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Honey is the most important bee product. There are many secondary metabolites, carbohydrates, enzymes, and vitamins in honey, thus, honey has antimicrobial activity. In this study, in vitro antimicrobial activity of forty-two honey and eight propolis ethanolic extracts (PEE) were investigated against 16 microorganisms. Total phenolic content ranged between 20.00–124.10 mg GAE/100 g and 103–232 mg GAE/g for honey and raw propolis samples, respectively. Pine and oak honeydew honeys had higher antimicrobial activity than four different grades of Manuka Honeys up to 18 mm minimum inhibition zone diameters. The ethanolic propolis extracts showed much higher antimicrobial activity than the honey samples. Fungi species were inhibited by the propolis samples. Helicobacter pylorii (H. pylorii) was the most sensitive, whereas Streptococcus agalactiae was the most resistant bacteria among the studied microorganisms. Brazilian and Zonguldak propolis had the closest antimicrobial activity to ampicillin, streptomycin, and fluconazole. It can be concluded that both honey and propolis could be used in preservative and complementary medicine.

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The goal of the work is to determine the bioactive pharmaceutical metabolites produced by the Fusarium oxysporum YP9B isolate. Ten new natural compounds were isolated from the ethyl acetate extract of the F. oxysporum YP9B strain. Their structures were elucidated by spectroscopic methods using 1D and 2D NMR, UV, FT-IR, and mass spectra (LC-QTOF MS and GC-FID/MS). Identified compounds were named as; (1-benzyl-2-methoxy-2-oxoethyl)-2-hydroxy-3-methylbutanoate (1), 2-oxo-8-azatricyclo[9.3.1.13,7]-hexadeca-1(15),3(16),4,6,11,13-hexaen-10-one (2), 2,3-dihydroxypropanoic, hexadecanoic anhydride (3a), 2,3-dihydroxypropanoic (9Z)-octadecenoic anhydride (3b), 2,3-dihydroxy-propanoic (9Z,12Z)-octadecadienoic anhydride (3c), 2,3-dihydroxypropanoic (11Z)-octadecenoic anhydride (4a), 2,3-dihydroxypropanoic, (9E,12E)-octadecadienoic anhydride (4b), 3-hydroxy-1,2,6,10-tetramethylundecyl hexzadecanoate (5a), 3-hydroxy-1,2,6,10-tetramethylundecyl (9E)-octadecaenoate (5b), and 3-hydroxy-1,2,6,10-tetramethylundecyl octadecanoate (5c). Antimicrobial activities of the isolates obtained from the YP9B strain were determined. Cytotoxic and antiviral activities were tested for the isolates against VERO, MCF-7, PC-3, and A549. Compounds 5a-c, 1, and 3a-c showed bacteriostatic activity at low concentrations, and 4a-b and 2 were found to be bactericides. MIC and MBC values against Mycobacterium smegmatis for the compounds 5a-c and 1 were determined to be ​​ <0.5 µg/mL and 0.46 µg/mL, respectively. The experimental result showed that compounds 2, 5a-c and 1 have strong cytotoxic (7.51±1.38 and 19.13± 0.68 (µM) IC50) activity. The antiviral activity against HSV type-1 was determined to be 1.25 µM for compounds 4a-c and 0.312 µM for compound 1.

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This study was performed to determine the antibacterial activity of methanol extracts of 23 bryophyte species against Paenibacillus larvae isolates that cause American foulbrood diseases in honeybee larvae. The honey and larva samples were collected from nine different locations of Rize in Turkey. A total of 22 gram-positive spore-forming bacteria were isolated from the larva and honey samples. According to the results of morphological, biochemical, and molecular (16S rRNA gene sequencing) tests, 10 isolates of the 22 gram-positive spore-forming bacteria were identified as P. larvae. A total of 10 bryophyte species (Polytrichum formasum, Polytrichum commune, Calliergonella cuspitada, Calliergonella lindbergi, Metzgeria conjugata, Isothecium alopecuroides, Syntrichia calcicola, Syntrichia intermedia, Tortella densa, and Grimmia alpestris) among 23 bryophytes showed good antimicrobial activity against P. larvae isolates according the results of agar-well diffusion method and minimal inhibition concentration experiments.

Novel substituted fluoroquinolone derivatives, compounds 6-20 were designed, synthesized, and evaluated for antituberculosis and antibacterial activity. Antibacterial activities of the compounds were determined and compound 14 was found to be the most potent antimicrobial agent owing to minimal inhibitory concentration (MIC) value of <1.16 μg/μl for all tested bacteria. Further, compounds were tested in vitro for their antimycobacterial activity against Mycobacterium tuberculosis H37Rv. Most of the compounds showed antimycobacterial effects with 1.56-25.00 μg/ml MIC values. Compounds 14 and 18 were found to be the most active derivatives due to their MIC at 1.56 μg/ml. Selected compounds 11, 14, 17, and 18 were tested for M. tuberculosis DNA supercoiling assay and they had IC 50 values within a range of 6.35-15 μM. Mechanism of binding to DNA gyrase enzymes was evaluated using in silico molecular modeling studies and it was shown that compounds 6-20 adopt a similar binding mode as already known for fluoroquinolone drugs.

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