Melissa officinalisessential oil loaded polycaprolactone membranes: evaluation of antimicrobial activities and cytocompatibility for tissue engineering applications

Antimicrobial biomaterials play important role in tissue engineering applications to protect damaged tissue from infections. The aim of this study is producing antimicrobial polycaprolactone (PCL) membranes by using a plant based antimicrobial agent. Therefore,Melissa officinalisessential oil (MEO) was investigated against ten types of microorganisms and remarkable antimicrobial activity was demonstrated. PCL:MEO membranes were prepared by solvent casting method by mixing MEO into PCL in various ratios (PCL:0M, PCL:0.25M, PCL:0.5M, and PCL:1M w/w). Water contact angle measurements showed that hydrophilicity of the membranes increased with increasing concentrations of MEO from 103.44° to 83.36° for PCL:0M and PCL:1M, respectively. It was determined that there was an inverse relationship between the MEO concentration and the mechanical properties. Notable antioxidant activity of PCL/MEO membranes was exhibited by the inhibition percent of 2,2-diphenyl-1-picrylhydrazyl (DPPH) which was increased from 24.74% to 44.79% for PCL:0M and PCL:1M, respectively. The antimicrobial activity of MEO was also highly maintained in PCL membranes. For PCL/MEO membranes, at least 99.9% of microorganisms were inhibited. Cytocompatibility of the membranes were investigated by resazurin assay, scanning electron microscopy analysis and 4',6-diamidino-2-phenylindole (DAPI) staining. PCL:0.25M and PCL:0.5M membranes supported the viability of L929 cells more than 87% when compared to PCL:0M membranes on day 6. However, the viability of L929 cells on PCL:1M membranes was about 43% indicating significant decrease on cellular activity. In conclusion, PCL:0.25M and PCL:0.5M membranes with their high antimicrobial activity, acceptable mechanical properties and cytocompatible properties, they can be considered as an alternative biomaterial for tissue engineering applications.

Volatile metabolites from new cultivars of catnip and oregano as potential antibacterial and insect repellent agents

Plant based natural products have been widely used as antibacterial and insect repellent agents globally. Because of growing resistance in bacterial plant pathogens and urban pests to current methods of control, combined with the long- and short-term negative impact of certain chemical controls in humans, non-target organisms, and the environment, finding alternative methods is necessary to prevent and/or mitigate losses caused by these pathogens and pests. The antibacterial and insect repellent activities of essential oils of novel cultivars of catnip (Nepeta cataria L. cv. CR9) and oregano (Origanum vulgare L. cv. Pierre) rich in the terpenes nepetalactone and carvacrol, respectively, were evaluated using the agar well diffusion assay and petri dish repellency assay. The essential oils exhibit moderate to high antibacterial activity against three plant pathogens, Pseudomonas cichorii, Pseudomonas syringae and Xanthomonas perforans of economic interest and the individual essential oils, their mixtures and carvacrol possess strong insect repellent activity against the common bed bug (Cimex lectularius L.), an urban pest of major significance to public health. In this study, the essential oils of catnip and oregano were determined to be promising candidates for further evaluation and development as antibacterial agents and plant-based insect repellents with applications in agriculture and urban pest management.

Chemical composition, anticancer and antibacterial activity of Nepeta mahanensis essential oil

Background

Conventional cancer treatments, such as chemotherapy, radiation therapy, and surgery, often affect the patients’ quality of life due to their serious side effects, indicating the urgent need to develop less toxic and more effective alternative treatments. Medicinal plants and their derivatives are invaluable sources for such remedies. The present study aimed to determine the chemical composition, anticancer and antibacterial activities of Nepeta mahanesis essential oil (EO).

Methods

The chemical composition of EO was analyzed by gas chromatography-mass spectrometry (GC-MS). Cytotoxicity and apoptosis/necrosis induction of EO was analyzed by MTT assay and Flow cytometry. Real-time PCR was performed to evaluate the Bax/Bcl2 gene expression. Also, the effect of the EO on the cells’ mitochondrial membrane potential (MMP) and ROS level was assessed. DPPH assay was done to assess the free radical scavenging activity of the EO. The Antimicrobial activity, MIC, and MBC of the oil were determined via well-diffusion and broth microdilution methods.

Results

Based on the GC-MS analysis, 24 compounds were identified in the EO, of which 1,8-cineole (28.5%), Nepetalactone (18.8%), germacrene D (8.1%), and β-pinene (7.2%), were the major compounds. Also, the EO showed considerable cytotoxicity against MCF-7, Caco-2, SH-SY5Y, and HepG2 after 24 and 48 h treatment with IC₅₀ values between 0.0.47 to 0.81 mg/mL. It was revealed that this compound increased the Bax/Bcl2 ratio in the MCF-7 cells and induced apoptosis (27%) and necrosis (18%) in the cells. Moreover, the EO treatment led to a substantial decrease in MMP, which is indicative of apoptosis induction. A significant increase in ROS level was also detected in the cells following exposure to the EO. This compound showed strong DPPH radical scavenging activity (IC₅₀: 30). It was also effective against Gram-positive E. faecalis (ATCC 29,212) and Gram-negative E. coli (ATCC 11,333) bacteria.

Conclusions

The results of this study demonstrated that the EO of N. mahanesis could be considered a bioactive product with biomedical applications that can be used as an alternative cancer treatment and applied in the biomedical industries.

Phytochemical profiling of antimicrobial and potential antioxidant plant: Nepeta cataria

Traditional and phytochemical studies have confirmed the richness and diversity of medicinal plants such as Nepeta cataria (N. cataria), but more studies are needed to complete its metabolite profiling. The objective of this research was to enhance the metabolomic picture and bioactivity of N. cataria for better evaluation. Phytochemical analysis was performed by bio-guided protocols and gas chromatography-mass spectrometry (GC/MS). For this, solvents such as methanol, ethanol, water, acetone, and hexane were used to extract a wide number of chemicals. Antibacterial analysis was performed using the 96-well plate test, Kirby Bauer's disk diffusion method, and the resazurin microdilution test. Antioxidant activity was determined by the DPPH assay and radical scavenging capacity was evaluated by the oxygen radical absorbance capacity (ORAC) assay. GC/MS analysis revealed a total of 247 identified and 127 novel metabolites from all extracts of N. cataria. Water and acetone extracts had the highest identified metabolites (n = 79), whereas methanol extract was the highest in unidentified metabolites (n = 48). The most abundant phytochemicals in methanol extract were 1-isopropylcyclohex-1-ene (concentration = 27.376) and bicyclo [2.2.1] heptan-2-one (concentration = 20.437), whereas in ethanol extract, it was 9,12,15-octadecatrienoic acid (concentration = 27.308) and 1-isopropylcyclohex-1-ene (concentration = 25.854). An abundance of 2 methyl indoles, conhydrin, and coumarin was found in water extracts; a good concentration of eucalyptol was found in acetone extract; and 7,9-di-tert-butyl-1-oxaspiro is the most abundant phytochemicals in hexane extracts. The highest concentration of flavonoids and phenols were identified in hexane and methanol extracts, respectively. The highest antioxidant potential (DPPH assay) was observed in acetone extract. The ethanolic extract exhibited a two-fold higher ORAC than the methanol extract. This examination demonstrated the inhibitory effect against a set of microbes and the presence of polar and non-polar constituents of N. cataria. The results of this study provide a safe resource for the development of food, agriculture, pharmaceutical, and other industrial products upon further research validation.

Chemical Composition, Antioxidant, and Antimicrobial Activity of Dracocephalum moldavica L. Essential Oil and Hydrolate

Steam distillation was used for the isolation of Dracocephalum moldavica L. (Moldavian dragonhead) essential oil (DMEO). This aromatic herbaceous plant is widespread across the Northern Hemisphere regions and has been utilized in health-improving studies and applications. In addition to the DMEO, the hydrolate (DMH), a byproduct of the distillation process, was also collected. The DMEO and DMH were analyzed and compared in terms of their chemical composition, as well as their in vitro biological activities. The main component in DMEO was geranyl acetate, while geranial was dominant in DMH. The DMEO demonstrated better antioxidant and antimicrobial activities compared with the DMH against Staphylococcus aureus, Escherichia coli, Salmonella Typhimurium, and Listeria monocytogenes, which represent sources of food-borne illness at the global level. The DMEO and DMH show promise as antioxidant and antimicrobial additives to various products.

Quantitative Analysis of Phenolic Acids and Antiplatelet Activity of Melissa officinalis Leaf Extracts

The contents of total phenolic acids and rosmarinic acid were determined and the antiplatelet potential assessed of extracts of lemon balm ( Melissa officinalis L., Lamiaceae) leaf samples collected during 2014 and 2015. The quantity of total phenolic acids ranged from 4.8 to 8.5%, while the rosmarinic acid content ranged from 1.78 to 4.35%. Results of statistical analysis showed that the undiluted extracts have antiplatelet activity in the ADP test (final concentration 31.25 mg/L). While there are reports on antiplatelet activity of lemon balm essential oil, to the best of our knowledge, this is the first report on antiplatelet activity of lemon balm leaf extracts.

Volatile Constituents of Melissa officinalis Leaves Determined by Plant Age

The present study investigated changes in the content and chemical composition of the essential oil extracted by hydrodistillation from air-dried Melissa officinalis L. (lemon balm) leaves in the first and second year of plant growth. The lemon balm oil was analysed by GC-MS and GC-FID. The presence of 106 compounds, representing 100% of the oil constituents, was determined in the oil. The predominant components were geranial (45.2% and 45.1%) and neral (32.8% and 33.8%); their proportions in the examined samples of the oil obtained from one- and two-year-old plants were comparable. However, the age of lemon balm plants affected the concentration of other constituents and the proportions of the following compounds were subject to especially high fluctuations: citronellal (8.7% and 0.4%), geraniol (trace amounts and 0.6%), and geranyl acetate (0.5% and 3.0%), as well as, among others, isogeranial, E-caryophyllene, caryophyllene oxide, germacrene D, and carvacrol. The essential oil of two-year-old plants was characterized by a richer chemical composition than the oil from younger plants.

Total Phenolic Content and Antioxidative Properties of Commercial Tinctures Obtained from Some Lamiaceae Plants

The antioxidant level of commercial tinctures from three Lamiaceae plants, Salvia officinalis, Mentha piperita, and Melissa officinalis, have been determined by the Folin-Ciocalteu method, the 2.2-diphenyl-2-picrylhydracyl hydrate (DPPH) radical scavenging technique and ABTS assay. Total phenolic content was expressed as GAE (gallic acid equivalent) and ranged from 0.24 to 3.99 mg/mL. Antioxidant activity in the ABTS assay, calculated as TEAC (Trolox equivalent antioxidant capacity), ranged from 23.5 to 35.6 μmol Trolox/mL, while in the DPPH method, the EC50 value ranged from 0.04 to 0.07 mL/assay. Radical scavenging activity was correlated with total phenolic content. Correlations between ABTS and F-C methods, DPPH and F-C methods and ABTS and DPPH methods were calculated. The obtained results can be useful as additional information about the antioxidant activity of galenical preparations.

Microwave-Assisted Isolation of Essential Oils from Nepeta Crispa and N. Racemosa and Comparisons with the Conventional Method

In this study microwave-assisted hydrodistillation (MAHD) has been compared with the conventional method of hydrodistillation for the extraction of the essential oils from two Iranian Lamiaceae species: Nepeta crispa Willd and N. racemosa Lam. The essential oils extracted by MAHD for 40 min were quantitatively and qualitatively (aromatic profile) similar to those obtained by conventional hydrodistillation for 3.5 h. The MAHD method yields an essential oil with higher amounts of more valuable oxygenated compounds, and allows substantial savings of costs in terms of time, energy and plant material.

A Novel Isopimarane Diterpenoid with Acetylcholinesterase Inhibitory Activity from Nepeta sorgerae, an Endemic Species to the Nemrut Mountain

From the dichloromethane extract of Nepeta sorgerae, the isolation and structure elucidation are now reported of a new isopimarane diterpenoid, named sorgerolone, and two known triterpenoids, oleanolic acid and ursolic acid. Antioxidant activity of the extracts and the isolated terpenoids was determined by the DPPH free radical scavenging and lipid peroxidation inhibition (β-carotene bleaching) methods. Anticholinesterase activity of the extracts and isolates was investigated by Ellman's method against AChE and BChE enzymes. Although the antioxidant activity results were low, the AChE enzyme inhibition of the extracts and terpenoids was very promising.

Nepetalactone Content and Antibacterial Activity of the Essential Oils from Different Parts of Nepeta persica

The essential oils from the flower, leaf, stem and root of Nepeta persica Boiss., analyzed by GC and GC/MS, were shown to contain 4aβ,7α,7aβ-nepetalactone (58.5%, 62.3%, 66.2% and 27.1%, respectively), and 4aα,7α,7aβ-nepetalactone (33.0%, 28.3%, 24.9% and 7.6%, respectively). The other main component of the flower and stem oils was α-pinene (3.6% and 4.4%) and of the leaf oil β-ocimene (3.6%). In the root oil, other main constituents were α-pinene (40.4%), α-amorphene (5.3%), γ-cadinene (2.9%), and cis-calamenene (2.5%). Nepetalactone was the major component of the flower, leaf and stem oils, which are thus important sources of nepetalactone. Antibacterial activities of the flower, leaf, stem and root oils were evaluated using the microdilution broth method. Inhibitory effects on Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella typhi and Enterococcus faecalis were recorded. The flower, leaf, stem, and root oils had difference activities against the test microorganisms. The antibacterial property of the essential oils might be ascribed to their high content of nepetalactone isomers.

Antibacterial Activity and Composition of the Essential Oil of Nepeta Menthoides from Iran

The antibacterial activity and chemical composition of the essential oil obtained from the aerial flowering parts of Nepeta menthoides were analyzed by GC and GC-MS. Twenty-nine compounds representing 97.6% of the total oil were identified. Oxygenated monoterpenes (71.9%) were the principal fraction of the oil with 1,8-cineole (33.8%) and 4aα-7α-7aα-nepetalactone (23.2%) as the main constituents. The antibacterial activity of the oil and its two main constituents were tested against seven bacteria. High activity of the oil and its two main constituents was demonstrated against all the tested bacteria with MIC values in the range of 1.8 - 7.2, 0.9 - 7.2 and 1.8 - 15 mg/mL, respectively.

Essential Oil Composition of Two Subspecies of Nepeta Glomerulosa Boiss. from Iran

Essential oil compositions of Nepeta glomerulosa Boiss. subsp. glomerulosa and N. glomerulosa subsp. stapfiana (Bornm. ex Rech. f.) Rech. f., each gathered from two different locations, have been investigated by GC and GC/MS. 1,8-Cineole was the major compound in the oils of both collections of subspecies glomerulosa (27.4%, 30.6%), and was also a major constituent of subspecies stapfiana (14.9%, 17.8%). However, caryophyllene oxide was the predominant compound for both oils of subspecies stapfiana (32.0%, 24.1%). From the chemotaxonomic point of view, the two members of each subspecies comprised a separate group with a considerable distance from the other two, and the morphological differences of these two subspecies were well reflected in their essential oil compositions.