Mijat Božović

Essential Oil Extraction, Chemical Analysis and Anti-Candida Activity of Calamintha nepeta (L.) Savi subsp. glandulosa (Req.) Ball-New Approaches.

A comprehensive study on essential oils extracted from different Calamintha nepeta (L.) Savi subsp. glandulosa (Req.) Ball samples from Tarquinia (Italy) is reported. In this study, the 24-h steam distillation procedure for essential oil preparation, in terms of different harvesting and extraction times, was applied. The Gas chromatography–mass spectrometry (GC/MS) analysis showed that C. nepeta (L.) Savi subsp. glandulosa (Req.) Ball essential oils from Tarquinia belong to the pulegone-rich chemotype. The analysis of 44 samples revealed that along with pulegone, some other chemicals may participate in exerting the related antifungal activity. The results indicated that for higher activity, the essential oils should be produced with at least a 6-h steam distillation process. Even though it is not so dependent on the period of harvesting, it could be recommended not to harvest the plant in the fruiting stage, since no significant antifungal effect was shown. The maximum essential oil yield was obtained in August, with the highest pulegone percentage. To obtain the oil with a higher content of menthone, September and October should be considered as the optimal periods. Regarding the extraction duration, vegetative stage material gives the oil in the first 3 h, while material from the reproductive phase should be extracted at least at 6 or even 12 h.

Mentha suaveolens Ehrh. (Lamiaceae) Essential Oil and Its Main Constituent Piperitenone Oxide: Biological Activities and Chemistry †

Since herbal medicines play an important role in the treatment of a wide range of diseases, there is a growing need for their quality control and standardization. Mentha suaveolens Ehrh. (MS) is an aromatic herb with fruit and a spearmint flavor, used in the Mediterranean areas as a traditional medicine. It has an extensive range of biological activities, including cytotoxic, antimicrobial, antioxidant, anti-inflammatory, hypotensive and insecticidal properties, among others. This study aims to review the scientific findings and research reported to date on MS that prove many of the remarkable various biological actions, effects and some uses of this species as a source of bioactive natural compounds. On the other hand, piperitenone oxide (PO), the major chemical constituent of the carvone pathway MS essential oil, has been reported to exhibit numerous bioactivities in cells and animals. Thus, this integrated overview also surveys and interprets the present knowledge of chemistry and analysis of this oxygenated monoterpene, as well as its beneficial bioactivities. Areas for future research are suggested.

Multidisciplinary Approach to Determine the Optimal Time and Period for Extracting the Essential Oil from Mentha suaveolens Ehrh

A comprehensive study on essential oils (EOs) extracted from some Mentha suaveolens L. samples, collected in the countryside of Tarquinia, is reported. In this study, the procedure for essential oil preparation, in terms of harvesting and extraction time, was analyzed in detail for the first time. The GC/MS analysis, carried out on 18 samples, revealed that piperitenone oxide (PO), the main essential oils’ chemical constituent, is primarily responsible for the related antifungal activity. Nevertheless, EOs with lower PO content indicate that other chemicals, such as para-cymenene, may participate in exerting the EOs’ antifungal effect. Furthermore, the bacterial reverse mutation assay highlighted lack of mutagenic effect in all tested samples. Analysis of the results indicated that for higher activity, the essential oils should be produced with 3 h maximum hydrodistillation, regardless of the harvesting time. Differently, the maximum essential oil yield can be obtained in August and the highest piperitenone oxide percentage is obtainable in July.

Essential oil extraction, chemical analysis and anti-Candida activity of Foeniculum vulgare Miller – new approaches

Abstract A comprehensive study on essential oil samples of Foeniculum vulgare Miller from Tarquinia (Italy) is reported. A 24-h systematic steam distillation was performed on different harvested samples applying different extraction times. The GC-MS analysis of the residue outcome showed o-cymene, α-phellandrene, α-pinene and estragole as the major constituents. The predominance and continued presence of o-cymene makes this fennel oil a rather unique chemotype. An evident correlation between the antifungal activity and phenological stage is demonstrated. The most active fractions were particularly rich in estragole, as well as a significant amount of fenchone that possibly exerts some additive effect in the expression of overall antifungal potency. Pre-fruiting material produced oil particularly rich in o-cymene. With reference to the duration of the extraction, the maximum amount of oil was released within the first 3 h, whereas the reproductive phase material needed at least 6 h for the extraction.

Calamintha nepeta (L.) Savi and its Main Essential Oil Constituent Pulegone: Biological Activities and Chemistry

Medicinal plants play an important role in the treatment of a wide range of diseases, even if their chemical constituents are not always completely recognized. Observations on their use and efficacy significantly contribute to the disclosure of their therapeutic properties. Calamintha nepeta (L.) Savi is an aromatic herb with a mint-oregano flavor, used in the Mediterranean areas as a traditional medicine. It has an extensive range of biological activities, including antimicrobial, antioxidant and anti-inflammatory, as well as anti-ulcer and insecticidal properties. This study aims to review the scientific findings and research reported to date on Calamintha nepeta (L.) Savi that prove many of the remarkable various biological actions, effects and some uses of this species as a source of bioactive natural compounds. On the other hand, pulegone, the major chemical constituent of Calamintha nepeta (L.) Savi essential oil, has been reported to exhibit numerous bioactivities in cells and animals. Thus, this integrated overview also surveys and interprets the present knowledge of chemistry and analysis of this oxygenated monoterpene, as well as its beneficial bioactivities. Areas for future research are suggested.

Esential oils extraction: a 24-hour steam distillation systematic methodology

Abstract Steam distillation is known to be the most prevalent method of essential oil extraction. Despite many studies on extraction methods, there is no report about the impact of distillation process duration on the yield and oil quality. A new 24-h steam distillation process for extraction of plant essential oils is presented. For improving the total yield, prolonged and continued isolation was used. A selection of plant species from Lamiaceae and Apiaceae families was subjected to direct steam distillation and essential oils were collected at different times (1, 2, 3, 6, 12 and 24 h). The analysis included either annual or perennial species monitored in terms of different harvesting time. From these studies, it is conclusively that there is no rule about appropriate extraction time, and different plants need different periods for the essential oils to achieve the desired quality or quantity of extract. Thus, extraction duration is directly dependent on what the study is conducted for.

Chemical and Antimicrobial Analyses of Sideritis romana L. subsp. purpurea (Tal. ex Benth.) Heywood, an Endemic of the Western Balkan

A comprehensive study on essential oil and different solvent extracts of Sideritis romana L. subsp. purpurea (Tal. ex Benth.) Heywood (Lamiaceae) from Montenegro is reported. The gas chromatography-mass spectrometry analysis of the essential oil revealed a total of 43 components with bicyclogermacrene (23.8%), germacrene D (8%), (E)-caryophyllene (7.9%) and spathulenol (5.5%) as the major ones. Sesquiterpenoid group was found to be the most dominant one (64.8%), with 19.9% of the oxygenated forms. In the crude methanol extract of the investigated plant, obtained by Sohhlet exraction, the total phenol content was 14.7 ± 0.4 mg of GA/g, the total flavonoids were 0.29 ± 0.03% expressed as hyperoside percentage, whereas the total tannins content was 0.22 ± 0.04% expressed as pyrogallol percentage. For the antimicrobial activity determination, the following microorganisms have been used: methicillin-susceptible Staphylococcus aureus (MSSA (American Type Culture Collection (ATCC) 29213)) and methicillin-resistant S. aureus (MRSA (clinical strain)), Escherichia coli (ATCC 25922), carbapenem-susceptible Klebsiella pneumoniae (clinical strain), carbapenem-resistant K. pneumoniae (clinical strain) and Candida albicans (ATCC 14053). The essential oil showed high potency against MSSA and MRSA, both at high (~5 × 105 CFU/mL) and low (~5 × 103 CFU/mL) inoculum. With respect to MSSA, the minimal inhibitory concentration (MIC) value was 0.307 mg/mL, with bactericidal activity obtained at 0.615 mg/mL, while, in the case of MRSA, the MIC and minimal bactericidal concentration (MBC) values were 0.076 and 0.153 mg/mL, respectively. Regarding anti-Candida albicans activity, the MIC value was 2.46 mg/mL without reaching fungicidal activity. In addition to the observed essential oil efficacy, different solvent extracts were analyzed for their antimicrobial activity. Similarly to the essential oil, thehighest efficacy was observed against both MSSA and MRSA strains, at high and low inoculums, in the case of the 1,2-dichloroethane and methanol extracts. A potent fungicidal activity has been also found for the n-hexane and 1,2-dichloroethane extracts. It can be concluded that Sideritis romana L. subsp. purpurea (Tal. ex Benth.) Heywood provides a wide range of application in different fields such as phytochemistry, pharmacology, toxicology or pharmacognosy.

Sideritis romana L. subsp. purpurea (Tal. ex Benth.) Heywood, a new chemotype from Montenegro

Abstract A study on essential oil fractions of the Western Balkan endemic Sideritis romana L. subsp. purpurea (Tal. ex Benth.) Heywood collected in Montenegro is reported. The 24-h systematic steam distillation extraction procedure was performed. The gas chromatographic/mass spectrometric (GC/MS) analysis of the fractions showed γ-elemene and spathulenol as two main constituents, revealing a new chemotype of this plant species. Although varying in the content of these two main compounds, which makes the fractions quite different between each other, evaluation of the anti-Candida activity showed the lack of any significant efficacy.

Antimicrobial and Antibiofilm Activity and Machine Learning Classification Analysis of Essential Oils from Different Mediterranean Plants against Pseudomonas aeruginosa

Pseudomonas aeruginosa is a ubiquitous organism and opportunistic pathogen that can cause persistent infections due to its peculiar antibiotic resistance mechanisms and to its ability to adhere and form biofilm. The interest in the development of new approaches for the prevention and treatment of biofilm formation has recently increased. The aim of this study was to seek new non-biocidal agents able to inhibit biofilm formation, in order to counteract virulence rather than bacterial growth and avoid the selection of escape mutants. Herein, different essential oils extracted from Mediterranean plants were analyzed for their activity against P. aeruginosa. Results show that they were able to destabilize biofilm at very low concentration without impairing bacterial viability. Since the action is not related to a bacteriostatic/bactericidal activity on P. aeruginosa, the biofilm change of growth in presence of the essential oils was possibly due to a modulation of the phenotype. To this aim, application of machine learning algorithms led to the development of quantitative activity–composition relationships classification models that allowed to direct point out those essential oil chemical components more involved in the inhibition of biofilm production. The action of selected essential oils on sessile phenotype make them particularly interesting for possible applications such as prevention of bacterial contamination in the community and in healthcare environments in order to prevent human infections. We assayed 89 samples of different essential oils as P. aeruginosa anti-biofilm. Many samples inhibited P. aeruginosa biofilm at concentrations as low as 48.8 µg/mL. Classification of the models was developed through machine learning algorithms.

High Potency of Melaleuca alternifolia Essential Oil against Multi-Drug Resistant Gram-Negative Bacteria and Methicillin-Resistant Staphylococcus aureus

Purpose: Herein, an extended investigation of Tea tree oil (TTO) against a number of multi-drug resistant (MDR) microorganisms in liquid and vapor phases is reported. Methods: The activity of TTO was tested against methicillin-sensitive Staphylococcus aureus (MSSA), Escherichia coli, and clinical strains of methicillin-resistant S. aureus (MRSA), extended-spectrum beta lactamases producer carbapenem-sensitive Klebsiella pneumoniae (ESBL-CS-Kp), carbapenem-resistant K. pneumoniae (CR-Kp), Acinetobacter baumannii (CR-Ab), and Pseudomonas aeruginosa (CR-Pa). Minimal inhibitory/bactericidal concentrations (MIC/MBCs) and synergistic activity between TTO and different antimicrobials were determined. In the vapor assay (VP), TTO-impregnated discs were placed on the lid of a petri dish and incubated for 24 h at 37 °C. Results: TTO showed a potent bactericidal activity against all the tested microorganisms. TTO in combination with each reference antimicrobial showed a high level of synergism at sub-inhibitory concentrations, particularly with oxacillin (OXA) against MRSA. The VP assay showed high activity of TTO against CR-Ab. Conclusion: Evaluation of in-vitro activity clearly indicated TTO as a potential effective antimicrobial treatment either alone or in association with known drugs against MDR. Therefore, TTO could represent the basis for a possible role in non-conventional regimens against S. aureus and Gram-negative MDR. TTO in VP might represent a promising option for local therapy of pneumonia caused by CR-Ab.