Quantification of alcohols, diols and glycerol in fermentation with an instantaneous derivatization using trichloroacetyl isocyanante via liquid chromatography-massspectrometry.

A sensitive LC-MS/MS method was established to quantify diols and glycerol in fermentation broth using trichloroacetyl isocyanate as instantaneous derivatization reagent for monitoring the production of 1,3-propanediol and 2,3-butanediol from the biodiesel biorefinery process. Due to the derivatization reaction was very quickly at room temperature, only 1 min was needed for the reaction process. In addition, both extraction of analytes and evaporation of water were not employed in the analytical procedure. Furthermore, the isotope of chlorine was beneficial for understanding of the secondary mass spectrum and avoiding false positive results. Therefore, much more accurate results of diols and glycerol concentration in fermentation could be obtained even at very low levels for the evaluation of microbial metabolism pathway modification.

[A study on the NMR spectrum of methyl-ofloxacin].

Ofloxacin ((+/-)-9-fluoro-3-methyl-10-(4-methylpiperazin-1-yl)-7-oxo-2, 3-dihydro-7H-pyrido[1,2,3-de]-1, 4-benzoxazine-6-carboxylic acid) is a totally synthetic fluoroquinolone antimicrobial agent with a broad spectrum of activity against Gram-positive and Gram-negative bacteria and atypical pathogens such as Mycoplasma, Chlamydia and Legionella. Even though it is widely used for the treatment of gastrointestinal, pulmonary, urinary, and other infections, the comprehensive mechanism of action at molecular level has not been known so far. It is very important to understand the structural characteristics of the drug and the effects that are caused by the environments. With the purpose of deeply investigating the structure of Ofloxacin, an analog of Ofloxacin, Methyl-Ofloxacin (Me-OFL), was synthesized by methylation of 4'N in piperazine ring from Ofloxacin with CH3I. Then appropriate Me-OFL was dissolved in DC1/D2O and NaOH/D2O to prepare corresponding acidic and alkaline solutions. Systematic NMR spectroscopic investigation on Me-OFL in both acidic and alkaline solution was conducted using quantitative 1H and 13C spectra, DEPT, HSQC together with HMBC techniques. The spectra were recorded with Bruker AM-300 spectrometer and DRX500 spectrometer. Chemical shifts have been given in values referred to dioxane (deltaJ = 3.7, deltac = 67.8). Complete assignments on 1H and 13C signals of Me-OFL were obtained in different pH environments where the coupling constant between 13 C and 19F was found to be very helpful for the assignment of aromatic 13C signals. A comprehensive comparison between the 1H, 13C chemical shifts, together with the structural transformation in acidic and alkaline solutions was made and discussed in details. Due to the formation of hydrogen bond between COOH and C==O, the COOH and aromatic ring are in the same plane. As a result, a weak O...H--C hydrogen bond forms between C==O from the carboxyl group and 5-H from aromatic ring. In alkaline solution, the deprivation of H+ from COOH destroys not only the hydrogen bond between COOH and carbonyl group but also the weak hydrogen between the C==O from COOH and 5H. As a result, the 5H exhibited remarkable shift toward high field (1.02). Meanwhile, the chemical shift of 6C, 13C, 7C, 15C also exhibited remarkable shift to low field at 12. 04, 7.46, 4.33, 2.88 respectively. Such variations were related to the changes of p electrons from carboxyl group caused by the transformation between the carboxyl group and the carboxylate group in different pH environments. Comparison of deltaH, deltac data between Me-OFL and OFL in acidic solution and OFL in alkaline was made. In Me-OFL acidic solution, the chemical shift of 3'C, 5'C, 7'C, 8'C also exhibited remarkable shift to low field at 6.66-7.32 respectively, the chemical shift of 2'C and 6'C also exhibited remarkable shift to high field 6.04. In OFL acidic solution, the chemical shift of 2'C, 3'C, 5'C, 6'C, 7'C, 8'C also exhibited remarkable shift to high field within 2.39, Comparison between the protonation and the methylation on the 4'N atom from the piperazine ring was also made. The distribution of positive charge also showed difference. When protonation occurred on the piperazine ring, the positive charge was on the proton connected with 4'N. However, if methylation occurred, the positive charge is on the 4'-N atom.

Structural determination of saponins from Hedysarum polybotrys.

Four saponins (1-4) were isolated from the roots of Hedysarum polybotrys Hand.-Mazz. and obtained from Hedysarum (Tourn.) L for the first time. Their structures were identified on the basis of spectroscopic data. MS, 1D and 2D NMR including HMQC, HMBC, 1H-1H COSY and NOESY permitted correct assignments of all 1H and 13C signals of 1 and 2, and the 13C NMR data of 2 were reported for the first time.

Two new triterpene saponins from Lysimachia davurica.

Two new saponins, named davuricoside L (1) and davuricoside O (2), have been isolated from the whole plants of Lysimachia davurica. Their structures were determined by 1D and 2D NMR, FAB-MS techniques, and chemical methods.

Microbial hydroxylation of bufalin by Cunninghamella blakesleana and Mucor spinosus.

The microbial transformation of a cytotoxic bufadienolide, bufalin (1), was carried out using two strains of filamentous fungi. Cunninghamella blakesleana catalyzed the specific 12alpha-hydroxylation of bufalin and produced 12alpha-hydroxybufalin (2) and 7beta,12alpha-dihydroxybufalin (3) as the major metabolites, together with 7beta-hydroxybufalin (4) and 12beta-hydroxybufalin (5) in low yields. Two minor products were isolated from the culture broth of Mucor spinosus and were identified as 7beta,15alpha-dihydroxybufalin (6) and 5beta,7beta-dihydroxybufalin (7), respectively. Metabolites 2, 3, 6, and 7 are new compounds, and their structures were fully characterized by NMR and MS spectroscopy.

Structure elucidation and complete NMR spectral assignments of a new benzoxazolinone glucoside from Acanthus ilicifolius.

A new benzoxazolinone glucoside, 4-O-beta-D-glucopyranosyl-benzoxazolin-2(3H)-one, was isolated from Acanthus ilicifolius, a medicinal plant from south China. The complete (1)H and (13)C NMR assignments of the compound were carried out by using DEPT, HMBC, HMQC, NOESY and (1)H--(1)H COSY spectra.

Cimidahuside 1 and 2, two new cyclolanostanol xylosides from the aerial parts of Cimicifuga dahurica.

Cimidahuside 1 and 2, two new cyclolanostanol xylosides were isolated from the aerial parts of Cimicifuga dahurica (Turcz.) MAXIM, on the basis of spectral data and chemical evidences, their structures were determined to be (20R,24R)-24,25-epoxy-3-beta-(beta-D-xylopyranosyloxy)-9,19-cyclolanost-7-ene-16,23-dione (1), and (20R,24R)-24,25-epxy-15-alpha-hydroxy-3-beta-((bet-D-xylpyranosyoxy)-9,19-cyclanost-7-ene-16,23-dione (2), respectively.

Two new pterocarpenes from Hedysarum multijugum.

Two new pterocarpenes were isolated from the roots of Hedysarum multijugum, and their structures were elucidated as hedysarimpterocarpene B (1) and hedysarimpterocarpene C (2) on the basis of spectroscopic data.

[Studies on the chemical constituents from the aerial parts of Cimicifuga dahurica].

AIM: To seek for new bioactive constituents from the aerial parts of Cimicifuga dahurica. METHODS: Various column chromatographic techniques were employed for the isolation and purification of the ingredients. The structures were elucidated on the basis of 1H, 13CNMR, 1H-1H COSY, HMQC, NOESY and HMBC spectra and chemical reactions. RESULTS: Two cyclolanostanol xylosides, cimidahuside C and D were isolated from the EtOAc section of EtOH extracts. CONCLUSION: Cimidahuside C(1) and D(2) are new triterpenoid xylosides.

Two new cyclolanostanol xylosides from the aerial parts of Cimicifuga dahurica.

From the aerial parts of Cimicifuga dahurica, two new cyclolanostanol xylosides, cimilactone A (1) and cimilactone B (2), and three known compounds were isolated. On the basis of spectral and chemical evidence, the structures of 1 and 2 were determined to be 12beta-acetoxy-3beta-O-D-xylopyranosyloxy-24,25,26,27-tetranor-9,19-cyclolanost-16,23-lactone (1) and 12beta-acetoxy-3beta-O-D-xylopyranosyloxy-24,25,26,27-tetranor-9,19-cyclolanost-7-ene-16,23-lactone (2). The known compounds were identified as cimigenol 3-O-beta-D-xylopyranoside, 23-O-acetylshengmanol-3-O-beta-D-xylopyranoside, and 25-O-acetylcimigenol-3-O-beta-D-xylopyranoside, respectively.