School of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250000, PR China.
Shandong Institutes for Food and Drug Control, Jinan 250101, China.
Food Res Int. 2023 Feb;164:112323. doi: 10.1016/j.foodres.2022.112323. Epub 2022 Dec 10.
Mentha haplocalyx Briq (M. haplocalyx) is a herbaceous plant that has long been used as a food, medicinal spice, and flavoring agent in traditional Chinese medicine. Its secondary metabolites, having high commercial values, are mainly produced in tiny specialized structures called glandular trichomes (GTs). The primary purpose of this study was to examine the morphology and metabolites of peltate GTs in M. haplocalyx.Peltate GTs possessed globular dome shapes and intense auto-fluorescence on the surfaces of M. haplocalyx leaves. Structure subsidence and cuticle rupture were found throughout the aging stage of peltate GTs. According to histochemical staining results, the secretion of peltate GTs contained anthraquinone, flavonoids, phenolic acid and terpenoids. In M. haplocalyx peltate GTs and leaf tissues without peltate glandular trichomes, ten and two volatile compounds were identified respectively. Peltate GTs contained 42 non-volatile chemicals with a variety of structural types, including 20 flavonoids, 17 phenolic acids,1 diterpene, 3 anthraquinone and 1 alkane. Meanwhile, 15 non-volatile compounds were discovered in leaf tissues without peltate glandular trichomes, and they were all included in the list of peltate GTs' 41 components. Therefore, Peltate GTs were shown to be the primary site of not just volatile compounds but also non-volatile chemicals in M. haplocalyx. This study provides an important theoretical basis and technical approach for clarifying the bio-active metabolite biosynthesis in M. haplocalyx.
唇形科薄荷属薄荷（M. haplocalyx）是一种草本植物，在中国传统医学中，它一直被用作食品、药用香料和调味剂。其次生代谢产物具有很高的商业价值，主要产生于称为腺毛（GTs）的微小特化结构中。本研究的主要目的是研究薄荷属薄荷的盾形 GTs 的形态和代谢产物。
盾形 GTs 在薄荷属薄荷叶片表面呈球形圆顶状，具有强烈的自发荧光。在盾形 GTs 的老化阶段，发现结构下沉和角质层破裂。根据组织化学染色结果，盾形 GTs 的分泌物中含有蒽醌、类黄酮、酚酸和萜类化合物。在薄荷属薄荷的盾形 GTs 和没有盾形腺毛的叶片组织中，分别鉴定出 10 种和 2 种挥发性化合物。盾形 GTs 含有 42 种具有多种结构类型的非挥发性化学物质，包括 20 种类黄酮、17 种酚酸、1 种二萜、3 种蒽醌和 1 种烷烃。同时，在没有盾形腺毛的叶片组织中发现了 15 种非挥发性化合物，它们都包含在盾形 GTs 的 41 种成分列表中。因此，盾形 GTs 不仅是非挥发性化合物的主要产生部位，也是薄荷属薄荷中挥发性化合物的主要产生部位。本研究为阐明薄荷属薄荷生物活性代谢物的生物合成提供了重要的理论依据和技术方法。
