Comprehensive phytochemical characterization of limmo, a nearly extinct citrus fruit rich in health-relevant bioactive metabolites

Phytochemical constituents of essential oil, peel, and juice of limmo, a nearly extinct citrus fruit, have been comprehensively characterized. GC-FID profiles of limmo (LEO) and bergamot (BEO) essential oils exhibited strict similarity, even though BEO contains higher levels of γ-terpinene. The non-volatile LEO residue and extracts of limmo peel and juice were characterized using HPLC-ESI-Q-TOF MS/MS. Limmo peel displayed a remarkable diversity of bioactive phytochemical classes, including flavonoids, (furano)coumarins, and polymethoxyflavones, which are responsible for a high in vitro antioxidant capacity. Unlike LEO, the flavonoid profile of limmo juice closely resembles that of lemon, although the molecular signature of cholesterol-lowering 3-hydroxy-3-methyl-glutaryl (HMG) acylated derivatives confirms the chemotaxonomic parentage of limmo and Citrus bergamia. Findings offer inedited insights into the limmo phytochemical composition, highlighting its potential health benefits and possible applications for food, perfumery, and nutraceutical formulations, and emphasizing the opportunity for preservation efforts of this unique citrus fruit.