Cytotoxic flavonoids from two Lonchocarpus species

A new isoflavone, 4′-prenyloxyvigvexin A (1) and a new pterocarpan, (6aR,11aR)-3,8-dimethoxybitucarpin B (2) were isolated from the leaves of Lonchocarpus bussei and the stem bark of Lonchocarpus eriocalyx, respectively. The extract of L. bussei also gave four known isoflavones, maximaisoflavone H, 7,2′-dimethoxy-3′,4′-methylenedioxyisoflavone, 6,7,3′-trimethoxy-4′,5′-methylenedioxyisoflavone, durmillone; a chalcone, 4-hydroxylonchocarpin; a geranylated phenylpropanol, colenemol; and two known pterocarpans, (6aR,11aR)-maackiain and (6aR,11aR)-edunol. (6aR,11aR)-Edunol was also isolated from the stem bark of L. eriocalyx. The structures of the isolated compounds were elucidated by spectroscopy. The cytotoxicity of the compounds was tested by resazurin assay using drug-sensitive and multidrug-resistant cancer cell lines. Significant antiproliferative effects with IC₅₀ values below 10 μM were observed for the isoflavones 6,7,3′-trimethoxy-4′,5′-methylenedioxyisoflavone and durmillone against leukemia CCRF-CEM cells; for the chalcone, 4-hydroxylonchocarpin and durmillone against its resistant counterpart CEM/ADR5000 cells; as well as for durmillone against the resistant breast adenocarcinoma MDA-MB231/BCRP cells and resistant gliobastoma U87MG.ΔEGFR cells.     

A single chalcone and additional rotenoids from Lonchocarpus nicou

The lipophile extract of Lonchocarpusnicou 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.     

1H and 13C NMR assignments of new methoxylated furanoflavonoids from Lonchocarpus araripensis

Two new polymethoxylated flavonoids, 2',5',6'-trimethoxy-[2',3' : 3',4']furano dihydrochalcone and 2,4',4,5-tetramethoxy-[2',3' : 6,7]-furanodihydroaurone, were isolated from the root barks of Lonchocarpus araripensis, along with the known compounds 3,4,5,6-tetramethoxy-[2',3' : 7,8]-furanoflavan, 3,6-dimethoxy-1',1'-dimethylcromene-[2',3' : 7,8]-flavone, 3',4'-methylenodioxy-5,6-dimethoxy-[2',3' : 7,8]-furanoflavone, 3,5,6-trimethoxy-[2',3' : 7,8]-furanoflavanone, 3,5,6-trimethoxy-[2',3' : 7,8]-furanoflavone, and 6alpha-hydroxy-medicarpin. The complete (1)H and (13)C NMR assignments of the new furan flavonoids were performed using 1D and 2D pulse sequences, including COSY, HSQC, and HMBC experiments, and comparison with spectral data for analog compounds from the literature, particularly for the new furanodihydroaurone because of several inconsistencies on the carbonyl chemical shifts from the literature.     

A New 6,7-Seco-Ent-Kaurane Diterpenoid from Isodon eriocalyx Var. laxiflora

Isodon eriocalyx var. laxiflora C. Y. Wu & H. W. Li, is a perennial herb naturally growing in the southern area of Yunnan province. In our continuing studies1 on its leaves collected from Xishuanbana prefecture, a new 6,7-seco-ent-kaurane diterpenoid, named laxiflorin E (1), together with two known 6,7-seco-ent-kaurane diterpenoids2, eriocalyxin A (2) and laxiflorin C (3), was isolated. Their structures were established by spectroscopic analysis. Compound 1, obtained as colorless rhombus…     

Nor-dehydrodeguelin and nor-dehydrorotenone, C22 coumaronochromones from Lonchocarpus nicou

Lonchocarpus nicou roots lipophile extract yielded, among isoflavonoids, two coumaronochromones isomers. Spectroscopic analysis assigned the structure of nor-dehydrodeguelin to the former and (−)-nor-dehydrorotenone to the latter, the two products only differing by the cyclization of the C₅ side chain. Biogenetically, the two compounds could be considered as resulting either from cyclization of the corresponding 2′-hydroxyisoflavones and/or from oxidative ring-B contraction of the dehydrorotenoids parents.     

Two new diterpenoids from Isodon eriocalyx

Isodoneriocalyx(Dunn)Hara(Labiatae).Ithasbeenusedasfolkmedicinetotreatsorethroat,inflammationaswellasreducingbloodpressure'.Previousstudiesonthisgenushaverevealed,anumberofditerpenoidspossessvariousbioactivitiessuchasanti-tUmorandanti-bacterial='3act...     

Diterpenoids from Isodon Eriocalyx

Two new diterpenoids, Maoecrystal U and epi‐maoecrystal P , together with nine known diterpenoids and eight other known compounds were isolated from Isodon eriocalyx ( ). The structures of two new diterpenoids were elucidated as 6β‐acetoxy‐15β‐hydroxy‐3α,20‐epoxy‐ent‐kaur‐16‐ene‐1,7‐dione and 16(S)‐methoxymethy‐6β,7β‐dihydroxy‐7α,20‐epoxy‐ent‐kaur‐2,3‐ethenylene‐1,15‐dione on the basis of spectroscopic evidence, especially by 2D NMR techniques.     

Three New Diterpenoids from Isodon Eriocalyx

Isodoneriocalyxisknowntoberichinent-kaurenoids.Inspiteofthatmanyent-kaurenoidswereisolated,newent-kaurenoidswerestillisolatedfromcollectionindifferentregions'-,o.FromthedriedleavesofthisspeciescollectedinHeqingcounty,Yunnan,threenewcompounds,eriocalyxinsC-El-3,wereisolated.Inthispaper,wereportthestructureelucidationofthesenewcompoundsbyspectralanalysis.EriocaIyxinClC22H2sO7(HRMS4O4.l825calc4O4.1835),ElMS(7OeV)In/z(reI.Int%)t4O4[M1 (lO),386[M-H2O] 'lO),368IM-2H,O] (2O),344(l00),32…     

Substituted tubaic acids, new oxidative rotenoid metabolites from Lonchocarpus nicou

A lipophile extract of Lonchocarpus nicou roots afforded two likely O-substituted isomers of the known tubaic acids. Spectroscopic analysis assigned to the former, named (−)-rotoic acid, the new 4-(2,3-dihydro-6,7-dimethoxychromon-3-oxy) tubaic acid structure which differs from (−)-deguoic acid, the latter, by the β-tubaic acid part. Biogenetically, the two compounds could be considered as resulting from the parent rotenone and deguelin, respectively, by oxidative ring-C cleavage.