Liquid chromatography of gramicidin

Abstract

SummaryA simple, selective method is described for separation of more than 10 gramicidin components on Spherisorb ODS B, 5 I~m, 250 x 4.6 mm I. D. column, maintained at 50 ~ The mobile phase comprised methanol-water (71:29) at a flow rate of 1.0 mL min 1. Detection was by UVat 282 nm. Vahne gramicidins A, B and C were very well separated from the isoleucine gramicidins A, B and C. Four new gramicidin components were also resolved and their structures determined by liquid chromatography/mass spectrometry The names 10-methionine valine gramicidin C 4-methionine valine gramicidin A, vahne gramicidin A hydroxypropyl and isoleucine gramicidin A hydroxypropyl were proposed. Robustness of the liquid chromatography method was evaluated by performing a full factorial design experiment. The method also showed good repeatabihly, linearilyand sensitivily.

Hyphenation of liquid chromatography to ion trap mass spectrometry to identify minor components in polypeptide antibiotics

“…With the development of an improved separation technique [32] new unidentified gramicidins were separated from the described compounds. This method was miniaturized in terms of internal diameter of the column for coupling with the ion trap MS.…”

“…The bacitracin complex was separated into at least 22 peaks on a conventional YMC-Pack Pro C 18 column maintained at 30°C in a waterbath using non-volatile mobile phase additives [35]. On the basis of this method two different mobile phases comprising different volatile salts were developed for separation of the bacitracin components on a narrowbore column containing the same stationary phase.…”

“…Attempts have been made by different research groups to characterize commercially available polypeptide antibiotics [7] such as gramicidin [8], polymyxin B [9,10,11,12,13], polymyxin E [9,10,14,15,16,17,18], and bacitracin [19,20,21,22,23,24,25,26,27,28,29,30,31], which were the subject of our investigation. In most cases structural elucidation was carried out after time-consuming isolation and purification procedures but despite considerable efforts not all impurities were characterized and in the last few years, with the development of better separating liquid chromatography (LC) methods, more unidentified peaks have been separated and remain unidentified [32,33,34,35]. Checking the molecular structure of impurities and degradants is an important step in the quality control of a drug.…”

Fast separation of bacitracin on monolithic silica columns

“…Accordingly, a new nomenclature of some components of Bc was proposed (Fig. 1) [3][4][5]. Additionally in Supplement 4.5 of European Pharmacopoeia 4th, the component F is designated as E [4].…”

Packed column supercritical fluid chromatography of isomeric polypeptide pairs

“…In each case the N-terminus and C-terminus of gramicidin which are water insoluble were blocked by formyl and ethanolamine groups. Three forms of gramicidin (B, C, and A) were separated using a cyanopropylsilica column (4.6 mm × 50 mm, 5 m) in under five minutes; whereas by HPLC-MS it was difficult to achieve a notable separation of the three in less than 30 min [6].…”