Objective:To investigate the underlying mechanism of anti-inflammatory action of coumarin and eugenol in lipopolysaccharide(LPS)-stimulated RAW 264.7 cells.Methods:RAW 264.7 cells were treated with 2.5μg/mL of LPS,50...Objective:To investigate the underlying mechanism of anti-inflammatory action of coumarin and eugenol in lipopolysaccharide(LPS)-stimulated RAW 264.7 cells.Methods:RAW 264.7 cells were treated with 2.5μg/mL of LPS,50μM of coumarin,and 50μM eugenol for 24 h.The viability of the cells was assessed using MTT assay.The production of nitric oxide was determined using Griess reagent and DCFH-DA was used to measure the production of reactive oxygen species.The protein expression of NLRP3,IL-1β,NF-κB,and cyclooxygenase 2 was assessed using Western blot analysis.Results:Coumarin and eugenol showed anti-inflammatory effects against LPS-induced inflammatory response by ameliorating the expression of NLRP3 inflammasome and NF-κB,which further led to a subsequent reduction in IL-1β,nitric oxide,and reactive oxygen species.Conclusions:Coumarin and eugenol exert their anti-inflammatory activities by modulating the NLRP3 inflammasome pathway and NF-κB.These compounds may have promising therapeutic applications for the treatment of various inflammatory diseases.展开更多
Staphylococcus aureus is a serious foodborne pathogen threatening food safety and public health.Especially the emergence of methicillin-resistant Staphylococcus aureus(MRSA)increased the difficulty of S.aureus treatme...Staphylococcus aureus is a serious foodborne pathogen threatening food safety and public health.Especially the emergence of methicillin-resistant Staphylococcus aureus(MRSA)increased the difficulty of S.aureus treatment.Staphyloxanthin is a crucial virulence factor of S.aureus.Blocking staphyloxanthin production could help the host immune system counteract the invading S.aureus cells.In this study,we first screened for staphyloxanthin inhibitors using a virtual screening method.The outcome of the virtual screening method resulted in the identification of eugenol(300μg/mL),which significantly inhibits the staphyloxanthin production in S.aureus ATCC 29213,S.aureus Newman,MRSA ATCC 43300 and MRSA ATCC BAA1717by 84.2%,63.5%,68.1%,and 79.5%,respectively.The outcome of the growth curve assay,field-emission scanning electron,and confocal laser scanning microscopy analyses confirmed that eugenol at the test concentration did not affect the morphology and growth of S.aureus.Moreover,the survival rate of S.aureus ATCC 29213 and MRSA ATCC 43300 under H_(2)O_(2) pressure decreased to 51.9%and 45.5%in the presence of eugenol,respectively.The quantitative RT-PCR and molecular simulation studies revealed that eugenol targets staphyloxanthin biosynthesis by downregulating the transcription of the crtM gene and inhibiting the activity of the CrtM enzyme.Taken together,we first determined that eugenol was a prominent compound for staphyloxanthin inhibitor to combat S.aureus especially MRSA infections.展开更多
Spices are defined as any aromatic condiment of plant origin used to alter the flavor and aroma of foods. Besides flavor and aroma, many spices have antioxidant activity, mainly related to the presence in cloves of ph...Spices are defined as any aromatic condiment of plant origin used to alter the flavor and aroma of foods. Besides flavor and aroma, many spices have antioxidant activity, mainly related to the presence in cloves of phenolic compounds, such as flavonoids, terpenoids and eugenol. In turn, the most common uses of gum arabic are in the form of powder for addition to soft drink syrups, cuisine and baked goods, specifically to stabilize the texture of products, increase the viscosity of liquids and promote the leavening of baked products (e.g., cakes). Both eugenol, extracted from cloves, and gum arabic, extracted from the hardened sap of two species of the Acacia tree, are dietary constituents routinely consumed virtually throughout the world. Both of them are also widely used medicinally to inhibit oxidative stress and genotoxicity. The prevention arm of the study included groups: Ia, IIa, IIIa, Iva, V, VI, VII, VIII. Once a week for 20 weeks, the controls received saline s.c. while the experimental groups received DMH at 20 mg/kg s.c. During the same period and for an additional 9 weeks, the animals received either water, 10% GA, EUG, or 10% GA + EUG by gavage. The treatment arm of the study included groups Ib, IIb, IIIb e IVb, IX, X, XI, XII). Once a week for 20 weeks, the controls received saline s.c. while the experimental groups received DMH at 20 mg/kg s.c. During the subsequent 9 weeks, the animals received either water, 10% GA, EUG or 10% GA + EUG by gavage. The novelty of this study is the investigation of their use alone and together for the prevention and treatment of experimental colorectal carcinogenesis induced by dimethylhydrazine. Our results show that the combined use of 10% gum arabic and eugenol was effective, with antioxidant action in the colon, as well as reducing oxidative stress in all colon segments and preventing and treating genotoxicity in all colon segments. Furthermore, their joint administration reduced the number of aberrant crypts and the number of aberrant crypt foci (ACF) in the distal segment and entire colon, as well as the number of ACF with at least 5 crypts in the entire colon. Thus, our results also demonstrate the synergistic effects of 10% gum arabic together with eugenol (from cloves), with antioxidant, antigenotoxic and anticarcinogenic actions (prevention and treatment) at the doses and durations studied, in the colon of rats submitted to colorectal carcinogenesis induced by dimethylhydrazine.展开更多
[Objective] The aim of the study is to seek a good anesthetic to Fenneropenaeus chinensis. [Method] The anesthetic effect of eugenol to juvenile Fenneropenaeus chinensis was investigated. [Result] The juveniles could ...[Objective] The aim of the study is to seek a good anesthetic to Fenneropenaeus chinensis. [Method] The anesthetic effect of eugenol to juvenile Fenneropenaeus chinensis was investigated. [Result] The juveniles could be effectively anaesthetized by 50-400 mg/L eugenol aqueous solution with temperature of 24 ℃. Within the concentration range of 50-400 mg/L, the increase of the eugenol concentration could shorten the time required for anesthesia, meanwhile could prolong the time for recovery. The recovered rate of prawn reached 100% when the eugenol concentration was lower than 200 mg/L, while the recovered rate of prawn was just 66.67% when the eugenol concentration was higher than 400 mg/L. The survival rate of prawns in test group was 100% from the observation of three consecutive days. For the specific dose, the anesthetic effect enhanced with the increase of water temperature (18-27℃). [Conclusion] Eugenol is a safe and efficient anesthetics that can be applied in genetic breeding of prawn.展开更多
Eugenol, an aromatic product, exhibits anti-inflammatory properties, however, little is known about its effect in allergic inflammation mediated by Th2-type cells and cytokines. We examined the pharmacological potenti...Eugenol, an aromatic product, exhibits anti-inflammatory properties, however, little is known about its effect in allergic inflammation mediated by Th2-type cells and cytokines. We examined the pharmacological potential of this compound in a murine model of respiratory allergy to Bt （Blomia tropicalis）. For this, AJ mice were sensitized （100μg/animal s.c.） and challenged （10 μg/animal i.n.） with Bt mite extract. Sensitized animals were treated or not with eugenol （20, 40 or 80 mg/kg） and the following parameters were analyzed： number of total cells in BAL （bronchoalveolar lavage）; EPO （eosinophil peroxidase activity） and histopathological changes in the lungs; serum level of specific IgE, IgG1 and IgG2a and; concentration of Th2 cytokines on BAL and spleen cultures. In addition, the capability ofeugenol in relaxing tracheal smooth muscle was also evaluated. Our results showed that treatment with eugenol significantly reduced the airway inflammation, decreasing the cellular infiltrate, EPO and mucus in the lungs, as well as the production of Th2 cytokines. It was also demonstrated a dilator effect of eugenol observed by the relaxation of normal and hyper-reactivity isolated trachea upon carbachol stimulation. These results suggest that eugenol has potential as an anti-asthmatic drug by both bronchodilator and immunomodulatory properties.展开更多
Eugenol is a natural phenolic compound known for its health-promoting properties and its ability to add a floral scent to tea plants.Plant eugenol glycosides have been identified and shown to make important contributi...Eugenol is a natural phenolic compound known for its health-promoting properties and its ability to add a floral scent to tea plants.Plant eugenol glycosides have been identified and shown to make important contributions to fruit floral quality.However,the details of their biosynthesis and metabolism in tea plants are still unknown.Here,eugenol glucoside was unambiguously identified as a native metabolite in the tea plant,and its biosynthesis was shown to be induced by low temperature treatment.Through the analysis of UGTs induced by low temperature,the glycosyltransferase CsUGT78A15 was identified in tea,and its encoded protein was shown to catalyze the glucosylation of eugenol.Vmax/Km ratios showed that eugenol was the most suitable substrate for CsUGT78A15.Sugar donor preference analysis showed that CsUGT78A15 had a higher selectivity for glucose,followed by galactose and glucuronic acid.The expression of CsUGT78A15was correlatedwith the accumulation of eugenol glucoside in different tissues and genotypes of tea.Down-regulation of CsUGT78A15 led to a decreased eugenol glucoside content under cold stress,indicating that CsUGT78A15 plays an important role in the biosynthesis of eugenol glucoside under cold stress.The identification of eugenol glucoside in the tea plant and the discovery of a cold stress-induced eugenol glucosyltransferase in tea provide the foundation for the improvement of tea flavor under cold stress and the biotechnological production of eugenol glucoside.展开更多
Hydrodeoxygenation（HDO） is an effective alternative to produce value-added chemicals and liquid fuels by removing oxygen from lignin-derived compounds. Sulfide catalysts have been proved to have good activity for th...Hydrodeoxygenation（HDO） is an effective alternative to produce value-added chemicals and liquid fuels by removing oxygen from lignin-derived compounds. Sulfide catalysts have been proved to have good activity for the HDO and particularly high selectivity to phenolic products. Herein, we presented a novel way to prepare the layered structure sulfide catalysts（MgFeMo-S） derived from MgFe hydrotalcites via the intercalation of Mo in consideration of the memory effect of the calcined hydrotalcite. By varying the Mg/Fe mole ratio, a series of MgFeMo-S catalysts were successfully prepared and characterized by nitrogen adsorption/desorption isotherms, X-ray diffraction（XRD）, transmission electron microscopy（TEM）,and inductively coupled plasma optical emission spectrometer（ICP-OES）. The characterization results indicated that the MgFeMo-S catalyst has retained the unique layered structure, which can facilitate uniform dispersion of the MoS2 species on both the surface and interlayer of the catalysts. For the HDO of eugenol, the Mg1Fe2Mo-S catalysts exhibited the best HDO activity among all the catalysts due to its higher active metal contents and larger pore size. The HDO conversion was 99.6% and the yield of phenolics was 63.7%, under 5 MPa initial H2 pressure（measured at RT） at 300 ℃ for 3 h. More importantly,MoS2 species deposited on the interlayer galleries in the MgFeMo-S catalysts resulted in dramatically superior HDO activity to MoS2/Mg1Fe2-S catalyst. Based on the mechanism investigation for eugenol, the HDO reaction route of eugenol under sulfide catalytic system has been proposed for the first time. Further applicability of the catalyst on HDO of more lignin-derived compounds was operated, which showed good HDO activity and selectivity to produce aromatic products.展开更多
The present study aimed to evaluate <i>Syzygium aromaticum</i> (clove) plant extract, clove oil and eugenol for their antibacterial activity and their potential to eradicate bacterial biofilms alone and in...The present study aimed to evaluate <i>Syzygium aromaticum</i> (clove) plant extract, clove oil and eugenol for their antibacterial activity and their potential to eradicate bacterial biofilms alone and in combination with antibiotics. Anti-bacterial efficacy of <i>S. aromaticum</i> extract, clove oil and eugenol was evaluated as minimum inhibitory concentration (MIC) and subsequently sub-MICs was selected for inhibition of virulence factors against test bacterial strains. Biofilm cultivation and eradication was assayed using XTT reduction in 96-well microtiter plate. Checkerboard method was used to study the interaction between essential oils and antibiotics. <i>Staphylococcus aureus</i> MTCC3160, <i>Staphylococcus epidermidis</i> MTCC435, <i>Staphylococcus sciuri</i> (SC-01), <i>Staphylococcus auricularis</i> (SU-01) <i>and</i> <i>Streptococcus mutans</i> MTCC497 were found strong biofilm former among all the test bacterial strains. The potency of test agents was found in the order of eugenol > clove oil > <i>S. aromaticum</i> methanolic extract. Sub-MIC (0.5 × MIC) of clove oil and eugenol showed a significant reduction in cell surface hydrophobicity (<i>p </i>< 0.05) and hemolysin production in the test bacterial strains. Eugenol showed no increase in sessile MIC (SMIC) against <i>S. auricularis</i> (SU-01), <i>S. epidermidis</i> MTCC435 and <i>S. mutans</i> MTCC497 compared to planktonic MIC (PMIC). Antibiotics (vancomycin and azithromycin) exhibited upto 1000-folds increased in SMIC compared to PMIC against all the test bacterial strains. Synergy was observed between eugenol and antibiotics (vancomycin/azithromycin) against all the test bacterial strains in both planktonic and sessile mode. Highest synergy was exhibited between eugenol and azithromycin in planktonic mode (FICI value 0.141). Further, microscopy also confirmed the spectacular effect of combination treatment on pre-formed <i>S. aureus</i> MTCC3160 and <i>S. mutans</i> MTCC497 biofilms. These findings highlighted the promising role of clove oil and eugenol alone and in combination on pathogenic bacterial biofilms.展开更多
Eugenol, both in its pure form (EG) and included in essential clove oil (CO) was successfully solubilized in aqueous solution by forming inclusion complexes with β-cyclodextrins (β-CDs) and its modified hydroxy-prop...Eugenol, both in its pure form (EG) and included in essential clove oil (CO) was successfully solubilized in aqueous solution by forming inclusion complexes with β-cyclodextrins (β-CDs) and its modified hydroxy-propyl-β-CDs (HP-β-CDs). To investigate the molecular association between β-CDs/HP-β-CDs with pure EG and essential CO, phase solubility studies were undertaken. Essential CO formed insoluble complexes with β-CDs, but not with HP-β-CDs. The work clearly demonstrates complexes formation follow an order higher than 1:1 when high essential CO and β-CDs concentrations were used, however it was 1:1 in the case of essential CO-HP-β-CDs complexes. When pure EG was studied the results indicated that EG could form 1:1 inclusion complexes with β-CDs and HP-β-CDs. Based on the studies, the Kc values for pure EG were 4555 ± 225 M-1 and 10,633 ± 614 M-1 for β-CDs and HP-β-CDs, respectively, and 2005 ± 199 M-1 for essential CO-HP-β-CDs. These finding indicate that CDs are suitable for encapsulating EG.展开更多
基金supported by the Defence Institute of Physiology and Allied Sciences.
文摘Objective:To investigate the underlying mechanism of anti-inflammatory action of coumarin and eugenol in lipopolysaccharide(LPS)-stimulated RAW 264.7 cells.Methods:RAW 264.7 cells were treated with 2.5μg/mL of LPS,50μM of coumarin,and 50μM eugenol for 24 h.The viability of the cells was assessed using MTT assay.The production of nitric oxide was determined using Griess reagent and DCFH-DA was used to measure the production of reactive oxygen species.The protein expression of NLRP3,IL-1β,NF-κB,and cyclooxygenase 2 was assessed using Western blot analysis.Results:Coumarin and eugenol showed anti-inflammatory effects against LPS-induced inflammatory response by ameliorating the expression of NLRP3 inflammasome and NF-κB,which further led to a subsequent reduction in IL-1β,nitric oxide,and reactive oxygen species.Conclusions:Coumarin and eugenol exert their anti-inflammatory activities by modulating the NLRP3 inflammasome pathway and NF-κB.These compounds may have promising therapeutic applications for the treatment of various inflammatory diseases.
基金supported by the National Natural Science Foundation of China (31972169 and 32001798)。
文摘Staphylococcus aureus is a serious foodborne pathogen threatening food safety and public health.Especially the emergence of methicillin-resistant Staphylococcus aureus(MRSA)increased the difficulty of S.aureus treatment.Staphyloxanthin is a crucial virulence factor of S.aureus.Blocking staphyloxanthin production could help the host immune system counteract the invading S.aureus cells.In this study,we first screened for staphyloxanthin inhibitors using a virtual screening method.The outcome of the virtual screening method resulted in the identification of eugenol(300μg/mL),which significantly inhibits the staphyloxanthin production in S.aureus ATCC 29213,S.aureus Newman,MRSA ATCC 43300 and MRSA ATCC BAA1717by 84.2%,63.5%,68.1%,and 79.5%,respectively.The outcome of the growth curve assay,field-emission scanning electron,and confocal laser scanning microscopy analyses confirmed that eugenol at the test concentration did not affect the morphology and growth of S.aureus.Moreover,the survival rate of S.aureus ATCC 29213 and MRSA ATCC 43300 under H_(2)O_(2) pressure decreased to 51.9%and 45.5%in the presence of eugenol,respectively.The quantitative RT-PCR and molecular simulation studies revealed that eugenol targets staphyloxanthin biosynthesis by downregulating the transcription of the crtM gene and inhibiting the activity of the CrtM enzyme.Taken together,we first determined that eugenol was a prominent compound for staphyloxanthin inhibitor to combat S.aureus especially MRSA infections.
文摘Spices are defined as any aromatic condiment of plant origin used to alter the flavor and aroma of foods. Besides flavor and aroma, many spices have antioxidant activity, mainly related to the presence in cloves of phenolic compounds, such as flavonoids, terpenoids and eugenol. In turn, the most common uses of gum arabic are in the form of powder for addition to soft drink syrups, cuisine and baked goods, specifically to stabilize the texture of products, increase the viscosity of liquids and promote the leavening of baked products (e.g., cakes). Both eugenol, extracted from cloves, and gum arabic, extracted from the hardened sap of two species of the Acacia tree, are dietary constituents routinely consumed virtually throughout the world. Both of them are also widely used medicinally to inhibit oxidative stress and genotoxicity. The prevention arm of the study included groups: Ia, IIa, IIIa, Iva, V, VI, VII, VIII. Once a week for 20 weeks, the controls received saline s.c. while the experimental groups received DMH at 20 mg/kg s.c. During the same period and for an additional 9 weeks, the animals received either water, 10% GA, EUG, or 10% GA + EUG by gavage. The treatment arm of the study included groups Ib, IIb, IIIb e IVb, IX, X, XI, XII). Once a week for 20 weeks, the controls received saline s.c. while the experimental groups received DMH at 20 mg/kg s.c. During the subsequent 9 weeks, the animals received either water, 10% GA, EUG or 10% GA + EUG by gavage. The novelty of this study is the investigation of their use alone and together for the prevention and treatment of experimental colorectal carcinogenesis induced by dimethylhydrazine. Our results show that the combined use of 10% gum arabic and eugenol was effective, with antioxidant action in the colon, as well as reducing oxidative stress in all colon segments and preventing and treating genotoxicity in all colon segments. Furthermore, their joint administration reduced the number of aberrant crypts and the number of aberrant crypt foci (ACF) in the distal segment and entire colon, as well as the number of ACF with at least 5 crypts in the entire colon. Thus, our results also demonstrate the synergistic effects of 10% gum arabic together with eugenol (from cloves), with antioxidant, antigenotoxic and anticarcinogenic actions (prevention and treatment) at the doses and durations studied, in the colon of rats submitted to colorectal carcinogenesis induced by dimethylhydrazine.
文摘[Objective] The aim of the study is to seek a good anesthetic to Fenneropenaeus chinensis. [Method] The anesthetic effect of eugenol to juvenile Fenneropenaeus chinensis was investigated. [Result] The juveniles could be effectively anaesthetized by 50-400 mg/L eugenol aqueous solution with temperature of 24 ℃. Within the concentration range of 50-400 mg/L, the increase of the eugenol concentration could shorten the time required for anesthesia, meanwhile could prolong the time for recovery. The recovered rate of prawn reached 100% when the eugenol concentration was lower than 200 mg/L, while the recovered rate of prawn was just 66.67% when the eugenol concentration was higher than 400 mg/L. The survival rate of prawns in test group was 100% from the observation of three consecutive days. For the specific dose, the anesthetic effect enhanced with the increase of water temperature (18-27℃). [Conclusion] Eugenol is a safe and efficient anesthetics that can be applied in genetic breeding of prawn.
文摘Eugenol, an aromatic product, exhibits anti-inflammatory properties, however, little is known about its effect in allergic inflammation mediated by Th2-type cells and cytokines. We examined the pharmacological potential of this compound in a murine model of respiratory allergy to Bt （Blomia tropicalis）. For this, AJ mice were sensitized （100μg/animal s.c.） and challenged （10 μg/animal i.n.） with Bt mite extract. Sensitized animals were treated or not with eugenol （20, 40 or 80 mg/kg） and the following parameters were analyzed： number of total cells in BAL （bronchoalveolar lavage）; EPO （eosinophil peroxidase activity） and histopathological changes in the lungs; serum level of specific IgE, IgG1 and IgG2a and; concentration of Th2 cytokines on BAL and spleen cultures. In addition, the capability ofeugenol in relaxing tracheal smooth muscle was also evaluated. Our results showed that treatment with eugenol significantly reduced the airway inflammation, decreasing the cellular infiltrate, EPO and mucus in the lungs, as well as the production of Th2 cytokines. It was also demonstrated a dilator effect of eugenol observed by the relaxation of normal and hyper-reactivity isolated trachea upon carbachol stimulation. These results suggest that eugenol has potential as an anti-asthmatic drug by both bronchodilator and immunomodulatory properties.
基金the Science Fund for the National Natural Science Foundation of China(Grant Nos.31961133030,31870678)the National Key Research and Development Program of China(Grant No.2018YFD1000601)+1 种基金Distinguished Young Scientists of Anhui Province(Grant No.1908085J12)the Graduate Innovation Fund(Grant No.2020ysj-32).
文摘Eugenol is a natural phenolic compound known for its health-promoting properties and its ability to add a floral scent to tea plants.Plant eugenol glycosides have been identified and shown to make important contributions to fruit floral quality.However,the details of their biosynthesis and metabolism in tea plants are still unknown.Here,eugenol glucoside was unambiguously identified as a native metabolite in the tea plant,and its biosynthesis was shown to be induced by low temperature treatment.Through the analysis of UGTs induced by low temperature,the glycosyltransferase CsUGT78A15 was identified in tea,and its encoded protein was shown to catalyze the glucosylation of eugenol.Vmax/Km ratios showed that eugenol was the most suitable substrate for CsUGT78A15.Sugar donor preference analysis showed that CsUGT78A15 had a higher selectivity for glucose,followed by galactose and glucuronic acid.The expression of CsUGT78A15was correlatedwith the accumulation of eugenol glucoside in different tissues and genotypes of tea.Down-regulation of CsUGT78A15 led to a decreased eugenol glucoside content under cold stress,indicating that CsUGT78A15 plays an important role in the biosynthesis of eugenol glucoside under cold stress.The identification of eugenol glucoside in the tea plant and the discovery of a cold stress-induced eugenol glucosyltransferase in tea provide the foundation for the improvement of tea flavor under cold stress and the biotechnological production of eugenol glucoside.
基金supported by the National Natural Science Foundation of China (Grant nos. 21503144, 21406165, 51506147, 21376239)Major Projects of the National Natural Science Foundation of China (21690083)Tianjin Research Program of Application Foundation and Advanced Technique (Nos.16JCQNJC05400, 15JCQNJC08500)
文摘Hydrodeoxygenation（HDO） is an effective alternative to produce value-added chemicals and liquid fuels by removing oxygen from lignin-derived compounds. Sulfide catalysts have been proved to have good activity for the HDO and particularly high selectivity to phenolic products. Herein, we presented a novel way to prepare the layered structure sulfide catalysts（MgFeMo-S） derived from MgFe hydrotalcites via the intercalation of Mo in consideration of the memory effect of the calcined hydrotalcite. By varying the Mg/Fe mole ratio, a series of MgFeMo-S catalysts were successfully prepared and characterized by nitrogen adsorption/desorption isotherms, X-ray diffraction（XRD）, transmission electron microscopy（TEM）,and inductively coupled plasma optical emission spectrometer（ICP-OES）. The characterization results indicated that the MgFeMo-S catalyst has retained the unique layered structure, which can facilitate uniform dispersion of the MoS2 species on both the surface and interlayer of the catalysts. For the HDO of eugenol, the Mg1Fe2Mo-S catalysts exhibited the best HDO activity among all the catalysts due to its higher active metal contents and larger pore size. The HDO conversion was 99.6% and the yield of phenolics was 63.7%, under 5 MPa initial H2 pressure（measured at RT） at 300 ℃ for 3 h. More importantly,MoS2 species deposited on the interlayer galleries in the MgFeMo-S catalysts resulted in dramatically superior HDO activity to MoS2/Mg1Fe2-S catalyst. Based on the mechanism investigation for eugenol, the HDO reaction route of eugenol under sulfide catalytic system has been proposed for the first time. Further applicability of the catalyst on HDO of more lignin-derived compounds was operated, which showed good HDO activity and selectivity to produce aromatic products.
文摘The present study aimed to evaluate <i>Syzygium aromaticum</i> (clove) plant extract, clove oil and eugenol for their antibacterial activity and their potential to eradicate bacterial biofilms alone and in combination with antibiotics. Anti-bacterial efficacy of <i>S. aromaticum</i> extract, clove oil and eugenol was evaluated as minimum inhibitory concentration (MIC) and subsequently sub-MICs was selected for inhibition of virulence factors against test bacterial strains. Biofilm cultivation and eradication was assayed using XTT reduction in 96-well microtiter plate. Checkerboard method was used to study the interaction between essential oils and antibiotics. <i>Staphylococcus aureus</i> MTCC3160, <i>Staphylococcus epidermidis</i> MTCC435, <i>Staphylococcus sciuri</i> (SC-01), <i>Staphylococcus auricularis</i> (SU-01) <i>and</i> <i>Streptococcus mutans</i> MTCC497 were found strong biofilm former among all the test bacterial strains. The potency of test agents was found in the order of eugenol > clove oil > <i>S. aromaticum</i> methanolic extract. Sub-MIC (0.5 × MIC) of clove oil and eugenol showed a significant reduction in cell surface hydrophobicity (<i>p </i>< 0.05) and hemolysin production in the test bacterial strains. Eugenol showed no increase in sessile MIC (SMIC) against <i>S. auricularis</i> (SU-01), <i>S. epidermidis</i> MTCC435 and <i>S. mutans</i> MTCC497 compared to planktonic MIC (PMIC). Antibiotics (vancomycin and azithromycin) exhibited upto 1000-folds increased in SMIC compared to PMIC against all the test bacterial strains. Synergy was observed between eugenol and antibiotics (vancomycin/azithromycin) against all the test bacterial strains in both planktonic and sessile mode. Highest synergy was exhibited between eugenol and azithromycin in planktonic mode (FICI value 0.141). Further, microscopy also confirmed the spectacular effect of combination treatment on pre-formed <i>S. aureus</i> MTCC3160 and <i>S. mutans</i> MTCC497 biofilms. These findings highlighted the promising role of clove oil and eugenol alone and in combination on pathogenic bacterial biofilms.
文摘Eugenol, both in its pure form (EG) and included in essential clove oil (CO) was successfully solubilized in aqueous solution by forming inclusion complexes with β-cyclodextrins (β-CDs) and its modified hydroxy-propyl-β-CDs (HP-β-CDs). To investigate the molecular association between β-CDs/HP-β-CDs with pure EG and essential CO, phase solubility studies were undertaken. Essential CO formed insoluble complexes with β-CDs, but not with HP-β-CDs. The work clearly demonstrates complexes formation follow an order higher than 1:1 when high essential CO and β-CDs concentrations were used, however it was 1:1 in the case of essential CO-HP-β-CDs complexes. When pure EG was studied the results indicated that EG could form 1:1 inclusion complexes with β-CDs and HP-β-CDs. Based on the studies, the Kc values for pure EG were 4555 ± 225 M-1 and 10,633 ± 614 M-1 for β-CDs and HP-β-CDs, respectively, and 2005 ± 199 M-1 for essential CO-HP-β-CDs. These finding indicate that CDs are suitable for encapsulating EG.
