Sesquiterpene lactone containing Mexican Indian medicinal plants and pure sesquiterpene lactones as potent inhibitors of transcription factor NF-κB

The potential inhibitory effect of 54 Mexican Indian medicinal plants on the activation of transcription factor NF-κB was studied. Band-shift experiments identified the ethanolic leaf extracts of Artemisia ludoviciana ssp. mexicana, Calea zacatechichi, and Polymnia maculata (all rich in sesquiterpene lactones) as inhibitors of NF-κB down to a concentration of 25 μg/ml. The sesquiterpene lactones isohelenin and parthenolide prevented NF-κB activation completely as low as 5 μM. Treatment of HeLa cells with leaf extract of A. ludoviciana ssp. mexicana, isohelenin and parthenolide prevented the induction of transcription on the IL-6 promoter. These experiments identify the eudesmanolide and germacranolide type of sesquiterpene lactones as potent non-antioxidant inhibitors of NF-κB. All plants active in the NF-κB assay also showed a delay in the onset of capillary reactions of the allantois membrane in a physiological model for anti-inflammatory activity - the HET-CAM assay.