Analysis of Western Redcedar (Thuja plicata Donn) Heartwood Components by HPLC as a Possible Screening Tool for Trees with Enhanced Natural Durability

Abstract

A method is described for the quantitative analysis of seven known compounds, specifically plicatic acid, thujaplicatin methyl ether, beta-thujaplicin, gamma-thujaplicin, beta-thujaplicinol, thujic acid, and methyl thujate, in the ethanol extract of second growth western redcedar heartwood (Thuja plicata Donn) by high-performance liquid chromatography using diode array detection. The para bromo phenacyl ester of crotonic acid is synthesized for use as the internal standard for the method. Separation of compounds covering a wide range of polarities is achieved using an Inertsil ODS 3 3-micro column. Twenty seven second growth trees ranging in age from 40 to 125 years, originating from the coastal and interior regions of British Columbia, are selected for analysis and profiled using the described method. Samples consisting of five growth rings each are analyzed from the heartwood-sapwood boundary to the pith for each tree. Substantial variation in most heartwood compounds are detected within and between trees within a region. Significant variation in beta-thujaplicin, the ratio between gamma- and beta-thujaplicin, and methyl thujate is detected between coastal and interior populations.

Identification of Genes in Thuja plicata Foliar Terpenoid Defenses

“…secondary) metabolites, many of which are named after the Thuja genus. For example, thujaplicins are ring-expanded monoterpenoids with strong antifungal properties that provide heartwood rot resistance (DeBell et al, 1999;Daniels and Russell, 2007;Bentley, 2008). Thujic acid and related lignans serve a similar function, making the wood of T. plicata highly suitable for outdoor use (Taylor et al, 2006;Morris and Stirling, 2012).…”

New Method to Isolate Gamma-Thujaplicin from Western Red Cedar (Thuja plicataDonn.)

“…Based on the previous work of Daniels and colleagues [27,36] the selected outer butt heartwood of second-growth of WRC ( Figure 1) was cut from 30 or 25 growth rings from the sapwood/heartwood interface. The selected material was made into very small thin slices and dried about 1 week at room temperature.…”

“…[27] MICROMASS R Quattro micro TM API Mass Spectroscopy (MS): Ionization mode: ES-; Data type: Enhanced Mass; Function type: Scan; Mass range: 30 to 500 1 H-nuclear magnetic resonance (NMR): 1 H-NMR spectra was taken on AV400 Bruker NMR spectrometer (made in Switzerland).…”

Carbon stocks of western redcedar and western hemlock stands in Canada's inland temperate rainforests.

“…Although a typical climate -cold winter and cool summer -in the ICH study areas undoubtedly contributes to the long persistence of CWD (e.g., radiocarbon dating of decay class IV CWD indicated ages of 195-320 years) (Harmon et al 1986), the more decay-prone heartwood of interior cedar than coastal cedar (Daniels and Russell 2007) may have a large effect on decomposition rates of CWD. Harmon (2009) indicated that the presence of a wood-decomposing pathogen causing heart-rot might affect future decomposition rates by short-circuiting decomposer colonization, while another study indicated that initial slow rates of biomass loss from older pine logs corresponded to exceedingly decomposed, brown-rotted logs that retained no sapwood or bark (Harmon et al 2000).…”

“…We speculate that internal heartwood decay of western redcedar is more extensive in the interior than in coastal BC (Buckland 1946) which may further contribute to the low decayed-wood density observed in this study. Evidence for this is that concentrations of decay resistant compounds (e.g., B-thujaplicin) are lower in interior cedar (Daniels and Russell 2007). Within interior cedar, however, the magnitude of internal decay has been reported to be uniform irrespective of dry, moist, and wet subzones in the ICH (Stevenson et al 2010), suggesting that our decayed-wood density for interior western redcedar might be within a range of decayedwood densities in other ICH subzones, if such measurements were conducted.…”