Amporn Saekeea, Chutima Kuhakarna, Khetpakorn Chakarawetb,* and Sakchai Hongthongc,*
a Department of Chemistry and Center of Excellence for Innovation in Chemistry, (PERCH-CIC), Faculty of Science, Mahidol University, Bangkok 10400, Thailand
b Department of Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
c Program in Chemistry, Faculty of Science and Technology, Rajabhat Rajanagarindra University, Chachoengsao 24000, Thailand
* e-mail: khetpakorn.cha@mahidol.ac.th

The structural diversity and broad biological activities of xanthone derivatives have made them valuable scaffolds in natural product-based drug discovery. Among these, macluraxanthone, isolated from Garcinia schomburgkiana Pierre, has demonstrated mild antiviral activity, particularly against HIV-1 reverse transcriptase. Despite its potential, structural studies on its synthetic derivatives—especially regarding their solid-state properties—remain limited. This study explores the methylation of macluraxanthone using dimethyl carbonate, an environmentally friendly and sustainable methylating agent. The resulting derivatives were structurally characterized using spectroscopic techniques, including ¹H NMR, ¹³C NMR, and HR-ESI-MS. Additionally, the structure of 5,10-dihydroxy-9-methoxy-2,2-dimethyl-12-(2-methylbut-3-en-2-yl)-2H,6H-pyrano[3,2-b]xanthen-6-one was confirmed by single-crystal X-ray diffraction. Key supramolecular features, such as hydrogen bonding and – stacking interactions, were observed to influence molecular packing and may impact the compound’s biological activity. These findings contribute to the growing body of knowledge on the structure–activity relationships of xanthone-based scaffolds and provide a foundation for their further development in pharmaceutical applications.

Keywords: crystal structure; xanthone; natural products. 

Reference: Acta Crystallographica E 2025, 81, 219–223.

DOI: https://doi.org/10.1107/S2056989025001070