In vitro biological potential of the essential oil of some aromatic species used in Iranian traditional medicine

Chemical composition and antimicrobial activity of a newly identified chemotype of Achillea wilhelmsii K.Koch from Kashan, Iran

Achillea wilhelmsii K.Koch (Asteraceae) is traditionally used in Kashan (Iran) to control diabetes, headaches, kidney stones and heartburn. Due to its beneficial properties, the aerial parts of the plant were collected from the area of Maragheh (Kashan, Isfahan, Iran), in June 2022, during its full flowering, and the essential oil was obtained by hydrodistillation (Clevenger). The yield, composition and antimicrobial activity of the extractive solution were measured. Qualitative evaluation was performed by means of gas chromatography-mass spectroscopy method, and antimicrobial activity was determined against 12 strains of microorganisms by measuring inhibition halo, minimum inhibitory concentration, and minimum bactericidal concentration (MBC). The yield of essential oil was ~ 0.1071% (w/w) and it mainly contained oxygenated monoterpenes (47.87%), being for the first time fragranol (33.22%), fragranyl acetate (16.18%) and oleic acid (6.33%) the most abundant. The highest inhibitory halo was found against Candida albicans and Gram-positive Staphylococcus aureus (~ 10 mm). The essential oil was also effective against gram-negative bacteria such as Acinetobacter baumannii and Shigella dysenteriae, as the inhibition halo was ~ 9 mm and similar to that of rifampin, used as a reference. Therefore, it seems that this essential oil from and endemic species has a unique chemotype with potential antimicrobial activity, which may be a possible option for fragranol isolation and the production of natural antibiotics effective against various microorganisms.

Evaluation of Yield, Chemical Profile, and Antimicrobial Activity of Teucrium polium L. Essential Oil Used in Iranian Folk Medicine

Teucrium polium L. is used to treat many diseases like abdominal pains, indigestion, colds, and reproductive system diseases in Iranian folk medicine. This study was designed to investigate the yield, chemical profile of essential oil, and antibacterial and antifungal activity of this species. The flowering aerial parts of T. polium were collected from the Margh region of Kashan, Iran. The essential oil of the plant was extracted and separated using the Clevenger apparatus and analyzed using gas chromatography-mass spectrometry (GC-MS). The antimicrobial activity of the essential oil against a variety of standard microbial strains was investigated with the Agar well-diffusion method and determination of the lowest growth inhibitory and lethal concentration (MIC and MBC). The results showed that the yield of T. polium essential oil (TPEO) was 0.5778%. Based on the results of GC-MS, 76 compounds (99.3%) were identified in the TPEO, of which α-pinene (9.67%), β-caryophyllene (8.07%), β-pinene (5.04%), nerolidol (4.94%), and oleic acid (4.57%) were the dominant components. The results of antimicrobial tests showed that the TPEO on Staphylococcus aureus created the largest zone of inhibition (~ 14.29 mm). The dominant inhibitory activity of this essential oil was against Gram-negative bacteria Escherichia coli (~ 9.00 mm), which was almost similar to rifampin (~ 11 mm). It seems that the predominance of terpenoid and acidic compounds of the essential oil is one of the possible factors of the anti-bacterial activity of this essential oil. Therefore, the TPEO may be a promising and potential strategy to inhibit some bacterial strains.

Comparison of quantity, quality and antibacterial activity of essential oil Mentha longifolia (L.) L. under different traditional and modern extraction methods

Extraction is the first and most important step in obtaining the effective ingredients of medicinal plants. Mentha longifolia (L.) L. is of considerable economic importance as a natural raw material for the food and pharmaceutical industries. Since the effect of different extraction methods (traditional and modern methods) on the quantity, quality and antimicrobial activity of the essential oil of this plant has not been done simultaneously; the present study was designed for the first time with the aim of identifying the best extraction method in terms of these features. For this purpose, extracting the essential oil of M. longifolia with the methods of hydrodistillation with Clevenger device (HDC), steam distillation with Kaiser device (SDK), simultaneous distillation with a solvent (SDE), hydrodistillation with microwave device (HDM), pretreatment of ultrasonic waves and Clevenger (U+HDC) and supercritical fluid (SF) were performed. Chemical compounds were identified by gas chromatography coupled with mass spectrometer (GC-MS). Antimicrobial activity of essential oils against various clinical microbial strains was evaluated by agar diffusion method and determination of the minimum inhibitory concentration and minimum bactericidal concentration (MIC and MBC). The results showed that the highest and lowest yields of M. longifolia leaf essential oil belonged to HDC (1.6083%) and HDM (0.3416%). The highest number of compounds belonged to SDK essential oil and was equal to 72 compounds (with a relative percentage of 87.13%) and the lowest number of compounds was related to the SF essential oil sample (7 compounds with a relative percentage of 100%). Piperitenone (25.2-41.38%), piperitenone oxide (22.02-0%), pulegone (10.81-0%) and 1,8-cineole (5-35.0%) are the dominant and main components of M. longifolia essential oil were subjected to different extraction methods. Antimicrobial activity results showed that the lowest MIC value belonged to essential oils extracted by HDM, SDK, SDE and U+HDC methods with a value of 1000 μg/mL was observed against Gram-negative bacteria Shigella dysenteriae, which was 5 times weaker than rifampin and 7 times weaker than gentamicin. Therefore, it can be concluded that in terms of efficiency of the HDC method, in terms of the percentage of compounds of the HDM method, and in terms of microbial activity, the SDK, HDM and U+HDC methods performed better.

Is Camphor the Future in Supporting Therapy for Skin Infections?

The aim of this review is to present the potential application of camphor-a bicyclic monoterpene ketone-in the prevention of skin infections. Skin diseases represent a heterogeneous group of disorders characterized by prolonged symptoms that significantly diminish the quality of life. They affect the dermis, the epidermis, and even subcutaneous tissue. They very often have a bacterial or fungal background. Therapy for dermatological skin disorders is difficult and long-term. Therefore, it is important to find a compound, preferably of natural origin, that (i) prevents the initiation of this infection and (ii) supports the skin's repair process. Based on its documented anti-inflammatory, antibacterial, antifungal, anti-acne, anesthetic, strengthening, and warming properties, camphor can be used as a preventative measure in dermatological infectious diseases and as a component in medical and cosmetic products. This work discusses the structure and physicochemical properties of camphor, its occurrence, and methods of obtaining it from natural sources as well as through chemical synthesis. The use of camphor in industrial preparations is also presented. Additionally, after a detailed review of the literature, the metabolism of camphor, its interactions with other medicinal substances, and its antimicrobial properties against bacteria and fungi involved in skin diseases are discussed with regard to their resistance.

Comparative Cytotoxicity of Menthol and Eucalyptol: An In Vitro Study on Human Gingival Fibroblasts

The aim of this study was to assess the influence of eucalyptol and menthol on the cell viability, migration, and reactive oxygen species production of human gingival fibroblasts (GFs) in vitro. Three different concentrations of eucalyptol and menthol were prepared following ISO 10993-5 guidelines (1, 5, and 10 mM). GFs were isolated from extracted teeth from healthy donors. The following parameters were assessed: cell viability via MTT, Annexin-V-FITC and 7-AAD staining, and IC50 assays; cell migration via horizontal scratch wound assay; and cell oxidative stress via reactive oxygen species assay. Data were analyzed using one-way ANOVA and Tukey's post hoc test. Statistical significance was established at p < 0.05. Eucalyptol and Menthol exhibited high cytotoxicity on gingival fibroblasts, as evidenced by cytotoxicity assays. Eucalyptol showed lower levels of cytotoxicity than menthol, compared to the control group. The cytotoxicity of the tested substances increased in a concentration-dependent manner. The same occurred in a time-dependent manner, although even 10 min of exposure to the tested substances showed a high cytotoxicity to the GFs. Commercially available products for oral application with these substances in their composition should be tested for cytotoxicity before their use.

Chemical Profile and Biological Activities Of Piper mikanianum (Kunth) Steud Essential Oil for Development and Improvement of Oral Rinse

INTRODUCTION

Studies prove that the use of medicinal plants is a custom carried out by man since ancient times, the evolution of the pharmaceutical industry makes more people consume more natural products. Currently, we can observe that mouthwashes containing natural compounds have shown a growth in demand in the markets and in the professional community.

OBJECTIVE

The present study aims to carry out the chemical characterization and microbiological potential of Piper mikanianum (Kunth) Steud essential oil (EOPm), providing data that allows the development of a low-cost mouthwash formulation aimed at vulnerable communities.

METHODS

The evaluation of the antibacterial activity and modulator of bacterial resistance was performed by the microdilution method to determine the minimum inhibitory concentration (MIC). The chemical components were characterized by gas chromatography coupled to mass spectrometry, identified 28 constituents, in which Safrole Phenylpropanoid is the major compound, representing 72.6 % of the total composition, followed by α-pinene (10.7 %), Limonene (2 %), β-caryophyllene (2 %), E-nerolidol (1.9 %), spathulenol (1.3 %) and camphene (1.1 %).

RESULTS

The EOPm showed a MIC minimum inhibitory concentration≥1024 μg/mL for all bacterial strains used in the tests. When the EOPm modulating activity combined with chlorhexidine, mouthwash, ampicillin, gentamicin and penicillin G was evaluated against bacterial resistance, the oil showed significant synergistic activity, reducing the MIC of the products tested in combination, in percentage between 20.6 % to 98 .4 %.

CONCLUSIONS

We recommend the expansion of tests with greater variation of EOPm concentration combinations and the products used in this study, as well as toxicity evaluation and in vivo tests, seeking the development of a possible low-cost mouthwash formulation accessible to the most vulnerable population.

New Facts on the Antimicrobial Essential Oil of Satureja kitaibelii

The objective of the present study was to assess the difference in antimicrobial activity of Satureja kitaibelii Wierzb. ex Heuff. essential oil at three growth stages. In addition, using statistical and chemometric tools, we tried to explain why the essential oil from a certain vegetation stage shows the highest antimicrobial activity. S. kitaibelii essential oils demonstrated minimum inhibitory concentration values from 160 to 10000 μg mL-1 , and minimum microbicidal concentration values from 630 to 20000 μg mL-1 . Geraniol, borneol, limonene and p-cymene are the dominant compounds of S. kitaibelii essential oil. The most abundant compound, geraniol, possesses antimicrobial activity in a range of MIC values from 40 to 5000 μg mL-1 and MMC values from 80 to 10000 μg mL-1 . The highest activity of essential oil for all tested strains of microorganisms was recorded in November. Results of statistical analysis indicate that the percentage of dominant compounds of essential oils does not affect the antibacterial activity of essential oils. Chemometric analyses leads to the conclusion that borneol, spathulenol, caryophyllene oxide and limonene can be the main contributors to the antibacterial activity of essential oil from November and that their mutual ratio is important. These results may represent a new methodological approach for future research on essential oils.

Essential oils from Cuminum cyminum and Laurus nobilis and their principal constituents: evaluation of antifungal and antimycotoxigenic potential in Aspergillus species

The antifungal and antimycotoxigenic activities of the essential oils (EO) from Cuminum cyminum and Laurus nobilis, and their respective principal compounds, cuminaldehyde and 1,8-cineole, were evaluated against fungi of the genus Aspergillus: A. carbonarius, A. niger, A. ochraceus, and A. westerdijkiae. The antifungal activity was determined by the contact method and the mycelial growth of the fungi was evaluated. Scanning electron microscopic (SEM) images were obtained to suggest modes of action of the compounds analysed. The antimycotoxigenic activity was determined by high-performance liquid chromatograph. Aspergillus carbonarius was completely inhibited by cumin EO (500 µl l-1), by laurel EO and by cuminaldehyde (5000 µl l-1). The cumin EO (500 µl l-1) completely inhibited the growth of A. niger. All the samples inhibited the mycelial growth of A. ochraceus, especially cumin EO and cuminaldehyde (250 µl l-1). Aspergillus westerdijkiae was completely inhibited by cumin EO and cuminaldehyde (1000 µl l-1), by laurel EO and 1,8-cineole (10 000 µl l-1). A decrease in the production of ochratoxin A (OTA) was observed post-treatment, except in A. ochraceus, only inhibited by laurel EO. SEM images showed morphological changes in fungal structures and spore inhibition post-treatment. The results confirmed the antifungal and antimycotoxigenic effect of EO and their principal constituents on fungi evaluated.

Chemical Profiling and Antifungal Activity of Ziziphora clinopodioides Leaf Essential Oil against the Pathogen Verticillium dahliae

Essential oils (EOs) are often used as natural antifungal agents to control the growth of phytopathogenic fungi. The aim of this study was to determine the effect of Ziziphora clinopodioides leaf EO against Verticillium dahliae, a pathogenic fungus of cotton. Gas chromatography-mass spectrometry (GC/MS) analysis revealed the presence of 15 compounds of the total of extracted oil, which was consisted of 98.79 % monoterpenes and 0.61 % sesquiterpenes. The major constituents were pulegone (62.17 %), isomenthone (18.42 %), l-menthone (5.55 %) and piperitenone (3.99 %). The mycelial growth of Verticillium dahliae was completely inhibited at 0.24 μL/mL air under vapor phase condition. Considerable morphological variations were also observed in the fungal sclerotia at the contact phase at 3 μL/mL. This study demonstrated for the first time that Z. clinopodioides EO can effectively inhibit the growth of V. dahliae, implying that it has the potential to be explored as an antifungal agent against Verticillium Wilt of cotton.

Evaluation of the composition and antimicrobial activities of essential oils from four species of Lamiaceae Martinov native to Iran

In this study the essential oils obtained from four different plant species belonging to the Lamiaceae family were extracted by means of hydrodistillation and their composition and antimicrobial activity were evaluated. About 66 components were identified by using gas chromatography-mass spectrometry (GC-MS), and among all, thymol (67.7%), oleic acid (0.5-62.1%), (-)-caryophyllene oxide (0.4-24.8%), α-pinene (1.1-19.4%), 1,8-cineole (0.2-15.4%), palmitic acid (0.32-13.28%), ( +)spathulenol (11.16%), and germacrene D (0.3-10.3%) were the most abundant in all the species tested (i.e. Thymus daenensis, Nepeta sessilifolia, Hymenocrater incanus, and Stachys inflata). In particular, only the composition of essential oils from H. incanus was completely detected (99.13%), while that of the others was only partially detected. Oxygenated monoterpenes (75.57%) were the main compounds of essential oil from T. daenensis; sesquiterpenes hydrocarbons (26.88%) were the most abundant in S. inflata; oxygenated sesquiterpenes (41.22%) were mainly detected in H. incanus essential oil, while the essential oil from N. sessilifolia was mainly composed of non-terpene and fatty acids (77.18%). Due to their slightly different composition, also the antibacterial activity was affected by the essential oil tested. Indeed, the highest antibacterial and antifungal activities were obtained with the essential oil from T. daenensis by means of the inhibition halo (39 ± 1 and 25 ± 0 mm) against Gram-positive strains such as Staphylococcus aureus and Aspergillus brasiliensis. The minimal inhibitory concentration (MIC) and minimal bactericidal/fungicidal concentration (MBC/MFC) of the essential oils obtained from the four species varied from 16 to 2000 μg/mL and were strictly affected by the type of microorganism tested. As an example, the essential oils from H. incanus and S. inflata were the most effective against the Gram-negative bacterium Pseudomonas aeruginosa (MIC 16 and 63 μg/ml, respectively), which is considered one of the most resistant bacterial strain. Therefore, the essential oils obtained from the four species contained a suitable phytocomplexes with potential applications in different commercial area such as agriculture, food, pharmaceutical and cosmetic industries. Moreover, these essential oils can be considered a valuable natural alternative to some synthetic antibiotics, thanks to their ability to control the growth of different bacteria and fungi.

A GC-MC analysis of chemical compounds and identification of the antibacterial characteristics of the essential oil of two species exclusive to Iranian habitats: New chemotypes

BACKGROUND

The diversity found in the chemical compounds of a single species in different regions results in different biologic characteristics which can be considered as a strong source for identifying new chemotypes. Hymenocrater incanus Bunge and Dracocephalum kotschyi Boiss. are exclusive species of the Lamiaceae family which grow in the western and central habitats of Iran. This study was designed and carried out to determine the yield, identify the chemical compounds, and evaluate the antimicrobial characteristics of the essential oil (EO) of these two species in Iran for the first time.

METHODS

The flowering twigs of the species D. kotschyi and H. incanus were collected from the villages of Totmach and Kamu in Isfahan province respectively, in May 2019. The EO of these plants was extracted and separated using the water distillation method, utilizing the Clevenger device. The EO compounds were analyzed using a gas chromatograph coupled with a mass spectrometer (GC-MS). The evaluation of antimicrobial characteristics was carried out by determining the growth inhibition zone implementing the Agar method, the minimum inhibition concentration (MIC), and the minimum bactericidal/fungicidal concentration (MFC/MBC) utilizing liquid dilution culture.

RESULTS

The results indicated that the highest yield belonged to the EO of D. kotschyi at %2.6 (w/w). In this EO there were citral (%25.44), neral (%20.87), α-pinene (%14.48), trans-geranic acid methyl ester (%9.74), and D-limonene (%6.87). Moreover, H. incanus had the dominant compounds (-)-Spathulenol (%12.61), caryophyllene (%10.00), linolenic acid (%8.54), 1,8-cineole (%5.95), palmitic acid (%5.35), and α-cadinol (%5.17). The largest diameter of growth inhibition zone belonged to the H. incanus EO against the Gram-positive bacteria S. pyogenes (~17.67mm). The strongest inhibition activities in the form of growth inhibition diameter exhibited by the D. kotschyi EO were against the Gram-negative bacteria S. paratyphi-A serotype (~ 12 mm), K. pneumoniae, and Sh. dysenteriae (~ 11 mm) which was significant compared to the Gram-positive rifampin (~ 8 mm).

CONCLUSIONS

It can be seen that these species are new chemotypes with special and novel chemical compounds which can potentially be used to manufacture natural antibiotics against some bacterial strains.