Mentha longifolia_phenolic_composition

Mentha longifolia (L.) L. (ML) is characterised by polychemism in terms of volatiles and polyphenols. Despite this, ML has not yet been utilized in the industry. This study examined the specific polyphenol composition and its correlations with in vitro antioxidant properties of five accessions of different origins. The study included two habitats and three consecutive years.
The concentration of rosmarinic acid (RA) (4011-55145 mg/kg dry weight, DW), eriocitrin (0-45306 mg/kg), luteolin-7-O-rutinoside (161-30848 mg/kg), cynaroside (0-9076 mg/kg) and hesperidin (144-7138 mg/kg) showed significant, site – and year – independent differences among the accessions. The accumulation of eriocitrin demonstrated significant elevations, especially in the 2nd-year-old plantations (2-fold to 45-fold in comparison to 1st year). RA concentration presented phenophase-dependent changes, which were, however, different in the populations. Accumulation of hesperidin, on the other side, showed significant changes between habitats. Distinction of polyphenol chemotaxa in the species is proposed as a conclusion: one luteolin-7-O-glycosides-flavanone-RA-rich type, one luteolin-7-O-rutinoside/RA type, and two RA-based types, poorer in flavonoids, distinguishable by the presence or absence of eriocitrin and the flavone contents. RA and eriocitrin concentrations demonstrated the strongest correlation with the antioxidant activities of the extracts. Chemotypes rich in rosmarinic acid or flavonoids may serve as valuable raw materials for the food industry and in phytotherapy.

长叶薄荷（*Mentha longifolia* (L.) L.，简称ML）在挥发物与多酚组分上呈现多化学型特征。尽管具备该特性，ML目前尚未在工业中得到应用。本研究针对5份不同来源的长叶薄荷种质，分析了其特异性多酚组成，并探究了该组成与体外抗氧化活性的关联。试验设置了两种生境，并连续开展三年观测。
各供试种质间的迷迭香酸（rosmarinic acid, RA）、圣草苷（eriocitrin）、木犀草素-7-O-芸香糖苷（luteolin-7-O-rutinoside）、洋蓟苷（cynaroside）与橙皮苷（hesperidin）含量分别为4011~55145 mg/kg干重（dry weight, DW）、0~45306 mg/kg、161~30848 mg/kg、0~9076 mg/kg及144~7138 mg/kg，且其含量在种质间存在不受生境与年份影响的显著差异。圣草苷的积累量显著升高，尤其在人工种植园的二年生植株中，其含量较第一年提升2~45倍。迷迭香酸的含量表现出物候期依赖性变化，但不同种群间的变化模式存在差异。而橙皮苷的积累量则在不同生境间存在显著差异。基于上述结果，本研究提出可依据多酚化学型对该物种进行分类：一类为木犀草素-7-O-糖苷-黄烷酮-迷迭香酸富集型，一类为木犀草素-7-O-芸香糖苷/迷迭香酸型，另有两类基于迷迭香酸的类型（类黄酮含量较低），可通过圣草苷的有无以及黄酮类成分含量进行区分。
迷迭香酸与圣草苷的含量与提取物的抗氧化活性呈现最强相关性。迷迭香酸或类黄酮富集的化学型可作为食品工业与植物疗法领域的优质原料。