Characterization of chemical and sensory properties of Cabernet Sauvignon and Marselan wines made by flash détente technique

This study aimed to characterize the sensory profiles of wines produced using the flash détente (FD) technique and to identify the flavor compounds contributing to the sensory characteristics. The FD technique was applied to two major grape varieties, Cabernet Sauvignon and Marselan, from the Changli region of China to produce high-quality wines with aging potential. Compared to the traditional macerated wines, the FD wines showed greater color intensity, mainly due to the higher levels of anthocyanins. Regarding the aroma characteristics, FD wines were found to have a more pronounced fruitness, especially fresh fruit note, which was due to the contribution of higher concentration of esters. Concurrently, FD wines showed an increased sweet note which was associated with increased lactones and furanones. In addition, FD wines exhibited reduced green and floral notes due to lower levels of C6 alcohols and C13-norisoprenoids. With regard to mouthfeel, FD wines presented greater astringency and bitterness, which was due to the higher levels of phenolics. The total concentration of condensed tannins and condensed tannins for each degree of polymerization was considerably higher in FD wines due to the strong extraction of the FD technique. A significant increase in grape-derived polysaccharides and glycerol was also found in FD wines, contributing to a fuller body. This study contributed to an increase in the knowledge of the Changli region and demonstrated that the FD technique could be applied to the wine production in this region to address the negative impacts of rainfall in individual vintages.

One-pot process for the biotransformation of vegetable oils into natural deca- and dodecalactones

Deca- and dodecalactones are highly desired natural compounds that are essential for creating flavor formulations with fruity, peachy, creamy, and floral notes. Although natural ingredients are preferred by consumers, these lactones cannot be extracted from natural sources. Therefore, the biotechnological processes that produce these compounds in their natural form are crucial for the flavor industry. Here, we report a study on the biotransformation of vegetable oils into natural deca- and dodecalactones. The proposed process is performed one-pot, through the sequential use of three different biotransformation steps, namely the lipase-mediated hydrolysis of the triglycerides, the use of probiotic bacteria for the hydration of the unsaturated fatty acids and the transformation of the obtained hydroxy-fatty acids into lactones derivatives employing Yarrowia lipolytica. By using a specific vegetable oil in combination with a selected bacterial strain, it is possible to obtain a preferred lactone derivative such as γ-dodecalactone, dairy lactone, tuberose lactone, or δ-decalactone in a concentration ranging from 0.9 to 1.5 g/L. Overall, our method is suitable for the industrial production of these lactones as it is easily scalable, it can be performed in only one bioreactor and it makes use of generally recognized as safe (GRAS) microorganisms.

Computational evaluation of zirconocene catalysts for ε-caprolactone cationic ring-opening polymerization

This quantum chemical study presents the ligand effect and a structure-property relationship in the cationic ring-opening polymerization (CROP) of ε-caprolactone using zirconocene catalysts. We first examined the effects of catalyst structure on the initiation and chain propagation steps of the CROP process. A total of 54 catalyst structures were investigated to understand the influence of the ligand structure on the stability of the catalyst-monomer complex and polymerization activity. The properties of the catalysts were analyzed in terms of ancillary ligands, ligand substituents, and bridging units. Calculations showed that the polymerization follows a proposed cationic mechanism, with ring opening occurring via alkyl-bond cleavage. A correlation between complex stability and activation energy was also observed, with ligand substituents dominating in both steps. While the ancillary ligands directly affect the HOMO energy level, the bridges are mainly responsible for the catalyst geometries, resulting in reduced complex stability and higher activation energy for the propagation step. This study contributes to a better understanding of the structural characteristics of zirconocene catalysts, which offers guidance for improving CROP activities in lactone polymerization.

Frequency-dependent nonlinear optical response and refractive index investigation of lactone-derived thermochromic compounds

Nonlinear optical (NLO) switchable materials play a crucial role in the fields of electronics and optoelectronics. The selection of an appropriate switching approach is vital in designing such materials to enhance their NLO response. Among various approaches, thermos-switching materials have shown a 4-fold increase in NLO response compared to other photo-switching materials. In this study, we computationally investigated the geometric, electronic, and nonlinear optical properties of reversible lactone-based thermochromic compounds using the ωB97XD/6-311+G (d,p) level of theory. Molecular orbital studies are employed to analyze the electronic properties of the close and open isomers of these compounds, while time-dependent density functional theory (TD-DFT) analysis is utilized to evaluate their molecular absorption. Our findings reveal that the π-electronic conjugation-induced delocalization significantly influences the ON-OFF switchable nonlinear optical response of the lactone-based thermochromic compounds. Notably, among all compounds, the open isomer of lactone 2 exhibits the highest hyperpolarizability value (6596.69 au). Furthermore, we extended our analysis to investigate the frequency-dependent second and third-order hyperpolarizabilities. The most pronounced frequency-dependent NLO response is observed at 532 nm. Additionally, we calculated the refractive index of these thermochromic compounds to further assess their nonlinear optical response. The open isomer of lactone 1 demonstrates the highest refractive index value (3.99 × 10-14 cm2/W). Overall, our study highlights the excellent potential of reversible thermochromic compounds as NLO molecular thermos-switches for future applications.

Discovery of a novel series of medium-sized cyclic enteropeptidase inhibitors

Enteropeptidase is located in the duodenum that involved in intestinal protein digestion. We have reported enteropeptidase inhibitors with low systemic exposure. The aim of this study was to discover novel enteropeptidase inhibitors showing more potent in vivo efficacy while retaining low systemic exposure. Inhibitory mechanism-based drug design led us to cyclize ester 2 to medium-sized lactones, showing potent enteropeptidase inhibitory activity and improving the ester stability, thus increasing fecal protein output in vivo. Optimization on the linker between two benzene rings resulted in discovery of ether lactone 6b, exhibiting further enhanced enteropeptidase inhibitory activity and long duration of inhibitory state. Oral administration of 6b in mice significantly elevated fecal protein output compared with the lead 2. In addition, 6b showed low systemic exposure along with low intestinal absorption. Furthermore, we identified the 10-membered lactonization method for scale-up synthesis of 6b, which does not require high-dilution conditions.

Stereodivergent Biocatalytic Formal Reduction of α-Angelica Lactone to (R)- and (S)-γ-Valerolactone in a One-Pot Cascade

The formal asymmetric and stereodivergent enzymatic reduction of α-angelica lactone to both enantiomers of γ-valerolactone was achieved in a one-pot cascade by uniting the promiscuous stereoselective isomerization activity of Old Yellow Enzymes with their native reductase activity. In addition to running the cascade with one enzyme for each catalytic step, a bifunctional isomerase-reductase biocatalyst was designed by fusing two Old Yellow Enzymes, thereby generating an unprecedented case of an artificial enzyme catalyzing the reduction of nonactivated C=C bonds to access (R)-valerolactone in overall 41% conversion and up to 91% ee. The enzyme BfOYE4 could be used as single biocatalyst for both steps and delivered (S)-valerolactone in up to 84% ee and 41% overall conversion. The reducing equivalents were provided by a nicotinamide recycling system based on formate and formate dehydrogenase, added in a second step. This enzymatic system provides an alternative asymmetric approach to generate valuable chiral building blocks from an abundant bio-based chemical.

YUD18001 associated with Gastrodia elata

Ten undescribed C₁₂ polyketide phialocetones A-J, featuring twelve-, six- and five-membered lactone moieties, were isolated from a rhizospheric soil-derived Phialocephala sp. YUD18001 associated with Gastrodia elata. Their structures were established by NMR spectroscopic analysis and HRMS, while their absolute configurations were determined by computational methods and chemical reactions. All isolated compounds were evaluated for their anti-inflammatory and cytotoxic activities. As a result, phialocetone D exhibited moderate effects against NO production in lipopolysaccharide (LPS)-induced RAW264.7 cells with an IC₅₀ value of 14.77 μM, while phialocetone E showed cytotoxicity against HL-60 and SW480 cell lines with IC₅₀ values of 19.04 and 10.22 μM, respectively.

Desymmetrisation of meso-2,4-Dimethyl-8-Oxabicyclo[3.2.1]-Oct-6-Ene-3-Ol and its Application in Natural Product Syntheses

The compounds containing chiral centers and different functional groups serve as magnificent building blocks for the preparation of various natural products that are having immense biological activity. "Dimethyl-8-oxa-bicyclo[3.2.1]oct-6-en-3-ol" is one of the wonderful synthons to construct multiple stereo centers at a time during the asymmetric synthesis. In this account, we discuss our research efforts toward the synthesis of various simple and complex natural products from the past three decades (1995-2020) by using dimethyl-8-oxa-bicyclo[3.2.1]oct-6-en-3-ol as a synthon. Moreover, the synthetic utility of this starting material was investigated and well demonstrated. Further, we executed the desymmetrization of dimethyl-8-oxa-bicyclo[3.2.1]oct-6-en-3-ol by hydroboration to get different chiral centers. After obtaining the stereocenters, we could manage either the fragment, formal or total synthesis of natural products, by simple protection and deprotection sequence followed by C-C bond formation steps.

Lactone radical transformed methyl mercaptan-adsorbed activated carbon into graphene oxide modified activated carbon

Activated carbon was a widely-used adsorbent. However, it was usually classified as a hazardous waste after saturation adsorption for one pollution. For the first time, this article reported a regeneration method for the activated carbon saturated with methyl mercaptan. The regenerated carbon was partially transformed into graphene-oxide fragment with a thickness of 0.9-1.0 nm after a hydrothermal treatment at 180 °C. Electron paramagnetic resonance revealed that lactone group was transformed into lactone radical under the hydrothermal condition. The spins were increased from 4.54E+17-1.24E+18. The formed radical effectively reacted with the adsorbed methyl mercaptan and re-distributed the amorphous activated carbon to form lamellar graphene oxide. As a result, the spins were decreased from 1.24E+18-8.73E+17. At the same time, the amount of lactone group was decreased from 0.71 to 0.42 mmol/g. The regenerated activated carbon thus regained ability to adsorb methyl mercaptan. The main result of this paper puts forward a simple and low-cost method to obtain graphene oxide modified activated carbon from the regeneration of hazardous waste carbon. This conclusion makes contribution to the development of "zero-waste" conception.

Interaction of isolinderanolide E obtained from Nectandra oppositifolia with biomembrane models

A long-tail lactone, named isolinderanolide E, was obtained from Nectandra oppositifolia and incorporated in Langmuir monolayers of dipalmitoyl-phosphoethanolamine (DPPE) as a model of microbial membranes. The compound was dissolved in chloroform and mixed with DPPE to provide mixed solutions spread on the air-water interface. After solvent evaporation, mixed monolayers were formed, and surface pressure-area isotherms, dilatational rheology, Brewster angle microscopy (BAM), and infrared spectroscopy were employed to characterize the prodrug-membrane interactions. Isolinderanolide E expanded DPPE monolayers, denoting repulsive interactions. At 30 mN/m, the monolayer presented higher viscoelastic and in-plane elasticity parameters and an increased ratio of all-trans/gauche conformers of the alkyl chains, confirming molecular order. Morphology of the monolayer was analyzed by BAM, which revealed a more homogeneous distribution of Isolinderanolide E along the DPPE monolayer than the prodrug directly spread at the interface, which tends to aggregate. A molecular model proposing the molecular orientation of the amphiphilic drug is presented and explained by the distortion of the alkyl chains as well as by viscoelastic changes. In conclusion, the prodrug changes the thermodynamic, rheological, morphological, and structural properties of the DPPE monolayer, which may be essential to understand, at the molecular level, the action of bioactives in selected membrane models.

Identification, quantitation and sensorial contribution of lactones in brandies between China and France

Lactones are important flavor compounds in lots of foodstuffs. They also play an important role in brandy, but have not been studied at large. In this study, solid-phase extraction (SPE) and stir bar sorptive extraction (SBSE) combined with comprehensive two-dimensional gas chromatography and time-of-flight mass spectrometry (GC × GC-TOFMS) were applied to identify and quantify lactones in brandies between China and France. Totally 17 lactones were identified, four of which were detected only in SBSE. Among them, γ-valerolactone, γ-heptalactone, δ-octalactone, γ-undecanolactone and δ-dodecalactone were detected in brandy for the first time. The results of partial least squares-discriminant analysis (PLS-DA) revealed that lactones distinguished regional characteristics among different brandies. The omission test showed that four lactones (OAV > 1) had direct impact on the aroma of brandy, and other seven lactones at sub-threshold (0.1 < OAV < 1) provided peach and apricot aroma characteristics through synergistic effects.

The structure and role of lactone intermediates in linkage-specific sialic acid derivatization reactions

Sialic acids occur ubiquitously throughout vertebrate glycomes and often endcap glycans in either α2,3- or α2,6-linkage with diverse biological roles. Linkage-specific sialic acid characterization is increasingly performed by mass spectrometry, aided by differential sialic acid derivatization to discriminate between linkage isomers. Typically, during the first step of such derivatization reactions, in the presence of a carboxyl group activator and a catalyst, α2,3-linked sialic acids condense with the subterminal monosaccharides to form lactones, while α2,6-linked sialic acids form amide or ester derivatives. In a second step, the lactones are converted into amide derivatives. Notably, the structure and role of the lactone intermediates in the reported reactions remained ambiguous, leaving it unclear to which extent the amidation of α2,3-linked sialic acids depended on direct aminolysis of the lactone, rather than lactone hydrolysis and subsequent amidation. In this report, we used mass spectrometry to unravel the role of the lactone intermediate in the amidation of α2,3-linked sialic acids by applying controlled reaction conditions on simple and complex glycan standards. The results unambiguously show that in common sialic acid derivatization protocols prior lactone formation is a prerequisite for the efficient, linkage-specific amidation of α2,3-linked sialic acids, which proceeds predominantly via direct aminolysis. Furthermore, nuclear magnetic resonance spectroscopy confirmed that exclusively the C2 lactone intermediate is formed on a sialyllactose standard. These insights allow a more rationalized method development for linkage-specific sialic derivatization in the future.

Sweet scent lactones activate hot capsaicin receptor, TRPV1

In this study, we investigated the activation of Transient receptor potential vanilloid subtype 1, TRPV1, by lactones, a representative flavor ingredient currently used for foods and beverages. As a result, we found that some lactones having C4 acyl chain length, γ-octalactone, δ-nonalactone and β-methyl-γ-octalactone, γ-undecalactone with C7 acyl chain length and δ-undecalactone with C6 acyl chain length activated TRPV1. TRPV1 is known as a non-selective cation channels that respond to a wide range of physical and chemical stimuli such as high temperature, protons, capsaicin and so on. Furthermore, it has been also demonstrated that activation of TRPV1 induced energy expenditure enhancement and thermogenesis, suppressed accumulation of visceral fat in mice and prevented non-alcoholic fatty acid liver. Thus, lactones that function as TRPV1 agonists are thought to be important candidates for decreasing the risks of developing a metabolic syndrome.

Transformation of Prostaglandin D2 to 11-Dehydro Thromboxane B2 by Baeyer-Villiger Oxidation

Prostaglandin D₂ is one of five chief prostanoids formed in the cyclooxygenase pathway of arachidonic acid oxidation. Except for a single oxygen atom, PGD₂ is structurally identical to 11-dehydro thromboxane B₂ (11d-TxB₂ ), a urinary metabolite of the pro-aggregatory platelet activator, thromboxane A₂ . The close structural relationship suggested that one might be transformed to the other. Accordingly, we tested whether the cyclopentanone of PGD₂ can be expanded to the δ-lactone of 11d-TxB₂ in a Baeyer-Villiger oxidation. Oxidation of PGD₂ with two standard oxidants showed that 11d-TxB₂ was formed only with H₂ O₂ but not with peracetic acid. Byproducts of the H₂ O₂ -mediated oxidation were hydroperoxide derivatives and isomers of PGD₂ . Chemical oxidation of PGD₂ to 11d-TxB₂ may be a model for an equivalent enzymatic transformation, suggesting a possible link in the metabolism of PGD₂ and thromboxane A₂ .

Antiproliferative, cytotoxic and apoptotic activity of the bentonite transformation of sesquiterpene lactone glaucolide B to 5β-hydroxy-hirsutinolide on tumor cell lines

Numerous chemical compounds isolated from medicinal plants have anti-tumor properties, the effects of which on human cancer cells are currently under study. Here, the chemical transformation of glaucolide B were performed to produce a hirsutinolide. The antiproliferative and cytotoxic activity of 5β-hydroxy-hirsutinolide and its ability to induce apoptosis in tumor and non-tumor cells (lymphocyte cultures and the normal HaCaT cell line) (1a) are reported. We ascertained that compound 1a exerts an inhibitory effect on the proliferation of SK-Lu-1, MDA-MB-231 and CaSki cells in a dose-dependent manner at IC₅₀ values of 15, 18 and 30 μg/ml, respectively. The proliferation of lymphocyte cells treated with 1a was inhibited at a range from 14 to 28%, but the HaCaT cell line was not affected, suggesting that compound 1a has a selective action. Cytotoxic activity was evaluated by detecting the lactate dehydrogenase enzyme in supernatants from tumor and non-tumor cells. The 1a compound exhibited low or null cytotoxic activity in both cell types. The presence of apoptotic bodies and active caspase-3 in tumor cell lines treated with compound 1a are suggestive of apoptotic cell death. Notably, flow cytometry evaluation did not detect the presence of active caspase-3 on lymphocytes treated with this compound. Our results suggest that 5β-hydroxy-hirsutinolide is a molecule with antiproliferative activity and low cytotoxic activity in tumor and non-tumor cells; this induces apoptotic cell death in tumor cell lines through selective action. Hence, this lactone could be considered a molecule worthy of study as an anti-tumor agent with therapeutic potential.

Zaluzanin C Inhibits Differentiation of 3T3-L1 Preadipocytes into Mature Adipocytes

Background

An excess storage of body fat causes obesity. Since obesity increases risk of chronic diseases, it is important to inhibit excessive storage of fat. Zaluzanin C is a sesquiterpene lactone isolated from Ainsliaea acerifolia. The aim of this study was to demonstrate the effect of zaluzanin C on differentiation of 3T3-L1 preadipocytes into mature adipocytes.

Methods

The cytotoxicity of zaluzanin C and its effect on cell proliferation was determined. For the induction of adipocyte differentiation, 3T3-L1 preadipocytes were treated with differentiating medium containing 10 μg/mL insulin, 115 μg/mL methylisobutylxanthine, and 1 μM dexamethasone. Differentiated 3T3-L1 cells were subjected to Oil red O solution or used for Western blot analysis. Zaluzanin C was added to the cell culture medium at concentrations of 0, 1, 2.5, 5, and 10 μM.

Results

Zaluzanin C did not inhibit cell proliferation and showed no cytotoxicity at 10 μM concentration in 3T3-L1 cells. Therefore, concentration range of 0–10 μM zaluzanin C was used for subsequent experiments. Zaluzanin C inhibited accumulation of lipid droplets in 3T3-L1 adipocytes. To understand the underlying mechanism of zaluzanin C, expression of adipogenesis regulators was determined by Western blot analysis. Zaluzanin C suppressed peroxisome proliferator-activated receptor gamma (PPARγ) expression, an adipogenesis related transcription factor, and inhibited aP2/fatty acid-binding protein-4 expression, a target gene of PPARγ. However, it did not affect expression of CCAAT/enhancer-binding protein alpha related with acquisition of insulin sensitivity.

Conclusion

These data suggest that inhibitory effect of zaluzanin C on adipogenesis of 3T3-L1 adipocytes could be partially caused by suppressing PPARγ.

Discovery and synthesis of novel indole derivatives-containing 3-methylenedihydrofuran-2(3H)-one as irreversible LSD1 inhibitors

Lysine-specific demethylase 1 (LSD1), demethylase against mono- and di - methylated histone3 lysine 4, has emerged as a promising target in oncology. More specifically, it has been demonstrated as a key promoter in acute myeloid leukemia (AML), and several LSD1 inhibitors have already entered into clinical trials for the treatment of AML. In this paper, a series of new indole derivatives were designed and synthesized based on a lead compound obtained by a high-throughput screening with our in-house compound library. Among the synthetic compounds, 9e was characterized as a potent LSD1 inhibitor with an IC₅₀ of 1.230 μM and can inhibit the proliferation of THP-1 cells effectively. And most importantly, this is the first irreversible LSD1 inhibitor that is not derived from monoamine oxidase inhibitors. Hence, the discovery of 9e may serve as a proof of concept work for AML treatment.

Analysis of hydroxy triacylglycerol as a lactone precursor in milk fat using liquid chromatography electrospray ionization tandem mass spectrometry

Heating milk fat leads to lactone formation. Hydroxy fatty acids, esterified in triacylglycerol (TAG), are likely precursors of lactones in milk fat, but respective hydroxy TAG isomers have not been directly detected for several decades. In this study, we separated hydroxy TAG isomers-1,2-dipalmitoyl-3-(5-hydroxy decanoyl)-rac-glycerol (PP(C10-5OH)-TAG), 1,2-dipalmitoyl-3-(5-hydroxy dodecanoyl)-rac-glycerol (PP(C12-5OH)-TAG), 1,2-dipalmitoyl-3-(5-hydroxy tetradecanoyl)-rac-glycerol (PP(C14-5OH)-TAG), and 1,2-dipalmitoyl-3-(4-hydroxy dodecanoyl)-rac-glycerol-by using liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) with an octacocyl silylation column. This method revealed the presence of PP(C10-5OH)-TAG, PP(C12-5OH)-TAG, and PP(C14-5OH)-TAG in butter oil, whereas no hydroxy TAG isomers were detected in heat-treated butter oil. Furthermore, a heating test of hydroxy TAG standards showed a decrease in hydroxy TAG levels and an increase in the corresponding lactone levels. These changes were stimulated by adding a small amount of water. This is the first reported analysis of respective hydroxy TAG isomers in milk fat using LC-ESI-MS/MS.

Identification of biologically active δ-lactone eicosanoids as paraoxonase substrates

The mammalian paraoxonases (PONs 1, 2 and 3) are a family of esterases that are highly conserved within and between species. They exhibit antioxidant and anti-inflammatory activities. However, their physiological function(s) and native substrates are uncertain. Previous structure-activity relationship studies demonstrate that PONs have a high specificity for lipophilic lactones, suggesting that such compounds may be representative of native substrates. This report describes the ability of PONs to hydrolyze two bioactive δ-lactones derived from arachidonic acid, 5,6-dihydroxy-eicosatrienoic acid lactone (5,6-DHTL) and cyclo-epoxycyclopentenone (cyclo-EC). Both lactones were very efficiently hydrolyzed by purified PON3. PON1 efficiently hydrolyzed 5,6-DHTL, but with a specific activity about 15-fold lower than PON3. 5,6-DHTL was a poor substrate for PON2. Cyclo-EC was a poor substrate for PON1 and not hydrolyzed by PON2. Studies with the PON inhibitor EDTA and a serine esterase inhibitor indicated that the PONs are the main contributors to hydrolysis of the lactones in human and mouse liver homogenates. Studies with homogenates from PON3 knockout mouse livers indicated that >80% of the 5,6-DHTL and cyclo-EC lactonase activities were attributed to PON3. The findings provide further insight into the structural requirements for PONs substrates and support the hypothesis that PONs, particularly PON1 and PON3, evolved to hydrolyze and regulate a class of lactone lipid mediators derived from polyunsaturated fatty acids.

Synthesis and evaluation of 2-cyano-3, 12-dioxooleana-1, 9(11)-en-28-oate-13β, 28-olide as a potent anti-inflammatory agent for intervention of LPS-induced acute lung injury

The present study was designed to synthesize 2-Cyano-3, 12-dioxooleana-1, 9(11)-en-28-oate-13β, 28-olide (1), a lactone derivative of oleanolic acid (OA) and evaluate its anti-inflammatory activity. Compound 1 significantly diminished nitric oxide (NO) production and down-regulated the mRNA expression of iNOS, COX-2, IL-6, IL-1β, and TNF-α in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Further in vivo studies in murine model of LPS-induced acute lung injury (ALI) showed that 1 possessed more potent protective effects than the well-known anti-inflammatory drug dexamethasone by inhibiting myeloperoxidase (MPO) activity, reducing total cells and neutrophils, and suppressing inflammatory cytokines expression, and thus ameliorating the histopathological conditions of the injured lung tissue. In conclusion, compound 1 could be developed as a promising anti-inflammatory agent for intervention of LPS-induced ALI.

Fungal BVMOs as alternatives to cyclohexanone monooxygenase

FAD-dependent Baeyer-Villiger monooxygenases (BVMOs) have proven to be useful biocatalysts in the selective and specific oxygenation of various ketones. Despite the cloning, heterologous expression and characterization of close to 80 members of this enzyme family, some sub-groups of BVMOs still remain underrepresented and their evolutionary relationship uncertain. Until recently, very few fungal BVMOs have been described. Our previous investigations into BVMOs from the fungus Aspergillus flavus, yielded very little activity on simple cyclic ketones. Here we report on another four BVMOs from A. flavus that are more closely related to cyclohexanone monooxygenase (CHMO) from Acinetobacter sp. NCIMB 9871. Evolutionary analysis with other characterized BVMOs show their closest relationship to be with either cycloalkanone monooxygenase (CAMO) or 2-oxo-Δ³-4,5,5-trimethylcyclopentenylacetyl-coenzyme A monooxygenase (OTEMO). The OTEMO-related BVMO_AFL706 and BVMO_AFL334 were heterologously expressed in E. coli, purified and shown to be able to convert a range of cyclic and substituted cyclic ketones. Of the unsubstituted cyclic ketones, cyclohexanone showed the highest conversion with maximum turnover frequencies reaching 4.3s^-1 for BVMO_AFL706. Unlike CHMO_acinet, and many of the closely related BVMOs, no substrate inhibition was observed with cyclohexanone to a concentration of up to 30mM, creating the possibility for applications requiring high substrate loading. Aliphatic ketones were also readily converted with excellent regioselectivity. Similar to CHMO_acinet, acetophenones were not converted and the oxidation of rac-cis-bicyclo[3.2.0]hept-2-en-6-one occurs enantiodivergently, with the (1R,5S) isomer converted to the "normal" lactone and the (1S,5R) isomer to the "abnormal" lactone.

Solid-state 17O NMR study of 2-acylbenzoic acids and warfarin

We report synthesis and solid-state ¹⁷O NMR characterization of four site-specifically ¹⁷O-labeled 2-acylbenzoic acids (2-RC(O)C₆H₄COOH) where R=H and CH₃): 2-[3-¹⁷O]formylbenzoic acid, 2-[1,2-¹⁷O₂]formylbenzoic acid, 2-[3-¹⁷O]acetylbenzoic acid, and 2-[1,2,3-¹⁷O₃]acetylbenzoic acid. In the solid state, both 2-formyl- and 2-acetyl-benzoic acids exist as the cyclic phthalide form each containing a five-membered lactone ring and a cyclic hemiacetal/hemiketal group. Static and magic-angle-spinning ¹⁷O NMR spectra were recorded at 14.1 and 21.1T for these compounds, from which the ¹⁷O chemical shift and nuclear quadrupolar coupling tensors were determined for each oxygen site. These results represent the first time that ¹⁷O NMR tensors are fully characterized for lactone, cyclic hemiacetal, and cyclic hemiketal functional groups. We also report solid-state ¹⁷O NMR data for the cyclic hemiketal group an anticoagulant drug, warfarin. Experimental ¹⁷O NMR tensors in these compounds were compared with computational results obtained with a periodic DFT code BAND.

Metabolism of steroidal lactones by the fungus Corynespora cassiicola CBS 161.60 results in a mechanistically unique intramolecular ring-D cyclization resulting in C-14 spiro-lactones

The fungus Corynespora cassiicola metabolises exogenous steroids in a unique and highly specific manner. Central to this, is the ability of this organism to functionalise substrates (androgens, progestogens) at the highly stereochemically hindered 8β-position of the steroid nucleus. A recent study has identified that 8β-hydroxylation occurs through inverted binding in a 9α-hydroxylase. In order to discern the metabolic fate of more symmetrical molecules, we have investigated the metabolism of a range of steroidal analogues functionalised with ring-D lactones, but differing in their functional group stereochemistry at carbon-3. Remarkably, the 3α-functionalised steroidal lactones underwent a mechanistically unique two step intramolecular cyclisation resulting in the generation of a ring-D spiro-carbolactone. This rapid rearrangement initiated with hydroxylation at carbon 14 followed by transesterification, resulting in ring contraction with formation of a butyrolactone at carbon-14. Remarkably this rearrangement was found to be highly dependent on the stereochemistry at carbon-3, with the β-analogues only undergoing 9α-hydroxylation. The implications of these findings and their mechanistic bases are discussed.

Layer-by-layer nanoencapsulation of camptothecin with improved activity

160 nm nanocapsules containing up to 60% of camptothecin in the core and 7-8 polyelectrolyte bilayers in the shell were produced by washless layer-by-layer assembly of heparin and block-copolymer of poly-l-lysine and polyethylene glycol. The outer surface of the nanocapsules was additionally modified with polyethylene glycol of 5 kDa or 20 kDa molecular weight to attain protein resistant properties, colloidal stability in serum and prolonged release of the drug from the capsules. An advantage of the LbL coated capsules is the preservation of camptothecin lactone form with the shell assembly starting at acidic pH and improved chemical stability of encapsulated drug at neutral and basic pH, especially in the presence of albumin that makes such formulation more active than free camptothecin. LbL nanocapsules preserve the camptothecin lactone form at pH 7.4 resulting in triple activity of the drug toward CRL2303 glioblastoma cell.

Synthesis and anti-BVDV activity of novel δ-sultones in vitro: implications for HCV therapies

In this study we report the synthesis and activity against bovine viral diarrhea virus (BVDV) of a novel series of bicycle δ-sultones containing γ-lactones. BVDV is responsible for major losses in cattle. Some of the synthesized δ-sultones showed pronounced anti-BVDV activity with EC50 values of 0.12-1.0μM and no significant cytotoxicity. Among them, the ortho bromosubstituted derivative 4f (EC50=0.12μM) showed better antiviral activity than other derivatives and was 10 fold more that of than positive control ribavirin (EC50=1.3μM). BVDV is also considered to be a valuable surrogate for the hepatitis C virus (HCV) in antiviral drug studies. The above results provided a novel candidate for the development of anti-HCV agents.

3D-QSAR Studies on C24-Monoalkylated Vitamin D3 26,23-Lactones and their C2α-Modified Derivatives with Inhibitory Activity to Vitamin D Receptor

The ligand-based three-dimensional quantitative structure-activity relationship (3D-QSAR) for 82 inhibitors of 25-dehydro-1α-hydroxyvitamin D3 -26,23-lactone analogs has been studied by using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) models. The established CoMFA model in training set gives a cross-validated q(2) value of 0.516 and a non-cross-validated rncv (2) value of 0.667, while the CoMSIA model results in q(2) =0.517 and rncv (2) =0.632. In general, the predictive ability of the CoMFA model is superior to that of the CoMSIA model, with rpred (2) =0.639 for the CoMFA and rpred (2) =0.619 for the CoMSIA model. Based on the CoMFA contour maps, some key structural characters of vitamin D3 analogs responsible for inhibitory activity are identified, and some new C2α-modified 24-alkylvitamin D3 lactone analogs with high predicted pIC50 values are designed. The ligand functional group mutations by FEP simulation and docking studies reveal the rationality of the molecular design.

Dearomatization applications of I(III) reagents and some unusual reactivity amongst resorcinol derived cyclohexadienones

The oxidative dearomatization of resorcinol derivatives, which are outfitted with a lactic acid derived chiral tether, and mitigated by hypervalent iodine derivatives of PhIO, affords stable chiral cyclohexadienones as useful building blocks for the construction of many highly functionalized chiral six and seven-membered ring systems. Herein, we report a multitude of remarkable and unexpected diastereoselective transformations stemming from these cyclohexadienone adducts.