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Biotransformation of viridin, an antifungal produced by biocontrol agent, with non-viridin producing microorganisms is studied. The results show that some environmental non-targeted microorganisms are able to reduce it in the known phytotoxin viridiol, and its 3-epimer. Consequently, this reduction, which happens in some cases by detoxification mechanism, could be disastrous for the plant in a biocontrol of plant disease. However, a process fermentation/biotransformation could be an efficient approach for the preparation of this phytotoxin.

The search for active microorganisms for the biotransformation of guttiferone A (1) and C (6) has been successfully undertaken from a collection of endophytic fungi of Symphonia globulifera. Of the twenty-five isolates obtained from the leaves, three are active and have been identified as Bipolaris cactivora. The products obtained are the result of xanthone cyclisation with the formation of two regioisomers among four possible and corresponding to 1,16-oxy-guttiferone and 3,16-oxy-guttiferone. The biotransformation conditions were studied. Interestingly, both oxy-guttiferones A are present in the plant, and the ratio of 3,16-oxy-guttiferone to 1,16-oxy-guttiferone is 4 : 1, very close to that observed by biotransformation (3.8 : 1). These results are consistent with the involvement of endophytes in their formation pathway from guttiferone A, in planta. Finally, biotransformation made it possible to obtain and describe for the first time oxy-guttiferones C.

International audience; The search for active microorganisms for the biotransformation of guttiferone A (1) and C (6) has been successfully undertaken from a collection of endophytic fungi of Symphonia globulifera. Of the twenty-five isolates obtained from the leaves, three are active and have been identified as Bipolaris cactivora. The products obtained are the result of xanthone cyclisation with the formation of two regioisomers among four possible and corresponding to 1,16-oxy-guttiferone and 3,16-oxy-guttiferone. The biotransformation conditions were studied. Interestingly, both oxy-guttiferones A are present in the plant, and the ratio of 3,16-oxy-guttiferone to 1,16-oxy-guttiferone is 4 : 1, very close to that observed by biotransformation (3.8 : 1). These results are consistent with the involvement of endophytes in their formation pathway from guttiferone A, in planta. Finally, biotransformation made it possible to obtain and describe for the first time oxy-guttiferones C.

The relevant environmental hazard related to the presence of pharmaceuticals in water sources requires the development of high effective and suitable wastewater treatment technologies. In the present work, a hybrid process coupling electro-Fenton (EF) process and aerobic biological treatment (Bio-EF process) was implemented for the efficient and cost-effective mineralization of beta-blocker metoprolol (MPTL) aqueous solutions. Firstly, operating factors influencing EF process were assessed. MTPL solutions were completely mineralized after 4 h-electrolysis under optimal operating conditions and BDD anode demonstrated its oxidation superiority. The absolute rate constant of MTPL oxidation by OH ( k MTPL ) was determined by the competition kinetics method and found to be (1.72 ± 0.04) × 10 9 M −1 s −1 . A reaction pathway for the mineralization of the drug was proposed based on the identification of oxidation by-products. Secondly, EF process was used as pre-treatment. An increase of BOD 5 /COD ratio from 0.012 to 0.44 was obtained after 1 h EF treatment, along with 47% TOC removal and a significant decrease of toxicity, demonstrating the feasibility of a post-biological treatment. Finally, biological treatment successfully oxidized 43% of the total TOC content. An overall 90% mineralization of MPTL solutions was achieved by the Bio-EF process, demonstrating its potentiality for treating wastewater containing pharmaceutical residues.

International audience; A coupled Bio-EF treatment has been applied as a reliable process for the degradation of the pharmaceuticals furosemide (FRSM) and ranitidine (RNTD) in aqueous medium, in order to reduce the high energy consumption related to electrochemical technology. In the first stage of this study, electrochemical degradation of the drugs was assessed by the electro-Fenton process (EF) using a BDD/carbon-felt cell. Biodegradability of the drugs solutions was enhanced reaching BOD5/COD ratios close to the biodegradability threshold of 0.4, evidencing the formation of bio-compatible by-products (mainly short-chain carboxylic acids) which are suitable for biological post-treatment. Moreover, toxicity evaluation by the Microtox® method revealed that EF pre-treatment was able of detoxifying both, FRSM and RNTD solutions, constituting another indicator of biodegradability of EF treated solutions. In the second stage, electrolyzed solutions were treated by means of an aerobic biological process. A significant part of the short-chain carboxylic acids formed during the electrochemical phase was satisfactorily removed by the used selected microorganisms. The results obtained demonstrate the efficiency and feasibility of the integrated Bio-EF process.

International audience; Plants comprise many asymptomatic fungal endophytes with potential roles of plant protection against abiotic and biotic stresses. Endophytes communicate with their host plant, with other endophytes and with invading pathogens but their language remains largely unknown. This work aims at understanding the chemical communication and physiological interactions between the fungal endophyte Paraconiothyrium variabile and the phytopathogen Fusarium oxysporum. Oxylipins, common means of communication, such as 13-hydroperoxy-9,11-octadecadienoic acid (13-HPODE), had been shown in our earlier studies to be overproduced during dual culture between the two fungal antagonists. On the other hand, the mycotoxin beauvericin was reduced in the interaction zone. The present work addresses the mechanisms underlying these changes. Hydroperoxy oxylipins are produced by lipoxygenases and P. variabile contains two lipoxygenase genes (pvlox1 and pvlox2), whereas pvlox2, but not pvlox1, is specifically up regulated during the interaction and none of the F. oxysporum lox genes vary. Heterologous expression of pvlox2 in yeast shows that the corresponding enzyme PVLOX2 produces 13-HPODE and, therefore, is most likely at the origin of the overproduced 13-HPODE during the interaction. Compellingly, beauvericin synthase gene beas expression is induced and beauvericin amounts increase in F. oxysporum mycelium when in contact with P. variabile. 13-HPODE, however, does not affect beas gene expression. Beauvericin, indeed, inhibits P. variabile growth, which counteracts and biotransforms the mycotoxin leading to reduced amounts in the interaction zone which allows further expansion of the endophyte. In order to study the interaction between the protagonists in planta, we set up an in vitro tripartite interaction assay, including the model plant Arabidopsis thaliana. F. oxysporum rapidly kills A. thaliana plants, whereas P. variabile provides up to 85% reduction of plant death if present before pathogen attack. Future studies will shed light on the protection mechanisms and the role of oxylipins and beauvericin degradation herein with the long-term aim of using endophytes in plant protection.

Cocoa production is affected by the black pod disease caused by several Phytophthora species that bring, about each year, an estimated loss of 44% of world production. Chemical control remains expensive and poses an enormous risk of poisoning for the users and the environment. Biocontrol by using antagonistic microorganisms has become an alternative to the integrated control strategy against this disease. Trichoderma viride T7, T. harzanium T40, and T. asperellum T54, which showed in vivo and in vitro antagonistic activity against P. palmivora, were cultured and mycelia extracted. Inhibition activity of crude extracts was determined, and then organic compounds were isolated and characterized. The in vitro effect of each compound on the conidia germination and mycelia growth of four P. palmivora, two P. megakaria, and one P. capsici was evaluated. T. viride that displayed best activities produced two active metabolites, viridin and gliovirin, against P. palmivora and P. megakaria strains. However, no activity against P. capsici was observed. Besides being active separately, these two compounds have a synergistic effect for both inhibitions, mycelia growth and conidia germination. These results provide the basis for the development of a low-impact pesticide based on a mixture of viridin and gliovirine.

Furosemide is a widely prescribed diuretic whose unambiguous presence in water appointed it as an emerging pollutant. This work focuses on the electrochemical degradation of this drug in aqueous solutions by electrochemical advanced oxidation processes, electro-Fenton and anodic oxidation, using Pt/carbon-felt and boron doped diamond (BDD)/carbon-felt cells with H2O2 electrogeneration. The higher oxidation power of the electro-Fenton process using a BDD anode was demonstrated. The oxidative degradation of furosemide by electrochemically generated •OH radicals follows a pseudo-first order kinetics. The absolute rate constant of the oxidation reaction of furosemide by •OH was determined using a competition kinetics method and found to be 3.4 × 109 M−1 s−1. The evolution of the total organic carbon removal during the treatment as a mineralization efficiency parameter was investigated. It was found that the electrochemical degradation of furosemide yields formation of aromatic by-products which are oxidized afterwards to aliphatic carboxylic acids before their conversion to CO2 and inorganic ions (NH4+, NO3–, Cl–, and SO42–). The toxicity assessment by the Microtox® method revealed formation of oxidation reaction intermediates more toxic than the parent molecule. Nevertheless, the overall results confirm the high effectiveness of anodic oxidation and electro-Fenton processes for the removal of furosemide and its by-products from aqueous media.

Guttiferone A and cyclized analogs are naturally occurring polycyclic polyprenylated acyl phloroglucinols possessing antiparasitic activities. Naturally occurring xanthones possess increased activity, but are either rare or difficult to synthesize. In this paper, three optimized methodologies to access natural, hydroxylated and non-natural xanthonic skeletons from guttiferone A are described. These compounds will serve as starting materials for further SAR studies.

There is an obvious increasing interest to take advantage of microorganisms as natural reagents in organic synthesis. That requires to efficiently select the microorganism able to transform the molecule of interest. We disclose a combinatorial approach, which significantly reduces the number of assays. This new strategy in screening active microorganisms is based on incubation of mixtures of biomasses, in place of one-at-a-time screening strategies. By applying our method to sinomenine derivatives in a hemisynthesis context, we quickly identified two microorganisms in 8 and 10 assays among twenty-four microorganisms, for their abilities to metabolize this morphinane alkaloid into N -deprotected, N -oxide and dioxygenated metabolites.

International audience; Highly biologically active marine sesquiterpene ilimaquinone was selected for chemical modifications. Its biotransformation was investigated using a combinatorial approach as an original way to screen different strains of microorganisms. Mucor circinelloides ATCC 8541 was able to structurally modify ilimaquinone into three different compounds. A stereospecific epoxidation was observed and compared to chemical epoxidation. A hydroxylation of the decalin ring was also observed as well as an unexpected substitution on the quinone ring by ethanolamine. Compounds were evaluated against several cell lines.

Some widely prescribed drugs are sparsely metabolized and end up in the environment. They can thus be a focal point of ecotoxicity, either themselves or their environmental transformation products. In this context, we present a study concerning furosemide, a diuretic, which is mainly excreted unchanged. We investigated its biotransformation by two environmental fungi, Aspergillus candidus and Cunninghamella echinulata. The assessment of its ecotoxicity and that of its metabolites was performed using the Microtox test (ISO 11348-3) with Vibrio fischeri marine bacteria. Three metabolites were identified by means of HPLC-MS and 1H/13C NMR analysis: saluamine, a known pyridinium derivative and a hydroxy-ketone product, the latter having not been previously described. This hydroxy-ketone metabolite was obtained with C. echinulata and was further slowly transformed into saluamine. The pyridinium derivative was obtained in low amount with both strains. Metabolites, excepting saluamine, exhibited higher toxicity than furosemide, being the pyridinium structure the one with the most elevated toxic levels (EC50 = 34.40 ± 6.84 mg L−1). These results demonstrate that biotic environmental transformation products may present a higher environmental risk than the starting drug, hence highlighting the importance of boosting toxicological risk assessment related to the impact of pharmaceutical waste.

A facile and efficient strategy for the synthesis of α,β-unsaturated lactams through ring-closing metathesis of easily prepared diene amides is being reported here. Reaction conditions were optimized for metathetic cyclization of diene amides to obtain five- to sevenmembered unsubstituted and β-substituted α,β-unsaturated lactams in good to excellent yield.

A facile and efficient strategy for the synthesis of α,β-unsaturated lactams through ring-closing metathesis of easily prepared diene amides is being reported here. Reaction conditions were optimized for metathetic cyclization of diene amides to obtain five- to sevenmembered unsubstituted and β-substituted α,β-unsaturated lactams in good to excellent yield.

Various bacterial and fungal strains were screened for their ability to catalyse the regioselective hydrolysis of 1-benzylpyrrolidine-2,5-dicarbonitrile ( 1 ). Among the examined strains, Rhodococcus opacus sp-lma whole cells transformed both isomers of 1 into 1-benzyl-5-cyano-2-pyrrolidinone ( 2 ) and N -benzylacetamide ( 3 ). These reactions are difficult to achieve chemically and the synthesis of compound 2 did not compete with microbiological catalysis in terms of efficiency and respect for the guidelines of green chemistry. To distinguish between an oxidative or hydrolytic based-mechanism, the origin of the oxygen atom in 2 was investigated by using 18 O 2 and 18 OH 2 coupled with GC–MS analysis. These experiments confirmed that the oxygen atom in 2 came from water and not from molecular oxygen. The reaction is probably initiated by the dehydrogenation of 1 to generate the iminium ion, which could be trapped by a water molecule to form the cyanohydrin. The cyanohydrin intermediate would spontaneously break down to the γ-lactam product 2 . Conversion of 1 to 2 by induced rat liver microsomes suggests the involvement of a Cyt P-450-type enzyme. A mechanism that accounts for the formation of 3 is also proposed.

The actinomycete Streptomyces platensis grown in culture medium containing soybean peptones can transform terfenadine, an antihistamine drug, into its active metabolite fexofenadine. The microbial oxidation of methyl group of terfenadine into carboxylic acid could be an alternative to chemical ways to produce fexofenadine. This bioconversion requires three oxidation steps: a hydroxylation of one methyl group followed by the oxidation of the corresponding alcohol into the aldehyde and finally its oxidation into the carboxylic acid. The oxidation reaction of each step has been studied. Terfenadine and intermediates incubated with whole cells were not oxidized under argon whereas their biotransformation under 18 O 2 -enriched atmosphere gave labeled fexofenadine. P450 inhibitors, such as clotrimazole or fluconazole, inhibited oxidation activity of each step. While the two last steps could be catalyzed by dehydrogenases or oxidases, this study strongly demonstrates the role of at least one, or possibly several cytochromes P450, in the oxidation of terfenadine into fexofenadine by S. platensis cells. To our knowledge, this is one of the few examples of involvement of P450s in such three steps oxidation of a xenobiotic.

A series of 3'-aminoflavones 5,6,7,8-tetra- or 5,7-dioxygenated on the A-ring was synthesized from tangeretin or naringin, two natural Citrus flavonoids. These flavones were evaluated for antiproliferative activity, activation of apoptosis, and inhibition of tubulin assembly. The most antiproliferative flavones exhibit a common 5-hydroxy-6,7,8-trimethoxy substitution pattern on the A-ring.

The aim of this study was to found the best conditions to prepare metabolites of terfenadine, ebastine and analogues. For that purpose we investigated the structural substrate requirements needed for the oxidative whole cell activity and selected the most efficient conditions to obtain each compound. Our results showed that either alcohol or acid derivative arising from the oxidation of a methyl group is the main product, ratio depending on the microorganism used and on the culture conditions of cells. The oxidized metabolites were synthesized at preparative scale and isolated in 35–88% yield before characterization.

Twenty purified dehydrogenases cloned from bakers’ yeast ( Saccharomyces cerevisiae ) and expressed as fusion proteins with glutathione ( S )-transferase were tested for their ability to reduce three homologous cyclic β-keto esters. The majority of dehydrogenases reduced ethyl 2-oxo-cyclopentanecarboxylate, yielding a pair of diastereomeric alcohols with consistent (1 R )-stereochemistry. Ethyl 2-oxo-cyclohexanecarboxylate reductions afforded only cis -alcohol enantiomers. Ethyl 2-oxo-cycloheptanecarboxylate was accepted by two enzymes in the collection, and both yielded mainly the cis -(1 R ,2 S )-alcohol. Escherichia coli cells overexpressing the YDL124w gene were used in a dynamic kinetic resolution of ethyl 2-oxo-cyclohexanecarboxylate to produce the key intermediate in a chemo-enzymatic synthesis of (1 R ,2 S )-2-methyl-1-cyclohexanol, an important chiral building block.

Regioselective O-demethylation of the flavones tangeretin (1) and 3-hydroxytangeretin (6) into their 4'-O-demethylated metabolites was performed by using an Aspergillus niger strain. This method serves as a straightforward alternative to multistep synthesis or semisynthesis. The microbial approach is complementary to the chemical procedure, which furnishes a 5-O-demethylated product. P450 inhibitors prevented the biotransformation of tangeretin (1). These results suggest that a P450 oxidation system might be involved in this O-demethylation and demonstrate a consequent similarity in both microbial and mammalian metabolism of polymethoxylated flavones.

The biotransformation of terfenadine into a primary alcohol, hydroxyterfenadine, followed by its oxidation to an acid, fexofenadine, was investigated using Streptomyces platensis cells. Time-courses of metabolite formation were established, and the results underlined the modulation of the alcohol to acid formation ratio according to culture conditions. Optimization of the hydroxylation step (pH, temperature, culture medium composition) led to the preparation of hydroxyterfenadine with a good yield (51%) using cells grown in culture medium without soybean peptone. In contrast, when incubations were performed with cells cultured in a medium containing soybean peptone, the alcohol to acid formation ratio decreased. The efficiency of the conversion to fexofenadine was shown to depend on the age of the cells, thus suggesting the induction of an oxidative activity. Both the hydroxylation reaction and the following two-oxidation steps leading to the acid seemed to depend on oxygen.

The biosynthesis of pyrrocidines, fungal PK-NRP compounds featuring a strained [9]paracyclophane, was investigated in Acremonium zeae. We used a synthetic L-tyrosine probe, labelled with oxygen 18 as a reporter of phenol reactivity and carbon 13 as a tracer of incorporation of this exogenous precursor. The ((18)O)phenolic oxygen was incorporated, suggesting that phenol behaves as a nucleophile during the formation of the bent aryl ether.

We describe here a direct access to (4S)-isosclerone (+)-1, an important structural component of several natural products featuring a spirobisnaphthalene ring system. Starting with the commercially available 5-hydroxy-1,4-naphthalenedione (juglone), biotransformation by the isosclerone-producing endophytic fungus Paraconiothyrium variabile is described. The absolute configuration of (+)-1 was determined unambiguously using circular dichroism and by measurement of the optical rotation. Moreover, the biotransformations of other naphthalene derivatives were undertaken and led to the corresponding (4S)-hydroxy-1-tetralone. At last, this work brings some insights on the biosynthesis of natural tetralones.

The oxidation of tert-butyl-phenyl group of title compounds by some microorganisms was studied. We have optimized the conditions of culture to increase the formation of acid metabolites and to avoid the formation of side products. We showed that an oxidative activity is induced by soybean peptones in Streptomyces platensis. The biologically active compounds, fexofenadine and carebastine, are produced in good yield (86-95%) by Absidia corymbifera.

Reduction of an α,β-unsaturated cyclic ketone with Geotrichum candidum affords the corresponding (S)-allylic alcohol, while enantiospecific oxidation of the corresponding racemic alcohols leaves the (R)-enantiomer unchanged, giving access to both enantiomeric forms. Subsequent chemical reduction of the double bond of these homochiral allylic alcohol allows all isomers of the corresponding cyclohexanols to be obtained.

International audience; The presence of trace levels of organic contaminants in the environment is currently an environmental concern. When these contaminants are subjected to environmental transformations, environmental transformation products (ETPs) are obtained, whose structures often remain unknown. The absence of information concerning these new compounds makes them unavailable and consequently makes their environmental detection as well as their (eco)toxicological study impossible. This report describes a multidisciplinary approach that seeks to both anticipate the fate and evaluate the impact of organic environmental contaminants. Our approach consists of three steps. First, isolated and fully characterized transformation products (TPs) of the parent molecule are obtained. In the second step, the parent molecule is subjected to environmentally relevant transformations to identify plausible ETPs. The detection of previously characterized TPs allows the concomitant identification of plausible ETPs. The third step is devoted to the toxicological evaluation of the identified plausible ETPs. Such an approach has recently been applied to furosemide and has allowed the identification of its main TPs. This report now seeks to identify and evaluate toxicologically plausible ETPs of this drug, which is also known as an environmental contaminant.

Fungal endophytes live inside plant tissues and some have been found to provide benefits to their host. Nevertheless, their ecological impact is not adequately understood. Considering the fact that endophytes are continuously interacting with their hosts, it is conceivable that both partners have substantial influence on each other's metabolic processes. In this context, we have investigated the action of the endophytic fungus Paraconiothyrium variabile, isolated from the leaves of Cephalotaxus harringtonia, on the secondary metabolome of the host-plant. The alteration of the leaf compounds by the fungus was monitored through metabolomic approaches followed by structural characterization of the altered products. Out of more than a thousand molecules present in the crude extract of the plant leaf, we have observed a specific biotransformation of glycosylated flavonoids by the endophyte. In all cases it led to the production of the corresponding aglycone via deglycosylation. The deglycosylated flavonoids turned out to display significant beneficial effects on the hyphal growth of germinated spores. Our finding, along with the known allelopathic role of flavonoids, illustrates the chemical cooperation underlying the mutualistic relationship between the plant and the endophyte.

Cyclic or acyclic α-alkyl-α-hydroxy-β-keto esters were reduced by baker’s yeast with high stereospecificity. In the former case, one enantiomer of the racemic mixture was transformed into optically active trans-dihydroxy compounds, while the remaining α-hydroxy-β-keto ester was enantiopure.

(S)-O-Acetyllactyl chloride is used as a versatile chiral derivatizing agent for the chromatographic determination of the enantiomeric excesses of alcohols or amines. However, some precautions must be taken to avoid its racemization during preparation and use. In addition, the racemic counterpart of this reagent can be used to determine the best analytical separation conditions.

The reduction of four- to eight-membered cyclic β-ketoesters to the corresponding β-hydroxyesters by various yeasts and fungi is described. The microbial reduction of ethyl cyclobutanone 2-carboxylate is reported for the first time. The different stereospecificities observed in these reductions involving a dynamic kinetic resolution are analysed. The enantiopure reduction products have been used in the synthesis of both enantiomers of functionalized lactones and epoxides.

Ranitidine (RNTD) is a widely prescribed histamine H2-receptor antagonist whose unambiguous presence in water sources appointed it as an emerging pollutant. Here, the degradation of 0.1 mM of this drug in aqueous medium was studied by electrochemical advanced oxidation processes (EAOPs) like anodic oxidation with electrogenerated H2O2 and electro-Fenton using Pt/carbon-felt, BDD/carbon-felt and DSA-Ti/RuO2–IrO2/carbon-felt cells. The higher oxidation power of the electro-Fenton process using a BDD anode was demonstrated. The oxidative degradation of RNTD by the electrochemically generated OH radicals obeyed a pseudo-first order kinetics. The absolute rate constant for its hydroxylation reaction was 3.39 × 109 M−1 s−1 as determined by the competition kinetics method. Almost complete mineralization of the RNTN solution was reached by using a BDD anode in both anodic oxidation with electrogenerated H2O2 and electro-Fenton processes. Up to 11 cyclic intermediates with furan moiety were detected from the degradation of RNTD, which were afterwards oxidized to short-chain carboxylic acids before their mineralization to CO2 and inorganic ions such as NH4+, NO3− and SO42−. Based on identified products, a plausible reaction pathway was proposed for RNTD mineralization. Toxicity assessment by the Microtox® method revealed that some cyclic intermediates are more toxic than the parent molecule. Toxicity was quickly removed following the almost total mineralization of the treated solution. Overall results confirm the effectiveness of EAOPs for the efficient removal of RNTD and its oxidation by-products from water.

The microbial reduction of the title compounds by various yeasts or filamentous fungi strains affords the corresponding (1 S ,2 R )- and/or (1 S ,2 S )-hydroxyesters in good yield and ee. The determination of their absolute configuration was achieved by transformation into known 2-methylcycloalkanone stereoisomers.

The catechol pharmacomodulation of the natural product guttiferone A, isolated from the Symphonia globulifera tree, led to the semisynthesis of a collection of twenty derivatives. The ester and ether derivatives of guttiferone A were evaluated for their anti-plasmodial, trypanocidal and anti-leishmanial activities. Some compounds described below have shown potent antiparasitic activity against Plasmodium falciparum, Trypanosoma brucei and Leishmania donovani in a range from 1 to 5 μM. The evaluation of guttiferone A derivatives against VERO cells highlighted catechol modulations as an interesting tool to decrease the toxicity and keep the activity of this natural compound. The current study revealed new molecules as promising new antiparasitic drug candidates.

The microbial reduction of β-ketoesters derived from 2-tetralone has been shown to produce good yields of 2-hydroxy-1-car☐y- or 3-hydroxy-2-car☐yesters. Baker's yeast invariably affords a high enantiomeric purity cis -hydroxyester, while fungi strains may produce, sometimes exclusively, cis - or trans - complementary stereochemistries. From a general survey of the baker's yeast reduction of cyclic β-ketoesters, a working model for predicting enantio- and diastereoselectivities of the reduction is proposed and discussed.

(R)- and (S)-δ-hydroxymethyl valerolactone and e-hydroxymethyl caprolactone were prepared as tert-butyldiphenylsilyl derivatives, in good yields and high enantiomeric purities, in a 5 step sequence, starting from the microbial stereospecific reduction of ethyl 2-oxocyclopentane or 2-oxocyclohexane carboxylates respectively.

Several aliphatic or aromatic 2-chloro-3-oxoesters are stereoselectively reduced by yeast or fungal strains, affording in fair to good yield and high enantiomeric excess some of the respective 2-chloro-3-hydroxyester stereoisomers.

Cis - and trans -glycidic esters may be synthesized in high enantiomeric purities by cyclisation with potassium carbonate in DMF of the corresponding syn - or anti -2-chloro-3-hydroxyesters, prepared by microbial reduction of 2-chloro-3-oxoesters. In contrast, more basic media such as sodium ethylate afford exclusively the trans -isomer, whatever the stereochemistry of the starting 2-chloro-3-hydroxyester is. Cyclisation of deuterated compounds showed that this result was due to a rapid isomerisation of the syn esters into anti isomers before cyclisation. An application of this reaction to the synthesis of (2 R ,3 S )-3-phenylisoserinc is described.

In addition to N-acetyl-indoline (2) and N-formylindoline (3), a new N-alkylated derivative of indoline was isolated after incubation with a number of fungal strains. Its structure was elucidated by spectral analysis and comparison with chemically synthetized racemic and optically active 4-hydroxy-2-(N-indolinyl)butane (4).

Benzoylphloroglucinol derivatives are natural products showing diverse biological activities that could be modulated by structural modifications. For this purpose, we studied the biotransformation of guttiferone A and of maclurin using a combinatorial approach for screening active microorganism strains. We found a novel and unexpected yeast-catalyzed oxidation that has selectively given a new oxy-guttiferone A and norathyriol.

The reduction of unsubstituted or methoxy-substituted (±)-2-carboxyethyl-1-tetralones by selected microorganisms affords optically active 1-hydroxy-2-carboxyethyl tetralins which can be used as versatile asymmetric synthons, for example in the preparation of biologically active methoxy-substituted 2R-aminotetralins. 1R,2R-(cis)-hydroxyesters of high optical purity are obtained with yeast strains, while the use of filamentous fungi leads to the enantiomeric 1S,2S-(cis)-hydroxyesters.

Fexofenadine, an antihistamine drug used in allergic rhinitis treatment, can be produced by oxidative biotransformation of terfenadine by Streptomyces platensis, which involves three consecutive oxidation reactions. We report here the purification and identification of the enzyme responsible for the first step, a cytochrome P450 (P450)-dependent monooxygenase. The corresponding P450, designated P450terf, was found to catalyze the hydroxylation of the t-butyl group of terfenadine and exhibited UV–Vis characteristics of a P450. Its interaction with terfenadine led to a shift of its Soret peak from 418 to 390 nm, as expected for the formation of a P450–substrate complex. In combination with spinach ferredoxin:NADP(+) oxidoreductase and ferredoxin, and in the presence of NADPH, it catalyzed the hydroxylation of terfenadine and some of its analogues, such as terfenadone and ebastine, with km values at the μM level, and kcat values around 30 min−1. Sequencing of the p450terf gene led to a 1206 bp sequence, encoding for a 402 aminoacid polypeptide exhibiting 56–65% identity with the P450s from the 107L family. These results confirmed that P450s from Streptomyces species are interesting tools for the biotechnological production of secondary metabolites, such as antibiotics or antitumor compounds, and in the oxidative biotransformation of xenobiotics, such as drugs.

The reduction of unsubstituted or methoxy-substituted (±)-2-carboxyethyl-1-tetralones by selected microorganisms affords optically active 1-hydroxy-2-carboxyethyl tetralins which can be used as versatile asymmetric synthons, for example in the preparation of biologically active methoxy-substituted 2R-aminotetralins. 1R,2R-(cis)-hydroxyesters of high optical purity are obtained with yeast strains, while the use of filamentous fungi leads to the enantiomeric 1S,2S-(cis)-hydroxyesters.

Yeast and fungi reduce methoxy-substituted 2-cyano-1-tetralones to cis-2-cyano-1-tetralols with high enantiomeric purity, but respective opposite absolute configurations, in moderate to high yields.

(R)- and (S)-δ-hydroxymethyl valerolactone and e-hydroxymethyl caprolactone were prepared as tert-butyldiphenylsilyl derivatives, in good yields and high enantiomeric purities, in a 5 step sequence, starting from the microbial stereospecific reduction of ethyl 2-oxocyclopentane or 2-oxocyclohexane carboxylates respectively.

The microbial reduction of β-ketoesters derived from 2-tetralone has been shown to produce good yields of 2-hydroxy-1-car☐y- or 3-hydroxy-2-car☐yesters. Baker's yeast invariably affords a high enantiomeric purity cis -hydroxyester, while fungi strains may produce, sometimes exclusively, cis - or trans - complementary stereochemistries. From a general survey of the baker's yeast reduction of cyclic β-ketoesters, a working model for predicting enantio- and diastereoselectivities of the reduction is proposed and discussed.