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The efficacy of 30 aromatic compounds and their mutual binary combinations was assessed for acute toxicity against the larvae Culex quinquefasciatus. Based on comparison of the lethal doses, thymol and p-cymene were selected as the most effective (LD50 = 18 and 21 mg L−1, respectively, and LD90 = 25 and 30 mg L−1, respectively). Although the LD50 for terpinolene and trans-anethole was also estimated at 21 mg L−1, their LD90 was significantly higher compared to the substances above (245 and 34 mg L−1, respectively). In total, 435 binary combinations were tested, of which 249 combinations showed a significant synergistic effect, while 74 combinations showed a significant antagonistic effect on mortality. Only nine substances were identified as being able to create a synergistic effect with more than 20 substances: limonene, trans-anethole, 4-allylanisole, carvacrol, isoeugenol, menthone, carvone, borneol, and camphor. The highest synergistic effect on larval mortality was achieved for the combinations: eugenol and isoeugenol, carvone and carvacrol, carvone and 4-allylanisole, carvone and α-terpineol, carvone and menthone, limonene and trans-anethole, limonene and menthone, α-pinene and menthone, β-citronellol and menthone, carvacrol and 4-allylanisole, carvacrol and terpineol, α-terpinene and trans-anethole, camphor and menthone, camphene and menthone, and 4-allylanisole and menthone. Significant differences between achieved mortality and the mutual mixing ratio were found for the five selected binary mixtures that had shown the most significant synergistic effect in the previous tests. The mixture of limonene and trans-anethole showed the highest mortality, with the mixing ratio 1:1; the mixture of eugenol and isoeugenol caused 90.2 % mortality, with the mixing ratio 1:3. One hundred percent mortality was achieved if carvacrol was contained in a mixture with carvone in a ratio >2. After a comparison of all our results, based on our experiments, we can choose two pairs that caused mortality higher than 90 % in concentrations lower than 20 mg L−1: limonene and trans-anethole (with the mixing ratio 1:1), and carvone and carvacrol (with the mixing ratio 1:2–3). The information gained can thus be used in the development of new botanical insecticides based on essential oils (EOs) and particularly in the creation of formulations.

This study aimed to evaluate the antibacterial activities of α-terpineol against common foodborne pathogenic bacteria by agar well diffusion, broth microdilution, and colony counting assay. Propulsive research was conducted to reveal the antibacterial mechanisms, including morphology, infrared spectroscopy, membrane fluidity, membrane permeability, proton motive force, and oxidative phosphorylation. Results indicated that the antibacterial activity of α-terpineol decreased in the following order: Escherichia coli O157:H7, Salmonella typhimurium, Listeria monocytogenes, and Staphylococcus aureus. With an initial cell count of 8 log CFU/mL, α-terpineol at 0.8% (v/v) reduced E. coli O157:H7 and S. aureus by approximately 5.6 and 3.9 log CFU/mL within 1 h, respectively. Remarkable destruction in cell envelopes and intracellular organizations was observed. The hydroxyl of α-terpineol might form glycosidic bonds with carbohydrates and hydrogen bonds with PO2− and COO− via infrared spectroscopy analysis. Generalized polarization of Laurdan revealed that the polar head groups of phospholipids transformed into close packed. The anisotropy variations of trimethyl amino-diphenylhexatriene (TMA-DPH) and DPH suggested membrane fluidity decreased. The N-phenyl-1-naphthylamine intake assay indicated that α-terpineol impaired the cell wall. Propidium iodide staining was indicative of damaged plasma membranes. Electron transport in the cytoplasmic membrane was impaired, inducing reactive oxygen species accumulation. Both membrane electrical potential and membrane pH gradient collapsed. The disruption of proton motive force and the leakage of ATP resulted in a deficit of intracellular ATP. Our research revealed the interaction between the hydroxyl group of α-terpineol and bacteria affects membrane function contributing to the bacteria’s death.Key points• α-Terpineol hydroxy formed glycosidic bonds and hydrogen bonds with bacteria• α-Terpineol increased the membrane gelation and reduced the membrane fluidity• Proton motive force and oxidative phosphorylation were impaired

A total of 98 compounds including 20 aldehydes, eight arenes, six acids, 17 alcohols, 13 ketones, nine esters, nine methoxyphenolics, three alkenes, seven alkanes, and six other components were tentatively identified in six Chinese dark teas (CDTs) using gas chromatography–mass spectrometry. Multivariate statistical analysis revealed that dark teas from Yunnan and Guangxi provinces could be classified into one group, and other CDTs belonged to the other cluster. The diagnostic volatile compounds being responsible for CDTs' discrimination were observed as (E,E)-2,4-decadienal, methoxyphenolics, geraniol, α-terpineol, 2,4-heptadienal, cis-jasmone, linalool oxides, and 2-nonenal. Furthermore, mature tea leaves were separately fermented using Eurotium cristatum and Aspergillus niger. The results showed that E. cristatum increased the contents of cis-jasmone, α-terpineol, ß-ionone, nonanal, and 2-pentylfuran, whereas A. niger advanced the levels of geraniol, linalool oxides, 9,12-octadecadienoic acid, and ß-ionone after short-term fermentation. Fungus species may contribute to forming the flavor of Chinese dark teas by affecting the volatile compounds during postfermentation. [Display omitted] •Various Chinese dark teas were analyzed using gas chromatography–mass spectrometry.•Metabolomics analysis reclassified these dark teas.•The marker volatile compounds were identified.•Eurotium cristatum increased cis-jasmone, α-terpineol, and ß-ionone.•Aspergillus niger increased geraniol, linalool oxides, 9,12-octadecadienoic acid, and ß-ionone.

This study investigates the antimicrobial efficacy, synergistic interactions, antibiofilm activity, molecular docking studies, and drug-likeness properties of α-terpineol, 4-carvomenthenol, and their derivatives isolated from nutmeg and mace ( Myristica fragrans Houtt.). α-Terpineol and 4-carvomenthenol were isolated from nutmeg essential oil and mace oleoresin respectively using column chromatography. Derivatization of α-Terpineol was derivatized into its ester, epoxide, ether, and allylic bromide while 4-carvomenthenol was derivatized to form its ester and epoxide. The antimicrobial activity of isolated compounds and their derivatives was assessed against Bacillus sp ., Staphylococcus aureus , Yersinia enterocolitica and Escherichia coli followed by testing of their synergistic interactions with streptomycin. Additionally, the antibiofilm activity of the most effective treatments alone and in combination with was tested in combination with streptomycin was also evaluated. Molecular docking studies were conducted to assess binding affinities of the most effective treatments for DNA gyrase and transpeptidase followed byADMET profiling to evaluate their drug-likeness. The ester derivatives of α-terpineol and 4-carvomenthenol demonstrated the highest antibacterial potential with MIC values ranging from 40 to 170 µg/ml. Both the ester derivatives showed significant synergistic interactions with streptomycin and exhibited strong to intermediate antibiofilm activity against all the tested bacteria. Molecular docking studies indicated favorable binding affinities (–6.56 to − 4.31 kcal/mol) of ester derivatives for DNA gyrase and transpeptidase as compared to their parent compounds having favorable physicochemical properties, meeting drug-likeness criteria. α-Terpineol ester and 4-carvomenthenol ester exhibited promising antimicrobial potential, synergistic interaction with streptomycin and antibiofilm properties, suggesting their potential as novel therapeutic agents. Further development and investigation of these compounds are warranted to explore their applications in clinical settings.

Background Alpha-Terpineol (α-Terpineol), a C 10 monoterpenoid alcohol, is widely used in the cosmetic and pharmaceutical industries. Construction Saccharomyces cerevisiae cell factories for producing monoterpenes offers a promising means to substitute chemical synthesis or phytoextraction. Results α-Terpineol was produced by expressing the truncated α-Terpineol synthase (tVvTS) from Vitis vinifera in S. cerevisiae . The α-Terpineol titer was increased to 0.83 mg/L with overexpression of the rate-limiting genes tHMG1 , IDI1 and ERG20 F96W-N127W . A GSGSGSGSGS linker was applied to fuse ERG20 F96W-N127W with tVvTS, and expressing the fusion protein increased the α-Terpineol production by 2.87-fold to 2.39 mg/L when compared with the parental strain. In addition, we found that farnesyl diphosphate (FPP) accumulation by down-regulation of ERG9 expression and deletion of LPP1 and DPP1 did not improve α-Terpineol production. Therefore, ERG9 was overexpressed and the α-Terpineol titer was further increased to 3.32 mg/L. The best α-Terpineol producing strain LCB08 was then used for batch and fed-batch fermentation in a 5 L bioreactor, and the production of α-Terpineol was ultimately improved to 21.88 mg/L. Conclusions An efficient α-Terpineol production cell factory was constructed by engineering the S. cerevisiae mevalonate pathway, and the metabolic engineering strategies could also be applied to produce other valuable monoterpene compounds in yeast.

A new type of heterogeneous catalyst for hydration of α -pinene was prepared. Montmorillonite K10 was treated by various acids (H 2 SO 4 , HCl, HNO 3 , and ClCH 2 COOH) and successfully used for the mentioned reaction. The used characterization techniques showed that the acid treatment improved the properties of K10 important for the catalytic activity (S BET and acidity). On the other hand, the morphology and particle size distribution remained the same. Regarding the selectivity (side and consecutive reactions can proceed), the optimal reaction conditions were found (temperature, type of the catalyst, amount of the catalyst, molar ratio α -pinene: water, type of water, solvent). Using the optimal reaction conditions, 60% conversion of α -pinene was achieved with 45% selectivity to α -terpineol (80 °C, 25 wt% of K10/HCl, or K10/H2SO4, n α -pinene :n water 1:7.5, 1,4-dioxane as a solvent, 24 h). Higher conversions of α -pinene, as well as higher selectivity to α -terpineol, were achieved using all acid treated K10 in comparison to raw K10. Considering the heterogeneous form of prepared catalysts, its availability, low price and easy method of preparation, these catalysts dispose of a large potential for application as catalysts for hydration reactions. Graphic Abstract

Cutaneous melanoma is an aggressive skin cancer known for its ability to metastasize, resist treatment, and result in poor outcomes. With rising global incidence, early diagnosis and effective treatment strategies are imperative. Plant-derived extracts and natural compounds have emerged as promising therapeutic agents against various cancers, including melanoma. α-Terpineol, a volatile monoterpenoid alcohol found in pine needle oil and other essential oils, has demonstrated significant antitumor activity. We evaluated α-terpineol’s effects using scratch wound, Transwell, and colony formation assays to assess migration, invasion, and clonogenicity. Cell proliferation and apoptosis were examined via EdU and AO/EB staining, while flow cytometry analyzed cell cycle distribution and apoptosis rates. Potential targets were identified through network pharmacology and molecular docking, while Western blotting confirmed pathways related to apoptosis. A B16-F10 xenograft model was used to further validate in vivo efficacy. In vitro studies demonstrated that α-terpineol inhibits melanoma cell proliferation, migration, and invasion by triggering apoptosis. Network pharmacology identified the JAK2/STAT3 signaling pathway as crucial, with Western blot analysis showing reduced levels of p-JAK2 and p-STAT3. In vivo, α-terpineol inhibited tumor growth without causing systemic toxicity. α-Terpineol may attenuate melanoma progression by inhibiting JAK2/STAT3 signaling, highlighting its potential as a novel therapeutic candidate.

α-Terpineol (CAS No. 98-55-5) is a tertiary monoterpenoid alcohol widely and commonly used in the flavors and fragrances industry for its sensory properties. It is present in different natural sources, but its production is mostly based on chemical hydration using α-pinene or turpentine. Moreover, many bioprocesses for the microbial production of α-terpineol via biotransformation of monoterpenes (limonene, α- and β-pinenes) are also available in the literature. In addition to its traditional use, α-terpineol has also been evaluated in other application fields (e.g., medical), since some biological properties other than aroma, such as antioxidant, anti-inflammatory, antiproliferative, antimicrobial, and analgesic effects, among others, have been attributed to this compound. Therefore, this review presents an original compilation of data regarding the production (extraction directly from nature; chemical synthesis; via biotechnological process), the chemical and biological properties, and the current market and novel applications of α-terpineol to guide further research in this area. Considering the information presented, we believe that α-terpineol applications may transcend the flavors and fragrances industry in the future.

Sour orange (Citrus aurantium L.), which belongs to the Rutaceae family, is used around the Mediterranean Sea for ornamental and agronomic purposes as a rootstock for the Citrus species. Peels and flowers, the most-used parts of Citrus aurantium L., have constituted a largely promising area of research for their many medicinal properties. However, the leaves of sour orange have not yet been studied extensively. The present study aimed at investigating the essential oil composition of sour orange leaves grown in Algeria and determining their antioxidant and anti-inflammatory properties. Essential oil composition of leaves harvested before flowering was determined by GC-MS. Total phenol content, antioxidant activities (DPPH) and elastase and collagenase inhibition were assessed. Forty-three volatile compounds were detected in essential oil from leaves with a yield of 0.57%. The major compounds were linalool, linalyl acetate and α-Terpineol. Results show that the total phenol content and antioxidant activity of essential oil are low, 3.48 ± 0.10 mg/g (Gallic Acid Equivalent/EO) and IC50 > 10,000 mg·L−1, respectively. In contrast, EO present an interesting level of elastase and collagenase inhibition. This result emphasizes the potential interest of the essential oil of sour orange mainly in relation to its anti-aging mechanism.

The monooxygenase activity of engineered CYP102A1 on α-terpineol was investigated. CYP102A1 M850 mutant (F11Y/R47L/D68G/F81I/F87V/E143G/L188Q/E267V/H408R) showed the highest catalytic activity toward α-terpineol among the engineered mutants produced by random mutagenesis. The major product (P1) of α-terpineol, p -menth-1-ene-3,8-diol, was characterized by high-performance liquid chromatography, gas-chromatography mass spectrometry, and nuclear magnetic resonance spectroscopy. Three minor products (P2–P4) of α-terpineol were considered as 6-hydroxy-α,α,4-trimethyl-3-cyclohexene-1-methanol (P2), trans -sobrerol (P3), and carvone hydrate (P4). Optimal conditions for product formation were determined as pH 7.0 and 30 °C. Production of p -menth-1-ene-3,8-diol was 0.87 mM at 1 h. Structure modeling using PyMOL and CAVER Web 1.2 server indicated that several mutations of CYP102A1 M850 were involved in access tunnels and active sites, resulting in increased activity toward α-terpineol. The major product, p -menth-1-ene-3,8-diol, of α-terpineol was produced by engineered CYP102A1 M850 via regioselective carbon hydroxylation. The engineered CYP102A1 could be a suitable biocatalyst for producing α-terpineol derivatives.