LC-DAD–ESI-MS/MS and NMR Analysis of Conifer Wood Specialized Metabolites

Abstract

Many species from the Pinaceae family have been recognized as a rich source of lignans, flavonoids, and other polyphenolics. The great common occurrence of conifers in Europe, as well as their use in the wood industry, makes both plant material and industrial waste material easily accessible and inexpensive. This is a promising prognosis for both discovery of new active compounds as well as for finding new applications for wood and its industry waste products. This study aimed to analyze and phytochemically profile 13 wood extracts of the Pinaceae family species, endemic or introduced in Polish flora, using the LC-DAD–ESI-MS/MS method and compare their respective metabolite profiles. Branch wood methanolic extracts were phytochemically profiled. Lignans, stilbenes, flavonoids, diterpenes, procyanidins, and other compounds were detected, with a considerable variety of chemical content among distinct species. Norway spruce (Picea abies (L.) H.Karst.) branch wood was the most abundant source of stilbenes, European larch (Larix decidua Mill.) mostly contained flavonoids, while silver fir (Abies alba Mill.) was rich in lignans. Furthermore, 10 lignans were isolated from the studied material. Our findings confirm that wood industry waste materials, such as conifer branches, can be a potent source of different phytochemicals, with the plant matrix being relatively simple, facilitating future isolation of target compounds.

Phytochemical Analysis of Pinus cembra Heartwood—UHPLC-DAD-ESI-MSn with Focus on Flavonoids, Stilbenes, Bibenzyls and Improved HPLC Separation

“…For flavonoid 1, comparison with MS data in literature supports the characterization of aromadendrin rather than eriodictyol [18][19][20]. Evidence for the presence of pinobanksin could not be identified, as MS data for flavonoid 3 rather suggest the detection of naringenin [15,[19][20][21][22][23] (m/z 215). C-ring cleavage leads to the detection of an 1,3 A + -fragment (m/z 153); also, the loss of the B-ring can be recognized as [M+H-B-ring] + (m/z 195).…”

“…The constituents can be grouped into seven flavonoids (1, 2, 3, 7, 8, 11, 12), four stilbenes (4, 6, 10, 13), two bibenzyls (5, 9), three fatty acids (14,16,17) and one diterpenic acid (15). Additional data for MS n in positive and negative ionization mode are given in Supplementary Materials (Tables S1 and S2).…”

“…a Confirmed via comparison with reference standard; b confirmed by NMR after isolation; * first report for Pinus cembra; 1 no detection due to weak ionization in respective mode. The constituents can be grouped into seven flavonoids (1, 2, 3, 7, 8, 11, 12), four stilbenes (4, 6, 10, 13), two bibenzyls (5, 9), three fatty acids (14, 16, 17) and one diterpenic acid (15). Additional data for MS n in positive and negative ionization mode are given in Supplementary Materials (Tables S1 and S2).…”

“…Additional data for MS n in positive and negative ionization mode are given in Supplementary Materials (Tables S1 and S2). Stilbenes 6 (pinosylvin, PS) and 10 (pinosylvin monomethyl ether, PSM) as well as corresponding bibenzyls 5 (dihydropinosylvin, DHPS) and 9 (dihydropinosylvin monomethyl ether, DHPSM) were previously described for Pinus cembra heartwood [4][5][6]9,15,16]. Stilbenes 4 (pinostilbene) and 13 (pinosylvin dimethyl ether) were only found in other Pinus species, including old references of occurrence in Pinus sibirica [24,25].…”

“…Patyra et al investigated branch wood methanolic extracts by LC-DAD-ESI-MS n to find fourteen compounds, of which six catechin derivatives and procyanidins, as well as taxifolin, a taxifolin hexoside, eriodictyol and pinobanksin can be assigned to the substance group of flavonoids. PSM was the only reported stilbene in P. cembra extracts [15]. Finally, Coniglio et al detected PS, DHPS, chrysin and pinocembrin in P. cembra knotwood extracts by LC-ESI-MS [16].…”