US Department of Agriculture, Appalachian Farming Systems Research Center, Agricultural Research Service, Beaver, West Virginia 25813, USA.
J Agric Food Chem. 2010 Feb 10;58(3):1691-8. doi: 10.1021/jf903222j.
There is limited information on how postharvest drying of Artemisia annua affects artemisinin (ART) biosynthesis and A. annua antioxidant capacity. Antioxidants may boost the bioactivity of ART and the crop commercial value. We evaluated the effect of freeze, oven, shade, and sun drying, time of drying, and light intensity on the leaf concentration of ART, dihydroartemisinic acid (DHAA), artemisinic acid (AA), and on the leaf antioxidant capacity. Freeze-dried samples had the lowest ART concentrations as compared to the other drying methods. However, the ferric reducing antioxidant power assay showed that freeze- and oven-dried samples had similarly high antioxidant activities, which declined significantly after plants were shade- and sun-dried. Shade drying for 1, 2, and 3 weeks, under ambient or low light, did not change the ART content but significantly decreased the leaf antioxidant activity, mainly if sun-dried. A significant decrease (82% average) in DHAA was observed for all drying procedures as compared to freeze drying, with a simultaneous, significant increase in ART (33% average). The average bioconversion of DHAA to ART was 43% for oven- and shade-dried plants and 94% for sun-dried plants, reiterating the hypothesis that DHAA, not AA, is the main biosynthetic precursor of ART and suggesting that sun drying improves the bioconversion from DHAA to ART. Data also indicate that oven drying for 24 h at 45 degrees C can provide good levels of both ART and antioxidants in leaves. These findings are valuable for the commercial production of ART and of bioactive antioxidants that might synergize with the antimalarial and anticancer effects of ART when combined in traditional preparations to improve human and animal health.
关于青蒿收获后干燥如何影响青蒿素（ART）生物合成和青蒿抗氧化能力的信息有限。抗氧化剂可能会提高 ART 的生物活性和作物的商业价值。我们评估了冷冻、烤箱、阴凉和阳光干燥、干燥时间和光照强度对叶片中 ART、二氢青蒿酸（DHAA）、青蒿酸（AA）浓度以及叶片抗氧化能力的影响。与其他干燥方法相比，冻干样品的 ART 浓度最低。然而，铁还原抗氧化能力测定表明，冻干和烤箱干燥样品具有相似的高抗氧化活性，在植物阴凉和阳光干燥后显著下降。阴凉干燥 1、2 和 3 周，在环境或低光照下，不会改变 ART 含量，但会显著降低叶片抗氧化活性，如果阳光干燥则更为明显。与冷冻干燥相比，所有干燥过程中 DHAA 的含量均显著下降（平均下降 82%），同时 ART 的含量显著增加（平均增加 33%）。对于烤箱和阴凉干燥的植物，DHAA 到 ART 的平均生物转化率为 43%，而对于阳光干燥的植物，生物转化率为 94%，这再次证实了 DHAA 而不是 AA 是 ART 生物合成的主要前体的假设，并表明阳光干燥可提高从 DHAA 到 ART 的生物转化率。数据还表明，在 45°C 的烤箱中干燥 24 小时可以为叶片提供良好水平的 ART 和抗氧化剂。这些发现对于 ART 的商业生产以及与 ART 的抗疟疾和抗癌作用协同增效的生物活性抗氧化剂的生产具有重要价值，当将它们组合在传统制剂中以改善人类和动物健康时。
