Synthesis, Stability, and Antidiabetic Activity Evaluation of (-)-Epigallocatechin Gallate (EGCG) Palmitate Derived from Natural Tea Polyphenols.

This work describes a novel approach for the synthesis of (-)-epigallocatechin gallate (EGCG) palmitate by a chemical-synthesis method, where the elevated stability of the EGCG derivative is achieved. Various parameters affecting the acylation process, such as the base, solvent, as well as the molar ratio of palmitoyl chloride, have been studied to optimize the acylation procedure. The optimized reaction condition was set as follows: EGCG/palmitoyl chloride/sodium acetate was under a molar ratio of 1:2:2, with acetone as the solvent, and the reaction temperature was 40 °C. Under the optimized condition, the yield reached 90.6%. The EGCG palmitate (PEGCG) was isolated and identified as 4'-O-palmitoyl EGCG. Moreover, the stability of PEGCG under different conditions was proved significantly superior to EGCG. Finally, PEGCG showed better inhibition towards α-amylase and α-glucosidase, which was 4.5 and 52 times of EGCG, respectively. Molecular docking simulations confirmed the in vitro assay results. This study set a novel and practical synthetic approach for the derivatization of EGCG, and suggest that PEGCG may act as an antidiabetic agent.

Solvent-free enzymatic production of high quality cetyl esters.

A solvent-free biocatalytic process for the synthesis of high quality cetyl laurate, myristate, palmitate and stearate has been optimized. This enzymatic procedure follows the fundamental principles of the Green Chemistry and lead to sustainable products, which can be labeled as natural and conform to the principal requirements for its use in high value-added goods. The four esters selected are the main components of spermaceti, a mixture of waxes very appreciated in cosmetic and pharmacy because of its physical properties and emolliency, which was formerly extracted from the head of the sperm whales. In this paper, the influence of the amount of biocatalyst, the commercially available Novozym(®) 435, and the temperature were studied in an open-air batch reactor before carrying out the synthesis in a high performance vacuum reactor with dry nitrogen input to shift the equilibrium towards product formation. Under optimal conditions, conversion was higher than 98.5 %. The characterization of the enzymatic cetyl esters puts in evidence that these are ultra-pure compounds, which have similar properties to the ones obtained through the conventional industrial processes with the extra benefit of being environmentally friendly.

2-Bromopalmitate analogues as activity-based probes to explore palmitoyl acyltransferases.

Reversible S-palmitoylation is an important post-translational modification that regulates the trafficking, localization, and activity of proteins. Cysteine-rich Asp-His-His-Cys (DHHC) domain-containing enzymes are evolutionarily conserved protein palmitoyl acyltransferases (PATs). The human genome encodes 23 DHHC-PATs that regulate diverse cellular functions. Although chemical probes and proteomic methods to detect palmitoylated protein substrates have been reported, no probes for direct detection of the activity of PATs are available. Here we report the synthesis and characterization of 2-bromohexadec-15-ynoic acid and 2-bromooctadec-17-ynoic acid, which are analogues of 2-bromopalmitate (2-BP), as activity-based probes for PATs as well as other palmitoylating and 2-BP-binding enzymes. These probes will serve as new chemical tools for activity-based protein profiling to explore PATs, to dissect the functions of PATs in cell signaling and diseases, and to facilitate the identification of their inhibitors.

Biosysthesis of corn starch palmitate by lipase Novozym 435.

Esterification of starch was carried out to expand the usefulness of starch for a myriad of industrial applications. Lipase B from Candida antarctica, immobilized on macroporous acrylic resin (Novozym 435), was used for starch esterification in two reaction systems: micro-solvent system and solvent-free system. The esterification of corn starch with palmitic acid in the solvent-free system and micro-solvent system gave a degree of substitution (DS) of 1.04 and 0.0072 respectively. Esterification of corn starch with palmitic acid was confirmed by UV spectroscopy and IR spectroscopy. The results of emulsifying property analysis showed that the starch palmitate with higher DS contributes to the higher emulsifying property (67.6%) and emulsion stability (79.6%) than the native starch (5.3% and 3.9%). Modified starch obtained by esterification that possesses emulsifying properties and has long chain fatty acids, like palmitic acid, has been widely used in the food, pharmaceutical and biomedical applications industries.

Efficacy and tolerability of a cream containing AR-GG27® (sorbityl furfural palmitate) in the treatment of mild/moderate childhood atopic dermatitis associated with pityriasis alba. A double-blind, placebo-controlled clinical trial.

AIM: Pityriasis alba (PA) is a skin disorder characterized by finely scaly, hypopigmented patches, typical of childhood, that also represents an atopic dermatitis (AD) minor sign according to Hanifin and Rajka criteria. It may be isolated or associated with AD representing, sometimes an atypical manifestation of AD during the long-term follow-up of the disease. Aim of the study was to evaluate of the efficacy and tolerability of AR-GG27® (sorbityl furfural palmitate) cream in the treatment of childhood mild or moderate AD associated with PA. METHODS: The trial is a single center, double-blind, randomized, placebo-controlled study. The study included patients of both sexes, aged between two months and 15 years, suffering from mild and moderate AD always associated with PA. Xerosis was present in all patients. The treatment with topical steroids or topical calcineurin inhibitors (TIMs) had to be suspended for at least 15 days. Any systemic therapy and phototherapy or sun exposure were withdrawn at least 30 days before. Emollients were stopped at least seven days before. During the trial, no other local or systemic treatments were allowed, as well as sun exposure. Patients affected by AD with viral, bacterial or fungal overinfection or patients with diabetes mellitus, severe systemic diseases or intolerance to one or more components of the product were excluded. The primary endpoint was the evaluation of the average change in the Investigator Global Assessment (IGA) after 15 and 30 days of treatment. The second endpoint was the evaluation of severity of three different clinical signs: erythema, excoriation desquamation, using a subjective five-point scale. Changes in pruritus severity was also considered during the entire period of treatment, through the use of a Visual Analogue Scale (VAS). A P<0.05, two tailed was considered as statistically significant. RESULTS: After 15 and 30 days there was a statistically significant difference in the group treated with AR-GG27®, compared to the placebo (respectively, P=0.0007 and P=0.005). After 15 days of treatment, itching was clearly reduced in AR-GG27® treated group compared with the placebo, both in the study population (P=0.01) and in patients where the symptom was present from the beginning (P=0.05). CONCLUSION: AR-GG27® showed a beneficial action associated with high compliance and tolerability in dermatological skin conditions characterized by inflammation and tissue oxidative stress in children, as PA with mild and moderate AD.

Pure, transparent-melting starch esters: synthesis and characterization.

Long chain starch esters were prepared by a new method using molten imidazole as solvent for the biopolymer. The advantage is the simplicity of the reaction mixture. Imidazole is acting not only as solvent, but also as reagent and base. The reaction succeeds via the imidazolide, which is formed in situ with an acid chloride. It yields highly pure derivatives, as could be shown by NMR spectroscopy and elemental analysis. No hints for desoxychloro substituents or other impurities could be found. The high quality of the products prepared is responsible for the occurrence of colorless melts. Although DSC measurements show a variety of thermal transitions, the formation of melts in the range of 40 to 255 °C could be observed with a hot stage microscope. The melting behavior can be adjusted by the type of ester moiety and the amount of ester functions introduced. In case of starch palmitates completely transparent melts are obtained within two distinct DS regions namely around 1.5 and 2.2 to 3.0. Upon cooling the melts form homogeneous films on different supports including glass. They show good adhesion and should therefore be a suitable basic material for the preparation of composites like laminated glass.

High Efficient Biosynthesis 2-Ethylhexyl Palmitate in a Rotating Packed Bed Reactor.

2-Ethylhexyl palmitate (2-EHP) is one of the important chemical products. Normally, 2-EHP is produced through the esterification. Since 2-EHP has a high viscosity, the mass transfer is significantly influenced with the product accumulation. In this work, a rotating packed bed reactor with intensive mixing was employed to solve the problem in the mass transfer during the enzymatic reaction. Under the optimal conditions, compared with the traditional continuous stirred-tank reactor (CSTR), the RPB reactor enhanced the final yield of 2-EHP, and shortened the reaction time to 1 h. In addition, the enzyme has a longer life-time in the RPB reactor, with production yield of closing to 99% after 9 batches. The results of this research indicated that the RPB has a great potential to be applied in the enzymatic production of 2-EHP. Application of the rotating packed bed in synthesis of 2-ethylhexyl palmitate.

Gastroprotective effect of carnosic acid gamma-lactone derivatives.

Carnosic acid (1) has been shown to possess gastroprotective activity in vitro and in vivo. However, little is known of the gastroprotective effect or cytotoxicity of carnosic acid gamma-lactone (3). To determine structure-activity relationships, a series of 17 esters of 3 were prepared including aliphatic, aromatic, and heterocyclic derivatives. Also, two units of 3 were coupled with succinic and phthalic acid as linkers. The compounds were assessed for their gastroprotective effect in the HCl/EtOH-induced gastric lesions model in mice and for cytotoxicity in human lung fibroblasts, human adenocarcinoma AGS cells, and Hep G2 hepatocellular carcinoma cells. At a single oral dose of 40 mg/kg, the gastroprotective effect increased moderately with the length of the alkyl chain. The best effects were observed for the butyrate (9) and chloroacetate (6) derivatives. Activity of fatty acid esters increased with chain length but decreased with unsaturation. The best gastroprotective effect, with lowest cytotoxicity, was found for the palmitate (11) and oleate (12) derivatives.

D-Glucose-fatty Acid Ester Synthesis with or without a Biocatalyst in the Same Organic Media.

Esterification of D-glucose with oleic- and palmitic acids were carried out in the absence and presence of a biocatalyst, Candida antarctica lipase. The reaction medium was a mixture of dimethyl sulphoxide and tert-butanol (1:4, v/v). The reaction products were analysed by FTIR, 1H-NMR and 13C-NMR, HSQC, and by ESI-MS. Results indicated that the ester products formed were 6-O-glucose oleate and 6-O-glucose palmitate both in the absence and in the presence of the biocatalyst, with yields above 90%.

Ratiometric fluorescent probes for selective and sensitive visualization of bacterial microenvironment protease activity.

The extracellular SspA protease of the human pathogen S. aureus is essential for evading the host immune defence system. Two novel FRET probes for selective real-time ratiometric imaging of SspA activity in live S. aureus cells are reported.

Protective effect of new S-acylglutathione derivatives against amyloid-induced oxidative stress.

Recent data support the role of oxidative stress in the pathogenesis of Alzheimer disease (AD). In particular, glutathione (GSH) metabolism is altered and its levels are decreased in affected brain regions and peripheral cells from AD patients and in experimental models of AD. In the past decade, interest in the protective effects of various antioxidants aimed at increasing intracellular GSH content has been growing. Because much experimental evidence suggests a possible protective role of unsaturated fatty acids in age-related diseases, we designed the synthesis of new S-acylglutathione (acyl-SG) thioesters. S-Lauroylglutathione (lauroyl-SG) and S-palmitoleoylglutathione (palmitoleoyl-SG) were easily internalized into the cells and they significantly reduced Abeta42-induced oxidative stress in human neurotypic SH-SY5Y cells. In particular, acyl-SG thioesters can prevent the impairment of intracellular ROS scavengers, intracellular ROS accumulation, lipid peroxidation, and apoptotic pathway activation. Palmitoleoyl-SG seemed more effective in cellular protection against Abeta-induced oxidative damage than lauroyl-SG, suggesting a valuable role for the monounsaturated fatty acid. In this study, we demonstrate that acyl-SG derivatives completely avoid the sharp lipoperoxidation in primary fibroblasts from familial AD patients occurring after exposure to Abeta42 aggregates. Hence, we put forward these derivatives as new antioxidant compounds which could be excellent candidates for therapeutic treatment of AD and other oxidative stress-related diseases.

Synthesis of 2-Ethylhexyl Palmitate Catalyzed by Enzyme Under Microwave.

2-Ethylhexyl palmitate has been prepared in organic solvents catalyzed by an immobilized lipase QLM. Microwave irradiation was used to improve the enzyme activity and shorten the reaction time. The reaction conditions under microwave have been optimized. Compared with that of the free QLM under classical heating, the immobilized QLM under microwave exhibited higher enzyme activity and the conversion could achieve 99% in about 3.0 h. Furthermore, the immobilized QLM displayed excellent reusability under microwave irradiation.

Optimization of Alkyldiethanolamides Synthesis from Terminalia catappa L. Kernel Oil through Enzymatic Reaction.

Alkyldiethanolamides (fatty acid diethanolamides) synthesis from Terminalia catappa L. kernel oil was optimized using lypozyme as a catalyst. The result showed that the optimal reaction conditions were 2 hours reaction time, with a ratio of oil mass (g) to diethanolamine (mmol) of 1:5, a ratio of oil mass to enzyme (g) of 1: 0.075, and a temperature of 40°C. The percentage of alkyldiethanolamides at optimum condition was 56-60%. The synthesis results were also analyzed by FTIR. FTIR spectra revealed specific absorption at several wave numbers (3434 cm-1, 1655 cm-1, 1280 cm-1), indicating that amide and alcohol bonds (C=O, C-N, and O-H) were formed. GC-MS was employed to identify the types of fatty acid diethanolamides that were successfully synthesized. The fatty acid diethanolamides formed were palmitoyldiethanolamide (Rt = 32.96 min) and oleyldiethanolamide (Rt = 35.57 min). The total nitrogen content of alkyldietanolamides was 0.26%, or 0.19 mmol of the amide group in 1 g of sample.

Biological evaluations of fatty acid esters originated during storage of Prasaplai, a Thai traditional medicine.

Three fatty acid esters, (E)-4-(3,4-dimethoxyphenyl)but-3-en-1-yl linoleate (1), (E)-4-(3,4-dimethoxyphenyl)but-3-en-1-yl oleate (2), and (E)-4-(3,4-dimethoxyphenyl)but-3-en-1-yl palmitate (3), originated during storage by the interaction of components in Prasaplai, were synthesized. These three artificial esters were subjected to four biological evaluations. All three compounds were active against Mycobacterium tuberculosis H(37)Ra for which compounds 1 and 3 had inhibitory concentration at 200 microg mL(-1) while compound 2 inhibited at 100 microg mL(-1). When all these compounds were subjected to anti-HSV-1 test, compound 2 showed positive activity at 42.6 microg mL(-1) without any cytotoxic activity against human vero cell line while compound 3 had the cytotoxicity to vero cell at IC(50) 38 microg mL(-1). Compound 1 was inactive for this test.

Effect of esterified oligosaccharides on the formation and stability of oil-in-water emulsions.

Hydrophobically modified oligosaccharides were prepared by an enzyme-catalyzed reaction of maltodextrin/xylo-oligosaccharide and palmitic acid. Maltodextrin with dextrose equivalent (DE) of 16 palmitate (DE16_P) and 9 palmitate (DE9_P), as well as xylo-oligosaccharide palmitate (Xylo_P), were used. The effect of the concentration (10-50% (w/w)) and type of esterified oligosaccharides on the Sauter mean diameter and droplet-size distribution, the rate of coalescence (Kc), and the creaming properties of O/W emulsions were investigated. Esterified oligosaccharides (EO) adsorbed to the surface of the oil droplets. EO formed polydisperse O/W emulsions with particle sizes between 12 and 70 µm, depended on concentration of EO. The Sauter mean diameter, Kc, and the creaming index decreased markedly, with increasing concentration of EO. The type of ester minimally affected the Sauter mean diameter at each ester concentration. DE9_P inhibited coalescence and creaming more efficiently than other EO, mainly due to the higher viscosity of the continuous phase.

Design, synthesis, and binding studies of new potent ligands of cannabinoid receptors.

Despite their different chemical structures, delta9-tetrahydrocannabinol (THC) and anandamide (AEA) have common pharmacological properties. This study was aimed at finding new cannabinoid receptor ligands that overcome the instability of AEA and its analogues. To this end we planned the synthesis of a series of compounds which retained both a rigid structure, like that of plant cannabinoids, and a flexible portion similar to that of anandamide. Binding studies on CB1 and CB2 receptors, anandamide membrane transporter (AMT), and fatty acid amide hydrolase (FAAH) showed that some of the newly developed compounds have high affinity and specificity for cannabinoid CB1 and CB2 receptors. Compound 25 is a potent CB1 and CB2 ligand, with affinity constants significantly lower than AEA and similar to WIN 55-212, compound 52 is a potent CB2 ligand, although not very selective over CB1 receptors, and compound 43 is CB2 ligand, with at least a 26-fold selectivity over CB1 receptors. Compound 25 behaved as a inverse agonist at CB1 receptors as assessed in the cyclic AMP functional assay.

Short and efficient route to the fully functionalized polar core of scyphostatin.

[reaction: see text]. Diastereoselective oxidative dearomatization of benzopyran 5 to the corresponding p-quinol 9b allows a fast, efficient, and versatile entry to scyphostatin's polar epoxycyclohexenone moiety as demonstrated by the preparation of its palmitoyl analogue 16 (R = (CH2)14CH3).

Esters, retroesters, and a retroamide of palmitic acid: pool for the first selective inhibitors of N-palmitoylethanolamine-selective acid amidase.

Cyclohexyl hexadecanoate, hexadecyl propionate, and N-(3-hydroxypropionyl)pentadecanamide, respectively ester, retroester, and retroamide derivatives of N-palmitoylethanolamine, represent the first selective inhibitors of "N-palmitoylethanolamine hydrolase" described so far. These compounds are devoid of affinity for CB(1) and CB(2) receptors and characterized by high percentages of inhibition of N-palmitoylethanolamine-selective acid amidase (84.0, 70.5, and 76.7% inhibition at 100 microM, respectively) with much lower inhibitory effect on either fatty acid amide hydrolase or the uptake of anandamide.

Synthesis and study of the antischistosomal potency and induced biological parameters of a new 2-palmitoyl analogue of the universal antihelminthic praziquantel.

2-Palmitoyl[1,2,3,6,7,11b]hexahydro-4H-pyrazino[2-la]isoquinoline-4-one [III] a highly lipophilic analogue of the universal antihelminthic PRAZIQUANTEL [I] was rationally multi-stepwise synthesized and antischistosomally and biochemically screened. The 2-palmitoyl conjugation was hypothesized to be an antischistosomal adjuvant (Tween 40 mimicry), to the reported crucial pyrazino-isoquinoline moiety. On a constant weight doses bases of I and III (500 mg/kg mouse body weight), the activity of III was found to be approximately 70% of I (mice infected with S. mansoni cercariae) and with satisfactory toxicological and biochemical profile (mice liver and kidney functions). Equivalent molar weight assay (M 1:1.4 for I and III, respectively), which could further plead in favour of the potency of III, was not yet tested. The analogue III, which favourable incorporates the human metabolically and physiologically compatible, palmitic acid segment, seems to be an antischistosomally promising candidate for more integrated studies.

In vitro evaluation of the antiviral activity of the synthetic epigallocatechin gallate analog-epigallocatechin gallate (EGCG) palmitate against porcine reproductive and respiratory syndrome virus.

In this study, epigallocatechin gallate (EGCG) palmitate was synthesized and its anti-porcine reproductive and respiratory syndrome virus (PRRSV) activity was studied. Specifically, EGCG palmitate was evaluated for its ability to inhibit PRRSV infection in MARC-145 cells when administered as pre-, post-, or co-treatment. EGCG and ribavirin were used as controls. The results showed that a 50% cytotoxic concentration (CC50) of EGCG, EGCG palmitate, and ribavirin was achieved at 2,359.71, 431.42, and 94.06 µM, respectively. All three drugs inhibited PRRSV in a dose-dependent manner regardless of the treatment protocol. EGCG palmitate exhibited higher cytotoxicity than EGCG, but lower cytotoxicity than ribavirin. EGCG palmitate anti-PRRSV activity was significantly higher than that of EGCG and ribavirin, both as pre-treatment and post-treatment. Under the former conditions and a tissue culture infectious dose of 10 and 100, the selectivity index (SI) of EGCG palmitate in the inhibition of PRRSV was 3.8 and 2.9 times higher than that of ribavirin when administered as a pre-treatment, while the SI of EGCG palmitate in the inhibition of PRRSV was 3.0 and 1.9 times higher than ribavirin when administered as a post-treatment. Therefore, EGCG palmitate is potentially effective as an anti-PRRSV agent and thus of interest to the pharmaceutical industry.