New iridoid glycosides from Anarrhinum pubescens

Abstract

Six metabolites (1–6) were isolated from the aerial parts of Anarrhinum pubescens Fresen. (Plantaginaceae) growing in Saint Catherine region in Egypt; two of them (1 and 4) are here reported to be newly identified naturally occurring iridoids. The isolated metabolites were identified as 6-O-foliamenthoyl-(6′-O-cinnamoyl)-antirrhinoside (1), 6′-O-cinnamoyl-antirrhinoside (2), the iridoid dimer, pubescensoside (4), antirrhinoside (5), 10-hydroxy-antirrhinoside (6), and the flavonoid, diosmin (3). Identification of the new metabolites was based on analysis of their collected spectroscopic data (NMR and HR-ESI-MS). Furthermore, compounds (1, 4, and 5) were subjected to cytotoxic testing against the human lung carcinoma cell line (A-549); compound 4 showed better cytotoxic activity as indicated by the obtained (IC₅₀).

Graphical Abstract

Keywords:

• Iridoids
• Anarrhinum pubescens
• Plantaginaceae
• Secondary Metabolites

Acknowledgments

The authors gratefully acknowledge the St. Catherine Protectorate staff members for their assistance in collecting and identifying the plant material.

Disclosure statement

The authors declare that they have no conflict of interest.

Additional information

Funding

This work was supported by the South Carolina IDeA Networks of Biomedical Research Excellence SC-INBRE under grant No. 2 P20 GM103499; National Science Foundation Historically Black Colleges and Universities - Undergraduate Program NSF HBCU-UP under grant No. HRD-1332516; and National Science Foundation Major Research Instrumentation grant No. NSF-MRI DBI-1429353.