Phytochemical Composition and In Vitro Antimicrobial Activity of Essential Oils from the Lamiaceae Family against Streptococcus agalactiae and Candida albicans Biofilms

Abstract: The antimicrobial activity of different essential oils (EOs) from the Lamiaceae family was evaluated on Streptococcus agalactiae, Candida albicans, and lactobacilli. S. agalactiae is the main cause of severe neonatal infections, such as sepsis, meningitis, and pneumonia. C. albicans is a primary causative agent of vulvovaginal candidiasis, a multifactorial infectious disease of the lower female reproductive tract. Lactobacilli represent the dominant bacterial species of the vaginal flora and constitute the natural defense against pathogens. On the basis of the preliminary results, the attention was focused on the EOs from Lavandula x intermedia Emeric ex Loisel. and Mentha arvensis L. By using gas chromatography (GS) retention data and mass spectra, it was possible to identify more than 90% of the total composition of the EO samples. The minimal inhibitory concentration (MIC) and anti-biofilm activity of the two EOs were determined against all isolated strains, using the EOs by themselves or in combination with each other and with drugs (erythromycin and fluconazole). The results showed a good antimicrobial and anti-biofilm activity of both EOs and a synergistic effect, leading to the best results against all the strains, resulted using the combinations EOs/EOs and antimicrobials/EOs

Use of Pinus sylvestris L. (Pinaceae), Origanum vulgare L. (Lamiaceae), and Thymus vulgaris L. (Lamiaceae) essential oils and their main components to enhance itraconazole activity against azole susceptible/not-susceptible Cryptococcus neoformans strains

Abstract Background: Cryptococcal infections, besides being a problem for immunocompromised patients, are occasionally being a problem for immunocompetent patients. In addition, the lower susceptibility of this yeast to azoles is a growing problem in health care. To date, there are very few molecules with any activity towards Cryptococcus neoformans, leading to heightened interest in finding new alternatives or adjuvants to conventional drugs for the treatment of mycosis caused by this yeast. Since the essential oils (EOs) are considered as a potential rich source of bioactive antimicrobial compounds, we evaluated the antifungal activity of Origanum vulgare (oregano), Pinus sylvestris (pine), and Thymus vulgaris (thyme red) EOs, and their components (\u3b1-pinene, carvacrol, thymol) compared with fluconazole, itraconazole, and voriconazole, against C.neoformans clinical strains. Then, we investigated the effect of EOs and components in combination with itraconazole. Methods: EO composition was analysed by Gas chromatography-mass spectrometry (GC-MS). A broth microdilution method was used to evaluate the susceptibility of C.neoformans to azoles, EOs and components. Checkerboard tests, isobolograms and time-kill assays were carried out for combination studies. Results: C.neoformans isolates were susceptible to azoles, while one C.neoformans exhibited a reduced susceptibility to all test edazole drugs. All EOs exerted a good inhibitory activity against all C.neoformans strains. Pine EO was the most effective. Among components, thymol exerted the most remark able activity. By checkerboard testing and isobolographic analysis, combinations of itraconazole with oregano, pine, or thyme EOs, and carvacrol were found to be synergistic (FICI 64 0.5) against azole susceptible C.neoformans. Regarding the azole not susceptible C.neoformans strain, the synergistic effect with itraconazole was observed with thyme EO (chemotype: thymol 26.52%; carvacrol 7.85%), and carvacrol. Time-kill assays confirmed the synergistic effects of itraconazole and oregano or thyme EO against azole susceptible C.neoformans. Binary mixtures of itraconazole/thyme EO or carvacrol yielded additive effects on the azole not susceptible C.neoformans. Conclusions: Our findings highlight the potential effectiveness of thyme, oregano EOs, and carvacrol as natural and cost-effective adjuvants when used in combination with itraconazole. Identification of EOs exerting these effects could be one of the feasible ways to overcome drug resistance, reducing drug concentration and side effects

Polyphenolic profile of Cichorium intybus L. endemic varieties from the Veneto region of Italy

The present study was aimed at the investigation, through HPLCDAD-ESI-MS/MS, of polyphenols in seven autochthonous C. intybus varieties, already known from literature to contain various substances with antioxidant properties, from the Veneto region of Italy, namely 'Castelfranco', 'Chioggia', 'Rosa di Gorizia', 'Rosa di Verona', 'Treviso Precoce', 'Treviso Tardivo' and 'Verdon da Cortèl'. Thirteen polyphenols, belonging to hydroxycinnamic acid, flavone, flavonol and anthocyanin classes, were detected in most samples. The developed analytical method was validated in agreement with ICH guidelines. The total amount of polyphenols ranged from 52 to 386 (mean: 254) mg/100g fresh weight (F.W.). The results were further confirmed by Principal Composition Analysis (PCA), which highlighted peculiar features and similarities among analysed samples for each variety (except for 'Chioggia' samples). The developed method is suitable for routine analyses, as well as geographical characterization, selection of different C. intybus varieties and for the determination of related polyphenols dietary recommended intakes

Essential oils in ocular pathology: an experimental study

Introduction: The antimicrobial activity of essential oils (EOs) has been known for ages; in particular, the EOs of Melaleuca alternifolia, Thymus vulgaris, Mentha piperita, and Rosmarinus officinalis have been used for the treatment of fungal and bacterial infections. Methodology: This study focused on the in vitro cytotoxicity to normal human conjunctiva cells and antimicrobial activity of 20 EOs. Results: The oils tested showed no cytotoxic effect at very low concentrations. Rosmarinus officinalis, Melaleuca alternifolia, and Thymus vulgaris L. red thyme geraniol sel oils had good antimicrobial activity against Gram-positive and Gram-negative strains. Conclusions: The results of this study are of great interest and may have a major impact on public health, providing useful tips to optimize the therapeutic use of some natural drugs

Design, synthesis and evaluation against Chikungunya virus of novel small-molecule antiviral agents

Chikungunya virus is a re-emerging arbovirus transmitted to humans by mosquitoes, responsible for an acute flu-like illness associated with debilitating arthralgia, which can persist for several months or become chronic. In recent years, this viral infection has spread worldwide with a previously unknown virulence. To date, no specific antivirals treatments nor vaccines are available against this important pathogen. Starting from the structures of two antiviral hits previously identified in our research group with in silico techniques, this work describes the design and preparation of 31 novel structural analogues, with which different pharmacophoric features of the two hits have been explored and correlated with the inhibition of Chikungunya virus replication in cells. Structure-activity relationships were elucidated for the original scaffolds, and different novel antiviral compounds with EC50 values in the low micromolar range were identified. This work provides the foundation for further investigation of these promising novel structures as antiviral agents against Chikungunya virus

Investigation of Hg Content by a Rapid Analytical Technique in Mediterranean Pelagic Fishes

Mercury (Hg) fish and seafood contamination is a global concern and needs worldwide sea investigations in order to protect consumers. The aim of this study was to investigate the Hg concentration by means of a rapid and simple analytical technique with a direct Mercury Analyzer (DMA-80) in pelagic fish species, Tetrapturus belone (spearfish), Thunnus thynnus (tuna) and Xiphias gladius (swordfish) caught in the Mediterranean Sea. Hg contents were evaluated also in Salmo salar (salmon) as pelagic fish not belonging to the Mediterranean area. The results obtained were variable, ranging between 0.015⁻2.562 mg kg−1 for T. thynnus species, 0.477⁻3.182 mg kg−1 for X. gladius, 0.434⁻1.730 mg kg−1 for T. belone and 0.004⁻0.019 mg kg−1 for S. salar, respectively. The total Hg tolerable weekly intake (TWI) and tolerable weekly intake % (TWI%) values according to the European Food Safety Authority (EFSA) were calculated. The results highlighted that the pelagic species caught in the Mediterranean Sea should be constantly monitored due to their high Hg contents as well as their TWI and TWI% with respect to S. salar samples

Innovative methods for the extraction and chromatographic analysis of honey bee products

In this study, new and efficient chromatographic techniques were developed for a complete chemical characterization of raw propolis polyphenols and volatile compounds, which are responsible for the biological activity of the extracts widely used in apitherapy. The analysis of polyphenols, including phenolic acids and flavonoids, was performed by RP-HPLC coupled with UV/DAD and MS detection, using the new fused-core technology. Microwave-assisted extraction (MAE) was carried out for these constituents and its parameters were optimized by means of response surface experimental design methodology. The characterization of propolis volatile compounds was based on GC coupled with MS detection. In this ambit, a suitable HS-SPME extraction procedure was developed for the first time using a PDMS fiber. Both these chromatographic techniques were applied to raw propolis samples collected in different Italian regions to determine their metabolite fingerprinting, thus providing new and reliable tools for the complete chemical characterization of this biologically active material

Phytochemical analysis of Cedrelopsis grevei H. Baillon essential oil and evaluation of its antimicrobial and antifungal activity on plant pathogens

Cedrelopsis grevei H. Baillon is an aromatic and medicinal plant belonging to the Ptaeroxylaceae family from Madagascar. In this work, a detailed chemical characterization of the essential oil from the bark of C. grevei was performed, in combination with the evaluation of its antimicrobial activity. In particular, four samples of C. grevei essential oil were fully characterized by GC-MS and quantified by GC-FID. A total of 35 components were identified, according to their retention time data and mass spectra, representing 80% of the amount obtained by semi-quantification using relative response factors (RRFs) = 1. In the samples analyzed in this study, the major components were found to be ishwarane, β-elemene, α-copaene, calamenene, β-selinene, γ-muurolene, α-muurolene and β-pinene. Moreover, in addition to semi-quantification data, for the first time C. grevei essential oil quantification was performed by means of the experimental and predicted RRFs, using methyl octanoate as the internal standard. The biological activity of the essential oil was tested on plant pathogenic bacteria and fungi of interest in the ambit of biological agriculture and horticulture, including Agrobacterium tumefaciens, Agrobacterium vitis, Clavibacter michiganensis sub. michiganensis, Pseudomonas syringae pv syringae, Alternaria sp. and Fusarium oxysporum

Chemical composition and cytotoxic activity of Cedrelopsis grevei H. Baillon essential oil on human cancer cells

In this study, a detailed chemical characterization of Cedrelopsis grevei H. Baillon (Ptaeroxylaceae family) bark essential oil was perfomed. The GC analysis revealed a peculiar composition in terms of sesquiterpenes. The major components were found to be ishwarane, β-elemene, α-copaene, calamenene, β-selinene, γ-muurolene, α-muurolene and β-pinene. In addition to semi-quantification data, essential oil quantification was performed by means of the experimental and predicted relative response factors (RRF), using methyl octanoate as the internal standard. In vitro biological activity of C. grevei essential oil and its main isolated compounds (including ishwarane, β-elemene and α-copaene) was assayed for cytotoxic activity on human colon cancer cells CaCo-2 and human lung carcinoma cells A549 by means of the MTT assay. Furthermore, by combining the three main compounds, it was possible to evaluate the potential synergic effects. The results showed that the C. grevei essential oil exhibited interesting cytotoxic activity on both cancer cell lines

Innovative methods based on the fused-core technology for the HPLC analysis of natural products

Plant extracts are composed of a complex mixture of different phytochemicals (plant secondary metabolites). Frequently, these constituents work “synergistically” and cannot be separated into active parts. Consequently, it is necessary to define all the phytochemical constituents of plant extracts to understand the bioactivity and possible adverse effects of active compounds, and to enhance product quality control. Due to the complex composition of plant extracts, separation methods are highly recommended in phytochemical analysis. HPLC is the most frequently used technique for both quali- and quantitative analysis of natural compounds. However, the HPLC analysis of plant extracts usually requires a long analysis time on conventional fully porous stationary phases. The most recently reported strategy for improving the chromatographic performance in the analysis of complex matrices is based on the fused-core technology (also known as core-shell technology). In this ambit, this work provides several examples of the application of reversed-phase fused-core stationary phases for the metabolite profiling/fingerprinting of natural products widely used in phytotherapy, including propolis (phenolic acids and flavonoids), Humulus lupulus L. (prenylflavonoids and prenylphloroglucinols) and Echinacea pallida (Nutt.) Nutt. (polyacetylenes and polyenes). An additional example related to the phytochemical analysis of steviol glycosides in Stevia rebaudiana Bertoni is also provided. In particular, these examples demonstrate that the fused-core columns offer good chromatographic performance, such as narrow peaks, high resolution and a short analysis time