Chemical Constituents of Salix babylonica L. and Their Antibacterial Activity Against Gram-Positive and Gram-Negative Animal Bacteria

Insight into the Phenolic Composition of Cabernet Sauvignon Grapevine Berries During Fermentation-Towards the Application of Winery By-Products for Antibacterial Purposes

BACKGROUND

Wine production generates significant amounts of grape marc, which can serve as a potential source of bioactive compounds, including polyphenols.

OBJECTIVES

In this study, we aimed to investigate the polyphenol content of skin and seeds separated from grape marc, and test their extracts against two significant bacteria, Listeria monocytogenes (LM) and Staphylococcus aureus (SA).

METHODS

A comprehensive analysis of the phenolic composition in the skin, seeds, and juice/wine derived from Cabernet Sauvignon grape berries was conducted over an 18-day fermentation period. High-performance liquid chromatography was performed to identify and quantify the main flavan-3-ols, flavonols, anthocyanins, and stilbenes. In addition, the total phenolic content (TPC) was determined by the Folin-Ciocalteu method.

RESULTS

The TPC of both seeds and skins significantly decreased over time. In parallel, the TPC in the wine gradually increased, indicating a release of phenolic compounds into the wine. We found that the TPC in seeds was consistently higher than in the skin at all examined time points. The main flavonoids in seeds were flavan-3-ols (catechin and epicatechin), while anthocyanins (delphinidin-, cyanidin-, petunidin-, peonidin-, and malvidin-3-O-glucoside) were the predominant ones in skins. Crude seed and skin extracts enriched in phenolics were prepared, of which only the crude seed extract was proven effective against LM and SA. Following the time-kill assay, our findings revealed that the minimal bactericidal concentration of the crude seed extract against LM was 5.02 mg/mL after 12 h incubation, demonstrating the eradication of the living bacterial cell number by ~6 log. A 24 h exposure time was required for complete inactivation of SA, but a lower concentration was sufficient (2.54 mg/mL).

CONCLUSIONS

Grape waste remains a valuable source of polyphenols, with grape seeds, in particular, exhibiting significant antimicrobial activity against certain foodborne pathogens.

Discovery of Isograndidentatin D, a Novel Phenolic Glycoside, and Anti-Helicobacter pylori Phenolics from Salix koreensis Twigs

Salix koreensis Anderss (Salicaceae), commonly referred to as Korean willow, is native to East Asia, particularly Korea and China, and it has been used in traditional Korean folk medicine for its potent anti-inflammatory, analgesic, and antioxidant properties. In our ongoing research efforts to discover biologically new natural products, phytochemical analysis on an ethanolic extract of S. koreensis twigs yielded the isolation and identification of ten phenolic compounds (1-10), including a newly discovered phenolic glycoside (1) named isograndidentatin D, isolated via HPLC purification. The structure of compound 1 was determined through extensive 1D and 2D NMR spectral data analysis and high-resolution electrospray ionization mass spectrometry (HR-ESIMS). Its absolute configuration was established using DP4+ probability analysis combined with gauge-including atomic orbital NMR chemical shift calculations and chemical reaction methods. The other known compounds were identified as isograndidentatin B (2), trichocarposide (3), glanduloidin C (4), tremuloidin (5), 3-O-acetylsalicin (6), 2-O-acetylsalicin (7), salicin (8), salireposide (9), and coumaric acid (10), confirmed by comparing their NMR spectra with previously reported data and further verified through liquid chromatography/mass spectrometry (LC/MS) analysis. The isolated compounds 1-10 were tested for their anti-Helicobacter pylori activities. Among these, compounds 4 and 5 demonstrated moderate anti-H. pylori activity at a concentration of 100 μM. Specifically, compound 5 showed an inhibitory activity of 35.9 ± 5.4%, making it slightly more potent than compound 4, with 34.0 ± 1.0% inhibition. These results were comparable to that of quercetin, a known anti-H. pylori agent used as a positive control in this study, which showed 38.4 ± 2.3% inhibition. The remaining compounds exhibited very weak inhibitory effects. This study highlights the potential of S. koreensis twigs as a valuable natural source of bioactive compounds for therapeutic applications against H. pylori.

Hydromethanolic fraction from Abatia americana (Salicaceae) inhibits T24 bladder cancer cell line and the bacterium Listeria monocytogenes with high selectivity

Abatia americana is a Brazilian species that has yet to be the subject of scientific investigation. However, it represents a potential source of new antibacterial and anticancer drugs, given it belongs to the Salicaceae family. The objective of this study was to investigate the potential biological activities and chemical composition of this species. The chemical characterisation was conducted using UPLC-QTOF-MS/MS. The cytotoxicity was evaluated using the sulforhodamine B method and the antibacterial activity was determined through a microdilution assay. Within the fractions obtained, namely hexane (HF), ethyl acetate (EF), butyl alcohol (BF), and hydromethanolic (HMF), 37 compounds were identified. The fractions showed better antibacterial activity against Staphylococcus aureus and Listeria monocytogenes. Those with greater polarity (HMF; BF) showed better results, with lower minimum bactericidal concentration (MBC) and higher selectivity index. They also demonstrated cytotoxic and antiproliferative action for T24 tumour lineage. Among the fractions, the most promising is the HMF fraction, which showed satisfactory selectivity and did not inhibit normal cell proliferation. This is also the first time that biological effects have been reported for this species.

Potency of butylated hydroxytoluene and optimized black pepper extract as additives on quality characteristics of stored (4 °C) pork on various days

The potency of butylated hydroxytoluene and black pepper extract (BPE) as additives was explored. BPE was produced through upscale of desirability from 72 to 91.9%, yielding sixty-three bio-compounds. Next, control (0% antioxidant), vitamin E, and BPE groups were formed, each replicated five times in a Completely Randomized Design. Meat physico-chemical and fatty acid (FA) indices, malondialdehyde (MDA) content, and microbial profile were evaluated [day (d) 0, 5, and 10]. Results indicate BPE had lower (p < 0.05) pH (5.85) and least cooking loss (19.30%). BPE had reduced (p < 0.05) saturated FA (SFA) of 2.18 but higher poly unsaturated FA (PUFA)-13.17; UFA (18.82), PUFA: SFA (6.05), and omega 6 (7.69). Also, BPE had lowest (p < 0.05) MDA on d 5 (2.16) and 10 (3.45) of storage (4 °C), while coliform was not seen (p < 0.05) on BPE-incorporated samples on d 0 and 5. BPE contains bio-compounds that are effective and safe for meat storage.

Phytochemical Investigation and Biological Activities of Desmodium heterocarpon Extract as Anti-Tyrosinase: Isolation of Natural Compounds, In Vitro and In Silico Study

Tyrosinase is an important enzyme in the biosynthesis of melanin. Many skin-whitening agents that inhibit tyrosinase activity from natural sources have been identified because they are harmless and non-toxic. In this work, 114 samples of 54 Fabaceae plants were assessed for their anti-tyrosinase activity using a dopachrome method. The results found that Desmodium heterocarpon stems and roots demonstrated the highest tyrosinase inhibitory activity at 20 µg/mL (92.50 ± 1.09%), whereas the water extract of Artocarpus lacucha and kojic acid demonstrated 87.41 ± 0.61% and 95.71 ± 0.33%, respectively. Six compounds were isolated from this plant, including genistein (1); hexadecanoic acid (2); salicylic acid (3); β-sitosterol-D-glucoside (4); 2,3-dihydroxybenzoic acid (5); and 2,5-dihydroxybenzoic acid (6). Among them, 2,5-dihydroxybenzoic acid demonstrated a potential effect for tyrosinase inhibition with an IC50 of 57.38 µg/mL, while standards of kojic acid and the water extract of A. lacucha showed 2.46 and 0.15 µg/mL, respectively. 2,3-dihydroxybenzoic acid had a similar structure as 2,5-dihydroxybenzoic acid; however, it was shown to have tyrosinase inhibitory activity, with an IC50 of 128.89 µg/mL. Studies using computer simulations confirmed this reservation. The determination of antimicrobial activities found that 2,5-dihydroxybenzoic acid showed the strongest inhibitory activity against Staphylococcus aureus, with MIC and MBC of 5 and 5 µg/mL, respectively. In addition, it inhibited MRSA, S. epidermidis, Propionibacterium acnes, Escherichia coli, and Pseudomonas aeruginosa, with MIC and MBC of 15-30 and 15-40 µg/mL. It showed potential activities against yeast and filamentous fungi, such as Candida albicans, Microsporum gypseum, Trichophyton rubrum, and T. mentagrophytes, with MIC and MFC of 15 µg/mL. So, 2,5-dihydroxybenzoic acid could inhibit tyrosinase activity and microorganisms that cause skin diseases. Therefore, it can be concluded that this plant has advantageous properties that will be investigated and further developed for possible uses, particularly in the cosmetic and pharmaceutical industries.

Polyphenols and Phenolic Glucosides in Antibacterial Twig Extracts of Naturally Occurring Salix myrsinifolia (Salisb.), S. phylicifolia (L.) and S. starkeana (Willd.) and the Cultivated Hybrid S. x pendulina (Wender.)

(1) Background: Salix species occurring in Finland have not been well studied for their antimicrobial potential, despite their frequent use for lung and stomach problems in traditional medicine. Thus, twig extracts of three species of Salix that are found naturally in Finland and one cultivated species were screened for their antimicrobial properties against human pathogenic bacteria. S. starkeana and S. x pendulina were screened for antibacterial effects for the first time. (2) Methods: An agar diffusion and a microplate method were used for the screenings. Time-kill effects were measured using a plate-count and a microplate method. A DPPH-method using a qualitative TLC-analysis was used to detect antioxidant compounds in antimicrobial extracts. Metabolites from a S. myrsinifolia extract showing good antibacterial effects were identified using UPLC/QTOF-MS. (3) Results: A methanol extract of S. starkeana was particularly active against B. cereus (MIC 625 µg/mL), and a methanol extract of S. myrsinifolia showed good activity against S. aureus and B. cereus (MIC 1250 µg/mL) and showed bactericidal effects during a 24 h incubation of B. cereus. Moreover, a decoction of S. myrsinifolia resulted in good growth inhibition against P. aeruginosa. Our UPLC/QTOF-MS results indicated that proanthocyanidins (PAs), and especially the dimer procyanidin B1 (m/z 577) and other procyanidin derivatives, including highly polymerized proanthocyanidins, were abundant in S. myrsinifolia methanol extracts. Procyanidin B1 and its monomer catechin, as well as taxifolin and p-hydroxycinnamic acid, all present in S. myrsinifolia twigs, effectively inhibited B. cereus (MIC 250 µg/mL). (4) Conclusions: This study indicates that Finnish Salix species contain an abundance of antibacterial condensed tannins, phenolic acids and other polyphenols that deserve further research for the antibacterial mechanisms of action.

Systems biology strategy through integrating metabolomics and network pharmacology to reveal the mechanisms of Xiaopi Hewei Capsule improves functional dyspepsia

Functional dyspepsia (FD) is one of the more common functional disorders, with a prevalence of 20-25 %. It seriously affects the quality life of patients. Xiaopi Hewei Capsule (XPHC) is a classic formula originated from the Chinese Miao minority. Clinical studies have demonstrated that XPHC can effectively alleviate the symptoms of FD, but the molecular mechanism has not been elucidated. The purpose of this work is to investigate the mechanism of XPHC on FD by integrating metabolomics and network pharmacology. The mice models of FD were established, and gastric emptying rate, small intestine propulsion rate, serum level of motilin and gastrin were evaluate to study the interventional effect of XPHC on FD. Next, a metabolomics strategy has been developed to screen differential metabolites and related metabolic pathways induced by XPHC. Then, prediction of active compounds, targets and pathways of XPHC in treating FD were carried out by commonly used network pharmacological method. Finally, two parts of the results were integrated to investigate therapeutic mechanism of XPHC on FD, which were preliminary validated based on molecular docking. Thus, twenty representative different metabolites and thirteen related pathways of XPHC in treating FD were identified. Most of these metabolites were restored using modulation after XPHC treatment. The results of the network pharmacology analysis showed ten crucial compounds and nine hub genes related to the treatment of FD with XPHC. The further integrated analysis focused on four key targets, such as albumin (ALB), epidermal growth factor receptor (EGFR), tumor necrosis factor (TNF) and roto-oncogene tyrosine-protein kinase Src (SRC), and three representative biomarkers such as citric acid, L-leucine and eicosapentaenoic acid. Furthermore, molecular docking results showed that ten bioactive compounds from XPHC have good binding interactions with the four key genes. The functional enrichment analysis indicated that the potential mechanism of XPHC in treating FD was mainly associated with energy metabolism, amino acid metabolism, lipid metabolism, inflammatory reactions and mucosal repair. Our work confirms that network pharmacology-integrated metabolomics strategyis a powerful means to reveal the therapeutic mechanisms of XPHC improves FD, which contribute its further scientific research.

Optimization of Flavonoid Extraction from Salix babylonica L. Buds, and the Antioxidant and Antibacterial Activities of the Extract

The present study was designed to evaluate the chemical extraction, chemical composition, and antioxidant and antibacterial properties of the total flavonoids in Willow Buds (TFW). We investigated the optimal extraction of TFW using response surface methodology (RSM). Chemical compounds were analyzed using Q-Orbitrap LC-MS/MS. The DPPH radical scavenging capacity, hydroxy radical inhibitory ability, and superoxide anion radical inhibitory ability were explored to determine the antioxidant properties of flavonoid extractions. The antibacterial effect was assessed via minimal inhibitory concentration. The results demonstrated that the optimal extraction conditions were an ethanol concentration of 50%, a time of 35 min, and a liquid/material ratio of 70:1 mL/g. Under these conditions, the yield of TFW was 7.57%. Eight flavonoids, a phenolic glycoside, and an alkaloid were enriched in the Willow Buds. The TFW exhibited significant antioxidant activity, with IC₅₀ values of 0.18-0.24 mg/mL and antimicrobial activity against Escherichia coli, Salmonella enterica, Staphylococcus aureus, and Streptococcus pneumoniae. TFW may be explored as potential and natural compounds in food and pharmacological applications.

Biosynthesis of Silver Nanoparticles at Various pH values and their Applications in Capturing Irradiation Solar Energy

BACKGROUND

Metallic nanoparticles (NPs), in general, are able, due to the high surface area per unit volume, to absorb the maximum incoming light flux through the vicinity of plasmonic structures and then provide local heating. Thus, silver (Ag) NPs has been used to generate heat and increase the temperature of water from solar radiation energy. The optimal plasmonic heating generation can be obtained as soon as the wavelength of the light source is close to the plasmonic resonance wavelength of Ag NPs.

OBJECTIVE

Ag NPs have been fabricated through a straightforward, cheap, as well as environmentally friendly approach. In this study, Salix babylonica L., weeping willow leaf extract has been utilized as a reducing, capping, and stabilizing agent, without using any other toxic materials. The importance of this study lies in the generation of hot electrons, which can be obtained by collecting the solar spectrum near the infrared and infrared regions, which cannot be obtained by the conventional photocatalytic devices.

METHODS

Numerous characterization techniques such as; UV-Vis, FT-IR spectroscopy, X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis were used to study the optical, chemical, structural, morphological, properties of the Ag NPs.

RESULTS

The impact of pH on the properties of Ag NPs and their performance to generate heat during solar irradiation have been investigated intensively. This study showed that the synthesized Ag NPs with pH value 12 is the optimum condition and can increase the temperature of water dramatically.

CONCLUSION

An evaluation of the current patents displays that the field of green synthesis Ag NPs utilizing plant extracts is a vital field and produces rather stable, safe and effective Ag NPs. The novelty of this patent is that Ag NPs can be synthesized from a one-pot reaction without using any exterior stabilizing and reducing agent, which is not conceivable by means of the existing processes. This study, also, is rare and distinctive, and it demonstrates that even a slight quantity of the Ag NPs is significantly raising the temperature of water effectively.

nor 3′-Demethoxyisoguaiacin from Larrea tridentata Is a Potential Alternative against Multidrug-Resistant Bacteria Associated with Bovine Mastitis

Bovine mastitis is one of the most common diseases in dairy cows, and it causes significant economic losses in dairy industries worldwide. Gram-positive and Gram-negative bacteria can cause bovine mastitis, and many of them have developed antimicrobial resistance. There is an urgent need for novel therapeutic options to treat the disease. Larrea tridentata-derived compounds represent an important potential alternative treatment. The aim of the present study was to isolate and characterize antibacterial compounds from Larrea tridentata against multidrug-resistant bacteria associated with bovine mastitis. The L. tridentata hydroalcoholic extract (LTHE) exhibited antibacterial activity. The extract was subjected to a bipartition, giving an aqueous fraction (moderate antibacterial activity) and an organic fraction (higher antibacterial activity). Chromatographic separation of the organic fraction enabled us to obtain four active sub-fractions. Chemical analyses through HPLC techniques were conducted for the LTHE, fractions, and sub-fraction Ltc1-F3, from which we isolated two compounds, characterized by ¹H and ¹³C NMR analyses. Compound nor-3 demethoxyisoguaiacin exhibited the best antibacterial activity against the evaluated bacteria (MIC: 0.01–3.12 mg/mL; MBC: 0.02–3.12 mg/mL). The results indicated that nor-3 demethoxyisoguaiacin can be used as an alternative treatment for multidrug-resistant bacteria associated with mastitis.

Effect of Hybrid Type and Harvesting Season on Phytochemistry and Antibacterial Activity of Extracted Metabolites from Salix Bark

Hundreds of different fast-growing Salix hybrids have been developed mainly for energy crops. In this paper, we studied water extracts from the bark of 15 willow hybrids and species as potential antimicrobial additives. Treatment of ground bark in water under mild conditions extracted 12-25% of the dry material. Preparative high-performance liquid chromatography is proven here as a fast and highly efficient tool in the small-scale recovery of raffinose from Salix bark crude extracts for structural elucidation. Less than half of the dissolved material was assigned by chromatographic (gas chromatography and liquid chromatography) and spectroscopic (mass spectrometry and nuclear magnetic resonance spectroscopy) techniques for low-molecular-weight compounds, including mono- and oligosaccharides (sucrose, raffinose, and stachyose) and aromatic phytochemicals (triandrin, catechin, salicin, and picein). The composition of the extracts varied greatly depending on the hybrid or species and the harvesting season. This information generated new scientific knowledge on the variation in the content and composition of the extracts between Salix hybrids and harvesting season depending on the desired molecule. The extracts showed high antibacterial activity on Staphylococcus aureus with a minimal inhibitory concentration (MIC) of 0.6-0.8 mg/mL; however, no inhibition was observed against Escherichia coli, Enterococcus faecalis, and Salmonella typhimurium. MIC of triandrin (i.e., 1.25 mg/mL) is reported for the first time. Although antibacterial triandrin and (+)-catechin were present in extracts, clear correlation between the antibacterial effect and the chemical composition was not established, which indicates that antibacterial activity of the extracts mainly originates from some not yet elucidated substances. Aquatic toxicity and mutagenicity assessments showed the safe usage of Salix water extracts as possible antibacterial additives.

Invasive alien plants and weeds in South Africa: A review of their applications in traditional medicine and potential pharmaceutical properties

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional pharmacopoeias are constantly evolving and adapting, hence the assimilation of alien plants and weeds into traditional systems of healing. Invasive plants are detrimental to the ecosystem, however they are also potential sources of secondary metabolites with useful biological activities.

AIM OF THE REVIEW

The aim of this review was to investigate published reports of traditional use and biological activity of declared invasive alien plants and other weeds in South Africa.

MATERIALS AND METHODS

Information was retrieved from scientific databases including Scopus, Web of Science, ScienceDirect, Google Scholar, PubMed, Chemical Abstracts Services and books, theses, dissertations and technical reports. Keywords used for the search engines were "South Africa" or "southern Africa" in conjunction with "(native weeds OR alien invasive)" AND "medicinal". Separate searches were conducted on the individual invasive plant species recorded as having been used in ethnobotanical surveys to determine their known biological activities and chemical components.

RESULTS

A total of 89 plant species regarded as invasive species or weeds in South Africa were identified as being used in traditional medicine. The most commonly mentioned plant family was the Asteraceae with a total of 15 species followed by the Fabaceae and Solanaceae with 6 species each. Of the 89 species recorded, 68% were reported to have traditional usage with both phytochemical and biological data available. A history of traditional usage coupled with biological data was available for 12% of species. Records of traditional usage alone were linked to 11% of species. Invasive alien species comprised 61% of recorded species, while native and non-invasive alien weeds formed the remaining 39%.

CONCLUSIONS

The exploration of alternative uses for weeds and particularly invasive plants, whether native or alien, as medicines for possible commercialisation may lead to innovative mechanisms for putting such species to good use.

Heat Stress in Broiler Chickens and the Effect of Dietary Polyphenols, with Special Reference to Willow (Salix spp.) Bark Supplements-A Review

Over the last decade, there has been a growing interest in the use of a wide range of phytoadditives to counteract the harmful effects of heat stress in poultry. Willow (Salix spp.) is a tree with a long history. Among various forms, willow bark is an important natural source of salicin, β-O-glucoside of saligenin, but also of polyphenols (flavonoids and condensed tannins) with antioxidant, antimicrobial, and anti-inflammatory activity. In light of this, the current review presents some literature data aiming to: (1) describe the relationship between heat stress and oxidative stress in broilers, (2) present or summarize literature data on the chemical composition of Salix species, (3) summarize the mechanisms of action of willow bark in heat-stressed broilers, and (4) present different biological effects of the extract of Salix species in different experimental models.

Antimicrobial activity of medicinal plants used for urinary tract infections in pastoralist community in Ethiopia

BACKGROUND

Medicinal plants have wide medicament application used to prevent and management of many ailments. These plants are used for primary health care in pastoralist communities who are deprived of modern medical care. They possess extensive therapeutics bioactive coupled with varied chemical structures. However, scientific validation of efficacy and safety of plants used to treat the urinary tract infections haven't been fully exploited. The aim of this study was to evaluate antimicrobial activity and screening phytochemicals of medicinal plants used to treat urinary tract infections.

METHODS

In-vitro experimental study was carried out to evaluate the antimicrobial effect and screening phytochemical of Rumex abyssinicus, Cucumis pustulatus, Discopodium penninervium, Lippia adoensis, Euphorbia depauperata, and Cirsium englerianum. Against drug resistance microbes. 80% methanol was used for extraction of the plant parts. The susceptibility tests were investigated using disc diffusion and broth micro-dilution methods.

RESULTS

The majority of tested extracts showed antimicrobial activity on two or more drug-resistant bacteria with MIC value (1.0-128.0 μg/ml) and 9-27 mm inhibition zone in diameter. Extracts obtained from C.englerianum and E. depauperate showed more potent antibacterial activity on MRSA and Enterococcus faecalis with IZ 25 and 27 mm respectively. E. coli and K. pneumoniae were inhibited by those extracts with IZ ranging 9-25 mm and 11-27 mm respectively. E.faecalis and K. pneumoniae were more susceptible bacteria to the respective extracts. R. abyssinicus showed promising antifungal effect with had 21 mm IZ and MIC range 16-32 μg/ml on C.albicans. Alkaloids, flavonoids, phenolic and terpenoid were common phytochemical characterized in majority of screened plants.

CONCLUSION

Tested extracts exhibited significant antibacterial and antifungal activity. Hence, further structural elucidation of bioactive that inhibited the growth of microbes aforementioned plants may be used as precursors for the synthesis of new antibiotics in the future.

Phytochemistry, Pharmacology and Medicinal Uses of Plants of the Genus Salix: An Updated Review

The Willows (genus Salix), with more than 330–500 species and 200 hybrids, are trees, shrubs or prostrate plants that are widely distributed in Africa, North America, Europe, and Asia. The genus is traditionally used in folk medicine and represents a valuable source of biologically active compounds among them salicin, a prodrug for salicylic acid. Altogether, 322 secondary metabolites were characterized in the genus including flavonoids 94) (flavonols, flavones, flavanones, isoflavones, flavan-3-ols (catechins and procyanidins), chalcones, dihydrochalcone, anthocyanins, dihydroflavonols), phenolic glycosides (76), organic acids (28), and non-phenolic glycosides (17), sterols and terpenes (17), simple phenolics 13) and lignans 7) in addition to volatiles and fatty acids (69). Furthermore, willows exert analgesic, anti-inflammatory, antioxidant, anticancer, cytotoxic, antidiabetic, antimicrobial, antiobesity, neuroprotective and hepatoprotective activities. The current review provides an updated summary of the importance of willows, their chemical composition and pharmacological activities.

In Vitro Antibacterial Potential of Salix babylonica Extract against Bacteria that Affect Oncorhynchus mykiss and Oreochromis spp

Aquaculture development is limited by bacteria associated with several diseases; antibiotics are used for the treatment of these affections, but bacteria have developed resistance to these drugs. It is important to develop effective treatments that allow the production of antibiotic-free food. The aim of the present study is to evaluate the in vitro antibacterial effects of Salix babylonica hydro-alcoholic extract (SbHE) against Aeromonas hydrophila, Listonella anguillarum, Edwarsiella tarda, and Streptococcus iniae, bacteria that affect Oncorhynchus mykiss and Oreochromis spp. production. SbHE was obtained through the maceration technique. Reference strains were used and their sensitivity to antibiotics was determined. Minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of SbHE were determined. Results showed that three of four evaluated bacteria were multidrug resistant, except S. iniae. SbHE showed antibacterial activity against all bacteria. Results indicate an MIC of 1.56 to 25 mg/mL and an MBC of 3.12 to 100 mg/mL. The greatest inhibitory activity occurred against L. anguillarum obtaining a MIC of 1.56 mg/mL and an MBC of 3.12 mg/mL. Results indicate that SbHE has bactericidal activity against A. hydrophila, L.anguilalurm, and S. iniae as well as bacteriostatic activity against E. tarda and could be an alternative treatment against these bacteria.

Antibacterial and Hemolytic Activity of Crotalus Triseriatus and Crotalus Ravus Venom

Rattlesnakes have venoms with a complex toxin mixture comprised of polypeptides and proteins. Previous studies have shown that some of these polypeptides are of high value for the development of new medical treatments. The aim of the present study is to evaluate, in vitro, the antibacterial and hemolytic activity of Crotalus triseriatus and Crotalus ravus venoms. A direct field search was conducted to obtain Crotalus triseriatus and Crotalus ravus venom samples. These were evaluated to determine their antibacterial activity against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa through the techniques of Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC). Hemolytic activity was also determined. Antibacterial activity was determined for treatments (Crotalus triseriatus 2) CT2 and (Crotalus ravus 3) CR3, obtaining a Minimum Inhibitory Concentration of 50 µg/mL and a Minimum Bactericidal Concentration of 100 µg/mL against Pseudomonas aeruginosa. CT1 (Crotalus triseriatus 1), CT2, and CR3 presented hemolytic activity; on the other hand, Crotalus ravus 4 (CR4) did not show hemolytic activity. The results of the present study indicate for the first time that Crotalus triseriatus and Crotalus ravus venoms contain some bioactive compounds with bactericidal activity against Pseudomonas aeruginosa which could be used as alternative treatment in diseases caused by this pathogenic bacterium.

Antimicrobial mechanism of luteolin against Staphylococcus aureus and Listeria monocytogenes and its antibiofilm properties

Luteolin (LUT) is a naturally occurring compound found in a various of plants. Few recent studies have reported LUT antimicrobial activities against bacterial pathogens, however, the fundamental LUT mediated antimicrobial mechanism has never been elucidated. This study aimed to investigate the antimicrobial activities of LUT and its mode of action against Staphylococcus aureus and Listeria monocytogenes, either as planktonic cells or as biofilms. Here, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) of LUT against S. aureus and L. monocytogenes were determined using the broth microdilution method, and the antimicrobial mode of LUT was elucidated by evaluating the variations in both cell membrane integrity and cell morphology. Moreover, the biofilm inhibition was measured by crystal violet staining assay, while its qualitative imaging was achieved by confocal laser scanning microscope and field emission scanning electron microscope. MIC and MBC values of LUT against S. aureus were 16-32 and 32-64 μg/mL, and 32-64 and 64-128 μg/mL for L. monocytogenes. LUT destroyed the cell membrane integrity, as evidenced by a significant increase in the number of non-viable cells, and well-defined variations in cell morphology. Moreover, LUT presented robust inhibitory effects on the biofilm formation, enhanced antibiotics diffusion within biofilms and killed efficiently mono- and dual-species biofilm cells. Overall, LUT demonstrates potent antimicrobial properties on planktonic and biofilm cells, and the biofilm formation, and thus has the potential use as a natural food preservative in foods.

Anti-Fungal Efficacy and Mechanisms of Flavonoids

The prevalence of fungal infections is growing at an alarming pace and the pathogenesis is still not clearly understood. Recurrence of these fungal diseases is often due to their evolutionary avoidance of antifungal resistance. The development of suitable novel antimicrobial agents for fungal diseases continues to be a major problem in the current clinical field. Hence, it is urgently necessary to develop surrogate agents that are more effective than conventional available drugs. Among the remarkable innovations from earlier investigations on natural-drugs, flavonoids are a group of plant-derived substances capable of promoting many valuable effects on humans. The identification of flavonoids with possible antifungal effects at small concentrations or in synergistic combinations could help to overcome this problem. A combination of flavonoids with available drugs is an excellent approach to reduce the side effects and toxicity. This review focuses on various naturally occurring flavonoids and their antifungal activities, modes of action, and synergetic use in combination with conventional drugs.

Efficacy and Mechanism of Traditional Medicinal Plants and Bioactive Compounds against Clinically Important Pathogens

Traditional medicinal plants have been cultivated to treat various human illnesses and avert numerous infectious diseases. They display an extensive range of beneficial pharmacological and health effects for humans. These plants generally synthesize a diverse range of bioactive compounds which have been established to be potent antimicrobial agents against a wide range of pathogenic organisms. Various research studies have demonstrated the antimicrobial activity of traditional plants scientifically or experimentally measured with reports on pathogenic microorganisms resistant to antimicrobials. The antimicrobial activity of medicinal plants or their bioactive compounds arising from several functional activities may be capable of inhibiting virulence factors as well as targeting microbial cells. Some bioactive compounds derived from traditional plants manifest the ability to reverse antibiotic resistance and improve synergetic action with current antibiotic agents. Therefore, the advancement of bioactive-based pharmacological agents can be an auspicious method for treating antibiotic-resistant infections. This review considers the functional and molecular roles of medicinal plants and their bioactive compounds, focusing typically on their antimicrobial activities against clinically important pathogens.