Diterpenoids from Marmoritis complanata and their anti-inflammatory activity in zebrafish

In a phytochemical investigation of the Tibetan medicine Marmoritis complanata (Dunn) A. L. Budantzev, 30 compounds were identified: 9 undescribed abietane diterpenoids (1-9), 7 undescribed isopimarane diterpenoids (12-18) and 14 known compounds (10, 11 and 19-30). The structures of the undescribed compounds were determined using one-dimensional and two-dimensional nuclear magnetic resonance spectroscopy, high-resolution mass spectrometry, electronic circular dichroism and single-crystal X-ray diffraction. The concentration-gradient anti-inflammatory activity evaluation results indicated that most of the tested compounds exhibited concentration-dependent anti-inflammatory activity in the CuSO₄-induced zebrafish model. Abietane (7, 9 and 10) and isopimarane diterpenoids (13, 15, 18 and 24) particularly showed the most significant anti-inflammatory activity, almost equal to that of a positive control. This study provides a basis for the development of anti-inflammatory drug lead compounds.