Highest Ee Research Articles

In-vitro methane production potential and in-sacco degradability of conventional and non-conventional protein supplements

The study was taken up to assess the in-vitro methane and total volatile fatty acids (TVFAs) production; in sacco degradability and metabolizable energy (ME) availability from conventional and non conventional protein supplements like mustard cake (MC), deoiled mustard cake (DMC), deoiled groundnut cake (DGNC), soybean meal (SBM), cottonseed cake (CSC), corn gluten meal (CGM), maize oil cake (MOC), tomato pomace (TP) and spent brewers grains (SBG). The CP content varied from 18.2 (TP) to 66% (CGM). TP had the highest EE (11.0%) and lignin (13.5%) content. The net gas production (NGP) varied significantly from 80.7 ml/g DM (CSC) to 236.8 ml/g DM (MOC). The in-vitro methane production (expressed as ml/g DM) was the lowest from CSC and CGM, while the highest was observed from SBM and MOC. But when methane was expressed as per cent of NGP or as ml/g digestible OM at t1/2, the significantly lowest methane production was observed from TP followed by that from CSC, SBG MC and CGM. The protein supplement with high rumen undegradable protein (RUDP) content produced less methane as compared to the ones that had low UDP content. The TVFA production was the lowest from CSC, which may be due to the lowest degradability of OM and NDF. The digestion kinetic parameters for DM and CP revealed that the rate of degradation was significantly lowest in CGM and highest in DGNC (DM) and TP (CP). The effective degradability (ED) was lowest in CGM and highest was observed in SBM (DM) and DGNC (CP). The rumen UDP as per cent of total protein in CGM was significantly higher than all other protein supplements, it was followed by TP and was lowest in DGNC. It was concluded that the protein supplements with high rumen RUDP value like tomato pomace, cotton seed cake, spent brewer’s grains and corn gluten meal had low methane production potential.

Recency Effect of Verbal Summary Knowledge of Results on Motor Performance and Learning

It is necessary to clarify how instructors provide the feedback and how feedback perceived subjectively after motor learners repetitively practice a series of movements. This study was designed to examine the impacts of external and internal information on motor performance and learning. Thirty six participants (21.1 ± 2.3 years) were randomly assigned into one of the summary knowledge of results (SKR) in reverse order, error estimation and summary knowledge of results (EE + SKR) in reverse order, and knowledge of results (KR) 100% groups. Self-paced linear position was used as experimental task. All participants were practiced 84 trials during the acquisition phase, and 10-min immediate retention and 24-hrs delayed retention tests without KR administration. The performance during acquisition phase showed: (1) Groups × blocks interaction were found significant on AE. (2) The change score was found no significant difference. (3) The data from immediate and delayed retention tests showed no significant difference among three groups on AE in immediate retention test, while error estimation in EE + SKR in reverse order group was found significantly higher than that of SKR in reverse order and KR100% groups. Conversely, significant difference was found among three groups on AE and EE in delayed retention tests, and EE + SKR in reverse order was significantly higher EE than that of SKR in reverse order and KR100% groups. These findings suggested that (1) verbal SKR with recency effect was affected by external and internal information on motor performance of movement accuracy, but not in improvement, and (2) verbal SKR with recency effect were facilitated by internal information on motor learning of movement accuracy and error detection, and external information facilitated motor learning of movement accuracy.

Evaluation of the Properties of Gongronema latifolium in Phospholipon 90H Based Solid Lipid Microparticles (SLMs): An Antidiabetic Study

ABSTRACTContext: Gongronema latifolium Benth Hook, (Asclepiadaceae) is a tropical rainforest plant primarily used in traditional folk medicine in the treatment of malaria, diabetes, hypertension, and as laxative. Objective: To study the antidiabetic properties of Gongronema latifolium-loaded solid lipid microparticles (SLMs). Materials and methods: The methanolic extract of Gongronema latifolium leaves were obtained and formulated into SLMs using lipid matrix comprising of fat from Capra hircus and Phospholipon® 90H. The SLMs were characterized in vitro by determining the particle size and morphology, pH stability studies, and encapsulation efficiency EE%. Also, the antidiabetic properties of the Gongronema latifolium-loaded SLMs were studied in alloxan-induced diabetic rats. Results and discussion: The results show that the particle size of G. latifolium-loaded SLMs was within an acceptable range for SLMs. Highest EE% of 68% was obtained for SLMs containing 5% G. latifolium (batch F3). The formulations remained stable with insignificant pH reduction over time (p < 0.05). Gongronema latifolium-loaded SLMs had mean percentage reduction in blood glucose of 76% at 2 h, 42.3% at 8 h, and 24.4% at 12 h, while the group that received the reference-glibenclamide had 82.6, 61.7, and 46.7% at 2, 8, and 12 h, respectively, after oral administration of all samples. Gongronema latifolium-loaded SLMs had blood glucose reduction significantly higher than the pure extract and the glibenclamide (p < 0.05) at the concentrations used. Conclusions: Gongronema latifolium-loaded SLMs exhibited a good hypoglycemic effect and could be used for the treatment of diabetes.

Malestar psicológico y emoción expresada en cuidadores de pacientes con un trastorno de la conducta alimentaria

The main objective of this study was to evaluate the level of expressed emotion and psychological distress in caregivers of patients with an eating disorder, considering the differences in terms of sociodemographic and clinical characteristics. Fifty-three caregivers of patients with an eating disorder participed. The 39.6% of caregivers were men and 60.4% women, aged between 23 and 69 years old. The questionnaire used to assess expressed emotion was the Spanish version of the Level of Expressed Emotion (LEE) and for assessing distress the Spanish version of the Hospital Anxiety and Depression scale (HADS) and the General Health Questionnaire (GHQ-12). The results showed no statistically significant differences in expressed emotion in relation to the patient diagnosis and age of the caregivers. Significant differences were found regarding the type of relationship, the gender of the caregiver and illness duration; the caregivers with higher EE had more anxiety and depression than caregivers with lower EE.

Formulation, characterization and permeability study of nano particles of lipo-endomorphin-1 for oral delivery

Three different formulations of a lipid-modified endomorphin-1 peptide (C10LAA-Endo-1) were prepared, characterized, and evaluated for their permeability through Caco-2 cell membranes. Solid lipid nanoparticles (SLN), enteric coated (EC), and the EC-SLN of C10LAA-Endo-1 is a modified structure of endomorphin-1 for oral delivery. Physico–chemical characterization of the formulations showed that among all formulations, EC-[C10LAA-Endo-1] had the lowest particle size and the highest EE% and absolute zeta potential. Release of drug from SLN, EC-SLN and EC-[C10LAA-Endo-1] in acid media was 14.30 (±2.7)%, 3.0 (±1.0)% and 10.2 (±3.0)%, respectively. Release data in buffer media (pH = 7.4) showed that enteric coated formulations released C10LAA-Endo-1 more slowly than uncoated formulations. It was also demonstrated that direct coating of C10LAA-Endo-1 with Eudragit® S100 significantly enhanced the permeability of the compound through Caco-2 cell membranes with a 39-fold higher Papp compared to C10LAA-Endo-1. These findings indicated that EC-C10LAA-Endo-1 is a promising candidate to promote the oral delivery of the previously modified endomorphin-1 peptide analogue and is worthy of future animal investigations.

Fabrication and statistical optimization of surface engineered PLGA nanoparticles for naso-brain delivery of ropinirole hydrochloride: in-vitro–ex-vivo studies

Ropinirole hydrochloride (RPN), a nonergot dopamine D2-agonist used in the management of Parkinson’s disease, has poor oral bioavailability (52%) due to extensive hepatic metabolism. The intent of present research work was aimed at design and statistical optimization of RPN-loaded poly (lactic-co-glycolic acid) (PLGA)-based biodegradable nanoparticles (NPs) surface modified using natural emulsifier, vitamin E (d-α-tocopheryl polyethylene glycol 1000 succinate [TPGS]) for direct nose-to-brain delivery in order to avoid hepatic first-pass metabolism, and improve therapeutic efficacy with sustained drug release. RPN-NPs were prepared by modified nanoprecipitation technique and optimized using 23 factorial design of experiment. The effect of polymer and emulsifier concentration was evaluated on particle size and entrapment efficiency (EE%). Formulation PL6 was considered as desirable with highest EE% (72.3 ± 6.1%), PS (279.4 ± 1.8 nm), zeta potential (−29.4 ± 2.6 mV), and cumulative drug diffusion of 96.43 ± 3.1% in 24 h. The ANOVA results for the dependent variables demonstrated that the model was significant (p value < 0.05) for response variables. Histopathological study of optimized batch (PL6) demonstrated good retention of NPs with no severe signs of damage on the integrity of nasal mucosa. Differential scanning calorimetry revealed the absence of any chemical interaction between RPN, PLGA, and TPGS while SEM study confirmed spherical shape of optimized NPs. Accelerated stability studies of freeze-dried optimized batch demonstrated negligible change in the average PS and EE% after storage at 25 ± 2 °C/60 ± 5% (relative humidity (RH) for the period of three months. The promising results of optimized batch suggested practicability of investigated system for enhancement of bioavailability and brain targeting of CNS acting drugs like RPN.

Enantioselective arene epoxidation under mild conditions by Jacobsen catalyst: The role of protic solvent and co-catalyst in the activation of hydrogen peroxide

The epoxidation of arenes was achieved in high yield and with high enantioselectivity using the system Jacobsen catalyst:hydrogen peroxide:co-catalyst, ethanol as reaction solvent at 40°C. The effect on the catalytic performance of the use of protic (ethanol) and aprotic solvents and of co-catalysts with different acid–base properties was analyzed, as well as, different reaction temperatures, using as substrates indene, 6-cyan-2,2′-dimethylchromene, styrene and α-methylstyrene. The protic solvent showed a positive effect enhancing catalytic performances when compared with the aprotic solvent. For amphoteric co-catalysts (ammonium acetate, 2-methylimidazole and imidazole) it was observed the highest substrate conversions, whereas for basic co-catalysts (1-methylimidazole, 4-methylmorpholine N-oxide and pyridine), higher ee% and relatively lower C% were observed. Moreover, the reactions at 40°C showed higher enantiomeric induction than those performed at room or lower temperatures.The catalytic data are in accordance with a multi-step mechanism for hydrogen peroxide activation by the Mn(salen) complex with the formation of two catalytic active intermediates, existing in different extension depending on the reaction conditions: a hydroperoxy intermediate or oxo-metallocomplex. The activating effect of the protic solvent ethanol vs aprotic solvent was explained by the formation of hydrogen bonds between the solvent and the catalytic active intermediates.

Positively Charged Polymeric Nanoparticle Reservoirs of Terbinafine Hydrochloride: Preclinical Implications for Controlled Drug Delivery in the Aqueous Humor of Rabbits

Frequent instillation of terbinafine hydrochloride (T HCl) eye drops (0.25%, w/v) is necessary to maintain effective aqueous humor concentrations for treatment of fungal keratitis. The current approach aimed at developing potential positively charged controlled-release polymeric nanoparticles (NPs) of T HCl. The estimation of the drug pharmacokinetics in the aqueous humor following ocular instillation of the best-achieved NPs in rabbits was another goal. Eighteen drug-loaded (0.50%, w/v) formulae were fabricated by the nanopreciptation method using Eudragit® RS100 and chitosan (0.25%, 0.5%, and 1%, w/v). Soybean lecithin (1%, w/v) and Pluronic® F68 (0.5%, 1%, and 1.5%, w/v) were incorporated in the alcoholic and aqueous phases, respectively. The NPs were evaluated for particle size, zeta potential, entrapment efficiency percentage (EE%), morphological examination, drug release in simulated tear fluid (pH 7.4), Fourier-transform IR (FT-IR), X-ray diffraction (XRD), physical stability (2 months, 4°C and 25°C), and drug pharmacokinetics in the rabbit aqueous humor relative to an oily drug solution. Spherical, discrete NPs were successfully developed with mean particle size and zeta potential ranging from 73.29 to 320.15 nm and +20.51 to +40.32 mV, respectively. Higher EE% were achieved with Eudragit® RS100-based NPs. The duration of drug release was extended to more than 8 h. FT-IR and XRD revealed compatibility between inactive formulation ingredients and T HCl and permanence of the latter's crystallinity, respectively. The NPs were physically stable, for at least 2 months, when refrigerated. F5-NP suspension significantly (P<0.05) increased drug mean residence time and improved its ocular bioavailability; 1.657-fold.

Libraries of Bisdiazaphospholanes and Optimization of Rhodium-Catalyzed Enantioselective Hydroformylation

Twelve chiral bis-3,4-diazaphospholane ligands and six alkene substrates (styrene, vinyl acetate, allyloxy-tert-butyldimethylsilane, (E)-1-phenyl-1,3-butadiene, 2,3-dihydrofuran, and 2,5-dihydrofuran) probe the influence of steric bulk on the activity and selectivity of asymmetric hydroformylation (AHF) catalysts. Reaction of an enantiopure bisdiazaphospholane tetraacyl fluoride with primary or secondary amines yields a small library of tetracarboxamides. For all six substrates, manipulation of reaction conditions and bisdiazaphospholane ligands enables state-of-the-art performance (90% or higher ee, good regioselectivity, and high turnover rates). For the nondihydrofuran substrates, the previously reported ligand, (S,S)-2, is generally most effective. However, optimal regio- and enantioselective hydroformylation of 2,3-dihydrofuran (up to 3.8:1 α-isomer/β-isomer ratio and 90% ee for the α-isomer) and 2,5-dihydrofuran (up to <1:30 α-isomer/β-isomer ratio and 95% ee for the β-isomer) arises from bisdiazaphospholanes containing tertiary carboxamides. Hydroformylation of either 2,3- or 2,5-dihydrofuran yields some of the β-formyl product. However, the absolute sense of stereochemistry is inverted. A stereoelectronic map rationalizes the opposing enantiopreferences.

Formulation and evaluation of novel solid lipid microparticles as a sustained release system for the delivery of metformin hydrochloride

The low encapsulation efficiency of conventional solid lipid microparticles (SLMs) especially for hydrophilic drugs has remained a challenge to drug formulation experts. This work seeks to address the issue of inefficient delivery of metformin hydrochloride (MTH), a potent hydrophilic oral antihyperglycemic agent, using novel SLMs based on solidified reverse micellar solutions (SRMS) prepared by melt-emulsification using a lipid derived from Capra hircus and Phospholipon® 90H. Characterization based on size, morphology, zeta potential, polydispersity index, encapsulation efficiency (EE%), loading capacity (LC) and time-resolved stability were carried out on the SLMs. The in vitro release of MTH from the SLMs was performed in phosphate buffer (pH 7.4) while the in vivo antidiabetic properties were investigated in alloxan-induced diabetic rats. Stable, spherical and smooth SLMs were obtained. Loading of MTH into the SLMs had no effect on the surface charge of the particles. The SLMs with 1.0%w/w PEG 4000 resulted in significantly (p < 0.05) higher EE% while those with 2.0%w/w gave the least. The LC values ranged from 20.3 to 29.1 and 14.6 to 24.1 for SLMs containing 500 mg and 250 mg of MTH, respectively. The in vitro release studies revealed significant release of MTH from the SLMs whereas the in vivo antidiabetic studies indicated that novel SLMs containing 500 mg of MTH gave significantly (p < 0.05) higher glucose reduction than glucophage®. This research has shown that SLMs based on SRMS offer a new and better approach of delivering MTH, thus encouraging further development of this formulation.

Study of the influence of selected variables on the preparation of prolonged release bioadhesive vaginal carbohydrate microspheres using experimental design

Degradable polymer multiparticulate drug delivery overcomes many conventional systems shortcomings. To evaluate, using a multi-varied experimental design, the influence of the selected variables on the physicochemical properties of designed formulae to prepare sustained-release mucoadhesive fluconazole vaginal microspheres for the localized treatment of vulvovaginal candidiasis overcoming oral delivery drawbacks. The microspheres where prepared following the ionotropic gelation and extrusion method. Also, the effect of polymer combination was investigated. Microspheres were characterized using SEM and FTIR. Optimum conditions for the preparation process were found to be curing time (X 1 ) = 4 h and drug concentration (X 2 ) = 8 %. Binary-polymeric microspheres showed more extended release patterns compared to single-polymeric microspheres. Among the former, M5 (chitosan-polycarpophil) attained the most extended diffusion-controlled drug release (MDT = 5.68 h), the highest EE% (81.75 %) and good mucoadhesive properties according to its ability to interact with mucin. This study shows that simple modification of some crucial and efficient variables allows microsphere tailoring to fit the desired physicochemical properties.

Psychological flexibility, occupational burnout and eating behavior among working women

Background: Occupational burnout is associated with diminished psychological flexibility and higher emotional (EE) and uncontrolled eating (UE). Psychological flexibility could be a mediating factor between burnout and eating behaviour. Objectives: To investigate differences in eating behaviour between those with different levels of psychological flexibility, and the association of the interaction between psychological flexibility and occupational burnout with eating behaviour. Design: The participants were working women (n = 263), who took part in the randomized controlled health intervention trial. Analyses were performed in a cross-sectional setting at baseline. Methods: Eating behaviour was measured using the Three Factor Eating Behaviour Questionnaire-18 [which evaluates EE, UE and cognitive restraint (CR)], psychological flexibility using Acceptance and Action Questionnaire-II and occupational burnout using Bergen Burnout Indicator-15. Participants were divided into four groups based on the quartile points of psychological flexibility. Results: The EE of those who were inflexible was higher than that of those whose flexibility was high moderate (p = 0.013) and who were flexible (p = 0.001). The UE of those who were inflexible was higher than the UE in the other groups with higher flexibility [low moderate (p = 0.034), high moderate (p een occupational burnout and EE and UE. Multivariate analysis of variances revealed that the combination of psychological flexibility and burnout had a stronger association with the variances of EE and UE than psychological flexibility alone. Conclusions: Persons who are psychologically inflexible have higher EE and UE. Future studies should investigate if increasing psychological flexibility helps decrease EE and UE.

Effects of Transplacental 17‐α‐Ethynyl Estradiol or Bisphenol A on the Developmental Profile of Steroidogenic Acute Regulatory Protein in the Rat Testis

Previous research from our laboratory has determined the transcript profiles for developing fetal rat female and male reproductive tracts following transplacental exposure to estrogens. Prenatal exposure to bisphenol A (BPA) or 17-α-ethynyl estradiol (EE) significantly affects steroidogenic acute regulatory (StAR) protein transcript levels in the developing male rat reproductive tract. The purpose of this study was to establish the intratesticular distribution and temporal expression pattern of StAR, a key gene involved in steroidogenesis. Beginning on gestation day (GD) 11, pregnant Sprague-Dawley rats were exposed daily to 10μg/kg/day EE and fetal testes were harvested at GD16, 18, or 20. Quantitative reverse transcriptase PCR (QRT-PCR) demonstrated no significant difference in StAR transcript levels present at GD16. However, at GD18, StAR transcripts were significantly decreased following exposure. Immunohistochemistry demonstrated similar StAR protein levels in interstitial region of GD16 testes and an obvious decrease in StAR protein levels in the interstitial region of GD18 testes. Moreover, starting at GD11 additional dams were dosed with 0.001 or 0.1 μg/kg/day EE or 0.02, 0.5, 400 mg/kg/day BPA via subcutaneous injections. QRT-PCR validated previous microarray dose-related decreases in StAR transcripts at GD20, whereas immunohistochemistry results demonstrated decreases in StAR protein levels in the interstitial region at the highest EE and BPA doses only. Neither EE nor BPA exposure caused morphological changes in the developing seminiferous cords, Sertoli cells, gonocytes, or the interstitial region or Leydig cells at GD16-20. High levels of estrogens decrease StAR expression in the fetal rat testis during late gestation.

Alkene epoxidation by manganese(III) complexes immobilized onto nanostructured carbon CMK-3

New heterogeneous catalysts were prepared through immobilization of Mn(III) complexes onto CMK-3 with different surface treatments. The [Mn(TF5PP)Cl] and [Mn(5-HOsalhd)Cl] complexes were anchored by a microwave-assisted protocol (CAT I and CAT III, respectively) and the Jacobsen catalyst was immobilized using conventional synthesis conditions (CAT II). XPS and FTIR revealed that the CMK-3 target functionalities for immobilization were the surface oxygen groups. XRD showed that the support treatments led to a decrease of its 2D-hexagonal order, but the complex grafting did not induce changes on the microstructure.CAT I was active in the epoxidation of cis-cyclooctene by H2O2, with substrate conversions and epoxide selectivities in the ranges of 38–30% and 100–97%, respectively, in three cycles with almost no complex leaching. CAT II was active in the epoxidation of 6-cyano-2,2-dimethylchromene using m-CPBA/NMO system with a substrate conversion similar to that of the free complex and higher ee %, but with some Mn leaching in the catalytic runs. CAT III was active in the epoxidation of indene, by H2O2, in ethanol with substrate conversions, epoxide selectivities and ee % values in the ranges of 45–37%, 83–86% and 10–12%, respectively. A correlation between the structural properties of the supports and the reaction times could be proposed. These results highlight the potentiality of CMK-3 to act as support for metal complexes with catalytic properties in oxidation reactions.

Interplay of Metalloligand and Organic Ligand to Tune Micropores within Isostructural Mixed-Metal Organic Frameworks (M′MOFs) for Their Highly Selective Separation of Chiral and Achiral Small Molecules

Four porous isostructural mixed-metal-organic frameworks (M'MOFs) have been synthesized and structurally characterized. The pores within these M'MOFs are systematically tuned by the interplay of both the metalloligands and organic ligands which have enabled us not only to direct their highly selective separation of chiral alcohols 1-phenylethanol (PEA), 2-butanol (BUT), and 2-pentanol (2-PEN) with the highest ee up to 82.4% but also to lead highly selective separation of achiral C(2)H(2)/C(2)H(4) separation. The potential application of these M'MOFs for the fixed bed pressure swing adsorption (PSA) separation of C(2)H(2)/C(2)H(4) has been further examined and compared by the transient breakthrough simulations in which the purity requirement of 40 ppm in the outlet gas can be readily fulfilled by the fixed bed M'MOF-4a adsorber at ambient conditions.

Asymmetric Epoxidation of Chromenes Using Manganese(III) Complexes with Novel Chiral Salen-like Schiff Base Ligands

Three novel chiral salen-like schiff base ligands and their Mn(III) complexes containing different amino acid unit have been synthesized and characterized. Asymmetric epoxidation reactions show these complexes are effective catalysts for the chromenes with buffer NaOCl as terminal oxidant and pyridine N-oxide as co-catalyst in the presence of ionic liquid. Good-to -excellent enantioselectivity and acceptable yields can be obtained under optimum reaction conditions. Catalyst 4c gives the highest ee (95%) for 6-chloro-2,2-dimethylchromene among these catalytic performances. Furthermore, compared the enantioselectivity of catalyst 4c with the other two catalysts 4a and 4b, the positive experimental results suggest that the steric effect of the ligands plays an important role in the asymmetric catalysis. Asymmetric epoxidation of chromenes with Mn (III) complex containing amino acid moiety

PEGylated estradiol benzoate liposomes as a potential local vascular delivery system for treatment of restenosis

This study was directed towards the preparation and optimization of PEGylated (PEG, poly(ethylene glycol)) estradiol benzoate (ESB)-loaded liposomes to be used for the treatment of restenosis by local vascular delivery. Various liposomal formulations were prepared by thin film hydration method followed by sonication. Response surface methodology was applied to study the influence of three different independent variables, on the response of entrapment efficiency (%EE). Liposomes were characterized in terms of size, zeta potential, %EE and release profile. Incorporation of ESB was higher in egg phosphatidylcholine (EPC) liposomes, whereas the drug was displaced from liposomes, as the cholesterol (Chol) content of liposome increased. The optimum formulation composed of EPC/dioleyloxy trimethylammonium propane/distearoylphosphatidylethanolamine-PEG2000 with a molar proportion of 8.5:1:0.5 had the highest EE. In vivo studies in the balloon-injured rat carotid arteries revealed the potential of ESB-loaded liposomes as efficient local and controlled drug delivery systems to reduce restenosis.

ChemInform Abstract: Asymmetric Addition of Phenylboronic Acid to Cycloalkanones Mediated by a Rh/Phosphoramidite Complex: A Comparison Between Tropos versus Nontropos Behavior.

Abstract Herein we report the asymmetric addition of phenylboronic acid to different cycloalkenones, mediated by a Rh(I) complex with the tropos phosphoramidite ( S )- L 1 or the nontropos phosphoramidite ( S )- L 2 ligand. Different values of enantiomeric purity of the 3-phenylcycloalkanone products have been obtained, mainly depending on the ring size of the substrates, with ( S )- L 1 affording higher ee values than ( S )- L 2 . These results could be explained by reasoning that for the tropos phosphoramidite, a ‘chiral pocket’ is formed when the ligand links to the metal atom. By fitting in this pocket, the substrate can stereoselectively coordinate to the Rh(I) atom, undergoing attack of the phenyl ring from the phenylboronic acid to a preferred enantioface. This causes the high (up to 96%) values of enantioselectivity observed with some of the substrates. A ‘chiral pocket’ cannot be formed with the nontropos ligand ( S )- L 2 and, as a consequence, the stereoselectivity is greatly reduced.

Multiple cycle reaction mechanism in the enantioselective hydrogenation of α,α,α-trifluoromethyl ketones

The enantioselective hydrogenation of 2,2,2-trifluoroacetophenone ( 1) on cinchona-modified Pt, combined with the diastereoselective hydrogenation of cinchonidine and NMR analysis of the modifier–substrate–product interactions, revealed the key role of the product ( S)-1-phenyl-2,2,2-trifluoroethanol ( 2) in enantioselection. We propose a multiple cycle mechanism including a racemic route (a) on the unmodified sites and three enantioselective routes. In the enantioselective cycles, there is an N–H–O type interaction between the quinuclidine N and the carbonyl O-atom of the substrate. At low conversion, the alkaloid alone is the source of chiral information (route b). With increasing conversion, the weakly acidic minor product ( S)- 2 forms an adduct with the alkaloid and this complex controls the enantioselection (route c, lower ee). The frequently applied strong acid additive TFA replaces ( S)- 2 and the alkaloid–TFA complex gives the highest ee (route d). The diastereoselective hydrogenation of cinchonidine disproves a former mechanistic model proposed in the literature.

Comparative Study on the Effects of Some Polyoxyethylene Alkyl Ether and Sorbitan Fatty Acid Ester Surfactants on the Performance of Transdermal Carvedilol Proniosomal Gel Using Experimental Design

The aim of this work was to investigate the effects of formulation variables on development of carvedilol (CAR) proniosomal gel formulations as potential transdermal delivery systems. Different non-ionic surfactants; polyoxyethylene alkyl ethers, namely Brij 78, Brij 92, and Brij 72; and sorbitan fatty acid esters (Span 60) were evaluated for their applicability in preparation of CAR proniosomal gels. A 2(3) full factorial design was employed to evaluate individual and combined effects of formulation variables, namely cholesterol content, weight of proniosomes, and amount of CAR added on performance of proniosomes. Prepared proniosomes were evaluated regarding entrapment efficiency (EE%), vesicle size, and microscopic examination. Also, CAR release through cellulose membrane and permeation through hairless mice skin were investigated. Proniosomes prepared with Brij 72 and Span 60 showed better niosome forming ability and higher EE% than those prepared with Brij 78 and Brij 92. Higher EE% was obtained by increasing both weight of proniosomes and amount of CAR added, and decreasing cholesterol content. Release rate through cellulose membrane was inversely affected by weight of proniosomes. In Span 60 proniosomes, on increasing percent of cholesterol, a decrease in release rate was observed. While in Brij 72 proniosomes, an enhancement in release rate was observed on increasing amount of CAR added. Permeation experiments showed that skin permeation was mainly affected by weight of proniosomes and that Span 60 proniosomal gels showed higher permeation enhancing effect than Brij 72. Proniosomal gel could constitute a promising approach for transdermal delivery of CAR.