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Bacterial virulence factors and biofilm development can be controlled by the quorum-sensing (QS) system, which is also intimately linked to antibiotic resistance in bacteria. In previous studies, many researchers found that quorum-sensing inhibitors (QSIs) can affect the development of bacterial biofilms and prevent the synthesis of many virulence factors. However, QSIs alone have a limited ability to suppress bacteria. Fortunately, when QSIs are combined with antibiotics, they have a better therapeutic effect, and it has even been demonstrated that the two together have a synergistic antibacterial effect, which not only ensures bactericidal efficiency but also avoids the resistance caused by excessive use of antibiotics. In addition, some progress has been made through in vivo studies on the combination of QSIs and antibiotics. This article mainly expounds on the specific effect of QSIs combined with antibiotics on bacteria and the combined antibacterial mechanism of some QSIs and antibiotics. These studies will provide new strategies and means for the clinical treatment of bacterial infections in the future. [ABSTRACT FROM AUTHOR]

Bioassay-guided fractionation of the crude extract of fermentation broth of one symbiotic strain Aspergillus sp. D from the coastal plant Edgeworthia chrysantha Lindl. led to isolation of one new meroterpenoid, tricycloalternarene 14b (1), together with four known analogs (2–5), tricycloalternarenes 2b (2), 3a (3), 3b (4), and ACTG-toxin F (5). Their chemical structures were unambiguously established on the basis of NMR, mass spectrometry, and optical rotation data analysis, as well as by comparison with literature data. Biological assays indicated that compound 2 exhibited potent in vitro cytotoxicity against human lung adenocarcinoma A549 cell line with an IC50 value of 2.91 μM, and compound 5 had a moderate inhibitory effect on Candida albicans, with an MIC value of 15.63 μM. The results indicated that this symbiotic strain D is an important producer of tricycloalternarene derivatives, with potential therapeutic application in treatment of cancer and pathogen infection. [ABSTRACT FROM AUTHOR]

α-Glucosidase (AGS) inhibitors have been regarded as an ideal target for the management of type 2 diabetes mellitus (T2DM) since they can maintain an acceptable blood glucose level by delaying the digestion of carbohydrates and diminishing the absorption of monosaccharides. In the process of our endeavor in mining AGS inhibitors from natural sources, the culture broth of two mangrove-derived actinomycetes Streptomyces sp. WHUA03267 and Streptomyces sp. WHUA03072 exhibited an apparent inhibitory activity against AGS. A subsequent chemical investigation into the two extracts furnished 28 secondary metabolites that were identified by spectroscopic methods as two previously undescribed linear polyketides 1–2, four benzenoid ansamycins 3–6, fourteen cyclodipeptides 7–18, one prenylated indole derivative 19, two fusicoccane-type diterpenoids 20–21, two hydroxamate siderophore 22–23, and five others 24–28. Among all of the isolates, 11 and 24 were obtained from actinomycetes for the first time, while 20–21 had never been reported to occur in a marine-derived microorganism previously. In the in vitro AGS inhibitory assay, compounds 3, 8, 9, 11, 14, 16, and 17 exhibited potent to moderate activity with IC50 values ranging from 35.76 ± 0.40 to 164.5 ± 15.5 μM, as compared with acarbose (IC50 = 422.3 ± 8.4 μM). The AGS inhibitory activity of 3, 9, 14, 16, and 17 was reported for the first time. In particular, autolytimycin (3) represented the first ansamycin derivative reported to possess the AGS inhibitory activity. Kinetics analysis and molecular docking were performed to determine the inhibition types and binding modes of these inhibitors, respectively. In the MTT assay, 3, 8, 9, 11, 14, 16, and 17 exhibited no apparent cytotoxicity to the human normal hepatocyte (LO2) cells, suggesting satisfactory safety of these AGS inhibitors. [ABSTRACT FROM AUTHOR]

Fungal microbes are important in the creation of new drugs, given their unique genetic and metabolic diversity. As one of the most commonly found fungi in nature, Fusarium spp. has been well regarded as a prolific source of secondary metabolites (SMs) with diverse chemical structures and a broad spectrum of biological properties. However, little information is available concerning their derived SMs with antimicrobial effects. By extensive literature search and data analysis, as many as 185 antimicrobial natural products as SMs had been discovered from Fusarium strains by the end of 2022. This review first provides a comprehensive analysis of these substances in terms of various antimicrobial effects, including antibacterial, antifungal, antiviral, and antiparasitic. Future prospects for the efficient discovery of new bioactive SMs from Fusarium strains are also proposed. [ABSTRACT FROM AUTHOR]

Chrysomycin A, a compound derived from marine microorganisms, proved to have a specific great in vitro inhibitory effect on methicillin-resistant Staphylococcus aureus (MRSA). It exhibits high safety for the skin, as well as a better therapeutic effect than the current clinical drug, vancomycin. Nevertheless, its poor water solubility highly limits the application and reduces the bioavailability. In view of this, we developed a cream of chrysomycin A (CA) to enhance the solubility for the treatment of skin infection, while avoiding the possible toxicity caused by systemic administration. A comprehensive orthogonal evaluation system composed of appearance, spreading ability, and stability was established to find the optimal formula under experimental conditions. The final product was odorless and easy to be spread, with a lustrous, smooth surface. The particle size of the product met Chinese Pharmacopoeia specifications and the entire cream showed long-term stability in destructive tests. The in vitro and in vivo studies indicated that CA cream had a similar anti-MRSA activity to commercially available mupirocin, showing its potential as an efficacious topical delivery system for skin infections treatment. [ABSTRACT FROM AUTHOR]

A chemical investigation into endozoic fungus Aspergillus niger L14 derived from the marine sponge of Reniera japonica collected off Xinghai Bay (China) resulted in the isolation of two dimeric naphtho-γ-pyrones, fonsecinone A (1) and isoaurasperone A (2). Through a combination of ECD spectra and X-ray diffraction analysis, the chiral axes of compounds 1 and 2 were unambiguously determined as Rα-configurations. Bioassay results indicated that these substances exhibited remarkably inhibitory effects on human pathogens Helicobacter pylori G27 and 159 with MIC values of ≤4 μg/mL, which are similar to those of the positive control, ampicillin sodium. To the best of our knowledge, this is the first report on absolute configuration of 1 and crystallographic data of 2, as well as their potent anti-H. pylori activities. [ABSTRACT FROM AUTHOR]

Marine sponges are one of the prolific producers of bioactive natural products with therapeutic potential. As an important subgenus of Haliclona, Reniera sponges are mainly distributed in the Mediterranean Sea and Atlantic area, and had been chemically investigated for over four decades. By an extensive literature search, this review first makes a comprehensive summary of all natural products from Reniera sponges and their endozoic microbes, as well as biological properties. Perspectives on strengthening the chemical study of Reniera sponges for new drug-lead discovery are provided in this work. [ABSTRACT FROM AUTHOR]

Longan (Dimocarpus longan Lour.) pericarp, the main by-product of aril and pulp processing, is abundant in phenolic compounds and worthy of further utilization. The present work firstly reported HPLC analysis and in vitro antioxidant evaluation of longan (cv. Shixia) pericarp-derived phenolics (LPPs), the purified longan pericarp extract (LPE), as well as their cytotoxic effect on lung cancer cell line, A549. The results indicated that the purified LPE had significant amounts of phenolics, with content of 57.8 ± 0.6 mg of gallic acid equivalents per gram of dry longan pericarp (mg GAE·g−1 DLP), which consisted of six phenolic compounds (A–F), including protocatechuic acid (A), isoscopoletin (B), quercetin (C), ellagic acid (D), corilagin (E), and proanthocyanidins C1 (F). Antioxidant assays showed that LPPs (10 μM) and LPE (1.0 mg·mL−1) had certain antioxidant activities, in which corilagin (E) possessed the best DPPH radical scavenging rate 71.8 ± 0.5% and •OH inhibition rate 75.9 ± 0.3%, and protocatechuic acid (A) exhibited the strongest Fe2+ chelating ability 36.4 ± 0.7%. In vitro cytotoxic tests suggested that LPPs had different effect on A549 cell line, in which corilagin (E) exhibited potent cytotoxicity with an IC50 value of 28.8 ± 1.2 μM. These findings were further confirmed by cell staining experiments. [ABSTRACT FROM AUTHOR]

Mango peel, the main by-product of juice processing, possesses appreciable quantities of bioactive phenolic compounds and is worthy of further utilization. The present work reports for the first time the HPLC analysis and in vitro antioxidant evaluation of mango peel phenols (MPPs) and their cytotoxic effect on the A549 lung cancer cell line. These results indicated that mango peel has the total phenolic content of 723.2 ± 0.93 mg·kg−1 dry mango peel (DMP), which consisted mainly of vanillic aldehyde, caffeic acid, chlorogenic acid, gallic acid, procyanidin B2 and oleanolic acid. Antioxidant assays showed that MPPs had strong antioxidant activities, with 92 ± 4.2% of DPPH radical scavenging rate, 79 ± 2.5% of ABTS radical inhibition rate and 4.7 ± 0.5 μM Trolox equivalents per kg−1 DMP of ferric reducing power. Gallic acid possess a stronger antioxidant capacity than other phenols. In vitro cytotoxic tests suggested that mango peel extract (MPE) had an IC50 value of 15 mg·mL−1 and MPPs had a stronger inhibitory effect on the A549 cell line. Oleanolic acid exhibited the strongest cytotoxicity, with an IC50 value of 4.7 μM, which was similar with that of the positive control 5-fluorouracil. [ABSTRACT FROM AUTHOR]