Chemometric investigation of light-shade effects on essential oil yield and morphology of Moroccan Myrtus communis L

Soil differentiation and soil comprehensive evaluation of in wild and cultivated Fritillaria pallidiflora Schrenk

Few studies have focused on the growth, soil quality and sustainability of medicinal plants under different soil conditions. In this study, the spatial heterogeneity of soil physical and chemical properties, the diversity of rhizosphere soil microbial community structure, and the characteristics of growth of the wild and cultivated medicinal plant, Siberian fritillary (Fritillaria pallidiflora Schrek) were analyzed, and the soil quality and ecosystem sustainability were comprehensively evaluated. The results showed that there was significant spatial variability of soil nutrients in the different habitats. Nitrate nitrogen (NO₃-N) was strongly variable, while those of the soil organic carbon (SOC) and available phosphorus (AP) were moderately variable. There was little variability among the soil available potassium (AK), electrical conductivity (EC), pH and ammonium nitrogen (NH₄-N). Inverse Distance Weighting spatial interpolation showed that SOC, NO₃-N, NH₄-H and EC were highly distributed in the southeastern part of the wild area, and the soil was more acidic in the original habitat than in the planting habitat. There was little AK and AP in the native habitat, and there was a high content in the planting habitat. Simultaneously, the soil microbial communities of the two soils also differed. The wild-type soil showed a "fungal" type, while the planted soil showed a "bacterial" type. Pathogenic bacteria were among the primary microflora in the planting area. In general, it is difficult to maintain the sustainable development and geo-herbalism of F. pallidiflora in today's cultivation mode because of the significant differences in soil nature, spatial heterogeneity and microbial community structure for the growth of F. pallidiflora. Therefore, future planting should focus on transforming it from intensive to mountain forest planting. This is highly significant for improving the planting efficiency of F. pallidiflora, protecting their geo-herbalism and germplasm resources, and maintaining the stability and sustainable development of the ecosystem.

Chemical composition, antibiofilm, cytotoxic, and anti-acetylcholinesterase activities of Myrtus communis L. leaves essential oil

BACKGROUND

The potential of essential oils (EOs) and of their principal constituents for eradication of biofilm and at the same time the research of new potential acetylcholinesterase inhibitors is gaining increasing interest in last years. The aims of this study were to determine the chemical composition and to evaluate the antibacterial, cytotoxic, and anti-acetylcholinesterase properties of Myrtus communis leaves essential oil and its main constituents.

METHODS

Essential oil was obtained by hydrodistillation of M. communis L. leaves and was analyzed by GC and GC-MS. The antimicrobial activity was carried out against both gram-negative and gram-positive bacteria. The microdilution method was used to estimate the minimum inhibitory concentrations (MICs). Then, the capacity of essential oil and its main constituent to inhibit biofilm growth, with the method of O'Toole and Kolterand, and the metabolic activity of biofilm cells through the MTT colorimetric method were evaluated at different times. Moreover, was studied the potential cytotoxic activity against SH-SY5Y cell line with MTT assay and the anti-acetylcholinesterase activity using Ellman's assay.

RESULTS

Myrtenyl-acetate, 1,8 cineole, α-pinene, and linalool were the main components in the EO. The myrtle EO, at the minimum tested dose (0.4 mg/ml), inhibited S. aureus biofilm by 42.1% and was capable of inhibiting the biofilm cell metabolism in all tested strains, except Staphylococcus aureus. Moreover, the EO showed good cytotoxic and anti-acetylcholinesterase activities IC₅₀ of 209.1 and 32.8 μg/ml, respectively.

CONCLUSIONS

The results suggest that myrtle EO and its main constituents could be used as possible products that could act against the resistant pathogenic species E. coli, P. aeruginosa, L. monocytogenes and S. aureus, on the other hand, as possible coadjutants in the treatment of neurological diseases.

Transcriptional response of Asarum heterotropoides Fr. Schmidt var. mandshuricum (Maxim.) Kitag. leaves grown under full and partial daylight conditions

BACKGROUND

Asarum heterotropides Fr. Schmidt var. mandshuricum (Maxim.) Kitag. is an important medicinal and industrial plant, which is used in the treatment of various diseases. The main bioactive ingredient is the volatile oil having more than 82 identified components of which methyleugenol, safrole, myristicin, and toluene account for about 70% of the total volume. As a sciophyte plant, the amount of light it absorbs through leaves is an important factor for growth and metabolism.

RESULTS

We grew Asarum plants under full, 50, 28, and 12% sunlight conditions to investigate the effect of different light irradiances on the four major volatile oil components. We employed de novo transcriptome sequencing to understand the transcriptional behavior of Asarum leaves regarding the biosynthetic pathways of the four volatile oil components, photosynthesis and biomass accumulation, and hormone signaling. Our results demonstrated that the increasing light conditions promoted higher percent of the four components. Under full sunlight conditions, cinnamyl alcohol dehydrogenase and cytochrome p450719As were upregulated and led the increased methyleugenol, safrole, and myristicin. The transcriptomic data also showed that Asarum leaves, under full sunlight conditions, adjust their photosynthesis-antenna proteins as a photoprotective response with the help of carotenoids. Plant hormone-signaling related genes were also differentially expressed between full sunlight and low light conditions.

CONCLUSIONS

High light induces accumulation of major bioactive ingredients A. heterotropides volatile oil and this is ascribed to upregulation of key genes such as cinnamyl alcohol dehydrogenase and cytochrome p450719As. The transcriptome data presented here lays the foundation of further understanding of light responses in sciophytes and provides guidance for increasing bioactive molecules in Asarum.

Productive, metabolic and anatomical parameters of menthol mint are influenced by light intensity

The cultivation of aromatic species to obtain essential oils has great economic importance, presenting an increasing demand from different industrial sectors, especially to menthol mint (Mentha arvensis L.) essential oil, rich in menthol (70-80%). Consortium cultivation has been an important practice in agricultural systems whose land use is necessary, consequently promoting strong competition for light in reduced space. Thus, this study aimed verifying if different light intensities might promote chemical, metabolical and anatomical alterations in menthol mint. Plants were grown in greenhouse at different average of light intensities (137, 254, 406 and 543 µmol photons m2 s1). Samples were collected 43 days after germination and submitted to following analyses: Gravimetric test, photosynthetic pigments, soluble fractions, enzymatic activity, N-total, trichome density and histochemistry and chemometric test based on essential oil chemical profile. Fresh mass gain, trichome density, essential oil content and soluble sugars were positively influenced by light intensity increase. On the other hand, total-N, NO3--N and pigments content have decreased influenced by light intensity increase. In the secretion from the trichomes, phenolic substances were reported, as well as lipophilic ones in the peltate ones. The increase of oxygenated monoterpenes was favored by light intensity decrease.

Discrimination of Myrtle Ecotypes from Different Geographic Areas According to Their Morphological Characteristics and Anthocyanins Composition

Myrtus communis L. is an evergreen shrub that produces berries with a high content in antioxidant compounds. Since these compounds have demonstrated a positive effect on human health, the interest on berries and their usages has increased. However, environmental conditions may affect the productivity of these species and consequently the quality of wild myrtle. Ecotypes from diverse geographical origins may result in significant variations in terms of bioactive compounds content as well as in chemical traits. For this reason, in this work ecotypes from two different localizations have been studied to determine if their differences in morphological and anthocyanins traits can be attributed to their origin and the environmental characteristics of these locations. For this, chemometric analyses such as Hierarchical Cluster Analysis and Principal Component Analysis, were employed. The results showed differences between the ecotypes depending on their location. In particular, myrtle berries from maritime zones present greater fruit size and amount of bioactive compounds, which means an improvement in the quality of the final product based on this raw material. It can be concluded that both morphological and anthocyanins traits are related to the location of the ecotype and allow selecting the best ecotype for the required applications.

Effect of shade level and mulch type on growth, yield and essential oil composition of damask rose (Rosa damascena Mill.) under mid hill conditions of Western Himalayas

A field experiment was conducted at the experimental farm of CSIR-Institute of Himalayan Bioresource Technology, Palampur, India for two consecutive years (2015–16 and 2016–17). The aim of the study was to test the hypothesis whether different shade level and mulch type would influence the growth, flower yield and essential oil profile of R. damascena. Yield attributes viz., numbers of flowers plant^-1, fresh flower weight plant^-1, flower yield, and essential oil yield were significantly higher under open sunny conditions as compared to 25% and 50% shade levels. However, plants grown under 50% shade level recorded significantly higher plant height (cm), plant spread (cm) and the lowest numbers of branches as compared to control. Among mulches, black polyethylene mulch recorded significantly higher growth, and yield attributes of damask rose as compared to other mulches. Black polyethylene mulch recorded 74.5 and 39.2% higher fresh flower yield as compared to without mulch, during 2015–16 and 2016–17, respectively. Correlation studies showed a positively significant correlation between quality and quantity traits. A total of twenty-six essential oil compounds were identified which accounted for a total of 88.8 to 95.3%. Plants grown under open sunny conditions along with the applications of black polyethylene mulch produced a higher concentration of citronellol and trans-geraniol. Damask rose planted in open sunny conditions and mulched with black polyethylene sheet recorded significantly higher flower yield.

Combined treatment of Thymus vulgaris L., Rosmarinus officinalis L. and Myrtus communis L. essential oils against Salmonella typhimurium: Optimization of antibacterial activity by mixture design methodology

To increase the sensibility of Salmonella typhimurium strain, a mixture of Thymus vulgaris L. (T. vulgaris L.), Rosmarinus officinalis L. (R. officinalis L.) and Myrtus communis L. (M. communis L.) essential oils (EOs) was used in combined treatment by experimental design methodology (mixture design). The chemical composition of EOs was firstly identified by GC and GC/MS and their antibacterial activity was evaluated. The results of this first step have shown that thymol and borneol were the major compounds in T. vulgaris and M. communis L. EOs, respectively, while 1,8-cineole and α-pinene were found as major compounds in R. officinalis L. The same results have shown a strong antibacterial activity of T. vulgaris L. EO followed by an important power of M. communis L. EO against a moderate activity of R. officinalis L. EO. Besides, 1/20 (v/v) was the concentration giving a strain response classified as sensitive. From this concentration, the mixture design was performed and analyzed. The optimization of mixtures antibacterial activities has highlighted the synergistic effect between T. vulgaris L. and M. communis L. essential oils. A formulation comprising 55% of T. vulgaris L. and 45% of M. communis L. essential oils, respectively, can be considered for the increase of Salmonella typhimurium sensibility.