Abstract: The optical density (OD) values of the extracts got with ethanol from 12 weeds in rice fields were determined using spectrophotometry. The OD values of the extracts from Echinochloa crusgall,Leptochloa chinensis,Cyperus iria and Monochoria vaginalis after 8 h extraction are 0.0165, 0.0215, 0.0235 and 0.0120, respectively,which were lower than that of tea polyphenols significantly, while equivalent to that from Elsholtzia ciliata. It suggested that the substances from the ethanol extracts were excellent antioxidants with significant antioxidation potential. By using water solution containing 0.3% antioxidant, the conditions of the ratio of solvent quantity to sample material of 12∶1, extraction of 8 h and temperature of 80℃ were the optimal parameters for collecting the antioxidants from Monochoria vaginalis.

Key words: weeds, alcohol extracts, antioxidant, extraction technique

摘要： 采用分光光度法，测定了12种稻田杂草植株的乙醇提取液的吸光度(OD) 值。结果表明，稗、千金子、碎米莎草和鸭舌草8 h提取液的吸光度分别为0.0165、0.0215、0.0235和0.0120，均显著低于抗氧化剂茶多酚的，而与香薷的相当，表明这4种杂草乙醇提取物的抗氧化作用显著。在液料比12∶1、提取时间8 h、提取温度80℃，以0.3%抗氧化剂水溶液为溶剂，加工获得的鸭舌草乙醇提取液的抗氧化作用最强。

关键词: 杂草, 乙醇提取液, 抗氧化剂, 提取技术