Occurrence of C8-C10 esters in Mediterranean Myrtus communis L. leaf essential oil

Expanding the Knowledge Related to Flavors and Fragrances by Means of Three-Dimensional Preparative Gas Chromatography and Molecular Spectroscopy

As universally known, gas chromatography (GC) coupled with mass spectrometry (MS) allows us to acquire spectra that can be searched in specific databases to attain qualitative information on a peak of interest. When not present in databases, structure elucidation is required before including a new component in a library: from that moment, scientists all around the world will be able to identify the new molecule with analytical confidence after GC-MS analysis. Conversely, if data are not shared in commercial databases, even if a molecule is studied and elucidated, it appears to be unknown or only identifiable on the basis of third-party data taken from the literature, which is a serious limitation. The present paper deals with a case that confirms this assumption. A component of Myrtus communis L. volatile fraction was tentatively identified based on literature data. Despite this, reliable identification could not be achieved due to the lack of a corresponding spectrum in commercial MS databases. Afterwards, the target component was isolated in a reasonable quantity and with a high degree of purity for downstream characterization by spectroscopic techniques. For this purpose, preparative (prep) GC may appear insufficient for the isolation of volatile components from highly complex samples. In this study, a prep-MDGC system was implemented for the isolation of the compound of interest from myrtle oil, consisting of three wide-bore columns of different selectivity coupled by means of Deans switch transfer devices. Based on the NMR and GC-FTIR data acquired, the unknown compound was identified as 2,2,5,5,7,7-hexamethyl-3,7-dihydro-1-benzofuran-4,6(2H,5H)-dione. Noticeably, this is a known molecule, yet its mass spectrum had never been registered into MS databases and thus was not available to the scientific community. Finally, the spectrum was included for the first time in a commercial library, namely the FFNSC 5.0 MS database. The aim of the present study was to highlight the opportunity to make analytical data quickly available in a reliable way by registering them in searchable MS databases to improve the identification means for researchers all over the world.

Botanic Garden as a Factory of Molecules: Myrtus communis L. subsp. communis as a Case Study

A novel perception of botanic gardens as complex “factories of molecules” (Lombardy Region Project–Lr. 25/2016, year 2021), that mediate plant–environment interactions, and are the basis of their utility for humans, is presented. The core-topic is the medicinal plant heritage of the Ghirardi Botanic Garden (Toscolano Maderno, Brescia, Italy) of the University of Milan. In this work, we studied Myrtus communis L. subsp. communis (Myrtaceae) at multiple scale levels: macro- and micromorphological, with special emphasis on the secretory structures responsible for the production of secondary metabolites; phytochemical, with the analysis of the essential oil (EO) composition from leaves (fresh, dried, stored at −20 °C and at −80 °C) and fruits over two consecutive years (2018 and 2019); bio-ecological, with a focus, based on literature data, on the ecology and biological activity of the main EO components. The occurrence of secretory cavities producing terpenes, along with flavonoids, was proven. A high level of chemical variability across the obtained EO profiles emerged, especially that concerning quantitative data. However, regardless of the different conservation procedures, the examined plant part, or the phenological stage, we detected the presence of three ubiquitous compounds: α-pinene, 1,8-cineole, and linalool. The overall results will serve to enrich the Ghirardi Botanic Garden with novel labeling showing accurate and updated scientific information in an Open science perspective.

Gastroprotective Effect of Microencapsulated Myrtus communis Essential Oil against Ethanol/HCl-Induced Acute Gastric Lesions

Myrtus communis L. essential oil (EO), mainly composed of myrtenyl acetate (30.6%), linalool (14.9%), α-pinene (11.10%) and 1,8-cineole or eucalyptol (9.9%), was microencapsulated with maltodextrin by emulsification and spray-drying, reaching a yield and efficiency of 43.7 and 48.7%, respectively. The microencapsulated myrtle EO (MMEO) was then evaluated regarding its gastroprotective activity in a model of ethanol/HCl-induced acute gastric ulcer in Wistar rats. Pretreatment with MMEO induced a remarkable inhibition of gastric lesions and acidity, correlated to high healing and protection percentages. Moreover, it exerted a potent anti-inflammatory effect on the gastric mucosa, counteracting EtOH-induced gastric lipoperoxidation and preventing the depletion of the antioxidant enzyme activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx). Taken together, the gastroprotective action of encapsulated MMEO may be multi-factorial, and ascribable, at least in parts, to its anti-inflammatory and antioxidant properties.

Chemical Variability of Moroccan Myrtle Oil

Thirty-three oil samples isolated from aerial parts of Myrtus communis L. harvested in seven localities, from Northern to Central Morocco, have been analyzed by combination of chromatographic and spectroscopic techniques. The 33 compositions have been subjected to statistical analysis, hierarchical cluster analysis (HCA) and principal component analysis (PCA). Two groups have been differentiated on the basis of their myrtenyl acetate and α-pinene contents and each one was sub-divided in two sub-groups according to the contents of 1,8-cineole and linalool. The compositions of our 33 myrtle oil samples may be named as follow by their main components: sub-group IA (13/33): α-pinene/1,8-cineole/linalool; sub-group IB (6/33): 1,8-cineole/α-pinene; sub-group IIA (10/33): 1,8-cineole/myrtenyl acetate; sub-group IIB (4/33): myrtenyl acetate.

Composition and Chemical Variability of Myrtus communis Leaf Oil From Northwestern Algeria

Myrtus communis L. is a shrub growing wild in most countries all around the Mediterranean Sea and myrtle leaf oil is useful in the perfumery and pharmaceutical industries. Nowadays, “chemotyped” essential oils are more and more appreciated. Myrtle oil from eastern and central-north Algeria belong to the “α-pinene-cineole” chemotype. In contrast, Moroccan myrtle oil displayed appreciable content of myrtenyl acetate. Therefore, it appeared crucial to investigate the composition of myrtle leaf oil from northwestern Algeria in order to ensure the homogeneity of the composition of Algerian myrtle leaf oil. The chemical composition of 42 oil samples of M. communis isolated from leaves collected in five locations from Tlemcen Province was investigated by gas chromatography (GC) in combination with retention indices, GC-mass spectroscopy, and 13C nuclear magnetic resonance spectroscopy. Yields ranged between 0.13% and 1.04% (w/w). The chemical composition of the oils was largely dominated by monoterpene hydrocarbons, with α-pinene (24.3-59.0%) and 1,8-cineole (13.2-49.5%) being the major compounds followed by limonene (3.2-19.8%). The 42 compositions were submitted to statistical analyses. The combination of hierarchical cluster analysis and principal component analysis allowed the distinction of two groups, the second group being subdivided into two subgroups. Groups and subgroups were differentiated with respect to their contents of α-pinene and 1,8-cineole and, to a lesser extent, of limonene. This study ensures that Algerian myrtle leaf oil belongs to the “α-pinene-cineole” chemotype which displays various biological activities. The observed homogeneity could be a positive point to join the international market of essential oils.

Myrtucomvalones A–C, three unusual triketone–sesquiterpene adducts from the leaves of Myrtus communis ‘Variegata’

The first examples of triketone–cubebane adducts (1 and 2) with an unusual skeleton were isolated from Myrtus communis ‘Variegata’.

Combinatorial microfluidic droplet engineering for biomimetic material synthesis

Although droplet-based systems are used in a wide range of technologies, opportunities for systematically customizing their interface chemistries remain relatively unexplored. This article describes a new microfluidic strategy for rapidly tailoring emulsion droplet compositions and properties. The approach uses a simple platform for screening arrays of droplet-based microfluidic devices and couples this with combinatorial selection of the droplet compositions. Through the application of genetic algorithms over multiple screening rounds, droplets with target properties can be rapidly generated. The potential of this method is demonstrated by creating droplets with enhanced stability, where this is achieved by selecting carrier fluid chemistries that promote titanium dioxide formation at the droplet interfaces. The interface is a mixture of amorphous and crystalline phases, and the resulting composite droplets are biocompatible, supporting in vitro protein expression in their interiors. This general strategy will find widespread application in advancing emulsion properties for use in chemistry, biology, materials, and medicine.

Antifungal and Herbicidal Effects of Fruit Essential Oils of Four Myrtus communis Genotypes

The chemical composition of the essential oils isolated by hydrodistillation from the fruits of four selected Myrtus communis L. genotypes from Turkey was characterized by GC-FID and GC/MS analyses. 1,8-Cineole (29.20-31.40%), linalool (15.67-19.13%), α-terpineol (8.40-18.43%), α-pinene (6.04-20.71%), and geranyl acetate (3.98-7.54%) were found to be the major constituents of the fruit essential oils of all M. communis genotypes investigated. The oils were characterized by high amounts of oxygenated monoterpenes, representing 73.02-83.83% of the total oil compositions. The results of the fungal growth inhibition assays showed that the oils inhibited the growth of 19 phytopathogenic fungi. However, their antifungal activity was generally lower than that of the commercial pesticide benomyl. The herbicidal effects of the oils on the seed germination and seedling growth of Amaranthus retroflexus L., Chenopodium album L., Cirsium arvense (L.) Scop., Lactuca serriola L., and Rumex crispus L. were also determined. The oils completely or partly inhibited the seed germinations and seedling growths of the plants. The findings of the present study suggest that the M. communis essential oils might have potential to be used as natural herbicides as well as fungicides.

Myrtus communis L. as source of a bioactive and safe essential oil

In Algeria, Myrtus communis L. is distributed throughout the Tell Atlas and the coastal regions of Algiers and Constantine. The leaves are used in respiratory disorders, diarrhea and hemorrhoids. The aims of this work were to evaluate the antifungal and anti-inflammatory potential of well characterized essential oils (EO). Since EO can be applied by inhalation, dermal application and oral administration, we used several mammalian cell lines to assess safe bioactive doses. The chemical composition of two samples was investigated by GC-FID, GC-MS and (13)C NMR spectroscopy. Monoterpene derivatives are the main compounds: α-pinene (50.8 and 33.6%), 1,8-cineole (21.9 and 13.3%), linalool (2.7 and 14.8%), and linalyl acetate (0.5 and 9.5%). The antifungal evaluation revealed that the oils were more active against Cryptococcus neoformans (yeast) and Epidermophyton floccosum, Microsporum canis, Trichophyton rubrum (dermatophytes). The anti-inflammatory potential was evaluated using an in vitro model of lipopolysaccharide (LPS)-stimulated macrophages. Assessment of cell viability was made through the MTT assay. Both oils were able to significantly inhibit NO production, without affecting cell viability, in concentrations up to 0.64 mg/mL. These promising results, disclose bioactive concentrations of Myrtle essential oils with a safety profile suggesting a potential oral and topical application or use by inhalation.

Review of pharmacological effects of Myrtus communis L. and its active constituents

Myrtle (Myrtus communis L., Myrtaceae) is a medicinal herb used worldwide in traditional medicine. A large number of components have been isolated from this herb. Polyphenols, myrtucommulone (MC), semimyrtucommulone (S-MC), 1,8-cineole, α-pinene, myrtenyl acetate, limonene, linalool and α-terpinolene are among the compounds considered to be the main biologically active components. Various parts of this herb such as its berries, leaves and fruits have been used extensively as a folk medicine for several centuries. The herb is used traditionally for the treatment of disorders such as diarrhea, peptic ulcer, hemorrhoid, inflammation, pulmonary and skin diseases, although clinical and experimental studies suggest that it possesses a broader spectrum of pharmacological and therapeutic effects such as antioxidative, anticancer, anti-diabetic, antiviral, antibacterial, antifungal, hepatoprotective and neuroprotective activity. The present review attempts to give an overview on the phytochemical, pharmacological, toxicological and clinical studies of total extracts and the most relevant active ingredients of M. communis.

New compounds, chemical composition, antifungal activity and cytotoxicity of the essential oil from Myrtus nivellei Batt. & Trab., an endemic species of Central Sahara

ETHNOPHARMACOLOGIC RELEVANCE

Myrtus nivellei Batt. & Trab. (Myrtaceae) known as Sahara myrtle is appreciated by the Touaregs as medicinal plant. Infusion of leaves is employed against diarrhea and blennorrhea. Crushed leaves added to oil or to butter ointment have been traditionally used for the treatment of dermatosis. Aim of the study is to consider the traditional medicinal uses and the lack of scientific studies on their biological activities, the present study was designed to elucidate the chemical composition, the antifungal activity of its essential oils against fungi responsible for human infections, as well as, its cytotoxicity in the mammalian keratinocytes.

MATERIALS AND METHODS

Chemical analysis of Myrtus nivellei essential oil isolated by hydrodistillation of aerial parts (leaves and flowers), was carried out using a combination of chromatographic (CC, GC with retention indices) and spectroscopic techniques (MS, (13)C NMR, 2D NMR). The antifungal activity was evaluated by using broth macrodilution methods for yeasts and filamentous fungi. Cytotoxicity was tested in HaCaT keratinocytes through the MTT assay.

RESULTS

Ten samples coming from two localities of harvest were investigated. The chemical composition was largely dominated by 1,8-cineole (33.6-50.4%) and limonene (17.5-25.0%). The structure of two new compounds bearing the isoamylcyclopentane skeleton has been elucidated. The oil was more active against Cryptococcus neoformans with MIC of 0.16μL/mL followed by dermatophytes, with MICs of 0.64 and 1.25μL/mL. Furthermore, evaluation of cell viability showed no cytotoxicity in HaCaT keratinocytes at concentrations up to 1.25µL/mL.

CONCLUSIONS

The composition of Myrtus nivellei oil differed from that of Myrtus communis. The structure of two di-nor-sesquiterpenoids has been elucidated. It was possible to find appropriate doses of Myrtus nivellei oil with both antifungal activity and very low detrimental effect on keratinocytes. These findings add significant information to the pharmacological activity of Myrtus nivellei essential oils, specifically to its antifungal properties, thus justifying and reinforcing the use of this plant in traditional medicine.