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Abstract: In addition to known dibenzofuran derivatives such as (−)-usnic acid, (−)-isousnic acid and (−)-placodiolic acid, a Leprocaulon microscopicum acetone extract yielded a new compound, (±)-9-O-methylplacodiolic acid in a keto-enol equilibrium focused on the C-ring. Structures were established using mass spectrometry and combination of 1D and 2D NMR spectral data. 13C assignments of placodiolic acid were revised. Tautomers of the (±)-9-O-methylplacodiolic acid were only separated by GC and a thorough fragmentation study confirmed the structural features. To complete the study, evaluation of antiproliferative effects on HT-29 human colorectal cancer cells showed moderate activity for (−)-usnic acid only. [Copyright &y& Elsevier]

Abstract: The reinvestigation of Erica cinerea fresh aerial parts led to the isolation of two new diarylnonanoid aglycones along with their glucosides. From spectroscopic data, their structures were elucidated as rel-(3R,7R)-1,9-bis(p-hydroxyphenyl)-3,7-dihydroxynonan-5-one named ericanone, ericanone 3-β-d-glucoside, (3S)-3,7-anhydro-6,7-dehydroericanone and (3S)-3,7-anhydro-6,7-dehydroericanone 4′-β-d-glucoside. Contrary to the numerous diarylheptanoids more frequently distributed in the plant kingdom, the rare diarylnonanoids were previously restricted to the genus Myristica of the Myristicaceae plant family. [Copyright &y& Elsevier]

Abstract: In addition to the six diarylnonanoids and diarylnonanoid 3-O-glucosides previously reported from Erica cinerea, the multistep chromatographic processing of the acetone extract of the fresh aerial parts resulted in the isolation of three more representatives as glycosides derived from either (−)-ericanone or (−)-α-ericadione. From the spectroscopic data, the new structures were elucidated as (−)-(3S,7S)-ericanone 3-O-β-d-xylopyranoside, (−)-(3S,7S)-3″-hydroxyericanone 3-O-β-d-glucopyranoside, and (−)-(3S)-3″-hydroxy-α-ericadione 3-O-β-d-glucopyranoside respectively. In the 1H and 13C NMR spectra run in CD3OD, the latter metabolite was as (−)-α-ericadione 3-O-β-d-glucopyranoside, also found as a permanent mixture of the major s-trans (70%) and the minor s-cis (30%) conformers. Such result —in connection with the protic solvent— seems to have never been reported earlier for α-alkadiones. Moreover, mild acid hydrolysis of such a glucoside led directly to the 3,4-dehydrated aglycone moiety accompanied by its 6,7-dehydrated tautomer, according to two successive dehydrations of the anticipated aglycone. Furthermore, although missing in this species, the postulated β-ericadione continues to be regarded as an essential intermediate at the crossroads of the biogenesis of most of the E. cinerea 1,9-diarylnonanoids. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: The lipophile extract of Lonchocarpus nicou roots afforded the new pyranochalcone 3-O-methylabyssinone A as well as the new rotenoids 7′-hydroxytephrosin, and 7′-nor-6′-oxo-2′,3′-dehydrorotenone, both compounds occurring with the known 7′-hydroxydeguelin and 7′-nor-6′-oxo-2′,3′-dehydro-12aβ-hydroxyrotenone. Furthermore, two rotenoid epoxides previously reported as resulting from the direct oxidative conversion of rotenone and 12aβ-hydroxyrotenone, respectively, were isolated for the first time from a plant source. All the structures were established on the basis of UV, MS, and NMR data. [Copyright &y& Elsevier]