Two New Lupane-Type Triterpenes From the Stems and Leaves of Buxus latistyla Gagnep. and Their Cytotoxic Activity

Objectives: This study aims to evaluate the cytotoxicity of compounds isolated from Buxus latistyla Gagnep. against selected cell lines. Methods: The isolation process was carried out using combined chromatographic techniques. The structural elucidation of compounds was achieved by combining 1D-/2D-NMR and HRESIMS data. The absolute configurations of new compounds were also confirmed using ECD experiments. The sulforhodamine B colorimetric assay was employed to assess the toxicity of isolates against tested cell lines. Results: Two new lupane-type derivatives, 3 α-carbomethoxy-3 β-hydroxy-1,3-cyclo-1,2-seco-lup-20(29)-en-1-one (1) (buxlatistylate A) and 1 α-carbomethoxy-1 β-hydroxy-1,3-cyclo-2,3-seco-lup-20(29)-en-3-one (2) (buxlatistylate B), along with five known triterpenes, including lupeol (3), lupenone (4), betulin (5), 20(29)-lupene-2 α,3 α-diol (6), and 20(29)-lupene-2 α,3 α,28-triol (7), were isolated. Compounds 1, 2, 6, and 7 exhibited weak cytotoxic activity against human cancer cells MCF-7, SK-LU-1, and SW480, with IC₅₀ values ranging from 36.33 to 84.16 μM, whereas compounds 3-5 did not show toxicity toward tested cell lines. Conclusion: Compounds 1 and 2 are the first examples of lupane-type triterpenes containing the substituted cyclopentanone A-ring in their molecules. The biosynthetic pathways of these new compounds were also discussed and proposed herein. These findings indicate that B. latistyla holds potential for further in-depth studies on compounds with interesting structures that inhibit human cancer cells.