Three new diterpenoids from the rhizomes of Kaempferia minuta and their nitric oxide inhibitory effects.

A phytochemical investigation of the rhizomes of Kaempferia minuta led to the isolation of eleven diterpenoids, including three new compounds, designated minutins A-C (1-3). Their structures were elucidated by comprehensive spectroscopic analyses (IR, HRESIMS, 1D/2D NMR) together with electronic circular dichroism (ECD) calculations. Notably, minutin B (2) is a 3-methylisopimarane, a relatively uncommon class of diterpenoids. The isolated compounds were evaluated for their anti-inflammatory potential through inhibition of nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. Minutin B (2) exhibited the most potent activity, with an IC50 value of 13.24 ± 1.06 μM, surpassing the reference drug dexamethasone (16.51 ± 1.30 μM). These findings highlight K. minuta as a promising source of structurally unique diterpenoids with potential anti-inflammatory applications.