Preparation, characterization of amides from Piper wallichii (Miq.) Hand.-Mazz. and key compounds including pellitorine screened by fingerprint-efficacy correlation of antioxidant activity

Abstract

The industrial enrichment of fat-soluble compounds is a common challenge, which is also present in Piper wallichii (Miq.) Hand.-Mazz. (PWH). The stem of PWH is rich in amide alkaloid substances, although enrichment methods have been available for total amide alkaloids, their water-insoluble character has not yet been addressed by a green and efficient method. We have elaborated the adsorption characteristics of pellitorine and futoamide on macroporous resins. Synchronization of concentration and adsorption was used to solve the critical problem of enrichment on macroporous resins with lipid-soluble compounds that tend to clog the resin columns during the enrichment process. Fifteen batches of PSA (amide alkaloids of PWH) were prepared from PWH collected from multiple origins, and multidimensional fingerprints were established in combination with multivariate statistical analysis to evaluate the consistency and variability of the compounds in multiple batches. Then, the fingerprints were correlated with their corresponding antioxidant activities to identify the pharmacodynamic compounds, thus clarifying the key compounds. Finally, compound separation was performed to verify the accuracy of the antioxidant activity of the key compounds and fingerprint-efficacy correlation model. HP-20 macroporous adsorbent resin has optimal adsorption and desorption which was selected for the enrichment of PSA. The adsorption of PSA, including futoamide and pellitorine, on the HP-20 resin was consistent with the Pseudo-second order kinetic model and Langmuir isotherm model, and this adsorption was a spontaneous exothermic entropy increase mechanism. The on-column adsorption process was optimized to solve the phenomenon that the precipitation of fat-soluble amides were easy to block the glass column during the enrichment process of the macroporous adsorption resin, and the effective enrichment of PSA was achieved. The content of pellitorine and futoamide was 13.95 g/100 g and 3.11 g/100 g in prepared samples respectively. The percentage of PSA was more than 50 g/100 g. Seventeen differentiated compounds were screened by multivariate statistical analysis, antioxidant activity of 4 individual compounds isolated by fingerprint-efficacy correlation such as pellitorine were validated. The present study provided a more effective method for the enrichment of PSA, and initially elucidated the active compounds of the antioxidant activity of PWH, which will establish the basis for the industrialization of PSA in the future.