Alpha-pyrone glycosides from Scutellaria salviifolia Benth

Abstract

Scutellaria salviifolia Benth. is an endemic species growing in Turkey that belongs to the family Lamiaceae. As a result of a phytochemical study on the aerial parts of S. salviifolia Benth., two new and 10 known compounds were isolated from the aqueous fraction of methanolic extract. The new compounds are methyl-$\alpha $-pyrone glucosides, 3,4-dihydroxy-6-methylpyran-2-one 3-$O$-$\beta $-glucopyranoside (=scusalvioside A, 1), and 3,4-dihydroxy-6-methylpyran-2-one 3-$O$-$\beta $-(6$'$-$O$-$E$-caffeoyl) glucopyranoside (=scusalvioside B, 2) with new skeletal structures. Along with them, 3 phloroglucinol glucosides [phlorin (3), tadehaginoside (4), and 6$^{\prime \prime} $-$O$-$Z$-$p$-coumaroyl phloroglucinol-1-$O$-$\beta $-glucopyranoside (5)], 6 flavonoids [apigenin (6), apigenin 5-$O$-$\beta $-glucopyranoside (7), isoschaftoside (8), luteolin 7-$O$-$\beta $-glucuronide (9), luteolin 4$'$-$O$-$\beta $-glucopyranoside (10), and hispidulin (11)], and one phenylethanoid glycoside [martynoside (12)] were also isolated as known compounds. Compounds 2 and 8 were isolated as a mixture. Structure elucidations of the isolated compounds were carried out using UV, $^{1}$H NMR, $^{13}$C NMR, 2D NMR, and HR-ESI-MS analyses. Moreover, the phenylethanoid glycosides acteoside (13) and leucosceptoside A (14) were also detected in the plant by HPLC-DAD study. Tadehaginoside, 6$^{\prime \prime} $-$O$-$Z$-$p$-coumaroyl phloroglucinol-1-$O$-$\beta $-glucopyranoside, and luteolin 4$'$-$O$-$\beta $-glucopyranoside were reported for the first time from a Scutellaria species with this study.