Terpinolene

Variations of volatile flavour compounds in finger citron (Citrus medica L. var. sarcodactylis) pickling process revealed by E-nose, HS-SPME-GC-MS and HS-GC-IMS.[Pubmed:33292962]

Food Res Int. 2020 Dec;138(Pt A):109717.

The pickled products of finger citron are famous in southern China for their unique taste and flavor. Although pickling process involves complex treatments including salting, desalting, sugaring, cooking and drying, extended shelf-life up to ten years after pickling can be achieved. In this study, the variations of volatile flavour components in the pickling process of finger citron were investigated by electronic nose (E-nose), headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS). HS-SPME-GC-MS identified 85 substances, and HS-GC-IMS identified 81 substances, including terpenoids (21), aromatic hydrocarbons (11), alcohols (11), aldehydes (10), esters (7), phenols (6), acids (5), ethers (2), ketones (2), and other species (10). Linalool, limonene, (E)-3,7-dimethyl-1,3,6-octatriene, myrcene, 3-carene, beta-pinene, alpha-pinene, Terpinolene, 1-methyl-4-(1-methylethyl)-1,4-cyclohexadiene, alpha-terpinene, (S)-beta-bisabolene, 1-isopropyl-2-methylbenzene and 1-methyl-4-(1-methylethenyl)-benzene were the stable substances at relatively high contents in finger citron at different pickling process. Salting and drying steps in the pickling process exerted greatest influence on the volatile components of finger citron. Salting promoted the generation of aldehydes, esters and acids, but led to the disappearance of alcohols, while drying promoted the generation of alcohols, phenols, aldehydes and acids at the expense of reduction in terpenoids. Our study revealed that the characteristic volatile compounds of finger citron pickled products was mainly formed by the biological reactions in the salting stage and thermal chemical transformations in the drying stage. This study also validated the suitability of E-nose combined with HS-SPME-GC-MS and HS-GC-IMS in tracking the changes of volatile components in finger citron during the pickling process.

Chemical composition, antioxidant capacity, and thermal behavior of Satureja hortensis essential oil.[Pubmed:33288856]

Sci Rep. 2020 Dec 7;10(1):21322.

Satureja hortensis is one of the representative plants from the Lamiaceae family, and its essential oil has been used in various applicative fields, from the food industry to aromatherapy. The changes that occur in heated samples at different temperatures (160, 175, 190 masculineC) over different periods (0.5 and 2.5 h) in Satureja hortensis essential oil composition and chemical properties were evaluated. The results showed that the major chemical composition constituents of the investigated essential oil are gamma-terpinene + alpha-Terpinolene and carvacrol + p-cymene and the thermal behavior is dependent on the content. This composition drastically changes through the heating of the samples and causes significant changes in thermal behavior. The present study demonstrated that the concentration of carvacrol in S. hortensis essential oil is increasing after heating treatment, and the sample heated at 190 masculineC for 2.5 h contained more than 91% carvacrol. This simple treatment is a rapid way to obtain carvacrol from the essential oil that has high potential as a natural preservative suitable for the food industry and alternative and complementary medicine.

Chemical Composition and Antimicrobial and Antioxidant Activities of Essential Oil of Sunflower (Helianthus annuus L.) Receptacle.[Pubmed:33187052]

Molecules. 2020 Nov 11;25(22). pii: molecules25225244.

Sunflower (Helianthus annuus L.) contains active ingredients, such as flavonoids, alkaloids and tannins. Nevertheless, few studies have focused on essential oil from the receptacle of sunflower (SEO). In this work, we investigated the chemical composition and antimicrobial and antioxidant activities of SEO. The yield of SEO was about 0.42% (v/w) by hydrodistillation. A total of 68 volatile components of SEO were putatively identified by gas chromatography-mass spectrometry (GC-MS). The main constituents of SEO were alpha-pinene (26.00%), verbenone (7.40%), Terpinolene (1.69%) and alpha-terpineol (1.27%). The minimum inhibitory concentration (MIC) of SEO against P. aeruginosa and S. aureus was 0.2 mg/mL. The MIC of SEO against S. cerevisiae was 3.2 mg/mL. The MIC of SEO against E. coli and Candida albicans was 6.4 mg/mL. The results showed that SEO had high antibacterial and antifungal activities. Three different analytical assays (DPPH, ABTS and iron ion reducing ability) were used to determine the antioxidant activities. The results showed that SEO had antioxidant activities. To summarize, the results in this study demonstrate the possibility for the development and application of SEO in potential natural preservatives and medicines due to its excellent antimicrobial and antioxidant activities.

Antioxidant Activities of a New Chemotype of Piper cubeba L. Fruit Essential Oil (Methyleugenol/Eugenol): In Silico Molecular Docking and ADMET Studies.[Pubmed:33182768]

Plants (Basel). 2020 Nov 10;9(11). pii: plants9111534.

Piper cubeba L. fruit is an important species used in folk medicine for different types of pains such as rheumatism, chills, flu, colds, muscular aches, and fever. This study examines the chemical constituents, antioxidant activity, and potential inhibitory effect against human peroxiredoxin 5, a key enzyme of P. cubeba essential oil from fruits. Using gas chromatography coupled with mass spectrometry (GC-MS), the principal components were methyleugenol (41.31%) and eugenol (33.95%), followed by (E)-caryophyllene (5.65%), p-cymene-8-ol (3.50%), 1,8-cineole (2.94%), and alpha-Terpinolene (1.41%). Results showed similar scavenging activity via 2,2-diphenyl-1-picrylhydrazyl DPPH radical scavenging activity (IC50 = 110.00 +/- 0.08 mug/mL), as well as very potent antioxidant activity against both ferric reducing/antioxidant power (FRAP) (106.00 +/- 0.11 mug/mL) and beta-carotene bleaching (IC50 = 315.00 +/- 2.08 mug/mL) assays when compared to positive butylated hydroxytoluene and ascorbic acid. The molecular docking approach has also been performed to screen the antioxidant activities of the major and potent compounds against human protein target peroxiredoxin 5. Results showed good binding profiles and attributed the strongest inhibitory activity to beta-caryophyllene oxide (-5.8 kcal/mol), followed respectively by isocembrol and alpha-selinene (-5.4 kcal/mol), and viridiflorol (-5.1 kcal/mol). Furthermore, ADME (absorption, distribution, metabolism and excretion)-related physicochemical and pharmacokinetic properties have been assessed and support our in vitro findings. This work demonstrates the powerful antioxidant potency of cubeba pepper and paves the way for the discovery and development of antioxidant agent with high potency.

Three molecules found in rosemary or nutmeg essential oils repel ticks (Dermacentor variabilis) more effectively than DEET in a no-human assay.[Pubmed:33089620]

Pest Manag Sci. 2020 Oct 21.

BACKGROUND: Development of new personal repellents to prevent tick bites is progressing to keep up with the increasing threat of tick-borne diseases in humans. However, the market share of natural, plant-based repellents is still quite small. We tested all of the major (>1%) components found in the essential oils of rosemary (Spanish variety) and nutmeg. These were tested with Dermacentor variabilis ticks, a robust tick capable of vectoring human diseases, in a no-human horizontal Petri dish assay. For comparison, we also tested the active ingredients currently recommended by the CDC and EPA as personal repellents for use against ticks. RESULTS: Of the 16 oil components tested, three performed significantly better than N,N-diethyl-meta-toluamide (DEET) in our assay. These compounds were myristicin and safrole found in the nutmeg oil, and Terpinolene found in nutmeg oil and as a minor (<1%) constituent of rosemary oil. The current market natural product, 2-undecanone, also performed strongly in our assay. CONCLUSIONS: Our assay focused on comparing active ingredients as potential repellents and found that many natural products can elicit a strong response from ticks. Terpinolene is the most promising active ingredient identified, owing to human health concerns regarding myristicin and safrole. Our results from examining individual terpenoids from two essential oils suggest that there remain unexploited natural compounds that could be further developed for new personal tick repellents.

Tangerines Cultivated on Madeira Island-A High Throughput Natural Source of Bioactive Compounds.[Pubmed:33076393]

Foods. 2020 Oct 15;9(10). pii: foods9101470.

Tangerines (Citrus reticulata) are popular fruits worldwide, being rich in many bioactive metabolites. The setubalense variety cultivated on Madeira Island has an intense aroma easily distinguishable from other tangerines, being traditionally used to enrich several foods and beverages. Nonetheless, setubalense volatile composition has never been characterized, and we aimed to unveil the bioactive potential of peels and juices of setubalense tangerines and compare them with the murcott variety grown in Portugal mainland. Using headspace solid-phase microextraction coupled to gas chromatography mass spectrometry (HS-SPME/GC-MS), we identified a total of 128 volatile organic metabolites (VOMs) in the juice and peels, with d-limonene, gamma-terpinene, beta-myrcene, alpha- and beta-pinene, o-cymene, and Terpinolene, the most dominant in both cultivars. In contrast, setubalense juices are richer in terpenes, many of them associated with health protection. Discriminant analysis revealed a pool of VOMs, including beta-caryophyllene and E-ocimene, with bioactive properties able to differentiate among tangerines according to variety and sample type (peel vs. juice). This is the first report on the volatile composition of setubalense tangerines grown on Madeira Island revealing that its pungent aroma is constituted by secondary metabolites with specific aroma notes and health properties. This is strong evidence of the higher nutraceutical value of such fruit for the human diet.

Effect of terpinolene against the resistant Staphylococcus aureus strain, carrier of the efflux pump QacC and beta-lactamase gene, and its toxicity in the Drosophila melanogaster model.[Pubmed:33002597]

Microb Pathog. 2020 Sep 28;149:104528.

Efflux pumps and beta-lactamases are mechanisms of bacterial resistance that exist in Staphylococcus aureus, where both mechanisms are expressed simultaneously in the SA K4100 strain, with its efflux pump being characterized as QacC (Quaternary Ammonium Compounds C). The search for inhibitors of these mechanisms has grown gradually, with research on isolated compounds, including terpenes, which have innumerable biological activities, being common. This study sought to evaluate the antibacterial activity of Terpinolene against the S. aureus K4100 strain, carrying a QacC efflux pump and beta-lactamase, as well as to evaluate its toxicity in the Drosophila melanogaster arthropod model. Determination of the Minimum Inhibitory Concentration (MIC) was performed by broth microdilution. Efflux pump inhibition was evaluated by the MIC reduction of Oxacillin and Ethidium Bromide (EtBr). beta-Lactamase inhibition was analyzed by the MIC reduction of Ampicillin with Sulbactam. Toxicity was verified by mortality parameters and locomotor assays in D. melanogaster. The results demonstrated that Terpinolene did not present a direct antibacterial activity (MIC >/= 1024 mug/mL). However, a reduction in MIC was observed when Terpinolene was associated with Oxacillin (161.26-71.83 mug/mL) and EtBr (45.25-32 mug/mL), possibly by a beta-lactamase and efflux pump inhibition, thus evidencing a modulatory activity. Terpinolene presented D. melanogaster mortality with an EC50 of 34.6 muL/L within 12 h of exposure. Additionally, Terpinolene presented damage to the locomotor system after the second hour of exposure, with the effect increasing in a concentration-dependent manner. In conclusion, new tests should be carried out to investigate the Terpinolene reinforcement of antibiotic activity and toxic activity mechanisms of action.

Enhanced anti-cancer activity of chitosan loaded Morinda citrifolia essential oil against A549 human lung cancer cells.[Pubmed:32853609]

Int J Biol Macromol. 2020 Dec 1;164:4010-4021.

In the present study, the chemical composition of Morinda citrifolia essential oils was determined by gas chromatography-mass spectrometry and was found to contain several anti-cancer compounds including L-scopoletin, nordamnacanthal, beta-morindone, alpha-copaene, 9-H-pyrido[3,4-b]indole, beta-thujene and Terpinolene. The physico-chemical characterization of chitosan, chitosan nanoparticles and Morinda citrifolia essential oils loaded chitosan nanoparticles combination was carried out by Fourier transform infrared spectroscopy, powder X-ray diffraction and dynamic light scattering coupled with zeta potential. The morphological observation obtained by scanning electron microscopy and transmission electron microscopy provided clear indication that the immobile chitosan polymer formed a coating onto the Morinda citrifolia essential oils surface. The cytotoxic effect of Morinda citrifolia essential oils loaded chitosan nanoparticles against A549 cells were investigated, resulting in 54% inhibition at 40 mug/ml(-1). Information about in vitro morphological modification, nucleus damages, ROS generation and cell cycle arrest was obtained by fluorescence microscopy and flow cytometer analysis. The toxicity evaluation against human red blood cells suggested that the Morinda citrifolia essential oils loaded chitosan nanoparticles possess minimum cytotoxicity. Altogether, the present study suggests that these Morinda citrifolia essential oils loaded chitosan nanoparticles are valuable biomaterials owing to their ability to fight against A549 cancer cells.

Chemical composition of the essential oil of Elaeoselinum asclepium (L.) Bertol subsp. meoides (Desf.) Fiori (Umbelliferae) collected wild in Central Sicily and its antimicrobial activity.[Pubmed:32820648]

Nat Prod Res. 2020 Aug 21:1-9.

In the present study, the chemical composition of the essential oils from flowers and leaves of Elaeoselinum asclepium (L.) Bertol subsp. meoides (Desf.) Fiori collected in Central Sicily was evaluated by GC and GC-MS. The main volatile components of the flowers were alpha-phellandrene (42.5%), Terpinolene (15.7%), p-cymene (11.6%) and beta-phellandrene (10.2%), whereas the ones of the leaves were p-cymene (44.0%), alpha-pinene (13.2%), alpha-phellandrene (11.0%), beta-phellandrene (10.2%) and beta-pinene (9.2%). Furthermore, the antibacterial and antifungal activities against some microorganisms infesting historical art craft were determined. The essential oil from leaves (EL) showed to be particularly active against Bacillus subtilis, Staphylococcus aureus and Proteus vulgaris. [Figure: see text].

Identification of key odorants in honeysuckle by headspace-solid phase microextraction and solvent-assisted flavour evaporation with gas chromatography-mass spectrometry and gas chromatograph-olfactometry in combination with chemometrics.[Pubmed:32817641]

PLoS One. 2020 Aug 20;15(8):e0237881.

At present, the identification of honeysuckle aroma depends on experienced tasters, which results in inconsistencies due to human error. The key odorants have the potential to distinguish the different species and evaluate the quality of honeysuckle. Hence, in this study, a more scientific approach was applied to distinguish various honeysuckles. The volatile compounds of different species and parts of honeysuckle were separately extracted by headspace-solid phase microextraction (HS-SPME) and solvent assisted flavor evaporation (SAFE). Compounds with greater volatility such as aldehydes, limonene, gamma-terpinene, and Terpinolene were preferentially extracted by HS-SPME. As a complementary extraction method to HS-SPME, SAFE was found to recover comparatively more polar compounds such as eugenol, decanoic acid, and vanillin. Subsequently, key odorants with the highest flavour dilution (FD) factors were detected by aroma extract dilution analysis (AEDA). These were benzaldehyde, 4-ethylphenol, decanoic acid, vanillin, 3-methyl-2-butenal, and beta-ionone in honeysuckle flowers and gamma-octalactone, 4-ethyl phenol, and vanillin in honeysuckle stem. Finally, principal component analysis (PCA) was conducted to analyze not only the key odorants of species and parts of honeysuckle but also their different origins. The results of PCA suggested that the species of honeysuckle contributed much more to variations in aroma rather than their origins. In conclusion, the application of the key odorants combined with PCA was demonstrated as a valid approach to differentiate species, origins, and parts of honeysuckle.

Potentiation of antifungal activity of terbinafine by dihydrojasmone and terpinolene against dermatophytes.[Pubmed:32790923]

Lett Appl Microbiol. 2020 Aug 13.

Dermatophytoses are infections that affect keratinized tissues. Their main etiologic agents are fungi of the genera Microsporum and Trichophyton. The emergence of resistant fungi and the clinical relevance of dermatophytosis have encouraged studies that aim to increase the arsenal of drugs or act on mechanisms that confer multiple drug resistance. This study investigated the modulating activity of terbinafine promoted by dihydrojasmone and Terpinolene against Microsporum canis LM 216, Trichophyton interdigitale H6 and T. interdigitale Deltamdr2. The minimum inhibitory concentration (MIC) of test drugs was determined by broth microdilution. The effect of the drugs tested on plasma membrane functionality was analysed. Terbinafine MIC was determined in sub-inhibitory concentrations of monoterpenes. Finally, it was performed an association study with terbinafine and monoterpenes. Dihydrojasmone presented lower MIC values than Terpinolene. All fungi were sensitive to terbinafine, starting at 1 mug ml(-1) . All tested drugs increased K(+) release (P < 0.05), affecting the functionality of the plasma membrane. Dihydrojasmone modulated the sensitivity of all strains against terbinafine, and Terpinolene modulated the sensitivity of M. canis LM 216 and T. interdigitale Deltamdr2. The monoterpenes and terbinafine drug associations presented synergism. In conclusion, the results suggest that the dihydrojasmone and Terpinolene are promising antifungal agents that potentiate the antifungal activity of terbinafine against dermatophytes.

[Electrophysiological and behavioral responses of gall midge, Jaapiella sp. to volatiles of host plant Lycium barbarum].[Pubmed:32715695]

Ying Yong Sheng Tai Xue Bao. 2020 Jul;31(7):2299-2306.

Plant-derived volatiles are important for guiding herbivorous insects to their host plants. Jaapiella sp. (Diptera: Cecidomyiidae) is the most serious pest of Lycium barbarum. The young flower buds of L. barbarum are attractive to females of Jaapiella sp. for oviposition in the field. In this study, we compared response of Jaapiella sp. to volatiles from flower buds of L. barbarum at different stages, and clarified the crucial semiochemicals attracting Jaapiella sp. to lay eggs. Volatiles from young and mature flower buds were collected using SPME, and then identified and quantified by gas chromatography-mass spectrometry (GC-MS). Both electrophysiological and behavior experiments were conducted to measure the attraction of eight synthetic compounds to females and screen the crucial components based on gas chromatography-electroantennogram detection (GC-EAD) and Y-tube bioassays, respectively. Results showed that qualitative and quantitative diffe-rences between two odor profiles. Consistent electroantennographic response was observed for eight compounds from headspace collections, of which five synthetic compounds (3-carene, camphene, Terpinolene, d-limonene, and (+)-pinene) were essential for significant preference or avoidance. Our results indicated that these compounds from L. barbarum flower buds could be effective candidates as oviposition attractant or repellents of Jaapiella sp., which would be helpful in the exploitation of new control agent to Jaapiella sp. in the field.

[Allelopathic effects of velvetleaf volatile oil on germination and seedling growth of wheat, maize, and soybean].[Pubmed:32715688]

Ying Yong Sheng Tai Xue Bao. 2020 Jul;31(7):2251-2256.

Velvetleaf (Abutilon theophrasti) is a common weed in dryland, which can reduce crop yield. Allelopathy is one of the possible reasons resulting in crop yield reduction. In this study, we analyzed the allelopathic effect of velvetleaf volatile oil components on germination and seedling growth of three dryland crops, wheat (Triticum aestivum), maize (Zea mays), and soybean (Glycine max). A total of 26 compounds in velvetleaf volatile oil were identified by GC-MS, accounting for 98.1% of the total chromatographic peak areas. The terpenes with lower molecular weight in the volatile oil were alpha-pinene, eucalyptol, alpha-Terpinolene, beta-terpinene, trans-alpha-ionone, and trans-beta-ionone. The saturated aqueous solution of velvetleaf volatile oil could inhibit seed germination of three crops by filter paper and soil. Velvetleaf volatile oil could inhibit the seedling growth of three crops through air, filter paper, and soil. Wheat was the most susceptible to volatile oil, followed by maize and soybean. The inhibitory effect of volatile oil on the growth of wheat was the strongest in air medium, followed by filter paper and soil medium. The lower molecular weight of terpene components from volatile oil might be the important allelochemicals.

Antioxidant, DNA damage protective, antibacterial activities and nitrite scavenging ability of essential oil of Amomum kravanh from China.[Pubmed:32662302]

Nat Prod Res. 2020 Jul 14:1-5.

Chemical composition, in vitro antioxidant, DNA damage protective, nitrite scavenging activities, as well as antibacterial activity of Amomum kravanh fruits essential oil against several foodborne pathogens, were investigated. Results showed that the 1,8-cineole (58.53%) was found as the main component, followed by alpha-pinene (8.32%), alpha-terpinyl acetate (4.68%), alpha-Terpinolene (4.12%), alpha-terpinene (3.55%), beta-pinene (3.49%). The essential oil had significant antioxidant activity, the protective effect against DNA damage, and nitrite scavenging activity. These biological activities were dose-dependent, increasing with the higher dosage in a certain concentration range. The essential oil exhibited antibacterial activity against four foodborne pathogens with the minimum inhibitory concentration (MIC) of 5-10 mg/mL and minimum bactericide concentration (MBC) of 10-20 mg/mL. The antibacterial effects of essential oil were greater against Gram-positive bacteria as compared to Gram-negative bacteria. These results suggested that essential oil could be available as a significant natural agent for prevention of food oxidation and spoilage.