Radial distribution of soluble phenolics was investigated at different heights in stems of Juglans nigra, J. regia and hybrids J. nigra 23 × J. regia. Four major phenolic compounds were studied: hydrojuglone glucoside (HJG), quercitrin (QUER) and two unknown compounds characterized as two ellagic acid derivatives E1 and E2. HJG and E1 content increased gradually in the sapwood, peaked in the sapwood-heartwood transition zone, and decreased drastically in the heartwood. QUER was accumulated preferentially around the transition zone, and its content was relatively low in the outer part of the sapwood and in the inner part of the heartwood. E2 content was low in the sapwood and increased in the heartwood. The heartwood formation was marked by the accumulation of new soluble compounds. The relationship between wood extractives and wood colour were evaluated and discussed. HJG was considered to be a major precursor of heartwood colour providing chromophores through hydrolysis (deglucosylation), oxidation and polymerization processes.

Natural wood colouring process in Juglans sp. (J. nigra, J. regia and hybrid J. nigra 23 ×J. regia) depends on native phenolic compounds accumulated in the transition zone between sapwood and heartwood

Three new compounds, a diarylheptanone glucoside (1), 4,5, 8-trihydroxy-alpha-tetralone 5-O-beta-d-[6'-O-(3", 5"-dimethoxy-4"-hydroxybenzoyl)]glucopyranoside (2), and 1,4, 8-trihydroxy-3-naphthalenecarboxylic acid 1-O-beta-d-glucopyranoside methyl ester (3), were isolated from the roots of Juglans mandshurica, and their structures were elucidated on the basis of spectroscopic studies including 2D-NMR.

Cytotoxic compounds from the roots of Juglans mandshurica.

A new (2) and three known diarylheptanoids (1, 3, and 4), along with one known sesquiterpenoid (5), were isolated from the roots of Juglans mandshurica, and their structures were elucidated on the basis of spectroscopic studies. Four of these compounds (2-5) exhibited moderate cytotoxicities against human colon carcinoma and human lung carcinoma cell lines with IC(50)'s ranging from 2 to 25 microg/mL.

Cytotoxic Diarylheptanoids from the Roots of Juglans mandshurica

(−)-Regiolone, an α-tetralone from Juglans regia: structure, stereochemistry and conformation

Four new diarylheptanoids (1-4), along with two known tetralones (5, 6), were isolated from the roots of Juglans mandshurica and their structures were elucidated on the basis of spectroscopic studies.

M.Hari Babu

Papers

A new bisjuglone from Juglans regia root bark