title: New polymorphs of 9-nitro-camptothecin prepared using a supercritical anti-solvent process.
abstract: Recrystallization and micronization of 9-nitro-camptothecin (9-NC) has been investigated using the supercritical anti-solvent (SAS) technology in this study. Five operating factors, i.e., the type of organic solvent, the concentration of 9-NC in the solution, the flow rate of 9-NC solution, the precipitation pressure and the temperature, were optimized using a selected OA16 (4(5)) orthogonal array design and a series of characterizations were performed for all samples. The results showed that the processed 9-NC particles exhibited smaller particle size and narrower particle size distribution as compared with 9-NC raw material (Form I), and the optimum micronization conditions for preparing 9-NC with minimum particle size were determined by variance analysis, where the solvent plays the most important role in the formation and transformation of polymorphs. Three new polymorphic forms (Form II, III and IV) of 9-NC, which present different physicochemical properties, were generated after the SAS process. The predicted structures of the 9-NC crystals, which were consistent with the experiments, were performed from their experimental XRD data by the direct space approach using the Reflex module of Materials Studio. Meanwhile, the optimal sample (Form III) was proved to have higher cytotoxicity against the cancer cells, which suggested the therapeutic efficacy of 9-NC is polymorph-dependent.
authors.affiliation: School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 510640 China.
authors.forename: Yinxia
authors.initials: Y
authors.lastname: Huang
authors.affiliation: School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 510640 China.
authors.forename: Hongdi
authors.initials: H
authors.lastname: Wang
authors.affiliation: School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 510640 China.
authors.forename: Guijin
authors.initials: G
authors.lastname: Liu
authors.affiliation: School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 510640 China. Electronic address: cebjiang@scut.edu.cn.
authors.forename: Yanbin
authors.initials: Y
authors.lastname: Jiang
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry*; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000737:chemistry; D010316:Particle Size; D012997:Solvents
chemical_list: D000970:Antineoplastic Agents; D012997:Solvents; C079905:rubitecan; D002166:Camptothecin
keywords: 9-Nitro-camptothecin; Cytotoxicity; Micronization; Physicochemical properties; Polymorph; Supercritical anti-solvent process; solvent