Two New Ionone Derivatives from Rhododendron przewalskii Maxim

Two new ionone derivatives,named rhododendrone and rhododendronside,were isolated from the alcohoilc extract of the aerial parts of Rhododendron przwalskii Maxim.Their structures were elucidated on the basis of spectroscopic analysis.     

Phenolic Components from Rhododendron latoucheae Part 5 in the series "Chemical Studies on Ericaceae Plants

Chemicalc0mponentsofthegenusRhododendronwithvariousbioactivities,suchasantitussiveandantitracheitishavebeenidentifiedbefore'.T0thebestofourkn0wledge,theplantRhododendronlatoucheaeFinetetFranchofthegenushasnotbeenstudiedchemicallyupt0n0w.Wehereinrep0rtthestructuraIelucidationoftw0newnaturalphen0licc0mpoundsnamed( )-rhodolat0uchollandisoepirh0d0dendrin4fromtheleavesofR.laloucheae.Besides,sixotherknownc0mpounds,( )-rh0d0dendr0l2,epirh0d0dendrin3.4-(3'-O-0-D-glucopyranosyl-4'-hy5,4-(4'-O-6-D-g…     

Tricetin 4′-<Emphasis Type="Italic">O-α</Emphasis>-L-rhamnopyranoside: A new flavonoid from the aerial parts of <Emphasis Type="Italic">Erica arborea</Emphasis>

Reversed-phase preparative HPLC purification of the methanol (MeOH) extract of the aerial parts of Erica arborea resulted in the isolation of a new flavonoid glycoside, tricetin 4′-O-α-L-rhamnopyranoside, together with the known flavonoid, isorhamnetin 3-O-α-L-rhamnopyranoside. The structures of these compounds were determined by spectroscopic means. The antioxidant properties of these compounds were assessed by the DPPH assay. Published in Khimiya Prirodnykh Soedinenii, No. 2, pp. 138–140, March–April, 2008.     

A new triterpene from the leaves of Craibiodendron yunnanense

A new triterpene, taraxast-20(30)-en-3β,12β-diol (1), and eight known compounds were isolated from the leaves of Craibiodendron yunnanense. Their structures were established on the basis of spectral evidence. Published in Khimiya Prirodnykh Soedinenii, No. 1, pp. 35–37, January–February, 2008.     

Two additional 1,9-diarylnonanoid 3-glucosides from Erica cinerea among which an unusual α-dione in conformational equilibrium

Continuation of the phytochemical analysis of Erica cinerea fresh aerial parts resulted in the isolation of two new compounds with a very close chromatographic behavior. On the basis of spectroscopic evidence (UV, MS and NMR), the structures were established as (−)-(3S,6E)-1,9-bis(p-hydroxyphenyl)-3-hydroxynon-6-en-5-one 3-O-β-d-glucoside named 6,7-anhydroericaone 3-O-β-d-glucoside and (−)-(3S)-1,9-bis(p-hydroxyphenyl)-3-hydroxynonan-5,6-dione 3-O-β-d-glucoside named α-ericadione 3-O-β-d-glucoside. Unanticipated by its α-alkadione type structure —a very unusual feature in the plant kingdom— the latter metabolite was found as a mixture of the minor s-cis and the major s-trans conformers. Moreover, the GC-MS analysis of the aglycone moieties of such glucosides, pointed out the permanent absence of the molecular ion and the constant hydroxybenzylium base peak, as well as the conversion of the α-dione into the major α-keto-enol tautomer.     

Birhodomolleins D and E,two new dimeric grayanane diterpenes with a 3-O-2′ linkage from the fruits of Rhododendron pumilum

Two dimeric grayanane diterpenes with a novel 3-O-2 linkage, birhodomolleins D (1) and E (2), were isolated and structurally elucidated from the fruits of Rhododendron pumilum. Their structures were fully determined by comprehensive analysis of spectroscopic data.     

Two New Phenolic Glycosides from the Roots of Rhododendron molle

Two new phenolic glycosides,everninic acid methyl ester-2-O-β-O-xylopyran-osyl-(1→6)-β-D-glucopyranoside 1 and 7-hydroxyl-5-methoxyphthalide-7-β-D-xylopyranosyl-(1→6)-β-D-glucopyranoside 2 were isolated from the roots of Rhododendron molle G.Don. Their structures were determined by spectral evidence including 2D NMR techniques.     

Three new dimeric diterpenes from Rhododendron molle

Birhodomolleins A-C (1-3), three novel diterpenoids dimerized from two grayanane diterpenes through an oxygen bridge, were isolated from the flowers of Rhododendron molle. Their structures were elucidated by interpretation of their 1D and 2D NMR and other spectroscopic data. Birhodomollein A (1) contains a rare chloro-substitution on one of the grayanane moieties. These are the first examples of dimeric diterpenes from the Ericaceae family.     

One New Diterpene Glucoside from the Roots of Rhododendron molle

As a part of a continuing investigation on the active principles of Ericaceae plants, one new grayanane diterpene glucoside, rhodomoside A, was isolated from the n-BuOH fraction of the ethanol extracts of the roots of Rhododendron molle G. Don (Ericaceae). In this paper we describe the isolation and structural elucidation of rhodomoside A 1. Rhodomoside A 1, viscous syrup, has the molecular formula C26H42O10 based on HREIMS at m/z 514.2802 (calcd. 514.2778). Compound 1 gave positive …     

Divaccinosides A–D,four rare iridoid glucosidic truxillate esters from the leaves of Vaccinium bracteatum

Divaccinosides A–D (1–4), four rare iridoid glucoside cyclodimers in the truxillate forms, were characterized from the leaves of Vaccinium bracteatum. They were presumably biosynthesized from two known iridoid glucoside monomers, vaccinoside (5) and 10-O-trans-p-coumaroyl-6α-hydroxyl-dihydromonotropein (6), via a [2+2] cycloaddition reaction. The structures of the new compounds were established by comprehensive spectroscopic measurements, combined with chemical conversions and single crystal X-ray crystallographic analyses.