Andrey Moacir Do Rosario Marinho

According to the World Health Organization (WHO), bacterial resistance is a critical global public health concern, highlighting the urgent need for novel antimicrobial agents. Tyrosol (1), a phenolic compound known for its broad spectrum of biological activities, served as the lead framework for the synthesis of three derivatives: 4‐(2‐acetoxyethyl)‐phenylacetate (2), 4‐(2‐(butyryloxy)‐ethyl)‐phenylbutyrate (3), and 4‐(2‐(benzoyloxy)‐ethyl)‐phenylbenzoate (4). Their structures were fully characterized by nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS). The antimicrobial activity of the compounds was evaluated against both Gram‐negative and Gram‐positive bacteria using the broth microdilution method. Among them, compound 2 exhibited the most potent activity, with minimum inhibitory concentrations (MICs) as low as 3.9 µg/mL. In addition, in silico ADME physicochemical properties were calculated using the SwissADME web tool. Compound 3 is also described for the first time in the literature.

This study investigated the effect of convective drying (40, 50, and 60 °C) on the drying kinetics and the physicochemical, phytochemical, and antimicrobial properties of Azadirachta indica leaves for food industry applications. The Midilli model best described the drying behavior. Increasing the temperature significantly reduced drying time and raised effective diffusivity, with an activation energy of 79.3 kJ mol⁻¹. Drying sharply reduced moisture content (78.54% to 5.84%) and water activity (< 0.40), ensuring material stability for storage. Essential oil yield remained constant (5.67%), but higher temperatures enhanced recovery per unit of dry mass. Chromatographic analyses revealed that drying temperature modulated volatile and phenolic profiles, affecting bioactive compound stability and transformation. The essential oil exhibited selective antimicrobial activity, particularly against Staphylococcus aureus, demonstrating strong potential against foodborne pathogens. Lower susceptibility in Gram-negative bacteria was attributed to structural barriers limiting hydrophobic compound action. Overall, temperature control is key to balancing process efficiency and bioactive preservation, confirming A. indica leaves as a viable source of natural antimicrobials and functional ingredients for food preservation.

Beneficial endophytic bacteria may confer advantages to their host plants and to the environment by pathogen control, while reducing pesticide use. The aim of this work was to determine the biochemical profile and antifungal activity of endophytic bacteria from black pepper roots against Fusarium solani f. sp. piperis , F. oxysporum , and Colletotrichum gloeosporioides , which cause fusariosis and anthracnose in black pepper. One hundred and sixty‐four endophyte bacteria strains isolated from black pepper roots were tested in vitro against three phytopathogenic fungi. Seven selected antagonistic strains were identified at the genus level by sequencing the 16S region of the ribosomal RNA. In addition, the production of lytic enzymes and siderophores was evaluated that may be related to the biocontrol of pathogenic microorganisms. The effect of ethyl acetate and ethanolic extracts of antagonistic strains on the germination of pathogen spores was evaluated. Strains C5.4, C5.9, T1.5, T4.1, T4.7, T6.2, and T6.4 showed antifungal activity with inhibition ranging from 30.27% to 61.42%, and were identified as species of the genus Burkholderia . The biochemical profile showed that strains produced lipase, esterase, protease, and siderophores, which may be related to their antifungal activity. The best results of antifungal activity were shown by the ethyl acetate extracts of strains C5.4, C5.9, T4.7, T6.2, T6.4, and T4.1, with percentages ranging from 4.71% to 51.89%. This study demonstrated that endophytic bacteria from black pepper have potential for the biocontrol of fungal diseases and can be further investigated to obtain a formulation for the control of pathogenic microorganisms associated with this crop.

The objective of this work was to investigate three endophytic bacterial strains as to their ability to promote the growth and rooting of black pepper stem cuttings, as well as to determine the mechanisms involved in the promoting activity through molecular methods. The strains were identified by 16S sequencing as belonging to the genera Bacillus, Priestia, and Lysinibacillus. They were characterized for the production of indoleacetic acid (IAA), phosphate solubilization, and siderophore production. In two assays, the roots of the cuttings were immersed in bacterial suspensions to evaluate growth promotion through plant height, stem diameter, and root and shoot dry mass. The Bacillus sp. C1.4 and Priestia sp. T2.2 strains were able to produce siderophores, whereas Priestia sp. T2.2 and Lysinibacillus sp. C5.11 produced IAA. In addition, Priestia sp. T2.2 significantly increased plant height and dry mass, whereas Lysinibacillus sp. C5.11 significantly increased root dry mass. Therefore, Priestia sp. T2.2 and Lysinibacillus sp. C5.11 are able to promote the growth and rooting of black pepper stem cuttings, respectively. This growth promotion is linked directly to the production of IAA and siderophores.

Turmeric is a spice that has gained significant popularity in global cuisine. Beyond its culinary applications, it possesses significant medicinal properties, including antioxidant, anti-inflammatory, and antibacterial properties, which are attributed to its majority compound, curcumin. In this study, we synthesized three curcuminoid derivatives via the Claisen–Schmidt method (1E,4E)-1-(2-methoxy-phenyl)-5-(3-methoxy-phenyl)-pent-1,4-dien-3-one (2a), (1E,4E)-1-(2-methoxy-phenyl)-5-(3,4,5-trimethoxy-phenyl)-pent-1,4-dien-3-one (2b), and (1E,4E)-5-phenyl-1-(2-methoxy-phenyl)-pent-1,4-dien-3-one (2c). The synthetic compounds were hydrogenated in the olefinic double bond (CH=CH) by biotransformation catalyzed by the fungus Exserohilum rostratum given (CH₂-CH₂) 3a, 3b, and 3c. All compounds were identified by NMR and MS. The compounds were evaluated for their antibacterial properties against Gram-positive and Gram-negative bacteria, with the results indicating good activity, highlighting that the bioreduction from 2a to 3a led to an improvement of up to eight times in the observed activity against S. typhimurium of 250 to 31.25 µg/mL. Additionally, compounds 2a, 2b, 3a, and 3b are not previously documented in the literature.

Siparuna guianensis (Siparunaceae) is an Amazonian plant known by the popular name of Negramina. There are several reports of the use of this plant in folk medicine. In the present work, we decided to study its extracts, aiming at the isolation of compounds and verifying their antimicrobial activities. After obtaining the extracts, the compounds were isolated through chromatographic methods and identified by nuclear magnetic resonance and mass spectrometry. The antimicrobial activities were performed through the microdilution method in 96‐hole plates. Six compounds were isolated, two of which belong to the flavonoid class, kaempferol‐3,7‐dimethyl ether ( 1 ) and herbacetin 3,7‐O‐dimethyl ether ( 2 ), and four belong to the aporphine alkaloid class: isobulbocapnine ( 3 ), norlirioferine ( 4 ), liriodenine ( 5 ), and anonaine ( 6 ). Of the six compounds isolated from S. guianensis , compounds 3 , 4 , 5 , and 6 are being reported for the first time in the species. The aporphine alkaloid compounds, isobulbocapnine ( 3 ) and norlirioferine ( 4 ) are being reported for the first time for the genus Siparuna . Compound 6 showed good activity against strains of phytopathogenic bacteria.

Chalcones are organic chromophores with diverse biological applications and potential for use in various electronic devices due to their recognized optical properties. This research focuses on the organic synthesis, FT-NMR characterization, and biotransformation of three azachalcones (1-3) using the Exserohilum rostratum fungus, yielding novel compounds (1a-3a). In vitro biological assays against Gram-positive and Gram-negative bacteria revealed promising pharmacological potential for these new chromophores. A key structural difference, the interchange of an HC = CH bond by a H₂C-CH₂ bond, significantly impacts biological and electronic properties. For instance, while biotransformed 1a exhibits similar activity to tetracycline and amoxicillin, compounds 2a and 3a demonstrate a 4-fold and thirty-fold increase in inhibitory activity against Gram-negative E. coli, respectively, compared to their parent compounds. Density functional theory calculations suggest that the biotransformation reaction reduces the refractive index (n), which may limit its applicability in certain light-handling applications. However, Hyper-Rayleigh scattering calculations indicate that these chromophores exhibit higher nonlinear optical (NLO) responses compared to standard NLO materials such as urea and p-nitroaniline, making them promising candidates for photonic and optoelectronic devices, such as nanostructured circuits. Interestingly, while the original molecules exhibit a dominant dipolar (Φ _J=1) NLO response, the biotransformed compounds, as stable isomers, display a predominant octupolar (Φ _J=3) architecture. These findings highlight the potential of these novel compounds for biotechnological and optoelectronic applications.

This study investigated bioactive compounds isolated from the mangrove endophytic fungus Actinomucor elegans AcCC18.1A for the control of Xanthomonas axonopodis pv. passiflorae (Xap), the causal agent of bacterial spot disease in passion fruit. Through classical chromatographic techniques, we isolated four phenolic compounds: tyrosol (1), 4-hydroxyphenylacetic acid (2), 4-formylphenyl-2-phenylacetate (3), and phenylacetic acid (4), with their structures elucidated through nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS). Among the isolated compounds, compound 3 was characterized as a new natural product. Antimicrobial assays were performed using the broth microdilution method against four Xap strains (Xap1-Xap4), with amoxicillin (3.9 µg mL–1) and tetracycline (3.9 µg mL–1) as positive controls. All compounds exhibited inhibitory activity, with compound 2 showing the highest efficacy (7.8 µg mL–1). These results underscore the biotechnological potential of mangrove endophytic fungi as sources of bioactive molecules against agricultural phytopathogens, offering new insights for developing sustainable strategies to control bacterial spot in passion fruit cultivation.

The search for antimicrobial compounds faces growing challenges due to resistance of bacteria to existing drugs. This study focuses on exploring Aspergillus sp. extracts from soil fungi as a valuable source of new lead compounds for drug discovery. Two aflavinine alkaloids isolated from mycelium methanolic extracts were tested against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus and Salmonella typhimurium bacteria. The compounds were docked with targets from the genus Bacillus to assess interactions, and global reactivity descriptors were calculated using density functional theory (DFT). The interactions of the compounds were assessed using molecular docking and dynamics simulations. Alkaloid 1, with an additional hydroxyl group, showed stronger inhibition of B. subtilis than the reference drugs, according to minimum inhibitory concentration (MIC) results. Energetic scores of 1 correlated with experimental results, indicating an electron-donor nature distinct from penicillin and tetracycline. Docking and dynamics studies showed that 1 had strong interactions with the active site of inosine-5’-monophosphate dehydrogenase (IMPDH). The results suggest that aflavinine alkaloids have potential as inhibitors of Gram-positive bacteria, suggesting possible antimicrobial mechanisms via interactions with IMPDH.

Naphthoquinones eleutherin and isoeleutherin have demonstrated promising antibacterial activity, probably due to their quinone structure, which can generate reactive oxygen species. The study examines the activities of pathogens, such as Staphylococcus aureus and Escherichia coli, associated with antimicrobial resistance and explores their potential mechanisms of action. The MIC, IC₅₀, and MBC were determined. PharmMapper 2017 server and GOLD 2020.1 software were utilized for molecular docking to identify protein targets and interaction mechanisms. The docking predictions were verified by redocking, focusing on structures with RMSD below 2 Å. The molecular docking revealed a significant affinity of eleutherin for the peptide, transcriptional regulator QacR, and regulatory protein BlaR1 with better interactions with BlaR1 than the crystallographic ligand (benzylpenicillin). Isoeleutherin demonstrated specific interactions with methionine aminopeptidase, indicating specificity and affinity. In summary, the difference in naphthoquinones activities may be related to structural differences. Eleutherin exhibits potential as a therapeutic adjuvant to reverse bacterial resistance in S. aureus, suggesting this molecule interferes with the antibiotic resistance mechanism. The absence of homologous proteins or variations in the structure of the target proteins could be the cause of the inactivity against E. coli.