Chemical composition and antimycotic activity of six essential oils (cumin, fennel, manuka, sweet orange, cedar and juniper) against different Candida spp

A Study of Metabolites from Basidiomycota and Their Activities against Pseudomonas aeruginosa

The World Health Organization (WHO) promotes research aimed at developing new drugs from natural compounds. Fungi are important producers of bioactive molecules, and they are often effective against other fungi and/or bacteria and are thus a potential source of new antibiotics. Basidiomycota crude extracts, which have previously been proven to be active against Pseudomonas aeruginosa ATCC27853, were subjected to liquid chromatographic separation by RP-18, leading to six macro-fractions for each fungal extract. The various fractions were tested for their bioactivities against P. aeruginosa ATCC27853, and ten of them were characterized by HPLC-HRMS and NMR. Further chromatographic separations were performed for a few selected macro-fractions, yielding seven pure compounds. Bioactivity was mainly found in the lipophilic fractions containing fatty acids and their derivatives, such as hydroxy or keto C-18 unsaturated acids, and in various complex lipids, such as glycolipids and related compounds. More hydrophilic molecules, such as GABA, phenethylamine, two chromogenic anthraquinoids and pistillarin, were also isolated, and their antibacterial activities were recorded. The novelties of this research are as follows: (i) the genera Cortinarius and Mycena have never been investigated before for the synthesis of antibiotic compounds; (ii) the molecules produced by these genera are known, but their production has never been reported in the investigated fungi; (iii) the determination of bacterial siderophore synthesis inhibition by certain compounds from Cortinarius and Mycena.

Thymus vulgaris Essential Oil in Beta-Cyclodextrin for Solid-State Pharmaceutical Applications

Antimicrobial resistance related to the misuse of antibiotics is a well-known current topic. Their excessive use in several fields has led to enormous selective pressure on pathogenic and commensal bacteria, driving the evolution of antimicrobial resistance genes with severe impacts on human health. Among all the possible strategies, a viable one could be the development of medical features that employ essential oils (EOs), complex natural mixtures extracted from different plant organs, rich in organic compounds showing, among others, antiseptic properties. In this work, green extracted essential oil of Thymus vulgaris was included in cyclic oligosaccharides cyclodextrins (CD) and prepared in the form of tablets. This essential oil has been shown to have a strong transversal efficacy both as an antifungal and as an antibacterial agent. Its inclusion allows its effective use because an extension of the exposure time to the active compounds is obtained and, therefore, a more marked efficacy, especially against biofilm-producing microorganisms such as P. aeruginosa and S. aureus, was registered. The efficacy of the tablet against candidiasis opens their possible use as a chewable tablet against oral candidiasis and as a vaginal tablet against vaginal candidiasis. Moreover, the registered wide efficacy is even more positive since the proposed approach can be defined as effective, safe, and green. In fact, the natural mixture of the essential oil is produced by the steam current method; therefore, the manufacturer employs substances that are not harmful, with very low production and management costs.

Extracts from Cabbage Leaves: Preliminary Results towards a “Universal” Highly-Performant Antibacterial and Antifungal Natural Mixture

Simple Summary

The large antibiotic consumption in the clinical, veterinary, and agricultural fields has resulted in a tremendous flow of antibiotics into the environment. This has led to enormous selective pressures driving the evolution of antimicrobial resistance in bacteria and yeasts. For this reason, the World Health Organization is promoting research to discover new natural products competitive with synthetic drugs in clinical performances. Compared with conventional drugs, the production of natural pharmaceuticals often has a lower environmental impact and lower economic costs of processes, especially when they originate from agricultural wastes. In the context of a circular economy, we aimed to successfully present preliminary results for the valorization of agricultural waste produced in cabbage cultivation by isolating a highly performant antibacterial and antifungal lipophilic natural mixture from cabbage leaves.

Abstract

As dramatically experienced in the recent world pandemic, viral, bacterial, fungal pathogens constitute very serious concerns in the global context of human health. Regarding this issue, the World Health Organization has promoted research studies that aim to develop new strategies using natural products. Although they are often competitive with synthetic pharmaceuticales in clinical performance, they lack their critical drawbacks, i.e., the environmental impact and the high economic costs of processing. In this paper, the isolation of a highly performant antibacterial and antifungal lipophilic natural mixture from leaves of savoy and white cabbages is proposed as successful preliminary results for the valorization of agricultural waste produced in cabbage cultivation. The fraction was chemically extracted from vegetables with diethyl ether and tested against two Candida species, as well as Pseudomonas aeruginosa, Klebsiella pneumoniae and Staphylococcus aureus reference strains. All the different fractions (active and not active) were chemically characterized by vibrational FT-IR spectroscopy and GC-MS analyses. The extracts showed high growth-inhibition performance on pathogens, thus demonstrating strong application potential. We think that this work, despite being at a preliminary stage, is very promising, both from pharmaceutical and industrial points of view, and can be proposed as a proof of concept for the recovery of agricultural production wastes.

A Systematic Study of the Antibacterial Activity of Basidiomycota Crude Extracts

The excessive consumption of antibiotics in clinical, veterinary and agricultural fields has resulted in tremendous flow of antibiotics into the environment. This has led to enormous selective pressures driving the evolution of antimicrobial resistance genes in pathogenic and commensal bacteria. In this context, the World Health Organization (WHO) has promoted research aiming to develop medical features using natural products that are often competitive with synthetic drugs in clinical performance. Fungi are considered an important source of bioactive molecules, often effective against other fungi and/or bacteria, and thus are potential candidates in the search of new antibiotics. Fruiting bodies of sixteen different fungal species of Basidiomycota were collected in the Italian Alps. The identification of fungal species was performed through Internal Transcribed Spacer (ITS) sequencing. Most species belong to genera Cortinarius, Mycena and Ramaria, whose metabolite contents has been scarcely investigated so far. The crude extracts obtained from the above mushrooms were tested for their inhibition activity against five human pathogens: Candida albicans ATCC 14053, C. glabrata ATCC 15126, Staphylococcus aureus NCTC 6571, Pseudomonas aeruginosa ATCC 27853 and Klebsiella pneumoniae ATCC 13883. Twelve crude extracts showed activity against P. aeruginosa ATCC 27853. Highest activity was shown by some Cortinarius species, as C. nanceiensis.

Host–Guest Inclusion Complexes of Essential Oils with Strong Antibacterial and Antifungal Features in Beta-Cyclodextrin for Solid-State Pharmaceutical Applications

Essential oils are widely recognized as natural alternatives to pharmaceutical antibacterial and antifungal agents. With respect to standard pharmaceutics, the advantages of essential oils are their (i) low production costs, (ii) lack of chemical and biochemical drawbacks that are intrinsic to the synthetic production process and (iii) good tolerance by humans. On the other hand, the liquid nature of essential oils poses concerns about their actual application in different therapeutic issues regarding their persistence and the ability to control or prolong drug release. In this study, two essential oils from oregano and winter savory showing antibacterial and antifungal features were complexed in a solid state with beta-cyclodextrin. Host–guest inclusion complexes were characterized using FT-IR spectroscopy, ESI-MS and GC-MS techniques. Manyfold terpenic and non-terpenic components of the oils could be observed and unambiguously identified as being included inside the carbohydrate hosts. Many of them provided a specific biocidal action. Indeed, essential oil host–guest inclusion products were tested against two Candida species and an S. aureus reference strain, showing that the oils effectively maintained their liquid performances. Solid-state tablets of the essential oil inclusion complexes embedded in polyvinylpyrrolidone could be obtained. These results pave the way for the solid-state application of essential oils in antibacterial and antifungal pharmaceutical treatments.

Mānuka Oil-A Review of Antimicrobial and Other Medicinal Properties

Mānuka oil is an essential oil derived from Leptospermum scoparium, a plant that has been used by the indigenous populations of New Zealand and Australia for centuries. Both the extracted oil and its individual components have been associated with various medicinal properties. Given the rise in resistance to conventional antibiotics, natural products have been targeted for the development of antimicrobials with novel mechanism of action. This review aimed to collate available evidence on the antimicrobial, anti-parasitic and anti-inflammatory activities of mānuka oil and its components. A comprehensive literature search of was conducted using PubMed and Embase (via Scopus) targeting articles from database inception until June 2020. Chemical structures and IUPAC names were sourced from PubChem. Unpublished information from grey literature databases, Google search, targeted websites and Google Patents were also included. The present review found extensive in vitro data supporting the antimicrobial effects of mānuka oil warrants further clinical studies to establish its therapeutic potential. Clinical evidence on its efficacy, safety and dosing guidelines are necessary for its implementation for medical purposes. Further work on regulation, standardization and characterization of the medicinal properties of mānuka oil is required for establishing consistent efficacy of the product.