RESUMO
Alkylamides, as the representative hemp flavor and active ingredients, can reflect the quality of Zanthoxylum bungeanum Maxim. However, conjugated triene structure exists in alkylamides, which is easy to be oxidized and decomposed in air, making it difficult to quantify. In this study, a method for the quantitative determination of alkylamides by 1 H-NMR technology was developed with 85% ethanol as the best extraction solvent, CDCl3 as the best deuterium dissolution reagent, pyrazine as the internal standard, and triple peaks of hydrogen protons on the amide bond at δ 6.33 ppm as the quantitative signal peak. Meanwhile, methodological verification was carried out to prove the reliability and effectiveness of the method. On this basis, the contents of alkylamides in nine germplasms of Zanthoxylum with monthly dynamics were obtained. The results showed that the alkylamides of Hancheng stingless Z. bungeanum (HC) exhibited the highest content in August (51.92 ± 0.96 mg/g), while the lowest was FG in June (1.23 ± 0.21 mg/g). The results of 1 H-NMR corresponded to those of HPLC, and the effectiveness of this method was verified. Accumulation dynamic results show that the best harvest period of Z. bungeanum is July and August. Moreover, the quality of nine varieties of Zanthoxylum bungeanum from a common garden was evaluated by the established 1 H-NMR fingerprint and chemometric analyses. The results showed that Hancheng stingless Z. bungeanum was the best germplasm. This study provides a new strategy for the quantitative determination of alkylamides in Z. bungeanum and improves the quality evaluation system of Z. bungeanum. PRACTICAL APPLICATION: The results provide a new research idea for the analysis of important chemical components of Z. bungeanum. Meanwhile, the study provides a scientific basis for the quality evaluation and high-quality germplasm resources of Z. bungeanum.
