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The aim of the study is to investigate chemical constituents of the leaves of Pieris japonica. The isolation and purification of the constituents were performed by various chromatography and spectral analysis. Three new phenolic glucosides, erythro-syringoylglycerol 4-O-beta-D-glucoside (1), 1-(2-beta-D-glucopyranoxyl-4-methoxyl-6-hydroxyphenyl)-3-hydroxyl-l-propanone (3), erythro-l-(4-hydroxyl-3-methoxyphenyl)-2-[4-(3-beta-D-glucopyranoxypropyl)-2 ,6-dimethoxyphenoxy]-1, 3-propanediol (4), along with five known phenolic glucosides, syringoylglycerol 8-O-beta-D-glucoside (2), magnolenin C (5), syringaresinol mono-beta-D-glucoside (6), 3-(4-hydroxyl-3-methyphenyl)-1 -propanol-l-O-beta-D-glucoside (7) and 3, 5-dimethoxyl-4-hydroxybenzyl alcohol 4-O-beta-D-glucoside (8) were isolated and identified from the plant leaves. Compounds 1 and 2 inhibited significantly (P <0.01) the proliferation of murine T and B cells at concentration of 1 x 10(-6) mol L(-1), in vitro.

Ten new grayanane diterpenoids, craiobiotoxins I-VIII (1-8) and craiobiosides A (9) and B (10), and five known grayanane diterpenoids, grayanotoxin XVIII, lyoniol A, lyoniol B, pieristoxin H, and grayanoside B were isolated from the leaves of Craiobiodendron yunnanense (Ericaceae). The structures of 1-10 were elucidated by spectroscopic methods including various 2D NMR and X-ray crystal diffraction experiments. In biological testing of our isolates, craiobiotoxin III (3) and lyoniol B showed moderate antifeedant activity.

A new minor 1,5-seco-5-oxo-grayanotoxin named grayanotoxin XXI ( 1 ), together with three known grayanotoxins, grayanotoxins I, IV and VIII, has been isolated from the leaves of Rhododendron decorum (Ericaceae). The structure of the new compound ( 1 ) was determined on the basis of spectroscopic data. [ABSTRACT FROM AUTHOR]

Abstract: Aim: To study the chemical constituents of the flowers of Rhododendron molle. Methods: Compounds were isolated by repeated chromatography over silica gel and Sephadex LH-20. Structures were elucidated based on spectral techniques, mainly 1D- and 2D-NMR and mass spectrometric analyses. Results: Two compounds (1 and 2) were isolated. Conclusions: Compounds 1 and 2 were identified as two new compounds: 2α, 10α-epoxy-3β, 5β, 6β, 14β, 16α-hexahydroxy-grayanane and benzyl 2, 6-dihydroxybenzoate-6-O-α-L-rhamnopyranosyl-(1→3)-β-D-glucopyranoside, respectively. [Copyright &y& Elsevier]