Xanthine Oxidase Inhibition by Monoterpene-Chalcone Conjugates from Kaempferia subglobosa and Molecular Docking Insights.

Kaempferia subglobosa is a perennial medicinal plant in the Zingiberaceae family, identified as a new species in January 2024. To uncover the biological benefits of K. subglobosa and its compounds, investigation of the metabolites of the roots and rhizomes, yielded three new monoterpene-chalcone conjugates, the globosones A-C, representing a rare metabolite group within the Zingiberaceae, along with six known compounds. The biogenetic pathway for the globosones involves an oxidative [3+2] cycloaddition between α-phellandrene and 4'-methoxy-4,2',6'-trihydroxychalcone. Biological testing revealed potent xanthine oxidase (XO) inhibition by globosones A and B, with IC50 values of 7.0±1.0 and 3.0±0.2 µM, respectively, surpassing the positive control drug allopurinol (IC50 7.2±0.1 µM). Globosones A-C also showed good aromatase inhibition (IC50 3.0-3.5 µM). Molecular docking studies indicated that globosones A and B may inhibit xanthine oxidase through binding at the FAD domain site. The physicochemical properties of these isolates suggest that they possess characteristics suitable for additional biological assessment in more advanced test systems. This study enhances an understanding of monoterpene-chalcone conjugate inhibitors of XO, and offers preliminary insights into the metabolites and bioactivities of K. subglobosa, uncovering potent biological activities associated with this newly discovered plant species.

Kaemtakols A-D, highly oxidized pimarane diterpenoids with potent anti-inflammatory activity from Kaempferia takensis.

Four highly oxidized pimarane diterpenoids were isolated from Kaempferia takensis rhizomes. Kaemtakols A-C possess a tetracyclic ring with either a fused tetrahydropyran or tetrahydrofuran motif. Kaemtakol D has an unusual rearranged A/B ring spiro-bridged pimarane framework with a C-10 spirocyclic junction and an adjacent 1-methyltricyclo[3.2.1.02,7]octene ring. Structural characterization was achieved using spectroscopic analysis, DP4 + and ECD calculations, as well as X-ray crystallography, and their putative biosynthetic pathways have been proposed. Kaemtakol B showed significant potency in inhibiting nitric oxide production with an IC50 value of 0.69 µM. Molecular docking provided some perspectives on the action of kaemtakol B on iNOS protein.