
 Conclusion: The crude extracts obtained from Actinomycetes showed significant antibacterial activity against the selected test organisms. This suggests the presence of bioactive compounds with potential antibacterial properties within these extracts.

Phytochemical screening and evaluation of antiradical and antibacterial activities of stem and root barks of Gardenia ternifolia Schumach. (Rubiaceae): A plant traditionally used in northern Côte d'Ivoire

Gardenia ternifolia is an Ivorian plant species used to treat tooth decay, hemorrhoidal crises, leprosy, skin diseases and rheumatism. The present study is based on phytochemical screening and evaluation of the antiradical and antibacterial activities of aqueous, hydroethanolic and ethanolic extracts of G. ternifolia stem and root barks. Phytochemical screening of secondary metabolites was carried out using tube color reaction methods and Thin Layer Chromatography (TLC). Phytochemical screening revealed the presence of polyphenols (flavonoids, coumarins, tannins), saponins, steroids and terpenoids in G. ternifolia stem and root extracts. Phenolic acids were revealed only in stems, while alkaloids were absent in both organs studied. Anti-radical activities were highlighted in both organs by qualitative and quantitative methods with respect to the DPPH free radical. However, quantitative spectrophotometric analysis showed better antioxidant activity in stems than in roots. Antibacterial activity assessed against 05 bacterial strains using the solid-medium diffusion and liquid-medium dilution methods showed that only the aqueous and ethanolic extracts of G. ternifolia stems were absolutely bactericidal against the Staphylococcus aureus strains tested (S.a ATCC 29213, S.a 06 UB/22 and S.a 27 UB/22). The results obtained could give the stems the ability to treat infections caused by S. aureus bacteria.