ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Analysis of streptolydigin degradation and conversion in cultural supernatants of Streptomyces lydicus AS 4.2501

Liangzhi Li, Jiaolong Fu, Yexian Qiu, and Jinlian Wang

School of Chemistry and Bioengineering, Suzhou University of Science and Technology, Suzhou, 215011 China

E-mail: liliangzhi01@163.com

Abstract: A variety of structural analogues of streptolydigin exists in the cultural supernatants of Streptomyces lydicus AS 4.2501. The degradation of streptolydigin in cultural supernatants with different pH values kept at 25°C in a thermostatic bath was investigated using LC-MS/MS detection. Analysis of the alkaline supernatants (pH 9.50) provides evidence of degradation and conversion between streptolydigin and its structural analogues. Interestingly, a new streptolydigin analogue was detected by LC-MS and photo-diode array (PDA) detection in the process of alkaline degradation. After 48 h in a thermostatic bath, the degradation of streptolydigin and its two analogues at pH 9.50 approached pseudo-first order kinetics. Comparatively, the degradation of streptolydigin was much more rapid in the cultural supernatants with pH 3.05, only requiring 2 hours. Qualitative analysis of the degradation products by LC-MS/MS and PDA indicated that hydrolysis of the epoxy ether bond and acid amide bond was the major mechanism of degradation in acidic cultural supernatants. Two degradation products in the acid supernatant were assumed.

Keywords: streptolydigin – degradation – conversion – LC-MS – Streptomyces lydicus

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-011-0050-1

Chemical Papers 65 (5) 652–659 (2011)