Chemical composition and antibacterial activity of seven uncommon essential oils

Antibacterial and antibiofilm effect of essential oils on staphylococci isolated from cheese - application of the oil mixture in a cheese model

The aim of the research was to examine the antimicrobial and antibiofilm effects of angelica, immortelle, laurel, hyssop, and sage plant dust essential oils (EOs) against isolated strains of Staphylococcus spp. from cheeses, in vitro and in the model of white cheese. MALDI-TOF MS analysis confirmed two Staphylococcus aureus strains and two coagulase-negative, identified as S. saprophyticus and S. warneri. All isolates produce biofilm, where the strains of S. aureus showed slightly better adherence. The main component of angelica EO was β-phellandrene (48.19 %), while α-pinene (20.33 %) were dominant in immortelle EO, in hyssop EO cis-pinocamphone (37.25 %), in laurel EO 1,8-cineole (43.15 %) and in sage EO epirosmanol (26.25 %). The sage EO exhibited the strongest antistaphylococcal activity against all isolates. Synergism was also detected in combination of sage with hyssop or laurel EO. Better antibiofilm activity was confirmed for sage EO compared to hyssop EO. The mixture of sage/laurel EOs reduced the total number of staphylococci in the cheese after 4 days. Results indicate that in vitro applied EOs showed significant antistaphylococcal and antibiofilm activity, while the oil mixture reduced the initial total number of staphylococci.

UV-A and UV-B combined with photosynthetically active radiation change plant growth, antioxidant capacity and essential oil composition of Pelargonium graveolens

BACKGROUND

The different wavelengths of solar radiation incident on earth [herein: Photosynthetically Active Radiation (PAR) , Ultra Violet-A (UV-A) and Ultra Violet-B (UV-B)] and their spectral balance not only have an impact on plants' growth, morphology and physiology, but also are important for the quality and quantity of plant secondary metabolites.

MATERIAL AND METHODS

In an outdoor study we addressed the effects of PAR intensity and UV-A and UV-B on the growth, yield, phenolic and flavonoid content, antioxidant activity and essential oil composition of Pelargonium graveolens L'Hér. The experiment was performed with split plots in a randomized complete block design with three replications. During the growth, two PAR intensities (ambient PAR and reduced PAR) and four UV treatments (ambient UV, enhanced UV-A, enhanced UV-B and enhanced UVA + B) were applied.

RESULTS

High PAR intensity decreased the length and width of leaf, the height of plant and fresh weight of aerial parts, and increased the dry weight of aerial parts. Enhanced UV-B irradiation was associated with reduced plant height, leaf expansion and fresh and dry weight of aerial parts. Interestingly, the negative effect of UV-B radiation on morphology and growth of plant was largely alleviated by high PAR intensity. The amount of total phenols and flavonoids, antioxidant activity and essential oil production of P. graveolens strongly increased with the increase of UV-B irradiation and PAR. On the other hand, UV-A radiation did not significantly influence total phenol and flavonoid content, antioxidant activity and essential oil composition. Moreover, the combination of high PAR intensity and UV-B led to further increases in total flavonoid content and antioxidant capacity. Both high PAR intensity and enhanced UV-B increased the percentage of geraniol in essential oil, leading to a slight reduction of citronellol/geraniol ratio which is a marker of quality for rose geranium essential oil.

CONCLUSIONS

Overall, we conclude that UV-B irradiation was associated to reduction of plant growth and yield, while, the adverse effect of UV-B irradiation on the plant was mitigated by high PAR intensity. On the other hand, both high PAR and enhanced UV-B boosted the production of phenols, flavonoids and essential oil. Considering that the lower citronellol/geraniol ratio is the most important indicator for the economic value of rose geranium essential oil, reducing citronellol/geraniol ratio under enhanced UV-B radiation and/or high PAR is likely to be favorable.

Virucidal Activity of Lemon Essential Oil against Feline Calicivirus Used as Surrogate for Norovirus

Norovirus (NoV) is regarded as a common cause of acute gastrointestinal illness worldwide in all age groups, with substantial morbidity across health care and community settings. The lack of in vitro cell culture systems for human NoV has prompted the use of cultivatable caliciviruses (such as feline calicivirus, FCV, or murine NoV) as surrogates for in vitro evaluation of antivirals. Essential oils (EOs) may represent a valid tool to counteract viral infections, particularly as food preservatives. In the present study, the virucidal efficacy of lemon EO (LEO) against FCV was assessed in vitro. The gas chromatography hyphenated with mass spectrometry (GC/MS) technique was used to reveal the chemical composition of LEO. The following small molecules were detected as major components of LEO: limonene (53%), β-pinene (14.5%), γ-terpinene (5.9%), citral (3.8%), α-pinene (2.4%), and β-thujene (1.94%). LEO at 302.0 μg/mL, exceeding the maximum non cytotoxic limit, significantly decreased viral titre of 0.75 log₁₀ TCID50/50 μL after 8 h. Moreover, virucidal activity was tested using LEO at 3020.00 μg/mL, determining a reduction of viral titre as high as 1.25 log₁₀ TCID50/50 μL after 8 h of time contact. These results open up perspectives for the development of alternative prophylaxis approaches for the control of NoV infection.

Ethnobotanical and Phytochemical Profiling of Medicinal Plants from Burkina Faso Used to Increase Physical Performance

Background: Some ergogenic medicinal plants are used in exercise and sport in Africa in order to increase sport performance. However, data on their composition and their possible impacts on health are limited. This study was initiated to provide ethnobotanical data on plants traditionally used to optimize physical performance and to perform a qualitative characterization of their main chemical groups. Methods: Ethnobotanical surveys in two communes (Dedougou and Nouna), of the region of Boucle du Mouhoun, Burkina Faso and phytochemical analyses of the most interesting plants were conducted. Results: A total of 50 respondents including traditional hunters dozo, farmers, healers, herbalists, marabouts, etc., were interviewed. Fifty-two species used in the optimization of exercise and sports have been identified. The most cited species were Cassia sieberiana, Tamarindus indica, Annona senegalensis, Gardenia sokotensis, Securidaca longepedunculata, and Ficus tonningii. These plants are known to prevent muscle and skeletal disorders, aches and pains, and mental disorders. The study identified several types of plants including those displaying stimulation, anxiolytic, sedative, adaptogenic, or erythropoietic activities. Phytochemical screening revealed the presence of phenolic compounds, alkaloids, terpenes, and steroids, which are similar molecules families of those of doping molecules. Additionally, TLC screening allowed the characterization of numerous terpene and flavonoid compounds including rutin. Conclusions: The possible structural similarity of the characterized chemical groups of these species with those of doping families raise concerns about the consequences of their consumption. However, the identification of the active molecules of these species remains to be performed in order to predict the real risks associated with their consumption.

Comprehensive Evaluation of the Antibacterial and Antifungal Activities of Carlina acaulis L. Essential Oil and Its Nanoemulsion

Plants are considered to be an excellent source of new compounds with antibiotic activity. Carlina acaulis L. is a medicinal plant whose essential oil (EO) is mainly characterized by the polyacetylene carlina oxide, which has antimicrobial properties. The aim of this study was to evaluate the antimicrobial and antifungal activities of C. acaulis EO, carlina oxide, and nanoemulsion (NE) containing the EO. The EO was obtained through plant roots hydrodistillation, and carlina oxide was purified from it through silica gel column chromatography. The NE containing C. acaulis EO was prepared with the high-pressure homogenization method, and the minimum inhibitory concentration (MIC) was determined against several bacterial and fungal strains for all the C. acaulis-derived products. The latter resulted active versus all the screened Gram-positive bacterial strains and also on all the fungal strains with low MIC values. For yeast, the EO and carlina oxide showed good MIC values. The EO-NE demonstrated a better activity than the pure EO on all the tested bacterial and fungal strains. The results suggest that C. acaulis-derived products could be potential candidates for the development of natural antibacterial and antifungal agents.

Overview on Innovative Packaging Methods Aimed to Increase the Shelf-Life of Cook-Chill Foods

The consumption of meals prepared, packaged, and consumed inside and outside the home is increasing globally. This is a result of rapid changes in lifestyles as well as innovations in advanced food technologies that have enabled the food industry to produce more sustainable and healthy fresh packaged convenience foods. This paper presents an overview of the technologies and compatible packaging systems that are designed to increase the shelf-life of foods prepared by cook–chill technologies. The concept of shelf-life is discussed and techniques to increase the shelf life of products are presented including active packaging strategies.

Synergistic Activity of New Diclofenac and Essential Oils Combinations against Different Candida spp

According to recent studies, Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) have shown a good antimicrobial and antifungal activity. Their association with essential oils (EOs) could be useful for the treatment of infections caused by Candida spp. The aim of this studyis to evaluate the synergistic antifungal activity of new combinations between Diclofenac Sodium Salt (DSS), a widely used NSAID, with EOs of Mentha × piperita, Pelargonium graveolens and Melaleuca alternifolia. The in-vitro antifungal activity was determined on different Candida strains. The determination of the chemical composition of EOs was carried out by gaschromatography-massspectrometry (GC-MS). Susceptibility testing of planktonic cells was performed by using the broth microdilution assay and checkerboard methods. Minimum Inhibitory Concentrations (MIC) of DSS was in a range from 1.02 to 2.05 μg/mL reaching a MIC value of 0.05 μg/mL when combined with Pelargonium graveolens (FICI = 0.23–0.35) or Menthapiperita (FICI = 0.22–0.30) EOs. These preliminary results show thatthe combination of the EOs with DSS improves the antifungal activity on all the tested Candida strains.

Impact of citronellol on river and soil environments using non-target model organisms and natural populations

Citronellol is an acyclic monoterpenoid with a wide range of pharmacological activities (antibacterial, antifungal, anti-lice, repellent, lipolytic, anti-allergic, anti-inflammatory, antispasmodic, antidiabetic, anti-cholesterol, among other) and potential to replace synthetic products. However, the impact of citronellol on the environment remains unknown. We analysed, for the first time, the environmental impact of citronellol on river and soil environments using non-target model organisms and natural populations. The acute toxicity of citronellol on the aquatic invertebrate Daphnia magna, the plant Allium cepa L and the earthworm Eisenia fetida was quantified. The effect of citronellol in a river ecosystem was analysed using river periphyton communities taxonomically characterised and a river microbial community characterised through 16 S rRNA gene sequencing. Finally, a microbial community from natural soil was used to monitor the effect of citronellol on the soil ecosystem. The results showed that E. fetida was most sensitive to citronellol (LC₅₀ = 12.34 mg/L), followed by D. magna (LC₅₀ = 14.11 mg/L). Citronellol affected the photosynthesis of the fluvial periphyton (LC₅₀ = 94.10 mg/L) and was phytotoxic for A. cepa. Furthermore, citronellol modified the growth and metabolism of both fluvial (LC₅₀ = 0.19% v/v) and edaphic (LC₅₀ = 5.07% v/v) bacterial populations. The metabolism of the microorganisms in the soil and water exposed to citronellol decreased with respect to the control, especially their ability to metabolise carbohydrates. Our results show that citronellol has a negative impact on the environment. Although acute effects cannot be expected, it is necessary to quantify the environmental levels as well as the long-term and persistent effects of this monoterpene.

Wild Italian Hyssopus officinalis subsp. aristatus (Godr.) Nyman: From Morphological and Phytochemical Evidences to Biological Activities

Three specimens of H. officinalis subsp. aristatus were collected in three areas of the Abruzzo region (Italy) and subjected to macroscopic and microscopic observation to support their botanical identification. The essential oils (EOs) obtained from the aerial parts of the samples were characterized with the object to define their phytochemical and pharmaceutical biology profile. They highlight three different chemotypes, including one never seen in previous literature (CIV17-EO, distilled from sample harvested in 2017 at Civitaretenga), that showed a fingerprinting with the predominance of (-)-limonen-10-yl-acetate (67.9%). In 2017 European Food Safety Authority (EFSA) reported the genotoxicity of similar compounds, therefore, to dismiss any safety concern for the CIV17-EO use as flavouring substance, the Ames test was performed with no evidence of mutagenic activity. Safety of use coupled with chemical characterization of this new chemotype set the stage for a better standardization of H. officinalis EOs. The ethanolic extracts, on the other hand, with qualitatively similar chemical profiles in which caftaric, chlorogenic and rosmarinic acid were the main molecules, showed interesting antioxidant activity and a slight cytotoxicity towards the A549 cell line that could indicate a starting point for the evaluation of an additional preventive tool for maintaining health status.

Ethnomedicinal uses, phytochemistry, and pharmacology of the genus Vepris (Rutaceae): A review

ETHNOPHARMACOLOGICAL RELEVANCE

Species of the genus Vepris are used in traditional African pharmacopeia for the treatment of various conditions, including chronic diseases and other parasitic. Further uses are against whooping cough and colic in children and as an antidote against snakebite. Data presented will enable the interested scientists to work on this genus applying the so-called "ethnopharmacologic approach", which may lead towards the discovery of the effective, safe plant medicinal products.

AIM OF THE REVIEW

This review article aims to collate and analyse the available information on the traditional uses, phytochemistry, pharmacology, and toxicological aspects of Vepris species in order to explore the trends and perspectives for further studies.

METHODOLOGY

The present review paper collected the literature published prior to August 2020 on the ethnomedicinal uses, phytochemistry, and pharmacology of the genus Vepris. The available information about the genus Vepris was collected via Google Books, Google Scholar, PubMed, ScienceDirect, SciFinder, Web of Science, and other internet sources. The Global Biodiversity Information Facility (www.gbif.org), Plants of the world online (www.plantsoftheworldonline.org), and The Plant List (www.theplantlist.org) databases were used to verify the scientific names and provide distribution information of Vepris species.

RESULTS

Comprehensive analysis of the literature provided information on ethnopharmacological uses of 30 species out of 83 members in the genus. A total of 213 compounds - predominantly alkaloids - were reported together with results from antioxidant, cytotoxic, antimicrobial, antiplasmodial, antitrypanosomal, antileishmanial, antidiabetic, antipyretic, analgesic, insect antifeedant, and toxicity assays. Arborinine (49) and skimmianine (4) isolated from the leaves of V. trichocarpa were tested toxic in rat skeletal myoblast cell line L6, a stable skeletal muscle progenitor cell line, while the leaves of V. heterophylla, the stem bark of V. louisii, and the roots of V. uguenensis were shown to be toxic against model organisms T. castaneum (Tenebrionidae), H. bakeri (Trychostrongylidae), and M. domestica (Muscidae), respectively. In addition, 6,7-methylenedioxy-5-hydroxy-8-methoxy-dictamnine (40) isolated from the leaves of a combined sample of V. renieri + V. suaveolens displayed an extremely low IC₅₀ of 0.67 μM against the normal fibroblastic lung cell line MRC-5 indicating high toxicity. Thus, medical use of these plant parts, as well of the stem bark of V. verdoorniana used locally in poison fishing, should be avoided if alternative treatments exist. Furthermore, a good number of significantly in vitro bioactive compounds have been reported from the genus Vepris: against malaria and against microbial infections.

CONCLUSIONS

Various Vepris species were found to be used in traditional African pharmacopeia. However, few of these species were studied for their bioactive chemical constituents with even fewer bioassay-guided isolation studies being reported. Moreover, detailed pharmacological studies in animal models to explore their mode of action were not reported. Therefore, future studies should focus on these aspects. In addition, we would like to recommend further research on some significantly bioactive crude extracts that were identified in this review: V. leandriana; V. lanceolata; V. nobilis; and V. trichocarpa, as well as those plants reported to be used against chronic diseases.

Anti-Biofilm Inhibitory Synergistic Effects of Combinations of Essential Oils and Antibiotics

In recent years, the increase of bacteria antibiotic- resistance has been a severe problem for public health. A useful solution could be to join some phytochemicals naturally present in essential oils (EOs) to the existing antibiotics, with the aim to increase their efficacy in therapies. According to in vitro studies, EOs and their components could show such effects. Among them, we studied the activity of Cinnammonum zeylanicum, Mentha piperita, Origanum vulgare, and Thymus vulgaris EOs on bacterial biofilm and their synergism when used in association with some common antibiotics such as norfloxacin, oxacillin, and gentamicin. The chemical composition of EOs was determined using gas chromatography (GC) coupled with mass spectrometry (MS) techniques. The EOs drug efficacy was evaluated on four different strains of Gram-positive bacteria forming biofilms. The synergistic effects were tested through the chequerboard microdilution method. The association EOs-antibiotics showed a strong destruction of the biofilm growth of the four bacterial species considered. The interaction of norfloxacin with EOs was the most effective in all the tested combinations against the strains object of this study. These preliminary results suggest the formulation of a new generation of antimicrobial agents based on a combination of antimicrobial compounds with different origin.

In Vitro Scolicidal Activity of the Sesquiterpenes Isofuranodiene, α-Bisabolol and Farnesol on Echinococcus granulosus Protoscoleces

Cystic echinococcosis (CE) remains an important challenge both in humans and animals. There is no safe and suitable remedy for CE, so the discovery of new compounds with promising scolicidal effects, particularly from herbal sources, is of great importance for therapeutic uses in the treatment and prevention of CE reappearance. Sesquiterpenes are C15 organic compounds made up of three isoprene units and mostly occurring as fragrant components of essential oils. They are of economic importance for the cosmetic and pharmaceutical industry, and recently attracted the attention of the scientific community for their remarkable parasiticidal properties. In the present study, we have focused on three known sesquiterpenes, isofuranodiene (IFD), α-bisabolol (BSB), and farnesol (FOH), as important phytoconstituents of the essential oils of wild celery (Smyrnium olusatrum), chamomile (Matricaria chamomilla), and acacia farnese (Vachellia farnesiana), respectively. Protoscoleces were recovered from fertile hydatid cysts and were exposed to different concentrations of the three tested compounds for different exposure times. The viability of protoscoleces was confirmed by 0.1% eosin staining. Results of scolicidal activity evaluations showed that IFD possessed the best effect against Echinococcus granulosus protoscoleces (LC₅₀ and LC₉₀ values of 8.87 and 25.48 µg/mL, respectively), followed by BSB (LC₅₀ of 103.2 µg/mL) and FOH (LC₅₀ of 113.68 µg/mL). The overall toxicity of IFD differed significantly from those of FOH and BSB, while there was no significant difference in toxicity between the latter compounds (p > 0.05). The present study showed that IFD seems to be a promising scolicidal agent and can be further tested to become a candidate for CE treatment.

Vepris macrophylla (Baker) I. Verd Essential Oil: An Antifungal Agent against Phytopathogenic Fungi

Rutaceae are widely used in ethnomedicine to treat infectious diseases in humans and plants. In this study, the antifungal activity of the Vepris macrophylla leaf essential oil (VEO) and its main components, citral and citronellol, was evaluated against six phytopathogenic fungi. In addition, the possible action of VEO on the synthesis of mycotoxins was evaluated as well. To determine the antifungal activity of VEO we used the agar dilution method and VEO showed inhibitory activity against all the tested fungi. In particular, VEO resulted to be fungicidal against Phytophthora cryptogea and Fusarium avenaceum. For all other fungi VEO exhibited fungistatic activity and the weakest effect was observed on Alternaria solani. Citral was very effective against P. cryptogea, F. avenaceum, F. poae and F. graminearum. On the other hand, citronellol showed good activity towards P. cryptogea and F. avenaceum and weaker activity towards F. poae and F. graminearum. It can be concluded that VEO can be considered a promising antifungal agent, especially against P. cryptogea and F. avenaceum, suggesting a possible use in the formulation of new selective and natural fungicides.

Virucidal activity of ginger essential oil against caprine alphaherpesvirus-1

The emergence of alphaherpesvirus strains resistant to commonly used antiviral drugs has prompted the research for alternative, biologically active anti-herpetic agents. Essential oils (EOs) have shown anti-infective properties against human herpes simplex viruses (HSV-1 and -2). Caprine alphaherpesvirus 1 (CpHV-1) induces genital lesions in its natural host and it is regarded as a useful homologous animal model for the study of HSV-2 infection, chiefly for the assessment of antiviral drugs in in vivo studies. In the present study we evaluated the activity in vitro of ginger EO (GEO) against CpHV-1. GEO was found to be effective as virucide on cell-free virus, inactivating CpHV-1 up to 100%. The virucidal activity of GEO is likely accounted for by disruption of herpesvirus envelope and its associated structures which are necessary for virus adsorption and entry into host cells. On the opposite, GEO was not able to inhibit virus adsorption and/or replication, as treatment of cells before and after infection did not abolish virus infectivity. GEO could be suggested for topical applications in in vivo experiments using CpHV-1/goat model, since the lipophilic nature of EOs favours their adsorption through the cutaneous/mucosal barrier, either alone or in conjunction with other molecules. These findings open several perspectives in terms of therapeutic possibilities for a number of human and animal alphaherpesviruses.