Xǔduō zhōngcǎoyào de yǒuxiào chéngfèn shì shēngwùjiǎn.
The active ingredient in many herbal medicines is an alkaloid.
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生物 (biology / living thing) + 碱 (alkali / base) = 'biology-base', i.e. a basic (alkaline) compound from a living source. Famous examples: caffeine 咖啡因, nicotine 尼古丁, morphine 吗啡, quinine 奎宁.