Characterization of phenolic chemotypes, anatomy, and histochemistry of Zanthoxylum bungeanum Maxim

The leaves of Zanthoxylum bungeanum Maxim. are important in traditional Chinese medicine and are a valuable nutritional source and flavoring agent. Although they are rich in phenolic compounds, the characterization of phenolic chemotypes of Zanthoxylum bungeanum has not been reported yet. Here, the profiles, accumulation kinetics, and tissue localization of phenolic compounds were analyzed in the leaves of 11 cultivars of Zanthoxylum bungeanum during growth and development. Twenty-seven phenolic compounds were identified, among which isoquercitrin, hyperoside, chlorogenic acid, quercitrin, myricetin, and ferulic acid existed in all cultivars, with ferulic acid and quercitrin being the most abundant. Chemometric analysis showed that the 11 cultivars were characterized by four chemotypes: 1) isoquercitrin, 2) rutin and hyperoside, 3) quercitrin, and 4) chlorogenic acid and quercitrin. Additionally, the accumulation dynamics of its main components were explored and the optimal harvest period for Zanthoxylum bungeanum leaves (early August) was determined. Moreover, anatomy and histochemical analysis results showed that the phenolics mainly accumulated in the epidermis, palisade tissue, and parenchyma cells. However, differences in the dimensions of these structures accounted for variations in phenolic accumulation, thus determining the different chemotypes. The classification of Zanthoxylum bungeanum chemotypes, and accumulation patterns of major chemical components, is valuable for the effective utilization of agricultural resources, quality evaluation, directional breeding, product multipurpose utilization, and development of plants.