Flavonoids and other compounds from the aerial parts of Viola etrusca

The non-volatile constituents of the rare species Viola etrusca ERBEN (Violaceae), collected at Mount Amiata, Italy, were phytochemically investigated for the first time. Two new flavonoid glycosides, 4'-methoxyrhamnetin (1) and violetruscoside (2), an isorhamnetin derivative, were isolated from the flowering aerial parts, together with eleven known substances, including eight flavonoids, a phenolic acid, glycerin, and a coumarin derivative. The NMR data of violanthin (10) and isoviolanthin (11) are reported for the first time.