Plantanone D, a new rare methyl-flavonoid from the flowers of Hosta plantaginea with anti-inflammatory and antioxidant activities.

Flowers of Hosta plantaginea have been used for the treatment of inflammation-related diseases in traditional Chinese medicine with limited scientific validation. In the present work, we reported one new rare methyl-flavonoid, plantanone D (1) and one known compound 4-hydroxybenzoic acid (2) from the flowers of H. plantaginea. Their structures were elucidated on the basis of chemical and spectral evidence, as well as by comparison with literature data. To the best of our knowledge, the methyl-flavonoid skeleton have not been reported from any species in Liliaceae family, compound 2 was isolated from the genus Hosta for the first time. The anti-inflammatory activities against cyclooxygenases (COX-1 and COX-2) and antioxidant activities in vitro results revealed that 1 exhibited significant COX-1 inhibition and moderate COX-2 inhibition compared to the reference celecoxib. Additionally, 1 displayed significant antioxidant activity compared to the positive control L-ascorbic acid.