A non‐canonical biosynthetic pathway furnishing the first natural brexane‐type bishomosesquiterpe... more A non‐canonical biosynthetic pathway furnishing the first natural brexane‐type bishomosesquiterpene (chlororaphen, C17H28) was elucidated in the γ‐proteobacterium Pseudomonas chlororaphis O6. A combination of genome mining, pathway cloning, in vitro enzyme assays, and NMR spectroscopy revealed a three‐step pathway initiated by C10 methylation of farnesyl pyrophosphate (FPP, C15) along with cyclization and ring contraction to furnish monocyclic γ‐presodorifen pyrophosphate (γ‐PSPP, C16). Subsequent C‐methylation of γ‐PSPP by a second C‐methyltransferase furnishes the monocyclic α‐prechlororaphen pyrophosphate (α‐PCPP, C17), serving as the substrate for the terpene synthase. The same biosynthetic pathway was characterized in the β‐proteobacterium Variovorax boronicumulans PHE5‐4, demonstrating that non‐canonical homosesquiterpene biosynthesis is more widespread in the bacterial domain than previously anticipated.
A non‐canonical biosynthetic pathway furnishing the first natural brexane‐type bishomosesquiterpe... more A non‐canonical biosynthetic pathway furnishing the first natural brexane‐type bishomosesquiterpene (chlororaphen, C17H28) was elucidated in the γ‐proteobacterium Pseudomonas chlororaphis O6. A combination of genome mining, pathway cloning, in vitro enzyme assays, and NMR spectroscopy revealed a three‐step pathway initiated by C10 methylation of farnesyl pyrophosphate (FPP, C15) along with cyclization and ring contraction to furnish monocyclic γ‐presodorifen pyrophosphate (γ‐PSPP, C16). Subsequent C‐methylation of γ‐PSPP by a second C‐methyltransferase furnishes the monocyclic α‐prechlororaphen pyrophosphate (α‐PCPP, C17), serving as the substrate for the terpene synthase. The same biosynthetic pathway was characterized in the β‐proteobacterium Variovorax boronicumulans PHE5‐4, demonstrating that non‐canonical homosesquiterpene biosynthesis is more widespread in the bacterial domain than previously anticipated.
The present report continues to focus on the broadening application of plant extracts for metalli... more The present report continues to focus on the broadening application of plant extracts for metallic corrosion control [1and 2] and reports on the inhibiting effect of the Xylopia frutescens alkaloidic extract on the corrosion of C38 steel in 1 M hydrochloric acid. This extract presents mainly aporphinoid alkaloids, with nitrogen, oxygen, and aromatic rings. The corrosion inhibition’s is studied by polarization curves and electrochemical impedance spectroscopy (EIS). Constant phase element parameters of EIS are graphically calculated for better data precision. Studies on the phytochemical constituents of the total extract were also established and the active(s) molecule(s) are identified by NMR spectroscopy. The total alkaloid extract of Xylopia frutescenswas found to be an inhibitor for C38 steel corrosion in 1 M HCl solution and its inhibition efficiency increased with increasing concentration. The study showed that the inhibition behavior of the crude extract is due to the presence of aporphinoid alkaloids in the crude extract. 1- F.Suedile,etal., Corrosion inhibition of zinc by Mansoa alliacea plant extract in sodium chloride media: Extraction, Characterization and Electrochemical Studies, Electrochim. Acta (2014), http://dx.doi.org/10.1016/j.electacta.2013.12.070 2- M. Chevalier, et al., Enhanced corrosion resistance of mild steel in 1 M hydrochloric acid solution by alkaloids extract from Aniba rosaeodora plant: Electrochemical, phytochemical and XPS studies, Electrochim. Acta (2013), http://dx.doi.org/10.1016/j.electacta.2013.12.023
A non‐canonical biosynthetic pathway furnishing the first natural brexane‐type bishomosesquiterpe... more A non‐canonical biosynthetic pathway furnishing the first natural brexane‐type bishomosesquiterpene (chlororaphen, C17H28) was elucidated in the γ‐proteobacterium Pseudomonas chlororaphis O6. A combination of genome mining, pathway cloning, in vitro enzyme assays, and NMR spectroscopy revealed a three‐step pathway initiated by C10 methylation of farnesyl pyrophosphate (FPP, C15) along with cyclization and ring contraction to furnish monocyclic γ‐presodorifen pyrophosphate (γ‐PSPP, C16). Subsequent C‐methylation of γ‐PSPP by a second C‐methyltransferase furnishes the monocyclic α‐prechlororaphen pyrophosphate (α‐PCPP, C17), serving as the substrate for the terpene synthase. The same biosynthetic pathway was characterized in the β‐proteobacterium Variovorax boronicumulans PHE5‐4, demonstrating that non‐canonical homosesquiterpene biosynthesis is more widespread in the bacterial domain than previously anticipated.
For the first time, ruthenium-based assemblies have been used as carriers for photosensitizers in... more For the first time, ruthenium-based assemblies have been used as carriers for photosensitizers in the treatment of rheumatoid arthritis by photodynamic therapy (PDT). These metallacages are totally soluble in physiological media and can transport photosensitizers (PS) in their cavity. After an incubation period, the PS is released in the cytoplasm and irradiation can take place. This strategy allows photosensitizers with low or null solubility in biological media to be evaluated as PDT agents in rheumatoid arthritis. The systems in which 21H,23H-porphine and 29H,31H-phthalocyanine are encapsulated show excellent photocytotoxicity and no toxicity in the dark. On the other hand, systems in which metalated derivatives such as Mg(II)-porphine and Zn(II)-phthalocyanine are used show good photocytotoxicity, but to a lesser extent than the previous two. Furthermore, the presence of Zn(II)-phthalocyanine significantly increases the toxicity of the system. Overall, fifteen different host–gue...
Quorum sensing (QS) is a bacterial communication mechanism used to express various survival or vi... more Quorum sensing (QS) is a bacterial communication mechanism used to express various survival or virulence traits leading to enhanced resistance. Chromobacterium violaceum is a commonly used strain that highlights anti-QS action of bioactive substances. Here, we wanted to see if 12 selected essential oils (EO) could exert anti-QS activity. We measured the sublethal minimal QS inhibitory concentration (MQSIC) by assessing violacein production of C. violaceum along with bacterial growth. To confirm the QS disruption, we also proceed to surface bacterial observations using scanning electron microscopy (SEM). We showed that cis-cis-p-menthenolide extracted and isolated from a plant endemic to occidental Mediterranean Sea islands, Mentha suaveolens ssp. insularis, acts as an inhibitor of violacein production and biofilm formation. Measured MQSIC was much lower than the minimal inhibitory concentration (MIC): 0.10 mg·mL−1 vs. 3.00 mg·mL−1. Moreover, disturbance of QS-related traits was conf...
The chemical composition of the essential oil (EO), microwave extract (ME) and hydrolate extract ... more The chemical composition of the essential oil (EO), microwave extract (ME) and hydrolate extract (HE) from the same batch of leaves of Fortunella japonica, was investigated by combination of chromatographic (GC, CC) and spectroscopic techniques (GC-MS, 13C NMR). F. japonica essential oil and extracts are complex mixtures of 28–60 compounds being mainly oxygenated sesquiterpenes. The EO composition was dominated by germacrene D (14.9%), β-elemol (9.1%), cis-guai-6-en-10p-ol (6.3%), β-eudesmol (5.5%), and δ-elemene (5.2%). Limonene was the unique monoterpene identified at appreciable amount (7.1%). The extract obtained by microwave assisted hydrodistillation contained as main components: β-elemol (12.4%), germacrene D (9.9%), cis-guai-6-en-10β-ol (9.0%), β-eudesmol (8.2%), germacra-1(10),5-dien-4α-ol (7.1%) and α-eudesmol (6.4%). Finally, the highest content of oxygenated sesquiterpenes (near 92%) was found in the hydrolate extract displaying cryptomeridiol (23.3%, but totally absent ...
Fruit oil from five species of kumquat ( Fortunella japonica, F. margarita, F. crassifolia, F. ob... more Fruit oil from five species of kumquat ( Fortunella japonica, F. margarita, F. crassifolia, F. obovata, and F. hindsii) grown in the same pedoclimatic conditions have been analyzed by a combination of chromatographic and spectroscopic techniques. The compositions of the five fruit oils were strongly dominated by limonene (84.2–96.3%). Other components present with appreciable contents were myrcene (1.3–12.9%) and germacrene D (0.3–2.4%).
NMR chemical profiling of a Laurenciella sp. using a computerized method developed in our laborat... more NMR chemical profiling of a Laurenciella sp. using a computerized method developed in our laboratory resulted in the identification of five new compounds (1-5) and 17 known compounds, among which 3-(E)-laurenyne represented by far the most abundant metabolite. Compounds 1 to 5 were isolated and fully characterized by detailed spectroscopic analysis. The absolute configuration and structural features of compound 1 were determined by single-crystal X-ray diffraction analysis. Compounds 1 to 4 are 12-membered cyclic ether acetogenins that are present in solution as interconverting conformers exhibiting an (aR) configuration of the bromoallene unit together with an S configuration at C-4. Among these, compound 3 is the first obtusallene derivative with bromine substituents at both the C-7 and C-12 positions. Compound 5 is an acetogenin bearing a [5.5.1]bicyclotridecane ring system. A plausible biosynthetic route to 1-4 is proposed.
A non‐canonical biosynthetic pathway furnishing the first natural brexane‐type bishomosesquiterpe... more A non‐canonical biosynthetic pathway furnishing the first natural brexane‐type bishomosesquiterpene (chlororaphen, C17H28) was elucidated in the γ‐proteobacterium Pseudomonas chlororaphis O6. A combination of genome mining, pathway cloning, in vitro enzyme assays, and NMR spectroscopy revealed a three‐step pathway initiated by C10 methylation of farnesyl pyrophosphate (FPP, C15) along with cyclization and ring contraction to furnish monocyclic γ‐presodorifen pyrophosphate (γ‐PSPP, C16). Subsequent C‐methylation of γ‐PSPP by a second C‐methyltransferase furnishes the monocyclic α‐prechlororaphen pyrophosphate (α‐PCPP, C17), serving as the substrate for the terpene synthase. The same biosynthetic pathway was characterized in the β‐proteobacterium Variovorax boronicumulans PHE5‐4, demonstrating that non‐canonical homosesquiterpene biosynthesis is more widespread in the bacterial domain than previously anticipated.
A non‐canonical biosynthetic pathway furnishing the first natural brexane‐type bishomosesquiterpe... more A non‐canonical biosynthetic pathway furnishing the first natural brexane‐type bishomosesquiterpene (chlororaphen, C17H28) was elucidated in the γ‐proteobacterium Pseudomonas chlororaphis O6. A combination of genome mining, pathway cloning, in vitro enzyme assays, and NMR spectroscopy revealed a three‐step pathway initiated by C10 methylation of farnesyl pyrophosphate (FPP, C15) along with cyclization and ring contraction to furnish monocyclic γ‐presodorifen pyrophosphate (γ‐PSPP, C16). Subsequent C‐methylation of γ‐PSPP by a second C‐methyltransferase furnishes the monocyclic α‐prechlororaphen pyrophosphate (α‐PCPP, C17), serving as the substrate for the terpene synthase. The same biosynthetic pathway was characterized in the β‐proteobacterium Variovorax boronicumulans PHE5‐4, demonstrating that non‐canonical homosesquiterpene biosynthesis is more widespread in the bacterial domain than previously anticipated.
The present report continues to focus on the broadening application of plant extracts for metalli... more The present report continues to focus on the broadening application of plant extracts for metallic corrosion control [1and 2] and reports on the inhibiting effect of the Xylopia frutescens alkaloidic extract on the corrosion of C38 steel in 1 M hydrochloric acid. This extract presents mainly aporphinoid alkaloids, with nitrogen, oxygen, and aromatic rings. The corrosion inhibition’s is studied by polarization curves and electrochemical impedance spectroscopy (EIS). Constant phase element parameters of EIS are graphically calculated for better data precision. Studies on the phytochemical constituents of the total extract were also established and the active(s) molecule(s) are identified by NMR spectroscopy. The total alkaloid extract of Xylopia frutescenswas found to be an inhibitor for C38 steel corrosion in 1 M HCl solution and its inhibition efficiency increased with increasing concentration. The study showed that the inhibition behavior of the crude extract is due to the presence of aporphinoid alkaloids in the crude extract. 1- F.Suedile,etal., Corrosion inhibition of zinc by Mansoa alliacea plant extract in sodium chloride media: Extraction, Characterization and Electrochemical Studies, Electrochim. Acta (2014), http://dx.doi.org/10.1016/j.electacta.2013.12.070 2- M. Chevalier, et al., Enhanced corrosion resistance of mild steel in 1 M hydrochloric acid solution by alkaloids extract from Aniba rosaeodora plant: Electrochemical, phytochemical and XPS studies, Electrochim. Acta (2013), http://dx.doi.org/10.1016/j.electacta.2013.12.023
A non‐canonical biosynthetic pathway furnishing the first natural brexane‐type bishomosesquiterpe... more A non‐canonical biosynthetic pathway furnishing the first natural brexane‐type bishomosesquiterpene (chlororaphen, C17H28) was elucidated in the γ‐proteobacterium Pseudomonas chlororaphis O6. A combination of genome mining, pathway cloning, in vitro enzyme assays, and NMR spectroscopy revealed a three‐step pathway initiated by C10 methylation of farnesyl pyrophosphate (FPP, C15) along with cyclization and ring contraction to furnish monocyclic γ‐presodorifen pyrophosphate (γ‐PSPP, C16). Subsequent C‐methylation of γ‐PSPP by a second C‐methyltransferase furnishes the monocyclic α‐prechlororaphen pyrophosphate (α‐PCPP, C17), serving as the substrate for the terpene synthase. The same biosynthetic pathway was characterized in the β‐proteobacterium Variovorax boronicumulans PHE5‐4, demonstrating that non‐canonical homosesquiterpene biosynthesis is more widespread in the bacterial domain than previously anticipated.
For the first time, ruthenium-based assemblies have been used as carriers for photosensitizers in... more For the first time, ruthenium-based assemblies have been used as carriers for photosensitizers in the treatment of rheumatoid arthritis by photodynamic therapy (PDT). These metallacages are totally soluble in physiological media and can transport photosensitizers (PS) in their cavity. After an incubation period, the PS is released in the cytoplasm and irradiation can take place. This strategy allows photosensitizers with low or null solubility in biological media to be evaluated as PDT agents in rheumatoid arthritis. The systems in which 21H,23H-porphine and 29H,31H-phthalocyanine are encapsulated show excellent photocytotoxicity and no toxicity in the dark. On the other hand, systems in which metalated derivatives such as Mg(II)-porphine and Zn(II)-phthalocyanine are used show good photocytotoxicity, but to a lesser extent than the previous two. Furthermore, the presence of Zn(II)-phthalocyanine significantly increases the toxicity of the system. Overall, fifteen different host–gue...
Quorum sensing (QS) is a bacterial communication mechanism used to express various survival or vi... more Quorum sensing (QS) is a bacterial communication mechanism used to express various survival or virulence traits leading to enhanced resistance. Chromobacterium violaceum is a commonly used strain that highlights anti-QS action of bioactive substances. Here, we wanted to see if 12 selected essential oils (EO) could exert anti-QS activity. We measured the sublethal minimal QS inhibitory concentration (MQSIC) by assessing violacein production of C. violaceum along with bacterial growth. To confirm the QS disruption, we also proceed to surface bacterial observations using scanning electron microscopy (SEM). We showed that cis-cis-p-menthenolide extracted and isolated from a plant endemic to occidental Mediterranean Sea islands, Mentha suaveolens ssp. insularis, acts as an inhibitor of violacein production and biofilm formation. Measured MQSIC was much lower than the minimal inhibitory concentration (MIC): 0.10 mg·mL−1 vs. 3.00 mg·mL−1. Moreover, disturbance of QS-related traits was conf...
The chemical composition of the essential oil (EO), microwave extract (ME) and hydrolate extract ... more The chemical composition of the essential oil (EO), microwave extract (ME) and hydrolate extract (HE) from the same batch of leaves of Fortunella japonica, was investigated by combination of chromatographic (GC, CC) and spectroscopic techniques (GC-MS, 13C NMR). F. japonica essential oil and extracts are complex mixtures of 28–60 compounds being mainly oxygenated sesquiterpenes. The EO composition was dominated by germacrene D (14.9%), β-elemol (9.1%), cis-guai-6-en-10p-ol (6.3%), β-eudesmol (5.5%), and δ-elemene (5.2%). Limonene was the unique monoterpene identified at appreciable amount (7.1%). The extract obtained by microwave assisted hydrodistillation contained as main components: β-elemol (12.4%), germacrene D (9.9%), cis-guai-6-en-10β-ol (9.0%), β-eudesmol (8.2%), germacra-1(10),5-dien-4α-ol (7.1%) and α-eudesmol (6.4%). Finally, the highest content of oxygenated sesquiterpenes (near 92%) was found in the hydrolate extract displaying cryptomeridiol (23.3%, but totally absent ...
Fruit oil from five species of kumquat ( Fortunella japonica, F. margarita, F. crassifolia, F. ob... more Fruit oil from five species of kumquat ( Fortunella japonica, F. margarita, F. crassifolia, F. obovata, and F. hindsii) grown in the same pedoclimatic conditions have been analyzed by a combination of chromatographic and spectroscopic techniques. The compositions of the five fruit oils were strongly dominated by limonene (84.2–96.3%). Other components present with appreciable contents were myrcene (1.3–12.9%) and germacrene D (0.3–2.4%).
NMR chemical profiling of a Laurenciella sp. using a computerized method developed in our laborat... more NMR chemical profiling of a Laurenciella sp. using a computerized method developed in our laboratory resulted in the identification of five new compounds (1-5) and 17 known compounds, among which 3-(E)-laurenyne represented by far the most abundant metabolite. Compounds 1 to 5 were isolated and fully characterized by detailed spectroscopic analysis. The absolute configuration and structural features of compound 1 were determined by single-crystal X-ray diffraction analysis. Compounds 1 to 4 are 12-membered cyclic ether acetogenins that are present in solution as interconverting conformers exhibiting an (aR) configuration of the bromoallene unit together with an S configuration at C-4. Among these, compound 3 is the first obtusallene derivative with bromine substituents at both the C-7 and C-12 positions. Compound 5 is an acetogenin bearing a [5.5.1]bicyclotridecane ring system. A plausible biosynthetic route to 1-4 is proposed.
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