Some recent results on the development of new and reliable procedures for the construction of diverse ring systems based on the chemistry of sp-hybridized species, especially allene functionality, are described. This review includes: (i) synthesis of the multi-cyclic skeletons by combination of the π-component of allene with suitable other π-components such as alkyne, alkene, or additional allene under Rh-catalyzed conditions; (ii) synthesis of heterocycles as well as carbocycles by reaction of the sp-hybridized center of allene with some nucleophiles in an endo-mode manner; and (iii) total syntheses of natural products and related compounds from the sp-hybridized starting materials.
In this review, new and reliable procedures for the construction of diverse ring systems based on the chemistry of sp-hybridized species are described. The synthetic application includes (i) multi-cyclic skeletons by the Rh-catalyzed reaction of allenes with other π-components such as alkyne, alkene, and allene, (ii) hetero- and carbocycles from appropriate allenes and nucleophiles, and (iii) natural products and related compounds.
The present study was designed to assess the bioequivalence of two agomelatine formulations (25-mg tablets) in healthy Chinese male subjects. This single-dose, open-label, randomized, four-way replicate study with a 1-week washout period was conducted in 60 healthy Chinese male volunteers under fasting conditions. Blood samples were collected over a 12-h period after a single dose of the 25-mg agomelatine test (T) formulation or a reference (R) formulation, and the drug concentrations were assayed by liquid chromatography tandem mass spectrometry (LC-MS/MS). Pharmacokinetic parameters were calculated using a non-compartmental model. Bioequivalence between the formulations was assessed. Tolerability and safety were monitored by physical examination, electrocardiogram (12-lead ECG), clinical laboratory tests, and adverse events (AEs). A total of 56 out of 60 subjects completed the study. No AEs were observed. The values of maximum plasma concentration (Cmax), maximum concentration (Tmax), area under curve (AUC)0–t and t1/2 were 12.032 ng/mL, 0.658 h, 12.637 ng·h/mL, and 0.813 h, respectively, for the test formulation, and 10.891 ng/mL, 0.709 h, 11.572 ng·h/mL, and 0.96 h, respectively, for the reference formulation. The intra-individual variability of Cmax and AUC0−t were 78.3 and 61.8%, respectively. The inter-individual coefficients of variance (CVs) of Cmax and AUC0−t were approximately 100%. The 90% confidence intervals for the ratio of means for the log-transformed Cmax (97.7–124.9%), AUC0−t (98.2–118%), and AUC0−∞ (97.8–117.2%) were within the guideline range of bioequivalence (80–125%). The test and reference formulations of agomelatine met the regulatory criteria for bioequivalence of the Chinese Food and Drug Administration. Significant intra-individual and inter-individual variations were found.
RSPP050 (AG50) is one of the semi-synthetic andrographolide that is isolated from Andrographis paniculata NEES (Acanthaceae). The anti-proliferation effects of AG50 against cholangiocarcinoma (HuCCT1) were displayed high cytotoxicity. Unfortunately, poor water solubility of AG50 limited its clinical applications. This study aimed to increase the concentration of AG50 in water and drug loading and release study in phosphate-buffered saline (PBS) in the absence/presence of pig liver esterase enzyme. Cytotoxicity of AG50-loaded polymeric micelles was evaluated against HuCCT1. AG50 loaded micelles were prepared by film sonication and encapsulated by polymers including poly(ethylene glycol)-b-poly(ε-caprolactone) (PEG-b-PCL) or poly(ethylene glycol)-b-poly(D,L-lactide) (PEG-b-PLA). Micelle properties were characterized such as solubility, drug loading, drug release and in vitro cytotoxicity against HuCTT1. AG50 was successfully loaded into both types of polymeric micelles. The best drug–polymer (D/P) ratio was 1 : 9. AG50/PCL and AG50/PLA-micelles had small particle size (36.4±5.1, 49.0±2.7 nm, respectively) and high yield (58.2±1.8, 58.8±2.9, respectively). AG50/PLA-micelles (IC50=2.42 µg/mL) showed higher cytotoxicity against HuCCT1 than AG50/PCL-micelles (IC50=4.40 µg/mL) due to the higher amount of AG50 released. Nanoencapsulation of AG50 could provide a promising development in clinical use for cholangiocarcinoma treatment.
Streptococcus pneumoniae (pneumococcus) is an important causative agent of acute invasive and non-invasive infections. Pneumolysin is one of a considerable number of virulence traits produced by pneumococcus that exhibits a variety of biological activities, thus making it a target of small molecule drug development. In this study, we aimed to evaluate the effect of morin, a natural compound that has no antimicrobial activity against S. pneumonia, is a potent neutralizer of pneumolysin-mediated cytotoxicity and genotoxicity by impairing oligomer formation, and possesses the capability of mitigating tissue damage caused by pneumococcus. These findings indicate that morin could be a potent candidate for a novel therapeutic or auxiliary substance to treat infections for which there are inadequate vaccines and that are resistant to traditional antibiotics.
The objective of this study was to develop sustained release matrix tablets of atenolol (AT) using different concentrations of polyvinyl acetate–polyvinylpyrrolidone mixture (KSR) (20, 30, or 40%) with various types of fillers such as spray dried lactose (SP.D.L), avicel pH 101 (AV), and emcompress (EMS). The physical characteristics of the prepared tablets were evaluated. Characterization of the optimized formulation was performed using Fourier transform (FT)-IR spectroscopy and differential scanning calorimetry (DSC). Moreover, the in vitro release profiles of AT formulations were investigated in different pH dissolution media. Drug release kinetics and mechanisms were also determined. The results revealed that there was no potential incompatibility of the drug with the polymer. The release profiles of AT were affected by the concentration of KSR, fillers used, and pH of the dissolution media. The drug release kinetic from most of the formulations obeyed Higuchi diffusion model. The selected formulae were investigated for their stability by storage at 30 and 40°C with atmospheric humidity and 75% relative humidity (RH), respectively. The results demonstrated that no change in the physicochemical properties of the tablets stored at 30°C/atmospheric RH in comparison with some changes at 40°C/75% RH. Finally, the in vivo study provided an evidence that the optimized AT tablet containing 40% KSR and SP.D.L exhibited prominent higher oral bioavailability and more efficient sustained-release effect than the drug alone or the commercial tablet product. It is noteworthy that KSR could be considered as a promising useful release retardant for the production of AT sustained release matrix tablets.
In this study three new spectrophotometric methods have been developed and validated for simultaneous determination of ternary mixture of metronidazole (MET), diloxanide (DLX) and mebeverine HCl (MEB) without prior separation steps. The newly introduced methods consisted of several steps utilizing either zero order or ratio spectra without the need for derivatization steps. The developed methods are called area under the curve (“AUC”), modified absorption factor (MAFM) and modified amplitude center (MACM) spectrophotometric methods. Selectivity and validity of the methods were checked by using different synthetic mixtures and by analysis of their combined dosage form where low standard deviation values and good percentage recoveries were obtained. Additionally, methods linearity, accuracy and precision were determined following United States Pharmacopoeia (USP) recommendations. The obtained results were found to agree with the reported ones when they were statistically compared using One Way ANOVA test. These methods are easily applied during drug quality control studies and in laboratories lacking the facilities of chromatographic methods of analysis. Data manipulation steps are very simple, hence these methods can be considered as time and money saving methods comparing to chromatographic methods of analysis.
Sulfoquinovosyl acylpropanediol (SQAP), a chemically modified analogue of sulfoquinovosyl acylglycerol (SQAG) that occurs in sea algae, has been reported to show a variety of biological activities, including accumulation in tumor cells and the inhibition of tumor cell growth. We report herein on a new concise and versatile synthesis of SQAP itself and derivatives bearing iodoaryl groups and boronclusters. This method should be useful for the design and synthesis of SQAG/SQAP derivatives for diagnosis and the treatment of cancer and related diseases.
We describe herein a manganese(IV) oxide-mediated oxidation of N-p-methoxyphenyl (PMP)-protected glycine derivatives for the synthesis of α-imino carboxylic acid derivatives. Using this methodology, utilization of unstable glyoxic acid derivatives was avoided. Furthermore, using this methodology we synthesized novel α-imino carboxylic acid derivatives such as α-imino phenyl ester, perfluoroalkyl etsers, imides, and thioester. The asymmetric Mannich reaction of those novel imine derivatives with 1,3-dicarbonyl compound is also described, and the novel α-imino imide gave improved chemical yield and stereoselectivity compared with those obtained by the use of the conventional α-imino ester-type substrate.
An efficient synthesis of ODM-201’s diastereomers has been developed from (R)-methyl 3-hydroxybutanoate or (S)-methyl 3-hydroxybutanoate, respectively, with high overall yield and excellent diastereomeric purity. The key step in this synthesis is the preparation of the key intermediate (R)-5-(1-((tert-butyldimethylsilyl)oxy)ethyl)-1H-pyrazole-3-carboxylic acid or (S)-5-(1-((tert-butyldimethylsilyl)oxy)ethyl)-1H-pyrazole-3-carboxylic acid through intramolecular 1,3-dipolar cycloaddition of the vinyl diazo carbonyl compounds.
A new pyranonaphthoquinone derivative, named 4-oxo-rhinacanthin A (1), was isolated from the roots of the Indonesian Rhinacanthus nasutus together with two known congeners, rhinacanthin A (2) and 3,4-dihydro-3,3-dimethyl-2H-naphtho[2,3-b]pyran-5,10-dione (3). The structure of 1 was elucidated based on its spectroscopic data. The absolute configuration of 1 was assigned by comparing its experimental Electronic Circular Dichroism (ECD) spectrum with the calculated ECD spectrum. Compounds 2 and 3 inhibited the growth of Staphylococcus aureus with inhibition zones of 16 and 20 mm at 25 µg/disc, respectively. Compound 3 also exhibited inhibitory activity against Mycobacterium smegmatis (20 mm at 25 µg/disc).
Two new naphtoquinones (smenocerones A and B, 1 and 2) and four known sesquiterpene cyclopentenones (dactylospongenones A–D, 3–6) were isolated from sponge Smenospongia cerebriformis living in the Eastern Sea of Vietnam. Their chemical structures were determined by high resolution electrospray ionization (HR-ESI)-MS, NMR spectroscopic analysis, and in comparison with the reported data. The chiroptical properties of compounds 3–6 were examined by experiment and theoretical calculation of circular dichroism (CD) spectra to prove their absolute configurations. Compound 2 significantly exhibited cytotoxic activity towards lung carcinoma (LU-1), hepatocellular carcinoma (HepG-2), promyelocytic leukemia (HL-60), breast carcinoma (MCF-7), and melanoma (SK-Mel-2) human cancer cells with IC50 values of 5.5±0.8, 3.2±0.2, 4.0±0.7, 4.1±0.8, and 5.7±1.1 µg/mL, respectively.
Fifteen steroids, including two new compounds, leptosteroid (1) and 5,6β-epoxygorgosterol (2), were isolated and structurally elucidated from the Vietnamese soft coral Sinularia leptoclados. Their cytotoxic effect against a panel of eight human cancer cell lines was evaluated using sulforhodamine B (SRB) method. Significant cytotoxicity against hepatoma cancer (HepG2, IC50=21.13±0.70 µM) and colon adenocarcinoma (SW480, IC50=28.65±1.53 µM) cell lines were observed for 1 and against acute leukemia (HL-60, IC50=20.53±2.26 µM) and SW480 (IC50=26.61±1.59 µM) for ergost-5-en-3β,7β-diol (8). In addition, 3β,7β-dihydroxyergosta-5,24(28)-diene (13) showed significant cytotoxic activity on all tested cell lines with IC50 values ranging from 13.45±1.81 to 29.01±3.21 µM.
In water, diketopiperazines cyclo(L-Pro-L-Xxx) and cyclo(L-Pro-D-Xxx) (Xxx=Phe, Tyr) formed an intramolecular hydrophobic interaction between the main skeleton part and their benzene ring, and both cyclo(L-Pro-L-Xxx) and cyclo(L-Pro-D-Xxx) took a folded conformation. The conformational changes from folded to extended conformation by addition of several deuterated organic solvents (acetone-d6, metanol-d4, dimethyl sulfoxide-d6 (DMSO-d6)) and the temperature rise were investigated using 1H-NMR spectra. The results suggested that the intrarmolecular hydrophobic interaction of cyclo(L-Pro-D-Xxx) formed more strongtly than that of cyclo(L-Pro-L-Xxx). Under a basic condition of 1.0×10−1 mol/L potassium deuteroxide, enolization of O1-C1-C9-H9 moiety of cyclo(L-Pro-L-Xxx) occurred, while that of the O4-C4-C3-H3 moiety did not. Cyclo(L-Pro-L-Xxx) epimerized to cyclo(D-Pro-L-Xxx), while cyclo(L-Pro-D-Xxx) did not change.