STUDY ON THE STRUCTURE-ACTIVITY RELATIONSHIP OF ISOLATED COMPOUNDS FROM CHRYSANTHEMUM SINENSE SABINE. AND NITRIC OXIDE INHIBITORY ACTIVITY

Abstract

It is known that nitric oxide (NO) radical is not only a physical mediator but, if excessive amounts, can be cytotoxic. An overproduction of NO is thought to contribute to the development of disease states such as cancer, diabetic, heart diseases…. The flower of Chrysanthemum sinense Sabine. (Asteraceae) has been used in Vietnamese traditional medicine for the treatment of rheumatism and inflammatory diseases. In the screening program for antioxidant activity of medicinal plants from Vietnam, the methanolic extract of the flower of C. sinense exhibited significant NO radical inhibitory activity with an IC₅₀ value of 142.8 μg/mL. Phytochemical analysis of the MeOH extract of C. sinense resulted in the isolation of 28 compounds including 15 flavonoids, 7 caffeoylquinic acid derivatives, and 6 simple phenolic compounds. All isolated compounds were tested on NO inhibitory activity, in which 9 compounds showed activities with IC₅₀ values ranging from 29.4 to 100 μM. The structure–activity relationship studies on active compound showed that the number and position of hydroxyl groups in the ring B of flavonoids plays a crucial role, while the methylation of the carboxyl group of dicaffeoylquinic acids promotes the NO inhibitory activity.