Essential Oil Yield Research Articles

Phytochemical compositions and antioxidant activity of green and purple basils altered by light intensity and harvesting time

Ocimum basilicum L. is one of the most important medicinal and vegetable crops due to its essential oil, pleasant aroma and taste. In this study, we evaluated the impact of different light intensities, including 100 %, 50 %, and 30 % of natural sunlight, on the growth, phytochemical compositions, and antioxidant activity of green and purple basil cultivars at two different harvest times: early morning and noon. The height of the plant, number of leaves per plant, length of the petiole, diameter of the stem, and fresh and dry weight of the shoot were all reduced by decreasing light intensity in both basil cultivars. When the plants of both cultivars were grown under full light intensity and were sampled at noon, they showed the highest phenolic and flavonoid contents. The highest antioxidant activity was detected in purple basil cultivars grown under 30 and 50 % of sunlight in both harvests. The green basil cultivar showed the highest antioxidant activity when exposed to 30 % sunlight and harvested in the early morning. The highest essential oil content and yield in both basil cultivars were obtained under full sunlight in the early morning harvests. In summary, light intensity and harvest time influence the phytochemical yield, composition, and growth of two studied basil cultivars. Optimal results, particularly for medicinal purposes, were achieved by morning harvesting to maximize the essential oil yield of basils.

Water Deficit Severity during the Preceding Year Determines Plant Tolerance to Subsequent Year Drought Stress Challenges: A Case Study in Damask Rose

Damask rose is an important essential oil crop. In the present study, plants were subjected to three different water deficit levels (70, 40, and 10% available water content) for two periods (June–October). Plant phenology, growth, essential oil yield, gas exchange features, membrane stability and major antioxidant defense elements were monitored across two years. Soil water deficit was related to quicker completion of the growth cycle (up to 7.4 d), and smaller plants (up to 49.7%). Under these conditions, biomass accumulation was jointly constrained by decreased leaf area, chlorophyll content, CO2 intake, and photosynthetic efficiency (up to 82.8, 56.9, 27.3 and 68.2%, respectively). The decrease in CO2 intake was driven by a reduction in stomatal conductance (up to 41.2%), while the decrease in leaf area was mediated by reductions in both number of leaves, and individual leaf area (up to 54.3, and 64.0%, respectively). Although the reactive oxygen species scavenging system was activated (i.e., proline accumulation, and enhanced activity of three antioxidant enzymes) by water deficit, oxidative stress symptoms were still apparent. These effects were amplified, as soil water deficit became more intense. Notably, the adverse effects of water deficit were generally less pronounced when plants had been exposed to water severity during the preceding year. Therefore, exposure to water deficit elicited plant tolerance to future exposure. This phenotypic response was further dependent on the water deficit level. At more intense soil water deficit across the preceding year, plants were less vulnerable to water deficit during the subsequent one. Therefore, our results reveal a direct link between water deficit severity and plant tolerance to future water stress challenges, providing for the first time evidence for stress memory in damask rose.

Extraction of essential oil from cinnamon (Cinnamomum burmannii) bark using microwave assisted extraction method

Cinnamon is one of the essential commodities that is very prospective and rich in benefits. The demand for cinnamon bark essential oil is always increasing every year. This condition indicates that the potential utilization of cinnamon bark essential oil is still wide open along with the development of the food, cosmetic and drug industries. The goal of this research is to extract the essential oil from cinnamon bark using Microwave Assisted Extraction (MAE) method, as well as to determine the best operation condition that can result the optimum yield of essential oil. This research was carried out with a variation of solvents of aquadest, 70% ethanol and ethyl acetate; variations of microwave power of 180, 300 and 450 W; and variations in extraction time of 60, 75 and 90 minutes. The results showed that the best solvent for extracting cinnamon bark essential oil was 70% ethanol. Furthermore, the best operating conditions were obtained using a microwave power of 300 W and an extraction time of 90 minutes, with an essential oil yield of 6.92 %. The physical properties of the essential oil obtained are a density of 1.1041 g/mL; refractive index 1.416; pH 6, light yellow color and a distinctive cinnamon aroma.

Enrichment of olive oil with sage (Salvia officinalis) leaf essential oil extracted by ultrasound pretreatment followed by hydrodistillation to increase its shelf life

Olive oil (OO) is a valuable food product, compared with other seed oils, for its health benefits, sensory attributes and higher economic value. The demand for natural antioxidants has recently grown due to the potential toxicity and carcinogenicity of synthetic antioxidants that are utilized in food industry. This study aimed to investigate the oxidative stability of OO enriched with sage (Salvia officinalis) essential oil (EO). The sage EO was extracted from the leaves by ultrasound (US) as a pretreatment followed by hyrodistillation (HD). The effects of US power level (60 and 90 W) and time (10, 20 and 30 mins) on the EO yield, total extraction time and quality characteristics were studied. Compared to the HD extraction, the US pretreatments before HD shortened the total extraction time to ≤ 54 mins, with the same extraction yield, instead of 240 mins with HD. Various EO samples extracted by these US pretreatments followed by HD (US+HD) were analyzed for their chemical compositions by GC–MS and compared with that of EO obtained by HD. Compositional analysis revealed that the most prominent oxygenated monoterpenes of EO samples were camphor, α-thujone, 1,8-cineole, β-thujone, bornyl acetate and endo-borneol. The EO extracted by US pretreatment at 60 W for 10 mins followed by HD for 34 mins was characterized by the highest quality index [(α- + βthujone)/camphor ratio] and higher levels of antioxidant constituents (α-pinene and camphene). The sage EO obtained by this technique was selected to enrich OO at 200, 400 and 600 mg/Kg of OO. Quality criteria of the OO such as acidity, peroxide value, conjugated dienes and trienes besides chlorophyll and carotenoid contents and fatty acids composition were measured. Results revealed that the addition of sage EO at 200 mg/Kg of OO increased the oxidative stability of OO measured by Rancimat by 36% instead of 21% by using the synthetic antioxidant butylated hydroxytoluene (BHT) at the same level. Moreover, the sensory attributes of the enriched OO were maintained. From this study, it can be concluded that sage EO can be used to increase the shelf life of OO.

Bioactive Profiling, Antibacterial Efficacy and Computational Modelling of Myrtus Communis Essential Oil (Morocco).

In the context of investigations into molecules of natural origin with biological activities. This study focuses on the development of Myrtus communis L., a medicinal plant found in the mountains of Morocco. The first, an analysis carried out on leaves using the inductively coupled plasma spectrometry technique, showed the almost total absence of heavy metals. Furthermore, we aim to identify the chemical composition of its essential oils by gas chromatography-mass spectrometry (GC/MS) analysis and assess its antibacterial efficacy in vitro and in silico. The average yield of essential oils was 0.9 %±0.06, and GC/MS analysis identified 35 constituents, with myrcene (27,38 %), limonene (16,51 %), α-pinene (7,32 %) being the major compounds. Remarkably, the essential oils displayed considerable antibacterial activity against various tested bacteria, including Escherichia coli (0.7 μL/mL), Escherichia pseudocoloides (2.8 μl/ml), Escherichia vekanda (2.8 μl/ml). Molecular docking has contributed to our understanding of the mechanism of antibacterial action of the main compounds in this essential oil.

A New Revolutionary Green Technology for the Extraction of Essential Oil Using Microwave and Ultrasound-assisted Techniques

Background: Essential oils are utilized in various food applications and are a rich source of naturally occurring volatile components. The extraction of essential oils has used conventional techniques for several years, but these methods require a long duration of time, more solvent, and high energy. However, recent advancements have led to novel and eco-friendly techniques that significantly enhance the essential oil yield while minimizing the use of resources. Method: This study describes the recent research on the extraction of essential oils and their components, focusing on microwave-assisted extraction (MAE) and ultrasound-assisted extraction (UAE). Result: This review explores the instrumentation, mechanism, and applications behind MAE and UAE. It also describes the emerging technologies for the extraction of essential oils, along with their optimized conditions. Conclusion: These techniques represent a more sustainable and efficient approach for the extraction of essential oil from various plant sources, aligning with the principles of green chemistry.

Adoption of arbuscular mycorrhizal fungi and biochar for alleviating the agro-physiological response of lavander (Lavandula angustifolia L.) subjected to drought stress

Increasing the productivity of crops in water deficit circumstances is of great significance in order to face the challenge of securing global food production. Nowadays, the use of biochar (BC) and arbuscular mycorrhizal fungi (AMF) are considered as one of the most effective methods for empowering plants to deal with drought stress. However, the literature regarding the effects of the simultaneous use of AMF+BC on plants under drought stress is scarce. Hence, the present study was conducted to consider the combined application of AMF and biochar on the physiological and biochemical properties of lavender under various levels of irrigation. The first factor includes three irrigation regimes of 90 % field capacity (FC), 60 % FC, and 30 % FC, respectively, corresponding to normal irrigation, mild and severe drought stress. The second factor included a fertilizer or microbial inoculant source, which were respectively: no inoculation (control), inoculation with AMF, BC, and co-application of AMF along with BC. The highest nutrient, chlorophyll and carotenoid content, and fresh, and dry weight of lavender were recorded under normal irrigation conditions with combined application of AMF+BC. The combined application of AMF+BC was significantly effective in increasing the activity of antioxidant enzymes against oxidative damage caused by drought stress and in reducing the accumulation of proline and malondialdehyde. An increase in phenolic, flavonoid, and concentration of essential oil was observed under mild stress and using AMF+BC, while the highest essential oil yield was recorded under a normal irrigation regime and treated with AMF+BC. The highest content of linalool, camphor, borneol, and linalyl acetate was obtained in mild stress by adding AMF+BC. It can be concluded that the use of AMF+BC combination treatment may be a useful strategy to improve the quantity and quality of lavender EO in drought-stress circumstances.

Optimization of Red Ginger (Zingiber officinale var. Rubrum) Extraction Using Microwave Assisted Hydrodistillation Method

Red ginger is a spice plant that has high economic and social value. One of the uses of red ginger is to process it into a product, namely essential oil. This study aims to determine the optimization of the extraction process conditions on solvent volume, time, and extraction power that can produce optimum yield and residual content of red ginger essential oil solvent. The extraction was carried out with the help of microwaves. The research method is experimental design and optimization process with Response Surface Methodology (RSM) type Box-Behnken Design (BBD). The results showed that the optimum yield was at 700 mL solvent volume, 1 min extraction time, and 10% power (69.9 watts) with the equation Y = 0.2076 + 0.0262A – 0.0300B – 0.0013C and the concentration conditions the optimum remaining solvent with the equation Y = 4.98 – 1.0000A + 4.56B + 5.44C. The optimal yield of red ginger essential oil was 0.205%, with a residual solvent content of 3.8%, specific gravity 0.885, acid number 1.399, refractive index 1.485. The results of the optimum residual solvent content of -6.023%. Based on the results obtained, the yield value with the help of microwaves is higher than that without the help of microwaves. Keywords: Essential oil, Microwave, Residual solvent content, Response surface methodology (RSM), Yield.

Co-application of biochar and selenium nanoparticles improves yield and modifies fatty acid profile and essential oil composition of fennel (Foeniculum vulgare Mill.) under cadmium toxicity.

Fatty acids and essential oils (EOs) are the primary variables that influence the quality of fennel (Foeniculum vulgare Mill.). Soil toxicity to cadmium (Cd) is the main environmental issue facing fennel, and priming methods like soil amendments and nanoparticles (NPs) are commonly utilized to deal with it. The goal of the current study was to examine the effects of biochar (BC) and selenium nanoparticles (Se NPs) on fennel plants in Cd-contaminated soils. The pot experiment was conducted with Cd stress at 0, 10, and 20mgkg-1 soil, BC at 5% (v/v), and foliar-spraying Se NPs at 40mg L-1 as a factorial completely randomized design (CRD) at a greenhouse condition in 2022. The findings demonstrated that Cd toxicity significantly decreased plant performance, while BC and Se NPs enhanced it. Without BC and Se NPs, Cd toxicity at 20mgkg-1 soil decreased biological yield (39%), seed yield (37%), EO yield (32%), and monounsaturated fatty acids (14%), while increased saturated fatty acid (26%) and polyunsaturated fatty acids (40%) of fennel. The main EO profile was anethole (65.32-73.25%), followed by limonene (16.12-22.07%), fenchone (5.57-6.83%), and estragole (2.25-3.65%), which mainly were oxygenated monoterpenes. The combined application of BC and Se NPs improved the yield, EO production, and fatty acid profile of fennel plants under Cd stress, increasing the plants' resistance to Cd toxicity.

Stability pattern and simultaneous selection for the stable essential oil-yielding genotypes of basil

Basil leaves are used to make a tea that promises to assist with vomiting, rheumatic pain, and loose motions. It includes a high concentration of antioxidants, which may increase longevity and health. The current study aims to assess the consistency, stability, and recommendations for producing essential oils from commercial genotypes and cultivars. To investigate genotype stability, field experiments were conducted in a semi-arid tropical climate in an RBD and replicated three times over three years in 2017, 2018, and 2019, at the CIMAP, RC, Hyderabad, south India. Each of the thirteen economic variables exhibited substantial diversity. In a three-year experiment, the stability of 20 basil genotypes was studied. There have been very few studies on the genotype and environmental interactions, stability, and diversity of basil. Nonetheless, no simultaneous assessments, stability, or reliability analyses have been performed in a multi-environment essential oil yield study on basil. According to the AMMI model, genotypes OC-6 and 8 for oil yield and OC-6 and 10 for linalool (%) were the most adaptable and stable varieties because they could withstand a wide range of environmental conditions. This leads to the conclusion that the most stable genotypes for linalool content (%) and essential oil production are OC-6, OC-8, and OC-10, all of which provide excellent yields. As a result, it is suggested that these genotypes and cultivars be commercialized.

Industrial Distillation Fractions of Garlic Essential Oil, Design, Synthesis, and Antifungal Activity Evaluation of Aliphatic Substituted Trisulfide Derivatives.

Garlic oil has a wide range of biological activities, and its broad-spectrum activity against phytopathogenic fungi still has the potential to be explored. In this study, enzymatic treatment of garlic resulted in an increase of approximately 50 % in the yield of essential oil, a feasible GC-MS analytical program for garlic oil was provided. Vacuum fractionation of the volatile oil and determination of its inhibitory activity against 10 fungi demonstrated that garlic oil has good antifungal activity. The antifungal activity levels were ranked as diallyl trisulfide (S-3)>diallyl disulfide (S-2)>diallyl monosulfide (S-1), with an EC50 value of S-3 against Botrytis cinerea reached 8.16 mg/L. Following the structural modification of compound S-3, a series of derivatives, including compounds S-4~7, were synthesized and screened for their antifungal activity. The findings unequivocally demonstrated that the compound dimethyl trisulfide (S-4) exhibited exceptional antifungal activity. The EC50 of S-4 against Sclerotinia sclerotiorum reached 6.83 mg/L. SEM, In vivo experiments, and changes in mycelial nucleic acids, soluble proteins and soluble sugar leakage further confirmed its antifungal activity. The study indicated that the trisulfide bond structure was the key to good antifungal activity, which can be developed into a new type of green plant-derived fungicide for plant protection.

Variability of the component composition of the essential oil of <i>Artemisia salsoloides</i> Willd. from natural populations of the flora of Dagestan

To study the variability of the gathering locality and componen t composition of essential oil from the aerial part of a little‐studied species – Artemisia salsoloides Willd. depending on abiotic environmental factors, such as height above the level of the place of growth. Aerial parts of A. salsoloides were collected during the flowering phase in four Dagestan natural populations to obtain essential oil using the Clevenger method. To determine the component composition of the samples obtained of essential oils of A. salsoloides, chromatography‐mass spectrometric analysis was used. The components were identified using the NIST08 and FFNSC mass spectral libraries. In total, 55 compounds were identified in the essential oil samples, where monoterpenoids account for 59.92 % – 75.98 % and sesquiterpenoids – for 23.24 % to 37.81 %. At the same time, 15 major compounds were identified. Thus, it should be noted that there was found to be a wide range of values for monoterpenoids: β‐pinene, trans‐β‐ocimene, cis‐alloocimene, benzene, 2,4‐pentadinyl, and among sesquiterpenoids – α‐copaene, β‐sesquiphilandrene, spathulenol. The quantitative yield of essential oil in the studied samples varied from 0.68 % to 1.36 % of airdried raw materials, depending on the growth location of the species. Four separate populations of A. salsoloides were identified by means of cluster analysis based on the component composition of the studied essential oils. For the first time, the composition of the essential oil of the aerial part of wild Dagestan samples of A. salsoloides was studied as depending on an abiotic factor (height above sea level) of the environment. The results obtained of the component composition of the essential oil of A. salsoloides samples showed the presence of a number of valuable compounds, which allow the use of essential oils as their sources.

Development and validation of an efficient approach for extracting essential oil, scutellarin, and rosmarinic acid from Perilla frutescens leaves using vacuum microwave-mediated rotary hydrodistillation and extraction in situ and a choline amino acid ionic liquid

In this study, an efficient vacuum microwave-mediated rotary hydrodistillation and extraction in situ (VMRHDE) device was used for extracting essential oil, scutellarin, and rosmarinic acid from Perilla frutescens leaves with choline amino acid ionic liquid solution. The extracted products were then analyzed through GC–MS and HPLC. The optimal parameters were determined through a Doehlert design matrix and desirability function, resulting in the use of 10 % choline glutamate ionic liquid ([Ch][Glu]), a liquid–solid ratio of 15 mL/g, a microwave irradiation time of 20 min, a microwave irradiation power of 540 W, and a rotary speed of 24 r/min. Under optimal operating conditions, the yields of essential oil, scutellarin, and rosmarinic acid were 0.41 % ± 0.02 %, 0.39 % ± 0.01 %, and 0.36 % ± 0.01 %, respectively. GC–MS analysis revealed that adding [Ch][Glu] significantly increased the content of perilla aldehyde and oxygenates in the essential oils. Methodological validation confirmed that the established method met the detection requirements, with recoveries of 99.20 % for scutellarin and 99.83 % for rosmarinic acid, demonstrating high accuracy. The linear relationship of scutellarin and rosmarinic acid was good in the concentration range, with R2 values of 0.9999 for both.

Chemical, physical, and biological evaluation of hydro-distilled essential oil from leaves of Ethiopian thymus species

ABSTRACT Physicochemical profile, phytochemical constituents, bioactivity, and thermal stability of the hydro-distilled essential oil (EO) for T.schimperi and T.serrulatus were investigated. EO yield for T.schimperi and T.serrulatus was 2.05± 0.09% and 1.2 ± 0.3% (w/w) respectively. The chemical profiles of the EO were analyzed using GC-MS (Gas Chromatography-Mass spectrometry).Twenty one (99.99 %) and Twenty (98.59%) EO components were identified from T. schimperi and T.serrulatus, respectively. The two stage mass losses, the first one (38%) was from 37°C to 164°C and (55%) from 46°C to 178°C for T.schimperi and T.serrulatus EO respectively and the second one was (11%) from 164°C to 220°C for T.schimperi and (8%) from 178°C to 223°C for T.Schimperi and T.serrulatus EO respectively were observed for TGA analysis.The essential oils in this study showed a strong antioxidant effect for different tests. IC50 value of 0.17 μg/mL on DPPH assay for both species; 73 ± 0.50 and 64 ± 3.4% inhibition for ABTS assay 4.6 ± 0.42 and 8.04 ± 0.9 mM Fe+2/mL percent in FRAP assay for T.schimperi and T.serrulatus respectively. Antimicrobial activities for both species EOs were investigated on Escherichia coli, Staphylococcus aureus, Salmonella typhi, and Streptococcus epidermidis. MIC values for E.coli and S.typhi were 0.5 and 1 μL/mL for T.schimperi, 2 and 4 μL/mL of T.serrulatus EO, for S.aureus and Streptococcus epidermidis were 0.2 and 4 μL/mL for T.schimperi, 2 and 0.5 μL/mL for T.serrulatus EO’s. MBC values for both E.coli and S.typhi were 2 μL/mL for T.schimperi and 4 μL/mL for T.serrulatus EO, While for S.aureus and Streptococcus epidermidis were 1 and 4 μl/ml for T.schimperi, 2 and 8 μL/mL for T.serrulatus EO.

Phytochemical analysis, post-harvest shade drying, and biological activities of Melaleuca linariifolia Sm. from foothills of Kumaun Himalayas, India

Melaleuca linariifolia Sm. (Genus: Melaleuca; Family: Myrtaceae) cultivated for its ornamental usages in the Kumaun Himalayan region of Uttarakhand is commercially known as flax-leaved paper bark tree. The present study analyzes the chemical variation of the essential oils obtained from aerial parts and flowers of M. linariifolia. The effect of post-harvest shade drying on the essential oil composition was also assessed in the study. Total of 16 compounds accounting for 94.2 % and 94.6 % were identified in the aerial parts and flowers essential oil, respectively. 1,8-Cineole (71.8 %–73.8 %) was identified as the predominant compound in both the studied essential oils followed by limonene (1.7 %–9.3 %) and α-terpineol (4.2 %–6.7 %). Moreover, the fresh aerial parts had 73.8% of 1,8-cineole content which increased up to 79.2% post-harvest drying. The study revealed oxygenated monoterpenes as the major class constituents with 1,8-cineole as the marker component ranging from 67.7 % to 79.2 % during the post drying analysis. While assessing the biological activities, the antioxidant activity of the oils was investigated in vitro using three assays: DPPH radical scavenging activity, Iron(II) complexing activity, and H2O2 radical scavenging activity. The oil also inhibited the activity of α-amylase with IC50 of 3.26 ± 0.04 μg/ml and protein denaturation with IC50 of 3.0 ± 0.03 g/ml. This is the first-time report of essential oil analysis of M. linariifolia flowers and post-harvest drying study from bhabar region of the Kumaun Himalayas. The high essential oil yield, rich chemical composition and biological activities suggest the cultivation of Melaleuca species as an industrial crop.

Profile and accumulation of essential oils from guayule (Parthenium argentatum A. Gray) accessions and hybrids

For guayule (Parthenium argentatum A. Gray) to become a viable market option, it will be necessary to exploit not only the rubber and resin components, but also other high-value plant products such as essential oils (EOs). A detailed EO profiling study was conducted on 16 guayule accessions for first time, which revealed significant differences in EO yield and profile among them. Accession AZ-2 had the highest yield up to 0.9% (dry weight), followed by CFS18–2005, CAL-7, and CFS17–2005. These yields were comparable with those of aromatic plants used in the industry, providing valuable economic insights. The volatile EO composition of the accessions was unique and discriminating. Volatile sesquiterpenes were the most abundant compounds at the beginning of the flowering stage (S1-June sampling), while monoterpenes became more abundant as flowering progressed (S2-July and S3-August sampling). At S1, it was possible to distinguish between hybrid (mariola and non-mariola) and other accessions by the EO profile. By the end of the summer season (S3, August 2023), the EO volatile profile could more easily distinguish the accessions according to their genetic origin, enabling the separation of pure guayule accessions. The extraction of guayule EOs on an industrial scale (1.2 Mg fresh biomass) demonstrated high yield and consistency in terms of volatile profile, underscoring its potential for commercial exploitation.

Effects of varieties, pre-treatment and ultrasound assisted extraction on yields and characteristics of essential oils from young pomelo (Citrus Grandis L.) peels

Essential oils were extracted from two Vietnam local varieties of pomelo namely Citrus Grandis L. CV Nam Roi and Citrus Grandis L. CV Da Xanh. Storage methods by freezing or drying of young fruit peels affect the yield of extracted essential oils. The yield of essential oils obtained from Da Xanh variety was higher in Nam Roi variety. The extraction under ultrasound assisted condition increased the yield by two folds. The composition of volatile compounds in pomelo essential oils varied with different pomelo varieties and storage methods of the materials. The dominant compound in young peels essential oils Nam Roi, Da Xanh is limonene (55 – 90%). Nam Roi peels essential oils have antioxidant and antimicrobial activities (inhibition ability against Bacillus subtilis and Staphylococcus aureus) higher than Da Xanh peels’ essential oils.

Phyto-pharmacological Evaluation of Pimenta dioica (Linn.) Merill, Essential oil for Anthelmintic and Antimicrobial potential

Pimenta dioica (Linn.) Merill., belongs to the family Myrtaceous, has been used as a spice and is well known for its culinary as well as medicinal values. The aim of the current study was to assess the in vitro antimicrobial, anthelmintic activity and phytochemical composition of the essential oil extracted from Pimenta dioica leaves. The extraction of essential oil was performed with the Clevenger apparatus, by hydro-distillation. Pimenta dioica essential oil yield was 1.03%. The GC-MS analysis of this Pimenta dioica essential oil showed that eugenol (74.72%) was the predominant component. The essential oil showed potent anthelmintic activity assay when analysed by the adult worm’s motility assay. It has shown a comparable paralysis and disintegration profile of the model organism to that of the standard drug albendazole. The essential oil was also found to be effective against common human pathogenic bacteria, including Staphylococcus aureus, Klebsiella, Escherichia coli, Chromobacterium violaceum and Proteus vulgaris. It also showed moderate antifungal activity against Candida albicans and Aspergillus niger. These results proved that Pimenta dioica essential oil could be used as a source of the lead molecule for developing novel anthelmintic or antimicrobial agents.

Improving nitrogen content in soil and lemon balm (Melissa officinalis L.) yield by purple nonsulfur bacteria Rhodopseudomonas palustris in two consecutive seasons.

The study was conducted to assess the effects of nitrogen (N)-fixing purple nonsulfur bacteria (PNSB) Rhodopseudomonas palustris TLS06, VNW02, VNW64, and VNS89 on soil fertility, N uptake, essential oil (EO) content, growth, and yield of lemon balm. The experiment followed a completely randomized block design with 9 treatments and 3 replications. The treatments consisted of (i) applying 100% N as the recommended fertilizer rate (RFR), (ii) applying 85% N as RFR, (iii) applying 70% N as RFR, (iv) applying 55% N as RFR, (v) the treatment ii combined with N-PNSB, (vi) the treatment iii combined with N-PNSB, (vii) the treatment iv combined with N-PNSB, (viii) 0% as RFR combined with N-PNSB, and (ix) 0% N as RFR. The results showed that applying N-PNSB increased the plant height, and the number of primary branches in both seasons. In addition, the treatment without N fertilizer combined with N-PNSB increased stem leaf biomass by 41.2 and 50.3% in both seasons as compared with the treatment without neither N fertilizer nor N-PNSB. For soil properties, among treatments without N fertilizer, the treatment with N-PNSB increased concentrations of NH4+, soluble P, and exchangeable K+ by 41.3, 41.4, and 26.8%, respectively, as compared with the treatment without N-PNSB at the end of the second season. Applying 85% N as RFR combined with N-PNSB had a greater yield by 5.78-11.8% as compared with the treatment with 100% N as RFR, and a greater EO content by 23% as compared with the treatment with 85% N as RFR.

Identification and variation analysis of the composition and content of essential oil and fragrance compounds in Phoebe zhennan wood at different tree ages.

Wood essential oil and wood products with special fragrances are high value-added forest products. Despite the availability of essential oil and volatile organic compounds (VOCs) from Phoebe zhennan wood, their variation and dependence on tree age have not been examined. After essential oil extraction and wood processing, the yields and compositions of essential oils and VOCs in wood from P. zhennan trees of different ages (10a, 30a, and 80a) were determined. The yield of essential oil from 30a wood was significantly greater than that from 10a and 80a wood. Liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) revealed 672 and 41 volatile compounds, respectively, in the essential oil and wood, the majority of which exhibited large fluctuations in relative content and composition depending on tree age. Sesquiterpenoids, fatty acids and conjugates may greatly contribute to the main components of essential oil from wood. Almost all major sesquiterpenoid compounds, such as caryophyllene α-oxide, eudesmo, and cubebene, were identified in the essential oils from the 30a and 80a wood, and their relative contents were much greater than those in the 10a wood. The main components of the wood fragrance were sesquiterpenoids. The types and relative contents of sesquiterpenoids from wood increased with tree age. These results suggest that choosing wood from trees of a suitable age will significantly improve the efficiency of wood utilization.