Isolation and structure elucidation of pyridine alkaloids from the aerial parts of the Mongolian medicinal plant Caryopteris mongolica Bunge

Dumaa Mishig,Chunsriimyatav Ganbaatar,Hans-Joachim Knölker,Tilo Lübken,Duger Regdel,Margit Gruner

doi:10.1038/s41598-021-93010-4

Dumaa Mishig, Chunsriimyatav Ganbaatar + Show 4 more

Open Access

https://doi.org/10.1038/s41598-021-93010-4

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Abstract

The seven pyridine alkaloids 1–7, the flavonoid acacetin (8), and L-proline anhydride (9) have been isolated from the aerial parts of the Mongolian medicinal plant Caryopteris mongolica Bunge. The structures of the natural products 1–9 have been assigned by MS, as well as IR, 1D NMR (1H, 13C, DEPT), and 2D NMR (COSY, HSQC, HMBC, NOESY) spectroscopic methods. The compounds 2 and 4–7 represent new chemical structures. Acacetin (8) and L-proline anhydride (9) have been obtained from C. mongolica for the first time.

Highlights

Caryopteris mongolica Bunge is a deciduous shrub and belongs to the Verbenaceae family
In our previous phytochemical investigation of the aerial parts of C. mongolica, we have identified some phenolic compounds such as acacetin, apigenin, luteolin, and caffeic a cid8
We describe the isolation of pyridine monoterpene alkaloids, isoquinoline alkaloids, a dipyrrolopyrazine, and a flavonoid from the aerial parts of C. mongolica and their structure elucidation using MS, as well as IR, 1H NMR, 13C NMR, and 2D NMR spectroscopic methods

Summary

Introduction

Caryopteris mongolica Bunge is a deciduous shrub and belongs to the Verbenaceae family. The 1H NMR spectrum of compound 3 exhibits three signals for the pyridine protons, a quartet of doublet of doublets for the methine group (H-7), two doublets of doublets for the two methylene protons at C-6, and one doublet at 1.46 ppm for the methyl group (Table 1).

Results

Conclusion