Limonoids and Furanocoumarins from a Cultivated <i>Citrus</i>  ×  <i>junos</i> Siebold ex Tanaka

Background Citrus fruits are among the most widely cultivated fruits worldwide, and contain bioactive compounds, including flavonoids, carotenoids, limonoids, coumarins, and vitamin C, some of which are significantly bioactive. Consequently, discovering new compounds from Citrus fruits is an important objective. Methods The seeds of C. × junos Siebold ex Tanaka were extracted with methanol, which afforded eleven constituent compounds whose chemical structures were elucidated using NMR and MS techniques. The anti-proliferative activities of the isolated compounds were evaluated using the WST-8 assay. Results Junosterpene, a new limonoid derivative, was isolated from the seeds of C. × junos , along with seven known limonoids, 21,23-dihydro-23-hydroxy-21-oxodeacetylnomilin, deacetylnomilin, 21,23-dihydro-21-hydroxy-23-oxonomilin, obacunoic acid, methyldeacetylnomilinate, limonin, and ichangin, and three known furanocoumarins, (−)-heraclenol, (−)-byak-angelicin, and (+)-oxypeucedanin hydrate. None of the isolated compounds exhibited significant anti-proliferative activity against the human glioblastoma cell lines T98G and U-251 MG. Conclusions The newly identified limonoid derivative is possible to contribute to the diverse bioactive profile of C. × junos and provides insight into its potential physiological or pharmacological properties.