Pd nanoparticles as catalysts for green and sustainable oxidation of functionalized alcohols in aqueous media

The previously described catalyst system for the aerobic oxidation of alcohols, comprising palladium(II) acetate in combination with neocuproine in a 1:1 mixture of water and a water-miscible cosolvent such as ethylene carbonate or dimethylsulfoxide, was shown to involve palladium nanoparticles as the active catalyst. The latter are formed in situ or can be preformed by reduction of the palladium-neocuproine complex with hydrogen and they are stabilized by both the neocuproine ligand and the cosolvent. This catalyst system was successfully used for the selective aerobic oxidation of the steroidal secondary alcohols, nandrolone and 5α-pregnan-3α-ol-20-one, to the corresponding ketones.     

Two new isospirostanol sapogenins from Reineckia carnea

Two new isospirostanol sapogenins named(25R)-5β-spirostane-(1α,3α)-diol(1) and(25R)-5β-spirostane-(1α,2α,3α,4α)tetrol(2) were isolated from the whole herb of Reineckia camea(Andr.) Kunth.The structures of the sapogenins were elucidated bychemical and spectral methods.     

Characterization and identification of steroidal alkaloids in Fritillaria species using liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry

Liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (LC/ESI-QTOF-MS/MS) was performed to study the fragmentation behaviors of steroidal alkaloids from Fritillaria species, the antitussive and expectorant herbs widely used in traditional Chinese medicine. We propose, herein, a strategy that combining key diagnostic fragment ions and the relative abundances and amounts of major fragment ions (the ions exceeding 10% in abundance) to distinguish different sub-classes of Fritillaria alkaloids (FAs). It was found that hydrogen rearrangement and induction effects result in ring cleavage of the basic skeletons occurred in the MS/MS process and produced characteristic fragment ions, which are useful for structural elucidation. This method was finally used to investigate the primary steroidal alkaloids in the extracts of eight major Fritillaria species. As a result, 41 steroidal alkaloids (29 cevanine type, 1 jervine type, 6 veratramine type and 5 secosolanidine type alkaloids) were selectively identified in these Fritillaria species. Twenty-six compounds were unambiguously identified by comparing with the reference compounds and 15 compounds were tentatively identified or deduced according to their MS/MS data. Logical fragmentation pathways for different types of FAs have been proposed and are useful for the identification of these types of steroidal alkaloids in natural products especially when there are no reference compounds available.     

A facile and efficient method for the synthesis of solasodine from diosgenin

A facile and high-yielding route for the synthesis of solasodine from diosgenin is devised. Ring opening of steroidal spiroketal under mild conditions with trifluoroacetyl trifluoromethanesulfonate (TFAT) provides an applicable protocol to prepare key intermediates 4 or 3-Ac-solasodine, which can potentially serve as a platform for the selective functionalization of C(3)-OH and N-H of solasodine. The simple operations without purification by column chromatography make this method suitable to scale up.     

Cortistatins J, K, L, novel abeo-9(10-19)-androstane-type steroidal alkaloids with isoquinoline unit, from marine sponge Corticium simplex

Three novel anti-angiogenic steroidal alkaloids, cortistatins J (1), K (2), L (3), have been isolated from the Indonesian marine sponge Corticium simplex. The chemical structures of cortistatins J (1), K (2), and L (3) were determined by 2D-NMR analysis to be unique abeo-9(10-19)-androstane-type steroidal alkaloids having isoquinoline unit instead of the side chain part, respectively. Cortistatin J (1) showed cytostatic anti-proliferative activity against human umbilical vein endothelial cells (HUVECs) at 8 nM, in which the selective index was 300-1000-fold in comparison with other cell lines.     

Determination and Fingerprint Analysis of Steroidal Saponins in roots of Liriope muscari (Decne.) L. H. Bailey by ultra high performance liquid chromatography coupled with ion trap time‐of‐flight mass spectrometry

Liriope muscari (Decne.) L. H. Bailey is a well‐known traditional Chinese medicine used for treating cough and insomnia. There are few reports on the quality evaluation of this herb partly because the major steroid saponins are not readily identified by UV detectors and are not easily isolated due to the existence of many similar isomers. In this study, a qualitative and quantitative method was developed to analyze the major components in L. muscari (Decne.) L. H. Bailey roots. Sixteen components were deduced and identified primarily by the information obtained from ultra high performance liquid chromatography with ion‐trap time‐of‐flight mass spectrometry. The method demonstrated the desired specificity, linearity, stability, precision, and accuracy for simultaneous determination of 15 constituents (13 steroidal glycosides, 25(R)‐ruscogenin, and pentylbenzoate) in 26 samples from different origins. The fingerprint was established, and the evaluation was achieved using similarity analysis and principal component analysis of 15 fingerprint peaks from 26 samples by ultra high performance liquid chromatography. The results from similarity analysis were consistent with those of principal component analysis. All results suggest that the established method could be applied effectively to the determination of multi‐ingredients and fingerprint analysis of steroid saponins for quality assessment and control of L. muscari (Decne.) L. H. Bailey.     

Regioselective formation of chlorohydrins from ring-opening of steroidal epoxides using silica-supported BiCl3: A spectral and X-ray crystallographic study

The ring opening of steroidal epoxides are carried out in a regioselective manner using bismuth chloride, ferric chloride, indium chloride, silica supported BiCl₃, FeCl₃ and InCl₃ under mild condition in variable yields. The products obtained were identified by various spectroscopic techniques. The structure of one of the compound has been determined by X-ray diffraction using the direct method and was refined on F2 by the full-matrix least-squares. A general mechanistic scheme for the reaction is proposed on the basis of current and previous results and the mode of epoxide ring-opening. The 3D Hirshfeld surfaces and the associated 2D fingerprint plots were also drawn in order to explore plausible intermolecular interactions. The fingerprint plots evidenced subtle distinctions in the intermolecular contacts for the independent molecules.     

Stereoselective approach to potential scaffold of A-nor B-aromatic OSW-1 analogues via [4+2] cycloaddition of o-quinodimethane

A-nor B-aromatic steroidal skeleton was efficiently constructed by means of o-quinodimethane chemistry with exclusive stereoselectivity. The benzocyclobutene substrate for generation of the o-quinodimethane intermediate and subsequent [4+2] cycloaddition could be synthesized via (E)-selective Julia–Kocienski olefination and diastereoselective Grignard addition reactions. The synthesized tricyclic steroid-like compound with a trans-diol substructure would be utilized for divergent syntheses of potentially antitumor OSW-1 analogues with the truncated steroidal aglycone.     

Ultrasonic extraction of steroidal alkaloids from potato peel waste

Potato processors produce large volumes of waste in the form of potato peel which is either discarded or sold at a low price. Potato peel waste is a potential source of steroidal alkaloids which are biologically active secondary metabolites which could serve as precursors to agents with apoptotic, chemopreventive and anti-inflammatory properties. The present study investigated the relative efficacy of ultrasound assisted extraction (UAE) and solid liquid extraction (SLE) both using methanol, to extract steroidal alkaloids from potato peel waste and identified optimal conditions for UAE of α-solanine, α-chaconine, solanidine and demissidine. Using response surface methodology optimal UAE conditions were identified as an amplitude of 61 μm and an extraction time of 17 min which resulted the recovery of 1102 μg steroidal alkaloids/g dried potato peel (DPP). In contrast, SLE yielded 710.51 glycoalkaloid μg/g DPP. Recoveries of individual glycoalkoids using UAE yielded 273, 542.7, 231 and 55.3 μg/g DPP for α-solanine, α-chaconine, solanidine and demissidine respectively. Whereas for SLE yields were 180.3, 337.6, 160.2 and 32.4 μg/g DPP for α-solanine, α-chaconine, solanidine and demissidine respectively. The predicted values from the developed second order quadratic polynomial equation were in close agreement with the experimental values with low average mean deviation (E < 5%) values. Predicted models were highly significant (p < 0.05) for all parameters studied. This study indicates that UAE has strong potential as an extraction method for steroidal alkaloids from potato peel waste.     

An intramolecular one-pot synthesis of steroidal triazoles via 1,3-dipolar cycloadditions of in situ generated diazo compounds

A novel synthetic route is reported for the preparation of steroidal triazoles via intramolecular 1,3-dipolar cycloaddition of a steroidal 16,17-seco-17-diazo-16-nitrile system. The structures of the products are established by X-ray and NMR studies. The in vitro antiproliferative activity of the steroidal triazoles against three tumor cell lines was evaluated.