Here, we compared the inhibitory efficacy of six iridoids constituting YPL-001 on mucus overexpression, and showed that verproside most effectively reduces COPD-related inflammation by suppressing the PKCδ activation and its downstream TNF/NF-κB and PMA/PKCδ/EGR-1 pathways. Here, NFKB1 is linked to chronic obstructive pulmonary disease.