# Three new terpenoids from the fruit peels of Citrus Hassaku Yu.Tanaka

## TL;DR

This study discovers three new compounds in Citrus Hassaku peels and tests their effects on cancer cell growth.

## Contribution

The isolation and characterization of three new terpenoids from Citrus Hassaku fruit peels.

## Key findings

- Three new compounds were isolated from Citrus Hassaku fruit peels.
- Compound 9 showed weak antiproliferative effects against human glioblastoma cells.

## Abstract

Citrus hassaku Yu. Tanaka is a relatively less-known species within the genus. In this study, we aimed to isolate novel compounds from this species, elucidate their chemical structures via spectroscopic and physicochemical analyses, and evaluate their antiproliferative effects using the WST-8 assay. Two new limonoids, 1-acetyl-sphaerocarpainic acid I (1) and 1-acetyl-sphaerocarpain I (2), and a new eremophilane-type nor-sesquiterpenoid enantiomer, 12-nor-11S-hydroxy-11-hydronootkatone (9), were isolated from the peels of C. hassaku, together with eleven known compounds: deacetylnomilin (3), nomilin (4), methyl nomilinate (5), obacunone (6), limonin (7), ichangin (8), nootkatone (10), (+)-(4R,5S,7R)-13-hydroxynootkatone (11), umbelliferone (12), auraptene (13), and marmin (14). Among them, compound (9) exhibited weak antiproliferative effects against human glioblastoma U-251 MG cells.

The online version contains supplementary material available at 10.1007/s11418-025-01983-7.