Jianming Ren

Phenolic antioxidants-functionalized quaternized chitosan: Synthesis and antioxidant properties

In this work, two kinds of phenolic antioxidants-functionalized quaternized chitosan were synthesized in order to develop aqueous soluble antioxidant-polymer conjugates. Quaternized chitosan conjugated with gallic acid or caffeic acid was carried out and the antioxidant properties of the products (namely gallic acid-quaternized chitosan and caffeic acid-quaternized chitosan) against hydroxyl-radical, superoxide-radical and DPPH-radical were evaluated in vitro, respectively. The scavenging activities of the obtained gallic acid-quaternized chitosan and caffeic acid-quaternized chitosan exhibit a remarkable improvement over those of either chitosan or quaternized chitosan. And the scavenging effect indices of the products were all higher than 90% at a concentration of 1000 μg/mL. Because gallic acid-quaternized chitosan and caffeic acid-quaternized chitosan are convenient to prepare and possess improved potential activities, these materials may represent an attractive new platform for utilizations of chitosan.

Synthesis and antifungal activity of thiadiazole-functionalized chitosan derivatives

A groups of novel water soluble chitosan derivatives containing 1,3,4-thiadiazole group were synthesized including 1,3,4-thiadiazole (TPCTS), 2-methyl-1,3,4-thiadiazole (MTPCTS), and 2-phenyl-1,3,4-thiadiazole (PTPCTS). Their antifungal activity against three kinds of phytopathogens was estimated by hypha measurement in vitro, and the fungicidal assessment shows that the synthesized chitosan derivatives have excellent activity against tested fungi. Of all the synthesized chitosan derivatives, MTPCTS inhibited the growth of the tested phytopathogens most effectively with inhibitory indices of 75.3%, 82.5%, and 65.8% against Colletotrichum lagenarium (Pass) Ell.et halst, Phomopsis asparagi (Sacc.) Bubak, and Monilinia fructicola (Wint.) Honey respectively at 1.0 mg/mL. These indices are higher than those of chitosan. These data also demonstrate that the hydrophobic moiety (alkyl and phenyl) and the length of alkyl substituent in thiadiazole tend to affect the antifungal activity of chitosan derivatives. It is hypothesized that thiadiazole groups enable the synthesized chitosan to possess obviously better antifungal activity and good solubility in water.

Synthesis of Water-Soluble Quaternized Chitosans and Their Antitumor Activity

water-soluble low-molecular-weight chitosan(LCTS) was prepared by hydrogen peroxide oxidation method and their quaternized derivatives(QLCTS) was also synthesized using previous methods. Their antitumor activity was studied, and the results showed that the LMW and its quaternized derivatives inhibited the growth of pancreatic carcinoma cell strain PANC-1 in vitro, and the inhibitory rate reached 59.2%.