Exploring Plant Extracts as a Novel Frontier in Antimicrobial Innovation: Plant Extracts and Antimicrobials.

The scientific exploration presented in this Special Issue offers a comprehensive overview of recent advancements in the realm of plant-derived antimicrobials [...].

Bioactivity and Metabolomic Profile of Extracts Derived from Mycelial Solid Cultures of Hypsizygus marmoreus.

The beech mushroom (Hypsizygus marmoreus) is a highly nutritious, edible medicinal mushroom native to East Asia. The present research investigated the impact of different substrates on the metabolite compositions of H. marmoreus mycelia cultivated in vitro. The substrates tested included malt extract agar, malt extract agar enriched with barley malt, and malt extract agar enriched with grape pomace. The study also assessed antimicrobial and antiradical activities of the extracts against gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus), gram-negative bacteria (Escherichia coli, Salmonella typhi, and Pseudomonas aeruginosa), yeasts (Candida albicans, C. tropicalis, and C. parapsilosis), and dermatophytes (Trichophyton mentagrophytes, T. tonsurans, T. rubrum, Arthroderma quadrifidum, A. gypseum, A. curreyi, and A. insingulare). The results revealed that the H. marmoreus mycelia extracts demonstrated antibacterial and antifungal activities against the tested microorganisms. Extracts obtained from the cultivation in substrates enriched with either barley malt or grape pomace exhibited the highest antibacterial activity among all the tested bacterial strains except for P. aeruginosa. The same extracts showed the highest inhibitory effect against C. albicans and C. parapsilosis. Noteworthy, the extract from the mushroom cultivated in the substrate enriched with grape pomace also exhibited remarkable efficacy against T. mentagrophytes and T. tonsurans. Terpenoid and carbapenem compounds could be related to the antimicrobial properties of the extracts from mushrooms cultivated in substrates enriched with grape pomace. In comparison, the higher antiradical properties could be related to the content of indole compounds. In conclusion, growth substrate selection affects the nutritional and medicinal properties of H. marmoreus, making it a valuable contribution to the understanding of the cultivation of this mushroom.

Appraisals on the chemical characterization and biological potentials of Ranunculus constantinopolitanus extracts using chromatographic, computational, and molecular network approaches.

In this context, phytochemicals were extracted from Ranunculus constantinopolitanus using ethyl acetate (EA), ethanol, ethanol/water (70%), and water solvent. The analysis encompassed quantification of total phenolic and flavonoid content using spectrophotometric assays, chemical profiling via high performance liquid chromatography-mass spectrometry/mass spectrometry (HPLC-MS/MS) for the extracts, and assessment of antioxidant activity via 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), Cupric reducing antioxidant capacity (CUPRAC), ferric reducing antioxidant power (FRAP), metal chelating (MCA), and phosphomolybdenum (PBD) assays. Moreover, antimicrobial activity was assessed against four different bacterial strains, as well as various yeasts. Enzyme inhibitory activities were evaluated against five types of enzymes. Additionally, the extracts were examined for their anticancer and protective effects on several cancer cell lines and the human normal cell line. All of the extracts exhibited significant levels of ferulic acid, kaempferol, and caffeic acid. All tested extracts demonstrated antimicrobial activity, with Escherichia coli and Pseudomonas aeruginosa being most sensitive to EA and ethanol extracts. Molecular docking studies revealed that kaempferol-3-O-glucoside strong interactions with AChE, BChE and tyrosinase. In addition, network pharmacology showed an association between gastric cancer and kaempferol-3-O-glucoside. Based on the results, R. constantinopolitanus can be a potential reservoir of bioactive compounds for future bioproduct innovation and pharmaceutical industries.

Diversity of Pleurotus spp. (Agaricomycetes) and Their Metabolites of Nutraceutical and Therapeutic Importance.

Pleurotus spp. have been gaining popularity as a source for the creation of functional foods, nutraceuticals and novel pharmaceuticals. Despite Pleurotus is a specious genus including 208 legitimate species, only a few of them such as P. ostreatus are commercially accessible. The genetic and metabolic diversity of Pleurotus both at specific and subspecific level is therefore of main concern for many researchers. In addition to the conventional morphological approach, molecular and biochemical markers have been greatly contributing to investigate these issues. In this study, samples from six Pleurotus species (P. eryngii is represented by three varieties) were molecularly identified and the phylogeny was inferred to assess the relationships between the various taxa. Strains in pure culture obtained from 6 out of 7 species were cultivated as mycelium in vitro to investigate the metabolites by untargeted LC-MS/MS-based metabolomics. The results pointed out species-specific metabolite patterns and highlighted a clear difference between the P. eryngii group and P. ostreatus, although the latter appears more versatile depending on the strain. This is the first study pointing out and comparing different metabolite patterns in Italian samples of Pleurotus species, including P. eryngii varieties.

Fomitopsis officinalis: Spatial (Pileus and Hymenophore) Metabolomic Variations Affect Functional Components and Biological Activities.

Fomitopsis officinalis is a holartic polyporous mushroom that forms large fruiting bodies on old standing trees, fallen logs, or stumps. F. officinalis is a medicinal mushroom species that is most commonly used in traditional European medicine. In this study, we explore the spatial metabolic differences in F. officinalis' mushroom parts, i.e., the cap (median and apical parts) and the hymenium. Additionally, chromatographic analysis was conducted in order to unravel the composition of specialized metabolites in the hydroalcoholic mushroom extracts. The potential antifungal and bacterial effects of extracts were tested against pathogen strains of Gram+ and Gram- bacteria, and yeast, dermatophytic, and fungal-pool species. Extracts from the apical part were the richest in terms of phenolic compounds; consistent with this finding, the extracts were also the most effective antiradical and antimicrobial agents with MIC values < 100 µg/mL for most of the tested bacterial and dermatophytic species. According to these findings, F. officinalis extracts are valuable sources of primary and secondary metabolites, thus suggesting potential applications in the formulation of food supplements with biological properties in terms of antioxidant and antimicrobial activities.

Comparative Investigation of Antimicrobial and Antioxidant Effects of the Extracts from the Inflorescences and Leaves of the Cannabis sativa L. cv. strawberry.

Cannabis sativa products have historically been used for healing purposes; now their biological properties are supported with scientific evidence, but modern research has not yet fully developed its therapeutic potential. This study focuses on the cultivar of C. sativa called strawberry to understand the biological and medical potentials of hydroalcoholic extracts from two different parts of the plant: leaves and inflorescences. Two biological assets were investigated including antioxidant and antimicrobial potential. Additionally, quantitative determination of phenolic and terpenophenol compounds was conducted. The antimicrobial action was highlighted for the hydroalcoholic extract from inflorescences, especially against Escherichia coli and Bacillus subtilis. Among the dermatophytes' strains, the most sensitive was Arthroderma currey. These effects could be related albeit partially to the pattern of the phenolics detected, among which the most prominent one was benzoic acid. On the other hand, antioxidant and antimicrobial effects of the extracts could be also mediated by the main terpenophenolics identified and quantified, namely cannabidiolic acid and cannabidiol. Collectively, the present data point to the potential use of the inflorescences from the C. sativa cultivar strawberry as a valuable plant material for the development of bioactive extracts with antioxidant and antimicrobial effects.

Untargeted Metabolomics Used to Describe the Chemical Composition, Antioxidant and Antimicrobial Effects of Extracts from Pleurotus spp. Mycelium Grown in Different Culture Media.

Pleurotus species isolated in vitro were studied to determine the effect of different media on their production of secondary metabolites, antimicrobial, and antioxidant activity. The different metabolites among Pleurotus samples covered a total of 58 pathways. Comparisons were made between the metabolic profiles of Pleurotus spp. mycelia grown in two substrates: Potato-dextrose-agar-PDA, used as control (S1), and PDA enriched with 0.5 % of wheat straw (S2). The main finding was that the metabolic pathways are strongly influenced by the chemical composition of the growth substrate. The antibacterial effects were particularly evident against Escherichia coli, whereas Arthroderma curreyi (CCF 5207) and Trichophyton rubrum (CCF 4933) were the dermatophytes more sensitive to the mushroom extracts. The present study supports more in-depth investigations, aimed at evaluating the influence of growth substrate on Pleurotus spp. antimicrobial and antioxidant properties.

Hydrosols from Rosmarinus officinalis, Salvia officinalis, and Cupressus sempervirens: Phytochemical Analysis and Bioactivity Evaluation.

The present work evaluates the aromatic waters of rosemary (Salvia rosmarinus Spenn. syn. Rosmarinus officinalis L.), sage (Salvia officinalis L.), and cypress (Cupressus sempervirens L.) obtained as innovative commercial products of a hydrodistillation process. All extracts were exhaustively analysed by GC-MS, 1H-NMR, and LC-MS in order to evaluate potential metabolite fingerprint differences. GC-MS appears to be the most exhaustive technique for the qualitative identification of the single constituents, although in this case, the use of 1H-NMR and LC-MS techniques allowed some useful considerations in semi-quantitative terms. Antimycotic effects were studied against Tricophyton, Candida, and Arthroderma species, resulting in weak activity. The toxicological impact was partly evaluated in vitro by means of allelopathy and brine shrimp lethality. Cytotoxicity was investigated in human colon cancer cells (HCT116) and in hypothalamic cells (Hypo-E22) challenged with hydrogen peroxide. Sage and rosemary hydrosols were the most effective antimycotics, whereas all hydrosols displayed antiradical effects. Cytotoxic effects against HCT116 cells (at 500 µL/mL) were related in silico to the endovanilloid TRPM8 and TRPV1 receptors. At lower concentrations (5-50 µL/mL), the hydrosols protected hypothalamic neurons Hypo-E22 cells from hydrogen peroxide-induced toxicity. The overall experience indicates that hydrolates are an important source of relevant phytochemicals with significant pharmacological potential.

Metabolomic Profiling and Biological Activities of Pleurotus columbinus Quél. Cultivated on Different Agri-Food Byproducts.

The genus Pleurotus (Fr.) P. Kumm (Pleurotaceae, Basidiomycota) comprises a cosmopolitan group of mushrooms highly appreciated for their nutritional value and health-promoting benefits. Despite there being many studies about the phytochemical composition of Pleurotus spp., there are very few reports dealing with the phytochemistry, antioxidant and antimicrobial activities of P. columbinus Quél. In this study, a mass spectrometry ultra-performance liquid chromatography mass spectrometry (UHPLC)-QTOF method, coupled with principal component analysis (PCA), was applied to the P. columbinus metabolome in order to investigate the influence of different agri-food residues as growth substrates for P. columbinus cultivation, on the bioactive chemical profile of fruiting bodies and evaluated their potential as antioxidants and antimicrobials. Additionally, a quantitative HPLC-DAD-MS analysis was conducted on phenolic and flavonoid compounds, that could explain, albeit partially, the observed biological effects of P. columbinus extracts. The qualitative metabolic profile identified 97 metabolites, whereas the quantitative HPLC-DAD-MS analysis confirmed the presence of phenolic and flavonoids, in the mushroom extracts, which also showed intrinsic scavenging/reducing and antimicrobial effects. The antibacterial effects were particularly evident against Escherichia coli, whereas Tricophyton and Aspergillus were the dermatophytes more sensitive to the mushroom extracts. The present study supports more in-depth investigations, aimed at evaluating the influence of growth substrate on P. columbinus antimicrobial and antioxidant properties. The extracts from P. columbinus revealed valuable sources of primary and secondary metabolites, thus suggesting potential applications in the formulation of food supplements with biological properties, above all in terms of antioxidant and antimicrobial properties.

Unravelling the Phytochemical Composition and the Pharmacological Properties of an Optimized Extract from the Fruit from Prunus mahaleb L.: From Traditional Liqueur Market to the Pharmacy Shelf.

Prunus mahaleb L. fruit has long been used in the production of traditional liqueurs. The fruit also displayed scavenging and reducing activity, in vitro. The present study focused on unravelling peripheral and central protective effects, antimicrobial but also anti-COVID-19 properties exerted by the water extract of P. mahaleb. Anti-inflammatory effects were studied in isolated mouse colons exposed to lipopolysaccharide. Neuroprotection, measured as a blunting effect on hydrogen-peroxide-induced dopamine turnover, was investigated in hypothalamic HypoE22 cells. Antimicrobial effects were tested against different Gram+ and Gram- bacterial strains. Whereas anti-COVID-19 activity was studied in lung adenocarcinoma H1299 cells, where the gene expression of ACE2 and TMPRSS2 was measured after extract treatment. The bacteriostatic effects induced on Gram+ and Gram- strains, together with the inhibition of COX-2, TNFα, HIF1α, and VEGFA in the colon, suggest the potential of P. mahaleb water extract in contrasting the clinical symptoms related to ulcerative colitis. The inhibition of the hydrogen peroxide-induced DOPAC/DA ratio indicates promising neuroprotective effects. Finally, the downregulation of the gene expression of ACE2 and TMPRSS2 in H1299 cells, suggests the potential to inhibit SARS-CoV-2 virus entry in the human host. Overall, the results support the valorization of the local cultivation of P. mahaleb.

Identification of Chemical Profiles and Biological Properties of Rhizophora racemosa G. Mey. Extracts Obtained by Different Methods and Solvents.

Mangrove forests exemplify a multifaceted ecosystem since they do not only play a crucial ecological role but also possess medicinal properties. Methanolic, ethyl acetate and aqueous leaf and bark extracts were prepared using homogenizer-assisted extraction (HAE), infusion and maceration (with and without stirring). The different extracts were screened for phytochemical profiling and antioxidant capacities in terms of radical scavenging (DPPH, ABTS), reducing potential (CUPRAC, FRAP), total antioxidant capacity and chelating power. Additionally, R. racemosa was evaluated for its anti-diabetic (α-amylase, α-glucosidase), anti-tyrosinase and anti-cholinesterase (AChE, BChE) activities. Additionally, antimycotic and antibacterial effects were investigated against Eescherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium, Listeria monocytogenes, Enterobacter cloacae, Bacillus cereus, Micrococcus luteus, Staphylococcus aureus, Aspergillus fumigatus, Aspergillus niger, Trichoderma viride, Penicillium funiculosum, Penicillium ludwigii and Penicillium verrucosum. Finally, based on phytochemical fingerprint, in silico studies, including bioinformatics, network pharmacology and docking approaches were conducted to predict the putative targets, namely tyrosinase, lanosterol-14-α-demethylase and E. coli DNA gyrase, underlying the observed bio-pharmacological and microbiological effects. The methanolic leave and bark extracts (prepared by both HAE and maceration) abounded with phenolics, flavonoids, phenolic acids and flavonols. Results displayed that both methanolic leaf and bark extracts (prepared by HAE) exhibited the highest radical scavenging, reducing potential and total antioxidant capacity. Furthermore, our findings showed that the highest enzymatic inhibitory activity recorded was with the tyrosinase enzyme. In this context, bioinformatics analysis predicted putative interactions between tyrosinase and multiple secondary metabolites including apigenin, luteolin, vitexin, isovitexin, procyanidin B, quercetin and methoxy-trihydroxyflavone. The same compounds were also docked against lanosterol-14α-demethylase and E. Coli DNA gyrase, yielding affinities in the submicromolar-micromolar range that further support the observed anti-microbial effects exerted by the extracts. In conclusion, extracts of R. racemosa may be considered as novel sources of phytoanti-oxidants and enzyme inhibitors that can be exploited as future first-line pharmacophores.