New 8,12;8,20-diepoxy-8,14-secopregnane hexa- and hepta-glycosides from the roots of Asclepias tuberosa.

Previously, phytochemical investigation of the roots of Asclepias tuberosa (Asclepiadaceae) led to the isolation of some 8,12;8,20-diepoxy-8,14-secopregnane tri-, tetra-, and penta-glycosides. An additional eight new minor 8,12;8,20-diepoxy-8,14-secopregnane glycosides were afforded in the recent investigation of this plant. These glycosides consisted of six or seven 2,6-dideoxy-hexopyranoses together with the aglycone, tuberogenin. The structures of each of these compounds were established using NMR, mass spectroscopic analysis and chemical evidence. As 8,12;8,20-diepoxy-8,14-secopregnane-type glycosides were observed only in A. tuberosa, these compounds were considered to be characteristic phytochemicals of this plant.

Flavonoid Glycosides from Sedum bulbiferum.

The MeOH extract from dried whole Sedum bulbiferum MAKINO (Crassulaceae) plants yielded 34 compounds, including six new flavonoid glycosides and 28 known compounds. The structures of new compounds were established using NMR, Mass spectroscopic analysis and chemical evidence.

Chemical constituents of aerial parts and roots of Pycnanthemum flexuosum.

An extract of whole plants of Pycnanthemum flexuosum showed an inhibitory effect on hyaluronidase activity. From an 80% acetone extract of aerial parts, 3-[(3E)-4-phenylbut-3-enoylamino]propionic acid, 3-O-ß-D-glucuronopyranosyl-echinocystic acid 28-O-ß-D-xylopyranosyl-(1→3)-[3,4-diacetyl-ß-D-xylopyranosyl-(1→4)]-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyl ester, vanillic acid 1-O-[(5-O-syringoyl)-ß-D-apiofuranosyl]-(1→2)-ß-D-glucopyranoside, and (4S,5R)-4-hydroxy-5-phenyl-tetrahydrofuran-2-one were isolated together with 30 known compounds. Six known compounds were isolated from an 80% acetone extract of roots, and eritrichin was revealed as a hyaluronidase inhibitor in P. flexuosum.

Caspicaosides E-K, triterpenoid saponins and cytotoxic acylated saponins from fruits of Gleditsia caspica Desf.

Seven bisdesmosidic triterpenoid saponins named caspicaosides E-K, were isolated from the methanolic fruit extract of Gleditsia caspica Desf. Their structures were determined by 1D and 2D NMR spectroscopy as well as high resolution mass spectrometry and acid hydrolysis. The saponins comprised echinocystic acid or oleanolic acid as the aglycone and saccharide moieties at C-3 and C-28. Like most Gleditsia saponins, the oligosaccharide moiety at C-3 was identified as ß-D-xylopyranosyl-(1→2)-α-L-arabinopyranosyl-(1→6)-ß-D-glucopyranosyl. The common oligosaccharide moiety linked to C-28 was determined as ß-D-xylopyranosyl-(1→3)-ß-D-xylopyranosyl-(1→4)-α-L-rhamnopyranosyl-(1→2)-ß-D-glucopyranosyl with the presence of additional ß-D-galactopyranose unit and/or another α-L-rhamnopyranose moiety. The C-28 saccharide moiety was acylated with a monoterpenic acid unit or a monoterpenic acid linked to a monoterpene-arabinoside unit at the ester-ß-D-glucopyranose C-6. Esterification of C-2 and C-3 hydroxyl groups of the terminal α-L-rhamnopyranose unit with a monoterpenic acid and epoxy-monoterpenic acid units, respectively, or with two identical monoterpenic acid units, was also shown. The acylated saponins caspicaosides G-K were assayed for their in vitro cytotoxicities against the three cell lines HCT116, HepG2 and MCF7. The tested saponins showed moderate to strong activities.

Diastereomers of lithospermic acid and lithospermic acid B from Monarda fistulosa and Lithospermum erythrorhizon.

Monardic acids A (1) and B (2), which are (7R,8R) diastereomers of lithospermic acid (LA) and lithospermic acid B, respectively, were isolated from Monarda fistulosa. A (7S,8R) isomer (3) of LA was also isolated from this plant, and a (7R,8S) isomer (7) of LA was obtained from Lithospermum erythrorhizon. The absolute configuration of 1 was confirmed by analysis of its hydrolysates, 7-epiblechnic acid and 2R-3-(3,4-dihydroxyphenyl)-2-hydroxypropanoic acid. The configuration in the dihydrobenzofuran moieties of 2, 3, and 7 was extrapolated by using the phenylglycine methyl ester method and a Cotton effect at approximately 250-260 nm in their electronic circular dichroism spectra. Diastereomers (1-3 and 7) displayed moderate hyaluronidase inhibitory and histamine release inhibitory activities.

A Penicillium sp. F33 metabolite and its synthetic derivatives inhibit acetyl-CoA:1-O-alkyl-sn-glycero-3-phosphocholine acetyltransferase (a key enzyme in platelet-activating factor biosynthesis) and carrageenan-induced paw edema in mice.

Acetyl-CoA:1-O-alkyl-sn-glycero-3-phosphocholine (lyso-PAF) acetyltransferase is a key enzyme in the biosynthesis of 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine (PAF) in inflammatory cells. Substances which inhibit this enzyme are of therapeutic interest. In this study, we screened for new inhibitors of lyso-PAF acetyltransferase with anti-inflammatory effects. In a metabolite from Penicillium sp. F33, we isolated an acetyltransferase inhibitor identified as dihydrofumigatin (2-methoxy-1,3,4-trihydroxy-5-methylbenzene) from high resolution mass spectrometer and NMR data. Dihydrofumigatin had strong acetyltransferase inhibitory activity, but was not stable in aqueous solution. Thus, we chemically synthesized its oxidized form fumigatin (3-hydroxy-2-methoxy-5-methyl-1,4-benzoquinone) and derivatives thereof, and evaluated their inhibitory effects. Strong inhibitory activity was observed for saturated fatty acid esters of fumigatin; the order of inhibition was 3-decanoyloxy-2-methoxy-5-methyl-1,4-benzoquinone (termed FUD-7, IC50 = 3 µM)>2-methoxy-5-methyl-3-tetradecanoyloxy-1,4-benzoquinone (termed FUD-8, IC50 = 20 µM)>3-hexanoyloxy-2-methoxy-5-methyl-1,4-benzoquinone (IC50 = 139 µM). Interestingly, these compounds also significantly suppressed the gene expression of lyso-PAF acetyltransferase/LPCAT2 in mouse bone marrow-derived macrophages stimulated by lipopolysaccharide (LPS). We further evaluated the effect of these substances on anti-inflammatory activity in vivo using the carrageenan-induced mouse paw edema test. FUD-7 and FUD-8 at 2.5 mg/kg showed significant, 47.9-51.7%, inhibition stronger than that of prednisolone at 10 mg/kg (41.9%). These results suggest that FUD-7 and FUD-8 are potent inhibitors with anti-inflammatory activity.

Lipase inhibitory and LDL anti-oxidative triterpenes from Abies sibirica.

A methanol extract of Abies sibirica Ladeb, a Mongolian medicinal plant, had an inhibitory effect on both lipase activity in mouse plasma and LDL anti-oxidative activity, which are preventative factors for arteriosclerosis. The extract was fractionated by silica gel column chromatography and its active constituents were sought. From lipid soluble fractions, 20 terpenoids including seven hitherto unknown triterpenes were isolated. The latter triterpenes had either a γ-lactone ring with a lactol or a derivative thereof. Their chemical structures were determined by spectroscopic methods. The lipase inhibitory activity and LDL anti-oxidative activity of these compounds were evaluated. Some constituents (either lipase inhibitory or LDL anti-oxidative activities) had moderate inhibitory activities.

Hydroxylation of (-)-epigallocatechin-3-O-gallate at 3'', but not 4'', is essential for the PI3-kinase/Akt-dependent phosphorylation of endothelial NO synthase in endothelial cells and relaxation of coronary artery rings.

(-)-Epigallocatechin-3-O-gallate (EGCg) has been shown to induce endothelium-dependent nitric oxide (NO)-mediated relaxation via the redox-sensitive Src/PI3-kinase/Akt-dependent phosphorylation of endothelial NO synthase (eNOS). Although the presence of 8 hydroxyl functions, mainly on B and D rings, is essential for the EGCg-induced activation of eNOS, the relative role of each individual hydroxyl function still remains unclear. This study examined the effect of selective replacement of hydroxyl functions by methoxy moieties on either the B or D ring on the EGCg-induced phosphorylation of Akt and eNOS, formation of reactive oxygen species (ROS) and NO in cultured coronary artery endothelial cells, and endothelium-dependent relaxation of coronary artery rings. Replacement of a single hydroxyl by the methoxy group on position 3', 4' or 4'' affected little the EGCg-induced phosphorylation of Akt and eNOS, formation of ROS and NO in endothelial cells, and induction of endothelium-dependent relaxations. In contrast, the single methylation at position 3'' and the double methylation at both positions 3' and 4' reduced markedly the phosphorylation of Akt and eNOS, the formation of ROS and NO in endothelial cells and the relaxation of artery rings. These findings suggest that the hydroxyl group at the 3'' position of the gallate ring is essential and, also, to some extent, the two hydroxyl groups at positions 3' and 4', for the EGCg-induced redox-sensitive activation of eNOS leading to the subsequent NO-mediated vascular relaxation.

Triterpene saponins from Clethra barbinervis and their hyaluronidase inhibitory activities.

An extract of Clethra barbinervis with an inhibitory effect on hyaluronidase activity was fractionated guided by the results of an assay. From the active fractions, seven new triterpene saponins (1-4, 6-8) and a new lignan glycoside (14) were isolated together with 14 known compounds (5, 9-13, 15-22). Some of the saponins (2, 3, 9) were revealed as hyaluronidase inhibitors similar to epicatechin (17).

Flavonoid glycosides from Botrychium ternatum.

The MeOH extract from dried whole Botrychium ternatum plants yielded 33 compounds, including seventeen new flavonoid glycosides and sixteen known compounds. The structures of new compounds were established using NMR spectroscopic analysis and chemical evidence.

Triterpene saponins from the pericarps of Akebia trifoliata.

Eleven new triterpene saponin components (1-11) were isolated from the MeOH extract of pericarp of Akebia trifoliata (THUNB.) KOIDZ. Each of their structures was determined using NMR techniques and mass spectrometry.

Triterpene saponins with hyaluronidase inhibitory activity from the seeds of Camellia sinensis.

The MeOH extract of the seeds of Camellia sinensis (L.) KUNTZE gave twelve new saponins (1-12) along with ten known saponins (13-22). These saponins (1-22) showed stronger hyaluronidase inhibitory activity than the positive control, rosmarinic acid.

Caffeic acid oligomers with hyaluronidase inhibitory activity from Clinopodium gracile.

Eight new caffeic acid oligomers, clinopodic acids J-Q (1-8), were isolated from whole plants of Clinopodium gracile, together with nine known caffeic acid oligomers. The caffeic acid oligomers with two to four dihydrobenzofuran rings were isolated as natural products for the first time. Clinopodic acid M (4) showed the strongest hyaluronidase inhibitory activity, IC(50) (19 µM) among the 22 compounds isolated from this plant.

Constituents from the roots of Taraxacum platycarpum and their effect on proliferation of human skin fibroblasts.

A MeOH extract from the roots of Taraxacum platycarpum has shown significant effects on the proliferation of normal human skin fibroblasts. Chemical analysis of the extract resulted in the isolation of 26 compounds, including eight new triterpenes, one new sesquiterpene glycoside, and seventeen known compounds. The structure of each new compound was established using NMR spectroscopy. Some triterpenes had a significant effect on the proliferation of normal human skin fibroblasts.

Hyaluronidase inhibitors from Keiskea japonica.

An extract of Keiskea japonica MIQ. showed an inhibitory effect on hyaluronidase activity. From the extract, four new phenylpropanoids, two new maltol glycosides, two new monoterpene glycosides, and two new phenolic compounds were isolated together with 19 known compounds. Among these constituents, two phenylpropanoids and a flavone glucuronide were revealed as hyaluronidase inhibitors.

8,12;8,20-diepoxy-8,14-secopregnane glycosides from roots of Asclepias tuberosa and their effect on proliferation of human skin fibroblasts.

A pregnane glycoside fraction from the roots of Asclepias tuberosa L. caused normal human skin fibroblasts to proliferate. This fraction contained 21 pregnane glycosides whose structures were established using NMR spectroscopic analysis and chemical evidence. The aglycones of most of these compounds were identified as 8,12;8,20-diepoxy-8,14-secopregnanes, such as tuberogenin or 5,6-didehydrotuberogenin, the same aglycones as constituents of the aerial parts of this plant. Some of these compounds also caused proliferation of skin fibroblasts.

Estrogenic and anti-estrogenic compounds from the Thai medicinal plant, Smilax corbularia (Smilacaceae).

From the rhizomes of Smilax corbularia Kunth. (Smilacaceae), 11 compounds, (2R,3R)-2″-acetyl astilbin, (2R,3R)-3″-acetyl astilbin, (2R,3R)-4″-acetyl astilbin, (2R,3R)-3″-acetyl engeletin, (2R,3S)-4″-acetyl isoastilbin, 2-(4-hydroxyphenyl)-3,4,9,10-tetrahydro-3,5-dihydroxy-10-(3,4-dihydroxyphenyl)-(2R,3R,10R)-2H,8H-benzo [1,2-b:3,4-b'] dipyran-8-one, 2-(4-hydroxyphenyl)-3,4,9,10-tetrahydro-3,5-dihydroxy-10-(3,4-dihydroxyphenyl)-(2R,3R,10S)-2H, 8H-benzo [1,2-b:3,4-b'] dipyran-8-one, 3,4-dihydro-7-hydroxy-4-(3,4-dihydroxyphenyl)-5-[(1E)-2-(4-hydroxyphenyl) ethenyl]-2H-1-benzopyran-2-one, 3,4-dihydro-7-hydroxy-4-(3,4-dihydroxy-phenyl)-5-[(1E)-2-(3,4-dihydroxyphenyl) ethenyl]-2H-1-benzopyran-2-one, 3,4-dihydro-7-hydroxy-4-(4-hydroxy-3-methoxyphenyl)-5-[(1E)-2-(4-hydroxyphenyl) ethenyl]-2H-1-benzopyran-2-one, and 5,7,3',4'-tetrahydroxy-3-phenylcoumarin along with 34 known compounds were isolated and characterized as 19 flavonoids, 14 catechin derivatives, 6 stilbene derivatives, and 6 miscellaneous substances. All isolates had their estrogenic and anti-estrogenic activities determined using the estrogen-responsive human breast cancer cell lines MCF-7 and T47D. The major constituents were recognized as flavanonol rhamnosides by the suppressive effect on estradiol induced cell proliferation at a concentration of 1µM. Meanwhile, flavanonol rhamnoside acetates demonstrated estrogenic activity in both MCF-7 and T47D cells at a concentration of 100µM, and they enhanced the effects of co-treated E2 on T47D cell proliferation at concentrations of more than 0.1µM.

Hyaluronidase inhibitory rosmarinic acid derivatives from Meehania urticifolia.

Nine new phenylpropanoids, rashomonic acids A-D (1-4) and meehaniosides A-E (5-9), along with four known compounds were isolated from Meehania urticifolia. The structure of each new compound was elucidated based on the results of spectroscopic analyses. Compounds 3-8 showed moderate hyaluronidase inhibitory activity with IC(50) values of 183-1049 µM.

New phenolic compounds from Meehania urticifolia.

A new phenylethanoid glycoside, rashomoside A (1), a new phenolic glucoside, rashomoside B (2), and a new shikimic acid derivative (3) were isolated from Meehania urticifolia together with 12 known flavones (4-15), three known phenylethanoid glycosides (16-18), and 13 other compounds (19-31). The structure of each of these compounds was elucidated based on the results of spectroscopic analysis.

Reinvestigation of the absolute stereochemistry of megastigmane glucoside, icariside B(5).

Icariside B(5) is one of the widely distributed megastigmane glucosides among plant sources. The absolute structure of icariside B(5) was reinvestigated by chemical conversion from the related compound and the application of the modified Mosher's method. As a result, the structure of icariside B(5) was revised to be (6S,9S)-6,9-dihydroxymegastigman-4-en-3-one 9-O-ß-D-glucopyranoside.