Antiviral Ability of Kalanchoe gracilis against Enterovirus 71 and Coxsackievirus A16

• Main Authors: Ching-Ying Wang, 王靜瑩
• Other Authors: Yuan-Shiun Chang
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/5eqw58

博士 === 中國醫藥大學 === 中國藥學暨中藥資源學系博士班 === 102 === Kalanchoe gracilis (Crassulaceae) is a traditional Chinese medicinal, a.k.a. Da-Huan-Hun, and usually used in injuries, pain, fever and inflammation in Taiwan. In 1998, enterovirus 71 (EV71) and coxsackie A16 (CVA16) outbroke with severe or even fatal cases occurred in Taiwan, causing public health concern. EV71 and CVA16 become two major endemic agents of HFMD in children in Taiwan. There are not yet specific vaccines or antiviral drugs for treating enterovirus infection in clinic. In this study, extracts and compounds of K. gracilis leaf and stem were divided into two groups for investigating the antiviral activities against EVs. HPLC analysis indicated leaf and stem extracts exhibiting different ingredients, such as ferulic acid, quercetin and kaempferol in the leaf extract, as well as caffeic acid and eupafol in stem extracts. Plaque reduction assay indicated IC50 values of K. gracilis leaf extract were 35.88 μg/ml for EV71, and 42.91 μg/ml for CVA16, repectively. Leaf extract showed potent activity in the procedures of pre- and post-treatment for virus. Leaf extract inhibit the virus yield production to 90%. IC50 values of K. gracilis leaf extract in cell-based FRET assay were 40.82 μg/ml for EV71 and 47.84 μg/ml for CVA16. IC50 value of K. gracilis leaf extract in 2A protease assay was 32.46 μg/ml for EV71. The result implied K. gracilis leaf extract inhibited the proteolytic activity of EV71 and CVA16 2A proteases. K. gracilis leaf extract also revises the NF-κB-mediated signaling that induced by the virus infected. K. gracilis leaf extract effective against enterovirus is via inhibited viral replication and viral 2A protease activity. In the other hand, K. gracilis stem extract, EA fraction, BuOH fraction and relative compounds processed low cyotoxicity. IC50 values of K. gracilis stem extract were 75.18 μg/mL for EV71, and 81.41 μg/mL for CVA16, respectively. Anti-EV activity of stem extract was weaker than leaf extract, but stem extract potently inhibited EVs replication. EA and BuOH fractions of stem extract also showed the competence on inhibiting viral 2A protease enzymatic activity. Among the ingredients, eupafolin reduced virus-induced expression of IL-6 and RANTES. In vivo experiments proved leaf and stem extract potently inhibiting viral titers in intestines of infected mice. Together with data of two parts showed K. gracilis extracts as potent therapeutics against EV71 and CVA16. K. gracilis, an indigenous herbal plant in Taiwan, could easily cultivate and develop antiviral drugs for treatment and prevention against EV71 and CVA16 infections.