Flavonoid Glycosides from the Leaves of Machilus philippinensis

Thirteen flavonoid glycosides ( 1‐7 , 11‐13 , 15 , 17 , and 18 ) were isolated from the EtOH extract of the leaves of Machilus philippinensis. Of these, kaempferol 3‐O‐(2‐O‐β‐D ‐apiofuranosyl)‐α‐L ‐rhamnopyranoside ( 1 ) and kaempferol 3‐O‐(2‐O‐β‐D ‐apiofuranosyl)‐a‐L ‐arabinofuranoside ( 2 ) are new natural products. By application of HPLC‐SPE‐NMR hyphenated technique, five additional flavonol glycosides were characterized ( 8‐10 , 14 , and 16 ). Their structures were elucidated based on spectroscopic analysis. Of these, quercetin 3‐O‐(6‐O‐α‐L ‐rhamnopyranosyl)‐β‐D ‐galactopyranoside ( 5 ) and kaempferol 3‐O‐α‐L ‐arabinopyranoside ( 15 ) showed moderate inhibitory activity against α‐glucosidase type IV from Bacillus stearothermophilus with the IC₅₀ values of 19.5 and 19.0 μM, respectively.     

Prenylated isoflavones from Flemingia philippinensis

Two new prenylated isoflavones, named flemiphilippinins E and F, were isolated from the roots of Flemingia philippinensis, together with six known ones. The structures of the above compounds were established by spectroscopic methods. Flemiphilippinins E and F were identified as 5,4'-dihydroxy-8-(3,3-dimethylallyl)-6',6'-dimethyl-5'-(1,1-dimethylallyl) pyrano(2',3':7,6)isoflavone and 5,4'-dihydroxy-4',4',5'-trimethyl-4',5'-dihydrofurano(2',3':7,8) isoflavone, respectively, by a combination of HR-EI-MS, (1)H NMR, (13)C NMR, HMQC, HMBC, and NOESY spectra.     

New Oxygenated Lignans from Kadsura philippinensis

Seven new oxygenated lignans, kadsuphilins G–M ( 1 – 7 , resp.), were isolated by chromatographic fractionation of an AcOEt extract of the aerial part of Kadsura philippinensis including four compounds with a dibenzocyclooctadiene skeleton, two with a bicyclooctane ring system, and one of 1,4‐biphenyldimethylbutane type. The structures of the isolated compounds were elucidated through extensive spectroscopic analyses, particularly 2D‐NMR experiments (HMQC, HMBC, and NOESY). The configuration of the chiral centers and the biphenyl moiety were determined by NOESY as well as CD spectroscopy, respectively.     

Seven New Lignan Esters from Kadsura philippinensis

Five new oxygenated lignans with a dibenzocyclooctadiene skeleton, kadsuphilols P–T ( 1 – 5 ), and two new C₁₉ homolignans, kadsuphilols U and V ( 6 and 7 ), were isolated by chromatographic fractionation of an AcOEt extract of the stems of Kadsura philippinensis. The structures of the isolated metabolites were elucidated through extensive spectroscopic analysis including HR‐ESI‐MS and 2D‐NMR (HMQC, COSY, and HMBC). The configuration at the chiral centers and at the biphenyl moiety were determined by interpretation of NOESY and CD data, respectively.     

A New Prenylated Isoflavone and a New Flavonol Glycoside from Flemingia philippinensis

A new prenylated isoflavonoid, flemiphilippinin G ( 1 ), and a new flavonol glycoside, flemiphilippininside ( 2 ), along with eleven known isoflavonoids were obtained from the roots of Flemingia philippinensis (Merr. et Rolfe) Li . Their structures were elucidated on the basis of spectroscopic data. The in vitro cytotoxicities of compounds 1 – 13 against MCF‐7, A549, and Hep‐G2 cell lines were determined by using the MTT (=3‐(4,5‐dimethylthazol‐2‐yl)‐2,5‐diphenyl‐2H‐tetrazolium bromide) colorimetric assay, and their antioxidant activities were evaluated by ferric‐reducing antioxidant power (FRAP) method. Compound 1 exhibited significant cytotoxicity against all the tested cell lines with IC₅₀ values of 4.8–7.3 μM , and compound 2 was found to be inactive. Both compounds 1 and 2 showed weak antioxidant activities with FRAP values of 110±15 and 124±16 μmol/g, respectively.     

Flavonol Glycosides and Cytotoxic Triterpenoids from Alphitonia Philippinensis

Three new flavonol glycosides, namely, isorhamnetin 3‐O‐(6″‐O‐(Z)‐p‐coumaroyl)‐β‐D ‐glucopyranoside ( 1 ), quercetin 3‐O‐α‐L ‐rhamnopyranosyl(1 → 2)‐α‐L ‐arabinopyranosyl(1 → 2)‐α‐L ‐rhamnopyranoside ( 2 ), and quercetin 3‐O‐α‐L ‐arabinopyranosyl(1 → 2)‐α‐L ‐rhamnopyranoside ( 3 ), were isolated from the stems of Alphitonia philippinensis. Their structures were established by spectral analysis. In addition, NMR data were assigned for ceanothenic acid ( 11 ). Some of the isolated triterpenoids and flavonoid glycosides showed cytotoxicity against human PC‐3 cells and hepatoma HA22T cells, and inhibition of replication on herpes simplex virus type‐1.