Ent-Labdane Diterpenoids from the Medicinal Plant Leucosceptrum canum

Three new ent-labdane diterpenoids, leucolactones L-N (1-3), along with one known analog (4), were isolated from the leaves of a Lamiaceae medicinal plant Leucosceptrum canum. Their structures were elucidated by spectroscopic analysis (1D and 2D NMR and HRMS), single-crystal X-ray diffraction, and quantum chemical calculations. Moderate anti-inflammatory activity of the isolates was observed by suppressing the secretion of cytokines TNF-α and IL-6 in LPS-induced macrophages RAW264.7, with IC₅₀ values ranging from 15.43 to 25.88 µM. In addition, compounds 1-3 exhibited moderate anti-adipogenesis activity by inhibiting triglyceride accumulation in 3T3-L1 cells with IC₅₀ values ranging from 12.20 to 22.55 µM.