a tannic acid that is extracted from black catechu as a white crystalline substance
catechin详细解释
cat.e.chin n.（名词）A crystalline substance, C5H 4O ', derived from catechu and used in tanning and dyeing. Also called catechol 儿茶酸：一种晶体物质，C5H 4O '，来源于儿茶，用于制革和染色 也作 catechol 来源：catech(u)catech(u)-in-in
