Hong-Min Liu

Synthesis of steroidal lactone by penicillium citreo-viride

The biotransformations of a series of steroids by the fungus penicillium citreo-viride A.C.C.C. 0402 have been investigated, and the conversion to the same product testolactone (1) was observed from progesterone (2), dehydroepiandrosterone (3), 4-androstene-3, 17-dione (4), 5-androstene-3, 17-diol (5) with the exception of pregnenolone (6) and 3beta-hydroxy-5, 16-pregnadien-20-one (7). The possible metabolic pathways of the biotransformations were also discussed in the paper and the fungus penicillium citreo-viride A.C.C.C. 0402 was isolated during screening stains from samples collected from Zhengzhou, Henan province of China.

Biotransformation of dehydroepiandrosterone (DHEA) with Penicillium griseopurpureum Smith and Penicillium glabrum (Wehmer) Westling.

Microbial transformation of dehydroepiandrosterone (DHEA, 1) using Penicillium griseopurpureum Smith and Penicillium glabrum (Wehmer) Westling has been investigated. Neither fungi had been examined previously for steroid biotransformation. One novel metabolic product of DHEA (1) transformed with P. griseopurpureum Smith, 15α-hydroxy-17a-oxa-d-homo-androst-4-ene-3,17-dione (5), was reported for the first time. The steroid products were assigned by interpretation of their spectral data such as (1)H NMR, (13)C NMR, IR, and HR-MS spectroscopy. P. griseopurpureum Smith was proven to be remarkably efficient in oxidation of the DHEA (1) into androst-4-en-3,17-dione (2). The strain was also observed to yield different monooxygenases to introduce hydroxyl groups at C-7α, -14α, and -15α positions of steroids. Preference for Baeyer-Villiger oxidation to lactonize D ring and oxidation of the 3β-alcohol to the 3-ketone were observed in both incubations. The strain of P. glabrum (Wehmer) Westling catalyzed the steroid 1 to generate both testololactone 3, and d-lactone product with 3β-hydroxy-5-en moiety 8. In addition, the strain promoted hydrogenation of the C-5 and C-6 positions, leading to the formation of 3β-hydroxy-17a-oxa-d-homo-5α-androstan-3,17-dione (9). The biotransformation pathways of DHEA (1) with P. glabrum (Wehmer) Westling and P. griseopurpureum Smith have been investigated, respectively. Possible metabolic pathways of DHEA (1) were proposed.

Separation and identification of purine nucleosides in the urine of patients with malignant cancer by reverse phase liquid chromatography/electrospray tandem mass spectrometry

Urinary-modified nucleosides have a potential role as cancer biomarkers for a number of malignant diseases. High performance liquid chromatography (HPLC) was combined with full-scan mass spectrometry, MS/MS analysis and accurate mass measurements in order to identify purine nucleosides purified from urine. Potential purine nucleosides were assessed by their evident UV absorbance in the HPLC chromatogram and then further examined by the mass spectrometric techniques. In this manner, numerous modified purine nucleosides were identified in the urine samples from cancer patients including xanthine, adenosine, N1-methyladenosine, 5-deoxy-5-methylthioadenosine, 2-methyladenosine, N6-threonylcarbamoyladenosine, inosine, N1-methylinosine, guanosine, N1-methylguanosine, N7-methylguanine, N2-methylguanosine, N2,N2-dimethyguanosine, N2,N2,N7-trimethylguanosine. Furthermore, a number of novel purine nucleosides were tentatively identified via critical interpretation of the combined mass spectrometric data including N3-methyladenosine, N7-methyladenine, 5-dehydro-2-deoxyinosine, N3-methylguanine, O6-methylguanosine, N1,N2,N7-trimethylguanosine, N1-methyl-N2-ethylguanosine and N7-methyl-N1-ethylguanosine.

A mild and selective method for cleavage of O-acetyl groups with dibutyltin oxide

A mild and efficient neutral method for the cleavage of O-acetyl groups with dibutyltin oxide has been developed. This method is especially useful in the synthesis of glycosides containing base- or acid-sensitive multifunctional groups.

Novel autoxidation and Michael addition of a butenolide-containing sugar leading to a C-branched-chain glucopyranosidulose, and X-ray structure of intermediates.

A butenolide-containing sugar available from the aldol condensation of methyl 4,6-O-benzylidene-alpha-D-glucopyranosid-2-ulose with diethyl malonate is autoxidized at the C-3 position into the corresponding alpha,beta-unsaturated gamma-lactone sugar by air, which subsequently undergoes 1,4-conjugate (Michael) addition of hydroxide ion (or water) leading to a C-branched-chain glucopyranosidulose. The autoxidations are also performed in weakly basic, neutral and weakly acidic medium, respectively.

Simultaneous determination of eight illegal dyes in chili products by liquid chromatography–tandem mass spectrometry

A sensitive and accurate method based on the use of liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the simultaneous determination of eight illegal synthetic dyes (Sudan (I-IV), Para Red, Rhodamine B, Chrysoidin and Auramine O) in chili products. A simple sample treatment procedure entailing the use of an extraction step with acetonitrile/H2O (9/1) without further cleanup was developed. HPLC was performed on a C18 column using a multistep gradient elution with 5mM ammonium acetate (pH 3.0 with formic acid) and methanol as the mobile phase. Mass spectral acquisition was done in multiple reaction monitoring (MRM) mode using positive electrospray ionization (ESI). Linear calibrations were obtained with correlation coefficients R(2)>0.99. Limit of detection (LOD) and limit of quantification (LOQ) for the studied dyes were in the ranges of 0.05-0.6μgkg(-1) and 0.3-3.0μgkg(-1) depending on matrices, respectively. The recoveries of the eight synthetic dyes in five matrices ranged from 70.5% to 119.2%. The intra- and inter-day precisions (RSDs) were between 2.3-15.8% and 5.7-15.6%, respectively. The applicability of the method to the determination of eight banned dyes in chili products was demonstrated.

Mild and selective deprotection method of acetylated steroids and diterpenes by dibutyltin oxide.

Dibutyltin oxide (DBTO) was first utilized for the deacetylation of steroid and diterpene esters. The results showed the deprotection of acetylated steroids and diterpenes separately with moderate catalysis dibutyltin oxide in methanol selectively removed part acetyl groups of these substrates, whereas several functional groups of the steroids and diterpenes were retained and neither isomerization nor degradation of these substrates was observed. It seems that the acetyl groups with lower steric hindrance or near carbonyl, alkoxy, or hydroxyl groups can be cleaved by the reaction, whereas the acetyl groups with higher steric hindrance or without carbonyl, alkoxy, or hydroxyl groups neighboring were retained under the same conditions. One of the interesting results obtained was the selective hydrolysis of the 3beta-O-acetyl group in the presence of the 6beta group in 3beta,6beta-Di-O-acetyl-5alpha-hydroxypregn-16-en-20-one. This allows for subsequent introduction of one unit at C-3 and the other unit at C-6. This procedure is useful for the synthesis of a series of closely related isomers of 3beta,5alpha,6beta-trihydroxypregn-16-en-20-one and other widespread polyhydroxysteroids in marine organisms and some terrestrial species.

Stereoselective synthesis of methyl 4,6-O-benzylidene-2-C-methoxycarbonylmethyl-α-d-ribo-hexopyranosid-3-ulose, and its X-ray crystallographic analysis

Methyl 4,6-O-benzylidene-2-C-methoxycarbonylmethyl-alpha-D-ribo-hexopyranosid-3-ulose has been stereoselectively synthesized in 65% yield by reaction of methyl 4,6-O-benzylidene-alpha-D-arabino-hexopyranosid-2-ulose with diethyl malonate. X-ray crystallographic structure analysis reveals that the chain-branch and the OH group are bonded to C-2 in axial and equatorial positions, respectively. The molecules in the crystal lattice are stacked along a one-dimensional chain, with intermolecular hydrogen bonds between O-8 of one molecule and 2-OH of the next as well as intramolecular hydrogen bonds between O-3 and 2-OH. All phenyl groups are parallel as well as the planes of sugar rings in the molecular columnar stacking.

A new synthetic method for preparing indole derivatives from 2-keto glycosides.

In this article, a new reaction of the addition of two molecules of aniline to 2-keto glycosides (glycoside 2-uloses, 2-ulosides) is reported. A possible pathway for the reaction is presented. This reaction provides a novel one-pot method for the synthesis of indole derivatives from sugars.

Separation and characterization of clindamycin phosphate and related impurities in injection by liquid chromatography/electrospray ionization mass spectrometry

A simple high-performance liquid chromatography/electrospray ionization tandem mass spectrometric (HPLC/ESI-MS/MS) method has been developed for the rapid identification of clindamycin phosphate and its degradation products or related impurities in clindamycin phosphate injection. Detection was performed by quadrupole time-of-flight mass spectrometry (Q-TOFMS) via an ESI source in positive mode. Clindamycin phosphate and its related substances lincomycin, 7-epilincomycin-2-phosphate, lincomycin-2-phosphate, clindamycin B, clindamycin B-2-phosphate, and clindamycin were identified simultaneously by HPLC/ESI-MS/MS results. Based on the MS/MS spectra of their quasi-molecular ions, the fragmentation pathways of clindamycin phosphate and its related substances were compared and proposed, which are specific and useful for the identification of the lincosamide antibiotics and related impurities. The method was rapid, sensitive and specific and can be used to identify clindamycin phosphate and its related impurities in clindamycin phosphate injection without control compounds.