Asteriscunolides A,B, C and D,the first humulanolides; Two pairs of conformationally stable stereoisomers

Following a preliminary comunication on Asteriscunolide A (the first reported natural humulanolide), three more configurationally and/or conformationally isomeric Asteriscunolides ( B, C and D ) from the same plant ($\text{Asteriscus aquaticus}$ L.) are described. The absolute configurations and the stable conformations of all four Asteriscunolides are established by an array of spectroscopic methods (CD, ¹H and ¹³C NMR) without resorting to X ray analysis.     

Validation of HPLC stability-indicating method for Vitamin C in semisolid pharmaceutical/cosmetic preparations with glutathione and sodium metabisulfite, as antioxidants

HPLC stability-indicating method was validated for Vitamin C (ascorbic acid) in semisolid pharmaceutical/cosmetic formulations containing glutathione and sodium metabisulfite, as antioxidants. The described procedure included a reliable, precise, accurate and specific method determination employing a 250 mm × 4.6 mm C₁₈ column, 0.2% metaphosphoric acid/methanol/acetonitrile (90:8:2, v/v/v) as the mobile phase and detection at 254 nm. Nicotinic and ascorbic acids were employed as standards, both presenting purity of 99.0%. Linearity was established for the ascorbic acid concentrations ranging form 1.0 to 12 μg mL⁻¹, accuracy/recovery percentage was 95.46-101.54%, precision values were 0.38 (intra-day) and 1.22% (inter-days), and LOD and LOQ were found to be 0.05 and 0.17 μg mL⁻¹, respectively. The working mobile phase elevated the ascorbic acid retention time to ≈3.5 min at a flow rate of 1.0 mL min⁻¹ and provided resolution of the active from the nicotinic acid (internal standard), degradation product (oxalic acid) and other excipients from the pharmaceutical/cosmetic preparations.     

Validation assay for total flavonoids, as rutin equivalents, from Trichilia catigua Adr. Juss (Meliaceae) and Ptychopetalum olacoides Bentham (Olacaceae) commercial extract

An ultraviolet spectrophotometric method was validated for total flavonoid quantitation, as rutin equivalents, present in the Trichilia catigua Adr. Juss (Meliaceae) and Ptychopetalum olacoides Bentham (Olacaceae) commercial extract. Parameters as linearity, interval (range), specificity, estimated limit of detection (LOD, microg/mL), estimated limit of quantitation (LOQ, microg/mL), recovery (R, %), precision or relative standard deviation (RSD, %), and accuracy (E, %) were established. The analytical method was validated according to the experimental results: correlation coefficient (r = 0.9997); interval (RSD = 0.15-0.47%; E = 98.98-101.24%); specificity to total flavonoids quantitation, as rutin equivalents, at wavelength 361.0 nm; LOD = 0.09 microg/mL and LOQ = 0.27 microg/mL; R = 99.36-102.14%; adequate intra- and interrun precision (0.30-0.49% and 0.31-0.81%), and intra- and interrun accuracy (100.60-102.38% and 98.58-100.38%).     

13C NMR, infrared, solvation and theoretical investigation of the conformational isomerism in 1-haloacetones (X = Cl, Br and I)

The solvent dependence of the 13C NMR spectra of chloroacetone (CA), bromoacetone (BA) and iodoacetone (IA) are reported and the 3J(CH) couplings analysed using ab initio calculations and solvation theory. In CA the energy difference (E(cis) - E(gauche)) between the cis (Cl-C-C=O 0 degrees) and gauche (Cl-C-C=O 155 degrees) conformers is 1.7 kcal mol(-1) in the vapour, decreasing to 0.8 kcal mol(-1) in CCl4 solution and to -1.0 kcal mol(-1) in the pure liquid. The conformational equilibrium, in BA, is between the more polar cis (Br-C-C=O 0 degrees) and gauche (Br-C-C=O 132 degrees) conformations. The energy difference (E(cis) - E(gauche)) is 1.8 kcal mol(-1) in the vapour, decreasing to 0.9 kcal mol(-1) in CCl4 solution and to -0.4 kcal mol(-1) in the pure liquid. The energy difference (E(cis) - E(gauche)), in IA, between the cis (I-C-C=O 0 degrees) and gauche (I-C-C=O 104 degrees) conformers is 1.1 kcal mol(-1) in the vapour phase, decreasing to 0.5 kcal mol(-1) in CCl4 solution and to -0.5 kcal mol(-1) in the pure liquid. The vapour state energy difference for BA [1.4 kcal mol(-1) at B3LYP/6-311++G(d,p)] and for IA [1.6 kcal mol(-1) at B3LYP/6-311++G(d,p)/LANL2DZ)] are in very good agreement with the above values. For CA the agreement is also satisfactory [1.4 kcal mol(-1) at B3LYP/6-311++G(d,p)].     

Liquid chromatography/triple quadrupole tandem mass spectrometry with multiple reaction monitoring for optimal selection of transitions to evaluate nutraceuticals from olive-tree materials

Optimal transitions have been selected for the identification and quantitation of the most interesting hydrophilic biophenols in extracts from olive-tree materials, which are of interest because of their nutraceutical properties. The tested materials were extra virgin olive oil, waste from oil production (known as alperujo), and olive-tree materials such as leaves, small branches and fruit stones. The identification and determination steps of the target biophenols are based on liquid chromatography/tandem mass spectrometry (LC/MS/MS) with a triple quadrupole (QQQ) mass detector. The interface between the chromatograph and the QQQ was an electrospray ionization source operated in the negative ion mode. Highly selective identification of the biophenols was confirmed by multiple reaction monitoring (MRM) using the most representative transitions from the precursor ion to the different product ions. Quantitative MS/MS analysis was carried out by optimization and selection of the most sensitive transition for each analyte, which resulted in estimated detection limits of 5.10 to 11.65 ng/mL for the extracts. The biophenols were extracted from the tested samples by different methods: liquid-liquid extraction for virgin olive oil, microwave-assisted leaching for olive leaves, branches and stones, and pressurized liquid leaching for alperujo. This study provides valuable information about the most suitable source for the isolation of each nutraceutical biophenol and enables us to obtain a complete profile of them in Olea Europaea.     

Nitrogen donor ligands bearing N–H groups: Effect on catalytic and cytotoxic activity of molybdenum η3-allyldicarbonyl complexes

Reactions of [Mo(η³-C₃H₅)Br(CO)₂(NCMe)₂] with the bidentate nitrogen ligands 2-(2′-pyridyl)imidazole (L1), 2-(2′-pyridyl)benzimidazole (L2), N,N′-bis(2′-pyridinecarboxamido)-1,2-ethane (L3), and 2,2′-bisimidazole (L4) led to the new complexes [Mo(η³-C₃H₅)Br(CO)₂(L)] (L = L1, 1; L2, 2; L4, 4) and [{Mo(η³-C₃H₅)Br(CO)₂}₂(μ-L3)] (3).The reaction of complexes 2 and 3 with Tl[CF₃SO₃] afforded [Mo(η³-C₃H₅)(CF₃SO₃)(CO)₂(L2)] (2T) and [{Mo(η³-C₃H₅)(CF₃SO₃)(CO)₂}₂(μ-L3)] (3T).Complexes 3 and 2T were structurally characterized by single crystal X-ray diffraction, showing the facial allyl/carbonyls arrangement and the formation of the axial isomer. In 2T, two molecules are assembled in a hydrogen bond dimer.The four complexes 1–4 were tested as precursors in the catalytic epoxidation of cyclooctene and styrene, in the presence of t-butylhydroperoxide (TBHP), with moderate conversions and turnover frequencies for complexes 1–3 and very low ones for 4. The increasing number of N–H groups in the complexes seems to be responsible for the loss of catalytic activity, compared with other related systems. The cytotoxic activities of all the complexes were evaluated against HeLa cells. The results showed that compounds 1, 2, 4, and 2T exhibited significant activity, complexes 2 and 2T being particularly promising.     

Characterization and evaluation of free and nanostructured ursolic acid incorporated in cosmetic formulation using thermal analysis

The ursolic acid (UA) increases the skin’s barrier function and acts in epidermal differentiation of keratinocytes in the epidermis, promoting cell renewal. Besides the mentioned properties UA also has antioxidant, antimicrobial, and anti-irritant functions to cosmetic formulations. Thus, it is necessary formulation studies to insure the development of quality cosmetic products containing this active, increasing its antioxidant potential within nanoparticles. This study aims to characterize and evaluate the thermal behavior of UA in free and nanostructured forms, and both incorporated into a cosmetic base formulation, using thermogravimetry and differential scanning calorimetry. Through the study were observed that free UA, in the embedded nanoparticles and in base formulation exhibited different behavior in similar thermal profile and relative to the presence of UA. The UA remained stable to a temperature of 250 °C and the technique has been shown to be effective for characterizing UA, evaluate water content, and stability of the formulation base.     

Pyrazolo[3,4,5-de]phthalazine. Syntheses of a practically unknown heterocyclic system

Simple procedures for the synthesis of 1,3-dihydropyrazolo[3,4,5-de]phthalazines (2), a practically novel type of heterocyclic compounds, have been developed. Compounds equally substituted at positions N¹ and N³ can be directly obtained from 4,7-dihalogenated benzalphthalides (1). Those with different R₂ and R₃ substituents are prepared through intermediate phthalazin-1-ones (3), whose synthesis is also considered.