Esparza Eliana, Hadzich Antonella, Kofer Waltraud, Mithöfer Axel, Cosio Eric G
Sección Química, Pontificia Universidad Católica del Perú, Avenida Universitaria 1801, San Miguel, Lima 32, Peru.
Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, 07745 Jena, Germany.
Phytochemistry. 2015 Aug;116:138-148. doi: 10.1016/j.phytochem.2015.02.030. Epub 2015 Mar 25.
Maca, Lepidium meyenii Walpers (Brassicaceae), is an annual herbaceous plant native to the high plateaus of the Peruvian central Andes. Its underground storage hypocotyls have been a traditional medicinal agent and dietary staple since pre-Columbian times. Reported properties include energizing and fertility-enhancing effects. Published reports have focused on the benzylalkamides (macamides) present in dry hypocotyls as one of the main bioactive components. Macamides are secondary amides formed by benzylamine and a fatty acid moiety, with varying hydrocarbon chain lengths and degree of unsaturation. Although it has been assumed that they are usually present in fresh undamaged tissues, analyses show them to be essentially absent from them. However, hypocotyls dried by traditional Andean postharvest practices or industrial oven drying contain up to 800μgg(-1) dry wt (2.3μmolg(-1) dry wt) of macamides. In this study, the generation of macamides and their putative precursors were studied during nine-week traditional drying trials at 4200m altitude and in ovens under laboratory conditions. Freeze-thaw cycles in the open field during drying result in tissue maceration and release of free fatty acids from storage and membrane lipids up to levels of 1200μgg(-1) dry wt (4.3μmolg(-1) dry wt). Endogenous metabolism of the isothiocyanates generated from glucosinolate hydrolysis during drying results in maximal benzylamine values of 4300μgg(-1) dry wt (40.2μmolg(-1) dry wt). Pearson correlation coefficients of the accumulation profiles of benzylamine and free fatty acid to that of macamides showed good values of 0.898 and 0.934, respectively, suggesting that both provide sufficient substrate for amide synthesis during the drying process.
玛卡，即玛咖独行菜（十字花科），是一种一年生草本植物，原产于秘鲁中部安第斯山脉的高原地区。自前哥伦布时代起，其地下贮藏的下胚轴就一直是传统的药物和饮食主食。据称其功效包括增强活力和提高生育能力。已发表的报告聚焦于干燥下胚轴中存在的苄基酰胺（玛卡酰胺），将其作为主要生物活性成分之一。玛卡酰胺是由苄胺和脂肪酸部分形成的仲酰胺，具有不同的烃链长度和不饱和度。尽管一直认为它们通常存在于新鲜未受损的组织中，但分析表明新鲜组织中基本不存在玛卡酰胺。然而，采用传统安第斯收获后处理方法干燥或工业烘箱干燥的下胚轴中，玛卡酰胺含量高达800μg g⁻¹干重（2.3μmol g⁻¹干重）。在本研究中，对海拔4200米处为期九周的传统干燥试验以及实验室条件下烘箱干燥过程中玛卡酰胺及其假定前体的生成情况进行了研究。干燥过程中田间的冻融循环导致组织浸软，并使贮藏和膜脂中的游离脂肪酸释放量高达1200μg g⁻¹干重（4.3μmol g⁻¹干重）。干燥过程中硫代葡萄糖苷水解产生的异硫氰酸酯的内源性代谢导致苄胺的最大含量达到4300μg g⁻¹干重（40.2μmol g⁻¹干重）。苄胺和游离脂肪酸积累曲线与玛卡酰胺积累曲线的皮尔逊相关系数分别显示出良好的值0.898和0.934，这表明二者都为干燥过程中的酰胺合成提供了充足的底物。
