Modification of nanoscale polymeric adsorbent for the preparative separation and purification of tacrolimus from fermentation broth of Streptomyces tsukubaensis.

Tacrolimus is an important immunosuppressant produced by microbial fermentation. In this study, a modified nanoscale polymeric adsorbent, Ag+-exchanged resin, was prepared and studied for the preparative separation and purification of tacrolimus from fermentation broth of Streptomyces tsukubaensis. The performance and absorption characteristics of the modified nanoscale polymeric adsorbent namely Ag-NPS was evaluated. Notably, Ag-NPS resin displayed the pronounced separation capacities for tacrolimus and its equilibrium adsorption data was well-fitted to the Langmuir isotherm. Moreover, the dynamic adsorption and desorption tests was carried out to obtain the operational parameters for further purification of tacrolimus. Finally, tacrolimus and the two major impurities, ascomycin and dihydrotacrolimus, were separated well in the scale-up purification process. The purity and recovery of tacrolimus was recorded to be 99.12±0.25% and 90.41±2.05%. In conclusion, this method displayed a high potential for separation and purification of tacrolimus and other unsaturated bioactive compounds in high yield from the fermentation broth.

Two novel amphomycin analogues from Streptomyces canus strain FIM-0916.

Three lipopeptides, the known compound amphomycin, together with two novel compounds named aspartocin D (1) and aspartocin E (2) were obtained from the fermentation broth extraction of Streptomyces canus strain FIM0916 by using various column chromatography techniques. Their structures were elucidated by using spectroscopic methods, mainly by an extensive NMR analysis. It was demonstrated that compounds 1 and 2 are novel analogues of amphomycin, whose structures are similar to aspartocins. Compounds 1 and 2 share the same cyclic decapeptide core of cyclo (Dab2-Pip3-MeAsp4-Asp5-Gly6-Asp7-Gly8-Dab9-Val10-Pro11-), differing only in the side-chain moiety corresponding to Asp1-△3-isohendecenoic acid and Asp1-△3-isododecenoic acid, for aspartocin D and aspartocin E. In bioassays, compounds 1 and 2 exhibited antimicrobial activities against Gram-positive bacteria in the presence of Ca(2+) (1.25 mM); particularly, the activities were enhanced with higher concentrations of calcium.