Macrolactin S, a novel macrolactin antibiotic from marine Bacillus sp.

A new 24-membered ring lactone, macrolactin S, was isolated from a culture broth of marine Bacillus sp. and its structure was established by various spectral analyses. Macrolactin S is the first macrolactin hydroxylated at C-12. Besides, the known compounds macrolactin A and macrolactin B were also isolated, which were elucidated on the basis of spectral data analyses and literature data comparison. They exhibited antibacterial activity against E. coli and S. aureus.

[New method for selectivity optimization in thin layer chromatography and its application in pharmaceutical analysis].

A new experimental design method named the step climbing method (SCM), as well as a new global criterion (NRC), are proposed for the selectivity optimization of thin layer chromatography. The method offers chromatographers a convenient means to decide the optimum developer composition for thin layer chromatography. The principle of the method is described, and examples of applications in pharmaceutical analysis are given to certify the feasibility of the method. Clearly, it may also be used for the selectivity optimization in high performance liquid chromatography.

[Assay of bilirubin of ox gallstone in Chinese patent medicines by differential spectrophotometry].

This paper describes that the absorption spectrum of bilirubin solution was changed obviously by photo-oxidation. The absorbance was measured at 453 nm before and after light irradiation. The contents of bilirubin of ox gallstone in Liuying pills, Liushen pills and Niuhuang Xiaoyan pills were determined by differential absorbance (delta A). Calibration graph was linear in the range of 1.6-8.0 micrograms/ml for delta A. The average recoveries for three Chinese patent medicines were over 93%. Determinations of bilirubin in Chinese patent medicines were not affected by other components.

[Use of the Powell method to optimize the composition of HPLC mobile phase--the separation of ephedrine and pseudoephedrine].

The isomers ephedrine and pseudoephedrine are difficult to be separated by HPLC. In this paper, the Powell method was successfully introduced to optimize the composition of mobile phase in HPLC. On a mu Bondapak C18 column (8-10 microns, 3.9 mm x 30 cm), KH2PO4 solution methanol mobile phase system was optimized for separating ephedrine and pseudoephedrine by the Powell method. The optimized composition of the mobile phase was found as: 0.01 mol/L KH2PO4 -MeOH = 94: 6 (V/V). The Powell method was carried out in a process illustrated by tables and figures and 0.95 peak separation function was achieved.

[Determination of ephedrine, pseudoephedrine and strychnine in jiufen san by HPLC].

An HPLC method was established to separate and determine ephedrine (I), pseudoephedrine (II) and strychnine (III) in Chinese traditional medicine, Jiufen San, on a mu-Bondapak C18 column (10 microns, 3.9 mm x 30 cm) by using 0.01 mol/L KH2PO4-methanol as mobile phase. The programmed gradient elution was carried out and recoveries were determined as 98.94 +/- 2.2% for I, 97.37 +/- 1.9% for II and 100.7 +/- 1.9% for III respectively. An extracting and pretreatment method was designed and the result showed that the extracting efficiency of this method was 1.33 times (I) and 1.29 times (II) higher than those of the Chinese Pharmacopoeia method.

[Studies on the simultaneous measurement of several cephalosporins by RP-HPLC (I)].

This paper reported the research on the simultaneous separation and determination of six cephalosporins by RP-HPLC. Six cephalosporins are cefalcor, cefalexin, cefradine, cefadroxil, cefominox and cefoxitin. The analytical conditions for this method were as follows: a Hypersil ODS C18(200 mm x 4.6 mm i.d., 5 microns), detection wavelength: 254 nm; a mobile phase solution of 50 mmol/L monopotassium phosphate (pH 3.4)-acetonitrile (87.5:12.5) and DAD detector. The flow rate was 1.0 mL/min. The calibration curves of the six compounds were linear, the correlation coefficients were 0.9951 for cefominox, 0.9999 for the others, the range were 164 ng-16.4 micrograms for cefominox, 99 ng-9.934 micrograms for cefadroxil, 104 ng-10.358 micrograms for cefalcor, 122 ng-12.224 micrograms for cefalexin, 107 ng-10.702 micrograms for cefradine and 115 ng-11.506 micrograms for cefoxitin. The recovery rates were 103.5% for cefominox, 99.3% for cefadroxil, 101.4% for cefalcor, 101.5% for cefalexin, 98.7% for cefradine and 97.6% for cefoxitin. Six cephalosporins were all stable in 50 mmol/L monopotassium phosphate (pH 3.4-4.6). When preparations of these cephalosporins were determined, it is indicated there were no difference between the results by using this method and the pharmacopoeia methods. The total separation time of these cephalosporins was within fifteen minutes. This method is simple, sensitive, rapid and accurate.