title: Chitosan-isoniazid conjugates: Synthesis, evaluation of tuberculostatic activity, biodegradability and toxicity.
abstract: Novel water-soluble chitosan-isoniazid conjugates were synthesized by two methods: (1) the carbodiimide method using isoniazid (INH) and N-(2-carboxyethyl)chitosan (CEC), and (2) the reaction between INH and N-(3-chloro-2-hydroxypropyl)chitosan (CHPC). The solubility of the conjugates under physiological conditions was enhanced by phosphorylation. Method (1) is preferable in terms of obtaining conjugates with a high content of active substance; depending on reaction conditions, the degree of substitution in the INH-CEC conjugates varies from 0.08 to 0.39. Ultrasound treatment increased the reaction rate by a factor of 1.3-1.5, but caused partial degradation of the polymer. Consecutive modification led to a considerable decrease in polymer biodegradability in the following order: chitosan>CEC or CHPC>conjugate. In vitro screening of the antimicrobial activity against Mycobacterium tuberculosis H37Rv demonstrated a comparable or slightly higher minimum inhibitory concentration for conjugates than for INH itself (0.20, 0.25, and 1.05 μg INH/mL for INH, CEC-INH, and CHPC-INH, respectively). A slug mucosal irritation test employing Limax flavus revealed a lower toxicity for the conjugates than for INH by a factor of 3-4; the most noticeable toxicity decrease was observed for the conjugates obtained by method (1). Studies of acute toxicity in mice revealed a 3-4-fold increase in median lethal dose for the conjugates compared with INH (LD50 210, 850, and 650 mg INH/kg for INH, CEC-INH, and CHPC-INH, respectively).
authors.affiliation: St. Petersburg State Chemical Pharmaceutical Academy, 14 Prof. Popov St., St. Petersburg 197022, Russian Federation.
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Berezin
authors.affiliation: Institute of Macromolecular Compounds of the Russian Academy of Sciences, 31 Bolshoi pr. VO, St. Petersburg 199004, Russian Federation; Institute of Chemistry, St. Petersburg State University, Universitetskii pr. 26, Petrodvorets, St. Petersburg 198504, Russian Federation. Electronic address: yury_skorik@mail.ru.
authors.forename: Yury A
authors.initials: YA
authors.lastname: Skorik
mesh_terms: D000818:Animals; D000995:Antitubercular Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology / Q000633:toxicity; D048271:Chitosan / Q000737:chemistry*; D054697:Cytostatic Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology / Q000633:toxicity; D049851:Gastropoda / Q000187:drug effects; D007538:Isoniazid / Q000737:chemistry*; D051379:Mice; D009169:Mycobacterium tuberculosis / Q000187:drug effects
chemical_list: D000995:Antitubercular Agents; D054697:Cytostatic Agents; D048271:Chitosan; D007538:Isoniazid
keywords: Activated ester method; Carbodiimide activation; Chitosan; Conjugate; Drug delivery; Isoniazid; Toxicity, Limax flavus