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Antimicrobial and Immunomodulatory Activities of Natural Products

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A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Natural Products Chemistry".

Deadline for manuscript submissions: closed (30 November 2023) | Viewed by 18088

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Dr. Beata Sadowska

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Department of Immunology and Infectious Biology, Institute of Microbiology, Biotechnology and Immunology, Faculty of Biology and Environmental Protection, University of Lodz, Banacha 12/16, 90-237 Lodz, Poland
Interests: medical microbiology; immunology; microbial biofilms; biofilm-associated infections; host–microbes interaction; microbial virulence factors and their interference with host immune response; biologically active natural products; antimicrobial and immunomodulatory activity of natural products; biomaterials; biomaterial-related infections; antimicrobial surfaces; biomaterial biocompatibility

Special Issue Information

Dear Colleagues,

Despite the progress in many fields, including microbiology, immunology, medicine, diagnostics and biochemistry, infectious diseases are still one of the most important problems of public health. The ongoing coronavirus pandemic (COVID-19), tuberculosis and malaria, which according to World Health Organization reports are responsible for the highest mortality rates around the world, as well as other difficult-to-treat infections caused by drug-resistant microorganisms reveal the shortage of effective antimicrobial medications. Nowadays, the search for natural products from various sources (e.g., plant-, animal- or microbe-derived) that have potential for use in human therapy or prophylaxis (except classic vaccination) is one of the most dynamically growing research trends. In the context of infections, two main aspects of the beneficial activity of natural products can be considered: antimicrobial effect and immunomodulatory activity to improve host defense mechanisms. Both of these aspects have to be widely understood. The antimicrobial effect covers not only biostatic/biocidal activity but also the impact on the expression of microbial virulence factors and all other manifestations of pathogenic behavior of the microorganisms. Immunomodulatory anti-infective activity comprises all mechanisms conditioning the strength of the so-called gates of infection and the host response to microbial invasion.

The present Special Issue is intended to highlight and summarize the advances in research on natural products with antimicrobial and/or immunomodulatory properties. This Special Issue welcomes original studies and review articles on these two aspects of a great range of plant-, animal- or microbe-based products to identify promising natural compounds beneficial for human health and to fight against infectious diseases.

Dr. Beata Sadowska
Guest Editor

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Keywords

natural products
biostatic/biocidal activity
antivirulence effect
antibiofilm activity
innate immunity
immune cell activity
immunomodulation
barrier cells

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Published Papers (6 papers)

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Research

14 pages, 3538 KiB

Open AccessArticle

Combating Cariogenic Streptococcus mutans Biofilm Formation and Disruption with Coumaric Acid on Dentin Surface

by Syed Sohail Ahmad, Muhammad Faisal Siddiqui, Farhana Maqbool, Ihsan Ullah, Fazal Adnan, Aqel Albutti, Noorah Alsowayeh and Ziaur Rahman

Molecules 2024, 29(2), 397; https://doi.org/10.3390/molecules29020397 - 13 Jan 2024

Cited by 1 | Viewed by 2448

Abstract

Streptococcus mutans, the primary cause of dental caries, relies on its ability to create and sustain a biofilm (dental plaque) for survival and pathogenicity in the oral cavity. This study was focused on the antimicrobial biofilm formation control and biofilm dispersal potential of Coumaric acid (CA) against Streptococcus mutans on the dentin surface. The biofilm was analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) viability assay, microtiter plate assay, production of extracellular polymeric substances (EPSs), florescence microscopy (surface coverage and biomass μm²) and three-dimensional (3D) surface plots. It was observed that CA at 0.01 mg/mL reduced bacterial growth by 5.51%, whereases at 1 mg/mL, a significant (p < 0.05) reduction (98.37%) was observed. However, at 1 mg/mL of CA, a 95.48% biofilm formation reduction was achieved, while a 73.45% biofilm dispersal (after 24 h. treatment) was achieved against the preformed biofilm. The MTT assay showed that at 1 mg/mL of CA, the viability of bacteria in the biofilm was markedly (p < 0.05) reduced to 73.44%. Moreover, polysaccharide (EPS) was reduced to 24.80 μg/mL and protein (EPS) to 41.47 μg/mL. ImageJ software (version 1.54 g) was used to process florescence images, and it was observed that the biofilm mass was reduced to 213 (μm²); the surface coverage was reduced to 0.079%. Furthermore, the 3D surface plots showed that the untreated biofilm was highly dense, with more fibril-like projections. Additionally, molecular docking predicted a possible interaction pattern of CA (ligand) with the receptor Competence Stimulating Peptide (UA159sp, PDB ID: 2I2J). Our findings suggest that CA has antibacterial and biofilm control efficacy against S. mutans associated with dental plaque under tested conditions. Full article

(This article belongs to the Special Issue Antimicrobial and Immunomodulatory Activities of Natural Products)

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13 pages, 2247 KiB

Open AccessArticle

Preparation of Herbal Extracts for Intestinal Immune Modulation Activity Based on In Vitro Screening and In Vivo Evaluation of Zingiber officinale Rosc. Extracts

by Su Ji Min, Sung Jin Kim, Jun Yeon Park, Chang-Seob Seo and You-Kyong Choi

Molecules 2023, 28(18), 6743; https://doi.org/10.3390/molecules28186743 - 21 Sep 2023

Cited by 3 | Viewed by 1422

Abstract

Ten traditional herbal extracts effective against diarrhea, infectious diseases, and bacterial activity were selected and analyzed for Peyer’s patch cell-mediated intestinal immunomodulatory activity in vitro and in vivo. Among the 10 herbal extracts, Zingiber officinale Rosc. (ZO) extract induced the highest secretion of immunoglobulin A (IgA) and granulocyte macrophage colony-stimulating factor (GM-CSF) in the cells of Peyer’s patches. Furthermore, animal experiments showed that IA production was enhanced with the oral administration of ZO extract (100 mg/kg and 300 mg/kg) for 10 days. In addition, 6-, 8-, 10-gingerol, and 6-, 8-, 10-shogaol, the six major index compounds of ZO extract, were analyzed using HPLC. Our study findings confirm the intestinal immunomodulatory activity of ZO extract and lay a strong foundation for future analytical studies aimed at determining the active components of ZO extracts. Full article

(This article belongs to the Special Issue Antimicrobial and Immunomodulatory Activities of Natural Products)

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26 pages, 3714 KiB

Open AccessArticle

Production of Bioactive Compounds with Broad Spectrum Bactericidal Action, Bio-Film Inhibition and Antilarval Potential by the Secondary Metabolites of the Endophytic Fungus Cochliobolus sp. APS1 Isolated from the Indian Medicinal Herb Andrographis paniculata

by Hiran Kanti Santra, Santanu Maity and Debdulal Banerjee

Molecules 2022, 27(5), 1459; https://doi.org/10.3390/molecules27051459 - 22 Feb 2022

Cited by 28 | Viewed by 4490

Abstract

Endophytes, being the co-evolution partners of green host plants, are factories of pharmaceutically valuable novel natural products. Cochliobolus sp. APS1, an endophyte of Andrographis paniculata (Green Chiretta), produces a plethora of natural bioactive compounds and the multipotent alkaloid Aziridine, 1-(2-aminoethyl)-, is the prime one among them. The isolate exhibited antibacterial, anti-biofilm, and antilarval potency. The MIC and MBC values of the ethyl-acetate culture extract ranged from 15.62 to 250 µg/mL against ten pathogenic microorganisms (including MRSA and VRSA). Killing kinetics data along with the leakage of macromolecules into the extracellular environment supports the cidal activity of the antibacterial principles. The broad spectrum antibacterial activity of Aziridine, 1-(2-aminoethyl)-, was optimized by a one-variable-at-a-time system coupled with response surface methodology, which led to a 45% enhancement of the antibacterial activity. The maximum response (22.81 ± 0.16 mm of zone of inhibition against MRSA) was marked in 250 mL Erlenmeyer flask containing 90 mL potato dextrose broth supplemented with (g%/L) glucose, 9.7; urea concentration, 0.74; with medium pH 6.48; after 8.76 days of incubation at 26 °C. APS1 strongly inhibited biofilm formation in the tested pathogenic microorganisms and acts as a larvicidal agent against the Dengue-vector Aedes aegypti. This is probably the first report of Aziridine, 1-(2-aminoethyl)-, from any endophytic source. Cochliobolus sp. APS1 possesses industrial importance for the production of bioactive alkaloids. Full article

(This article belongs to the Special Issue Antimicrobial and Immunomodulatory Activities of Natural Products)

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27 pages, 5790 KiB

Open AccessArticle

Facile Synthesis of Bio-Antimicrobials with “Smart” Triiodides

by Zehra Edis and Samir Haj Bloukh

Molecules 2021, 26(12), 3553; https://doi.org/10.3390/molecules26123553 - 10 Jun 2021

Cited by 6 | Viewed by 3292

Abstract

Multi-drug resistant pathogens are a rising danger for the future of mankind. Iodine (I₂) is a centuries-old microbicide, but leads to skin discoloration, irritation, and uncontrolled iodine release. Plants rich in phytochemicals have a long history in basic health care. Aloe Vera Barbadensis Miller (AV) and Salvia officinalis L. (Sage) are effectively utilized against different ailments. Previously, we investigated the antimicrobial activities of smart triiodides and iodinated AV hybrids. In this work, we combined iodine with Sage extracts and pure AV gel with polyvinylpyrrolidone (PVP) as an encapsulating and stabilizing agent. Fourier transform infrared spectroscopy (FT-IR), Ultraviolet-visible spectroscopy (UV-Vis), Surface-Enhanced Raman Spectroscopy (SERS), microstructural analysis by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-Ray-Diffraction (XRD) analysis verified the composition of AV-PVP-Sage-I₂. Antimicrobial properties were investigated by disc diffusion method against 10 reference microbial strains in comparison to gentamicin and nystatin. We impregnated surgical sutures with our biohybrid and tested their inhibitory effects. AV-PVP-Sage-I₂ showed excellent to intermediate antimicrobial activity in discs and sutures. The iodine within the polymeric biomaterial AV-PVP-Sage-I₂ and the synergistic action of the two plant extracts enhanced the microbial inhibition. Our compound has potential for use as an antifungal agent, disinfectant and coating material on sutures to prevent surgical site infections. Full article

(This article belongs to the Special Issue Antimicrobial and Immunomodulatory Activities of Natural Products)

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14 pages, 7192 KiB

Open AccessArticle

Anti-Allergic Diarrhea Effect of Diosgenin Occurs via Improving Gut Dysbiosis in a Murine Model of Food Allergy

by Chung-Hsiung Huang, Chorng-Liang Pan, Guo-Jane Tsai, Chun-Ju Chang, Wei-Chung Tsai and Shueh-Yu Lu

Molecules 2021, 26(9), 2471; https://doi.org/10.3390/molecules26092471 - 23 Apr 2021

Cited by 6 | Viewed by 2665

Abstract

Although the anti-allergic and prebiotic activities of diosgenin have been reported, the influence of diosgenin on intestinal immune and epithelial cells remains unclear. As the gut microbiota plays an important role in allergic disorders, this study aimed to investigate whether the anti-allergic diarrhea effect of diosgenin occurs via improving gut dysbiosis. In a murine food allergy model, the density of fecal bacterial growth on de Man, Rogossa and Sharpe (MRS) plates was diminished, and growth on reinforced clostridial medium (RCM) and lysogeny broth (LB) agar plates was elevated. However, the oral administration of diosgenin reduced the density of fecal bacteria and ameliorated diarrhea severity. Concordantly, reshaped diversity and an abundance of fecal microbes were observed in some of the diosgenin-treated mice, which showed a milder severity of diarrhea. The relevant fecal strains from the diosgenin-treated mice were defined and cultured with Caco-2 cells and allergen-primed mesenteric lymph node (MLN) cells. These strains exhibited protective effects against the cytokine/chemokine network and allergen-induced T-cell responses to varying degrees. By contrast, diosgenin limitedly regulated cytokine production and even reduced cell viability. Taken together, these findings show that diosgenin per se could not directly modulate the functionality of intestinal epithelial cells and immune cells, and its anti-allergic effect is most likely exerted via improving gut dysbiosis. Full article

(This article belongs to the Special Issue Antimicrobial and Immunomodulatory Activities of Natural Products)

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14 pages, 1430 KiB

Open AccessArticle

Evaluation of Anti-Biofilm Activity of Mouthrinses Containing Tannic Acid or Chitosan on Dentin In Situ

by Anton Schestakow, Moritz S. Guth, Tobias A. Eisenmenger and Matthias Hannig

Molecules 2021, 26(5), 1351; https://doi.org/10.3390/molecules26051351 - 3 Mar 2021

Cited by 11 | Viewed by 2469

Abstract

In contrast to enamel, dentin surfaces have been rarely used as substrates for studies evaluating the effects of experimental rinsing solutions on oral biofilm formation. The aim of the present in situ study was to investigate the effects of tannic acid and chitosan on 48-h biofilm formation on dentin surfaces. Biofilm was formed intraorally on dentin specimens, while six subjects rinsed with experimental solutions containing tannic acid, chitosan and water as negative or chlorhexidine as positive control. After 48 h of biofilm formation, specimens were evaluated for biofilm coverage and for viability of bacteria by fluorescence and scanning electron microscopy. In addition, saliva samples were collected after rinsing and analyzed by fluorescence (five subjects) and transmission electron microscopy (two subjects) in order to investigate the antibacterial effect on bacteria in a planktonic state and to visualize effects of the rinsing agents on salivary proteins. After rinsing with water, dentin specimens were covered by a multiple-layered biofilm with predominantly vital bacteria. In contrast, chlorhexidine led to dentin surfaces covered only by few and avital bacteria. By rinsing with tannic acid both strong anti-adherent and antibacterial effects were observed, but the effects declined in a time-dependent manner. Transmission electron micrographs of salivary samples indicated that aggregation of proteins and bacteria might explain the antiadhesion effects of tannic acid. Chitosan showed antibacterial effects on bacteria in saliva, while biofilm viability was only slightly reduced and no effects on bacterial adherence on dentin were observed, despite proteins being aggregated in saliva after rinsing with chitosan. Tannic acid is a promising anti-biofilm agent even on dentin surfaces, while rinsing with chitosan could not sufficiently prevent biofilm formation on dentin. Full article

(This article belongs to the Special Issue Antimicrobial and Immunomodulatory Activities of Natural Products)

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