Potent in vivo antifungal activity against powdery mildews of pregnane glycosides from the roots of Cynanchum wilfordii

Two new pregnane glycosides, kidjoranine 3-O-β-D-glucopyranosyl-(1 → 4)-β-D-glucopyranosyl-(1 → 4)-α-L-cymaropyranosyl-(1 → 4)-β-D-cymaropyranosyl-(1→4)-α-L-diginopyranosyl-(1 → 4)-β-D-cymaropyranoside (5) and caudatin 3-O-β-D-glucopyranosyl-(1 → 4)-β-D-glucopyranosyl-(1 → 4)-α-L-cymaropyranosyl-(1 → 4)-β-D-cymaropyranosyl-(1 → 4)-α-L-diginopyranosyl-(1 → 4)-β-D-cymaropyranoside (6), were isolated from the roots of Cynanchum wilfordii along with four known compounds (1-4). The antifungal activities of the six compounds against barley powdery mildew caused by Blumeria graminis f. sp. hordei were compared to the antifungal activity of polyoxin B. The caudatin glycosides (1, 4, and 6) showed stronger antifungal activities than polyoxin B, whereas kidjoranine glycosides (2, 3, and 5) had weaker activities than polyoxin B. A wettable powder-type formulation (C. wilfordii-WP20) of the ethyl acetate extract from C. wilfordii roots prohibited the development of barley powdery mildew much more effectively than the commercial fungicide polyoxin B-WP10. In addition, C. wilfordii-WP20 effectively controlled strawberry powdery mildew caused by Sphaerotheca humuli under greenhouse conditions. Thus, the crude extract containing the pregnane glycosides can be used as a botanical fungicide for the environmentally benign control of powdery mildews.     

Quantitative analysis of steroidal glycosides in different organs of Easter lily (Lilium longiflorum Thunb.) by LC-MS/MS

The bulbs of the Easter lily ( Lilium longiflorum Thunb.) are regularly consumed in Asia as both food and medicine, and the beautiful white flowers are appreciated worldwide as an attractive ornamental. The Easter lily is a rich source of steroidal glycosides, a group of compounds that may be responsible for some of the traditional medicinal uses of lilies. Since the appearance of recent reports on the role steroidal glycosides in animal and human health, there is increasing interest in the concentration of these natural products in plant-derived foods. A LC-MS/MS method performed in multiple reaction monitoring (MRM) mode was used for the quantitative analysis of two steroidal glycoalkaloids and three furostanol saponins, in the different organs of L. longiflorum. The highest concentrations of the total five steroidal glycosides were 12.02 ± 0.36, 10.09 ± 0.23, and 9.36 ± 0.27 mg/g dry weight in flower buds, lower stems, and leaves, respectively. The highest concentrations of the two steroidal glycoalkaloids were 8.49 ± 0.3, 6.91 ± 0.22, and 5.83 ± 0.15 mg/g dry weight in flower buds, leaves, and bulbs, respectively. In contrast, the highest concentrations of the three furostanol saponins were 4.87 ± 0.13, 4.37 ± 0.07, and 3.53 ± 0.06 mg/g dry weight in lower stems, fleshy roots, and flower buds, respectively. The steroidal glycoalkaloids were detected in higher concentrations as compared to the furostanol saponins in all of the plant organs except the roots. The ratio of the steroidal glycoalkaloids to furostanol saponins was higher in the plant organs exposed to light and decreased in proportion from the aboveground organs to the underground organs. Additionally, histological staining of bulb scales revealed differential furostanol accumulation in the basal plate, bulb scale epidermal cells, and vascular bundles, with little or no staining in the mesophyll of the bulb scale. An understanding of the distribution of steroidal glycosides in the different organs of L. longiflorum is the first step in developing insight into the role these compounds play in plant biology and chemical ecology and aids in the development of extraction and purification methodologies for food, health, and industrial applications. In the present study, (22R,25R)-spirosol-5-en-3β-yl O-α-l-rhamnopyranosyl-(1→2)-β-d-glucopyranosyl-(1→4)-β-d-glucopyranoside, (22R,25R)-spirosol-5-en-3β-yl O-α-l-rhamnopyranosyl-(1→2)-[6-O-acetyl-β-d-glucopyranosyl-(1→4)]-β-d-glucopyranoside, (25R)-26-O-(β-d-glucopyranosyl)furost-5-ene-3β,22α,26-triol 3-O-α-l-rhamnopyranosyl-(1→2)-β-d-glucopyranosyl-(1→4)-β-d-glucopyranoside, (25R)-26-O-(β-d-glucopyranosyl)furost-5-ene-3β,22α,26-triol 3-O-α-l-rhamnopyranosyl-(1→2)-α-l-arabinopyranosyl-(1→3)-β-d-glucopyranoside, and (25R)-26-O-(β-d-glucopyranosyl)furost-5-ene-3β,22α,26-triol 3-O-α-l-rhamnopyranosyl-(1→2)-α-l-xylopyranosyl-(1→3)-β-d-glucopyranoside were quantified in the different organs of L. longiflorum for the first time.     

Identification of antioxidative flavonols and anthocyanins in Sicana odorifera fruit peel

Ten flavonols and three anthocyanins were identified in the fruit peel of melo?n de olor (Sicana odorifera), and their structures were established by spectrometric and spectroscopic (ESI-MS and NMR) techniques. One of the identified flavonols, quercetin 3-O-(6'-O-malonyl)-β-D-glucopyranoside 4'-O-β-D-glucopyranoside, has not been reported before in the plant kingdom. Although quercetin-3-O-α-L-rhamnopyranosyl-(1→6)-β-d-glucopyranoside-4'-O-β-D-glucopyranoside had been reported before in literature and structure elucidation was done by comparison of NMR data with published data, to the best of our knowledge complete 1D and 2D NMR data have not been not delineated so far. Moreover, the antioxidant activity of pure compounds was measured by ABTS assay. It was established that quercetin 3-O-α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranoside, quercetin-3-O-(6'-malonyl)-glucopyranoside, quercetin-3-O-β-D-glucopyranoside, and quercetin-3-O-α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranoside-4'-O-β-D-glucopyranoside contribute significantly to the antioxidant activity exhibited by the fruit peel methanolic extract.     

Mechanochemical-assisted extraction and antioxidant activities of kaempferol glycosides from Camellia oleifera Abel. meal

A mechanochemical-assisted extraction (MCAE) method was proposed and investigated for the fast extraction of two kaempferol glycosides (kaempferol-3-O-[2-O-β-D-galactopyranosyl-6-O-α-L-rhamnopyranosyl]-β-D-glucopyranoside and kaempferol-3-O-[2-O-β-D-xylopyranosyl-6-O-α-L-rhamnopyranosyl]-β-D-glucopyranoside) from Camellia oleifera Abel. meal. The effects of operating parameters in terms of NaOH content, grinding time, extraction time, and ratio of solution to solid were evaluated by means of response surface methodology (RSM). Under the optimal conditions with a ratio of material to NaOH of 20:1 (g/g), a milling time of 15 min, and a ratio of solution to solid of 20:1 (mL/g) for 60 min, the maximum extraction yields of the two kaempferol glycosides reached 13.34 and 13.83%, respectively. The antioxidant activity of kaempferol glycosides extract was assessed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay and ferric thiocyanate (FTC) assay. Compared with the heat reflux extraction (HRE) method, the yield and the antioxidant activities of the extracts from MCAE with water as solvent were higher and stronger.     

A-type proanthocyanidins from lychee seeds and their antioxidant and antiviral activities

Two new A-type trimeric proanthocyanidins with two doubly bonded interflavanoid linkages, litchitannin A1 [epicatechin-(2β→O→7,4β→6)-epicatechin-(2β→O→7,4β→8)-catechin] (1) and litchitannin A2 [epicatechin-(2β→O→7,4β→6)-epicatechin-(2β→O→7,4β→6)-epicatechin] (2), were isolated from lychee (Litchi chinensis Sonn. cv. Heiye) seeds together with aesculitannin A (3), epicatechin-(2β→O→7,4β→8)-epiafzelechin-(4α→8)-epicatechin (4), proanthocyanidin A1 (5), proanthocyanidin A2 (6), proanthocyanidin A6 (7), epicatechin-(7,8-bc)-4β-(4-hydroxyphenyl)-dihydro-2(3H)-pyranone (8), and epicatechin (9). Their structures were elucidated on the basis of spectroscopic and chemical evidence. It is the first time that compounds 1-4, 7, and 8 have been reported in this species. Compounds 1-9 showed more potent antioxidant activity than L-ascorbic acid with ferric reducing antioxidant power (FRAP) values of 3.71-24.18 mmol/g and IC50 values of 5.25-20.07 μM toward DPPH radicals. Moreover, litchitannin A2 (2) was found to exhibit in vitro antiviral activity against coxsackie virus B3 (CVB3) and compounds 3 and 6 displayed antiherpes simplex virus 1 (HSV-1) activity.     

Maple syrup phytochemicals include lignans, coumarins, a stilbene, and other previously unreported antioxidant phenolic compounds

Twenty-three phenolic compounds were isolated from a butanol extract of Canadian maple syrup (MS-BuOH) using chromatographic methods. The compounds were identified from their nuclear magnetic resonance and mass spectral data as 7 lignans [lyoniresinol (1), secoisolariciresinol (2), dehydroconiferyl alcohol (3), 5'-methoxy-dehydroconiferyl alcohol (4), erythro-guaiacylglycerol-β-O-4'-coniferyl alcohol (5), erythro-guaiacylglycerol-β-O-4'-dihydroconiferyl alcohol (6), and [3-[4-[(6-deoxy-α-l-mannopyranosyl)oxy]-3-methoxyphenyl]methyl]-5-(3,4-dimethoxyphenyl)dihydro-3-hydroxy-4-(hydroxymethyl)-2(3H)-furanone (7)], 2 coumarins [scopoletin (8) and fraxetin (9)], a stilbene [(E)-3,3'-dimethoxy-4,4'-dihydroxystilbene (10)], and 13 phenolic derivatives [2-hydroxy-3',4'-dihydroxyacetophenone (11), 1-(2,3,4-trihydroxy-5-methylphenyl)ethanone (12), 2,4,5-trihydroxyacetophenone (13), catechaldehyde (14), vanillin (15), syringaldehyde (16), gallic acid (17), trimethyl gallic acid methyl ester (18), syringic acid (19), syringenin (20), (E)-coniferol (21), C-veratroylglycol (22), and catechol (23)]. The antioxidant activities of MS-BuOH (IC50>1000 μg/mL), pure compounds, vitamin C (IC50=58 μM), and a synthetic commercial antioxidant, butylated hydroxytoluene (IC50=2651 μM), were evaluated in the diphenylpicrylhydrazyl (DPPH) radical scavenging assay. Among the isolates, the phenolic derivatives and coumarins showed superior antioxidant activity (IC50<100 μM) compared to the lignans and stilbene (IC50>100 μM). Also, this is the first report of 16 of these 23 phenolics, that is, compounds 1, 2, 4-14, 18, 20, and 22, in maple syrup.     

Two new antioxidant malonated caffeoylquinic acid isomers in fruits of wild eggplant relatives

Fruits of the cultivated eggplant species Solanum melongena and its wild relative Solanum incanum have a high content of hydroxycinnamic acid conjugates, which are implicated in the human health benefits of various fruits and vegetables. Monocaffeoylquinic acid esters, in particular 5-O-(E)-caffeoylquinic acid, are usually predominant in solanaceous fruits and tubers. Two closely related caffeoylquinic acid derivatives with longer C(18) HPLC retention times than those of monocaffeoylquinic acids are minor constituents in cultivated eggplant fruit. In a prior study, the two compounds were tentatively identified as 3-O-acetyl- and 4-O-acetyl-5-O-(E)-caffeoylquinic acids and composed ≤2% of the total hydroxycinnamic acid conjugates in fruit of most S. melongena accessions. It was recently found that the pair of these caffeoylquinic acid derivatives can compose 15-25% of the total hydroxycinnamic acid conjugates in fruits of S. incanum and wild S. melongena. This facilitated C(18) HPLC isolation and structural elucidation using (1)H and (13)C NMR techniques and HR-ToF-MS. The isomeric compounds were identified as 3-O-malonyl-5-O-(E)-caffeoylquinic acid (isomer 1) and 4-O-(E)-caffeoyl-5-O-malonylquinic acid (isomer 2). Both exhibited free radical scavenging activity, albeit about 4-fold lower than that of the flavonol quercetin dihydrate. By contrast, the iron chelation activities of isomers 1 and 2, respectively, were about 3- and 6-fold greater than that of quercetin dihydrate. Reports of malonylhydroxycinnamoylquinic acids are rare, and only a few of these compounds have been structurally elucidated using both NMR and MS techniques. To the authors' knowledge, these two malonylcaffeoylquinic acid isomers have not previously been reported.     

Triterpenoid glycosides from the leaves of two cultivars of Medicago polymorpha L

The saponin composition of leaves from the Medicago polymorpha cultivars 'Santiago' and 'Anglona' belonging to the botanical varieties brevispina and vulgaris, respectively, was investigated by a combination of chromatographic, spectroscopic, and spectrometric techniques. Several compounds were detected and quantitated by HPLC analysis using the external standard method. Twelve triterpene saponins (1-12) were purified by reverse-phase chromatography and their structures elucidated by spectroscopic (1D and 2D NMR, ESI-MS/MS) and chemical methods. They were identified as glycosides of echinocystic acid, hederagenin, caulophyllogenin, bayogenin, and soyasapogenol B. Two of them (2, 10) were previously reported in M. polymorpha; five of them (4, 6, 7, 9, 12) were already identified in other Medicago species; and three of them (1, 8, 11) were found in other plant genera. The two saponins identified as 3-O-α-L-arabinopyranosyl-28-O-[β-D-glucopyranosyl(1→6)β-D-glucopyranoside] echinocystic acid (3) and 3-O-α-L-arabinopyranosyl-28-O-β-D-glucopyranoside echinocystic acid (5) are newly identified natural compounds. The presence of echinocystic acid is reported here for the first time in the genus Medicago. Saponins from the cultivar 'Anglona' were characterized by a higher amount of echinocystic acid glycosydes, whereas saponins from the cultivar 'Santiago' were characterized by a higher amount of hederagenin glycosydes.     

New isoflavonoid glycosides and related constituents from astragali radix ( Astragalus membranaceus ) and their inhibitory activity on nitric oxide production

Twenty-four secondary metabolites, including 16 isoflavonoids, 7 astragalasides, and 1 benzoquinone, have been isolated from the roots of Astragalus membranaceus (Astragali radix). Among these isolated isoflavonoids, (-)-methylinissolin 3-O-β-d-(6'-acetyl)-glucoside (1), (-)-methylinissolin 3-O-β-d-{6'-[(E)-but-2-enoyl]}-glucoside (2), and calycosin 7-O-β-d-(6'-acetyl)-glucoside (3) have been identified as new compounds on the basis of spectroscopic analysis; (-)-methylinissolin 3-O-β-d-glucoside (4) was isolated from the natural products for the first time. The nitric oxide (NO) production inhibitory activity of the major compounds has been assessed in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. To identify A. membranaceus, a fingerprint method was developed by using a high-performance liquid chromatography-evaporative light scattering detector (HPLC-ELSD) method. Furthermore, characteristic peaks for the 11 major compounds in the chromatogram were unambiguously confirmed.     

Isolation and identification of flavonoids accumulated in proanthocyanidin-free barley

Flavonoids accumulated in proanthocyanidin-free near-isogenic lines iso ant 13, iso ant 17, and iso ant 22 of Nishinohoshi, developed by backcross breeding using a leading cultivar, Nishinohoshi, as a recurrent parent and a proanthocyanidin-free mutant as a nonrecurrent parent in Japan, were examined. A new flavanone, (2RS)-dihydrotricin 7-O-β-D-glucopyranoside (1), known flavanones (2RS)-dihydrotricin (2) and (2RS)-homoeriodictyol (3), and known flavones chrysoeriol 7-O-[α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranoside] (4), chrysoeriol 7-O-β-D-glucopyranoside (5), tricin (6), and chrysoeriol (7) were isolated from iso ant 17 of Nishinohoshi. The structures and stereochemistries of the isolated flavonoids (1-7) were elucidated on the basis of spectroscopic analyses. The concentrations of the isolated flavonoids (1-7) in iso ant 13, iso ant 17, and iso ant 22 of Nishinohoshi were similar to each other, whereas the flavonoids 1-5 and 7 were not detected in Nishinohoshi, an old Japanese cultivar, Amaginijo, and North American cultivar Harrington. The concentration of tricin (6) in Nishinohoshi was a half those in iso ant 13, iso ant 17, and iso ant 22 of Nishinohoshi. Except for iso ant 13, iso ant 17, and iso ant 22 of Nishinohoshi, the concentration of tricin (6) was highest in Nishinohoshi, followed by Amaginijo and Harrington. Thus, tricin (6), its precursor dihydrotricin (2), and its glucopyranoside, dihydrotricin 7-O-β-D-glucopyranoside (1), as well as chrysoeriol (7) and homoeriodictyol (3) were accumulated in iso ant 13, iso ant 17, and iso ant 22 of Nishinohoshi probably by blocking at the step of flavanone 3-hydroxylase in the procyanidin biogenetic pathway, resulting in enhancement of the alternative biogenetic pathway.     

Polymorphism for novel tetraglycosylated flavonols in an Eco-model crucifer, Barbarea vulgaris

Nineteen apparent flavonoids were determined by HPLC-DAD in foliage of a chemotype (G-type) of Barbarea vulgaris , and four were isolated. Two were novel tetraglycosylated flavonols with identical glycosylation patterns, kaempferol 3-O-(2,6-di-O-β-d-glucopyranosyl)-β-d-glucopyranoside-7-O-α-l-rhamnopyranoside (1) and quercetin 3-O-(2,6-di-O-β-d-glucopyranosyl)-β-d-glucopyranoside-7-O-α-l-rhamnopyranoside (2). The identification of d/l configuration was tentatively based on susceptibility to α-l-rhamnosidase and β-d-glucosidases. A characteristic feature of 1 and 2 was appreciable water solubility, an expected consequence of the extensive glycosylation. A less complex pair of flavonols comprised 3-O-β-d-glucopyranoside-7-O-α-l-rhamnopyranosides of kaempferol and quercetin. Two natural chemotypes of B. vulgaris differed in levels of 1 and 2, with the P-type deficient in 1 and 2 and the insect-resistant G-type rich in 1 (ca. 3-4 μmol/g dry wt) and with moderate levels of 2 (ca. 0.3-0.8 μmol/g dry wt). However, there was only modest seasonal variation in flavonols 1 and 2, in contrast to a strong seasonal variation in insect resistance.     

Isolation and identification of sea buckthorn (Hippophae rhamnoides) phenolics with antioxidant activity and α-glucosidase inhibitory effect

This study was performed to evaluate the antioxidant and α-glucosidase inhibitory effects from the extract, fractions, and isolated compounds of sea buckthorn leaves. Six compounds, kaempferol-3-O-β-D-(6'-O-coumaryl) glycoside, 1-feruloyl-β-D-glucopyranoside, isorhamnetin-3-O-glucoside, quercetin 3-O-β-D-glucopyranoside, quercetin 3-O-β-D-glucopyranosyl-7-O-α-L-rhamnopyranoside, and isorhamnetin-3-O-rutinoside, were isolated from sea buckthorn leaf extracts. The butanol fraction (EC(50) = 1.81 μg/mL) along with quercetin 3-O-β-D-glucopyranoside (EC(50) = 1.86 μg/mL) had a higher DPPH radical-scavenging activity and showed stronger reducing power (OD(700) = 1.83 and 1.78, respectively). The butanol fraction (477 mg GAE/g) contained the highest amount of phenolic compounds and also the most powerful α-glucosidase inhibitory effect (86%) at 5 μg/mL. The results indicate that sea buckthorn leaf extracts could potentially be used for food additives and the development of useful natural compounds.     

Hydroxycinnamoylmalic acids and their methyl esters from pear (Pyrus pyrifolia Nakai) fruit peel

Two novel caffeoylmalic acid methyl esters, 2-O-(trans-caffeoyl)malic acid 1-methyl ester (6) and 2-O-(trans-caffeoyl)malic acid 4-methyl ester (7), were isolated from pear (Pyrus pyrifolia Nakai cv. Chuhwangbae) fruit peels. In addition, 5 known hydroxycinnamoylmalic acids and their methyl esters were identified: 2-O-(trans-coumaroyl)malic acid (1), 2-O-(cis-coumaroyl)malic acid (2), 2-O-(cis-coumaroyl)malic acid 1-methyl ester (3), 2-O-(trans-coumaroyl)malic acid 1-methyl ester (4), and 2-O-(trans-caffeoyl)malic acid (phaselic acid, 5). The chemical structures of these compounds were determined by spectroscopic data from ESI MS and NMR. Of all the isolated compounds, five hydroxycinnamoylmalic acids and their methyl esters (2-4, 6, 7) were identified in the pear for the first time.     

New anthocyanidin and anthocyanin pigments from blue plumbago

Phytochemical investigations of blue plumbago ( Plumbago auriculata Poir. syn. Plumbago capensis Thunb.) flowers have led to the isolation of six new anthocyanins based on three new anthocyanidins with 5,7-dimethoxylated A-rings. Their structures were identified by 2D nuclear magnetic resonance and high-resolution mass spectrometry as the 3-O-β-galactopyranosides (1,2,4) and 3-O-α-rhamnopyranosides (3,5,6) of 5,7-dimethyldelphinidin, 5,7-dimethylpetunidin, and 5,7-dimethylmalvidin. Identification of 1-6 implies new structures for the previously reported anthocyanidins pulchellidin, europinidin, and capensinidin to be 5,7-dimethoxy-3,3',4',5'-tetrahydroxyflavylium, 5,7,3'-trimethoxy-3,4',5'-trihydroxyflavylium, and 5,7,3',5'-tetramethoxy-3,4'-dihydroxyflavylium cations, respectively. The anthocyanins (0.4 mg/g flowers) were accompanied by the dihydroflavonol taxifolin 3'-O-β-glucopyranoside (1.4 mg/g) and the flavonols 5-methylquercetin 3-O-α-rhamnopyranoside (8.8 mg/g) and 5-methylquercetin (0.4 mg/g). The anthocyanins 1-6 are the first reported natural anthocyanins with no free hydroxyl groups in their 5- and 7-positions on their A-rings. They have thus no possibility of forming the tautomeric quinonoidal bases (anhydrobases), which are related to the free hydroxyl groups in the 5- and 7-positions of previously reported anthocyanins. The genes behind the 5,7-dimethoxylated anthocyanins might be useful for making anthocyanins with special properties (colors, etc.).     

Structure elucidation of procyanidin oligomers by low-temperature 1H NMR spectroscopy

Procyanidin dimers and trimers, needed as reference compounds for biological studies, have been synthesized from various natural sources using a semisynthetic approach and purified by high-speed countercurrent chromatography (HSCCC). In the past, it has been difficult to elucidate the structure of these compounds, especially the determination of the interflavanoid bond. Here, the structure of two B-type procyanidin dimers, with (+)-catechin ((+)-C) in the upper unit, and eight C-type procyanidin trimers, with (-)-epicatechin ((-)-EC) in the upper unit, have been elucidated using low-temperature (1)H NMR spectroscopy, as well as circular dichroism (CD) spectroscopy. This is the first time NOE interactions have been used to characterize the interflavanoid linkage in underivatized procyanidin trimers. Complete analyses of procyanidin C1 (-)-EC-4β→8-(-)-EC-4β→8-(-)-EC, (-)-EC-4β→8-(-)-EC-4β→8-(+)-C, (-)-EC-4β→6-(-)-EC-4β→8-(-)-EC, (-)-EC-4β→6-(-)-EC-4β→8-(+)-C, (-)-EC-4β→8-(-)-EC-4β→6-(-)-EC, (-)-EC-4β→8-(-)-EC-4β→6-(+)-C, (-)-EC-4β→8-(+)-C-4α→8-(-)-EC, procyanidin C4 (-)-EC-4β→8-(+)-C-4α→8-(+)-C, and procyanidin dimers B6 (+)-C-4α→6-(+)-C and B8 (+)-C-4α→6-(-)-EC are presented.     

Antifungal activity and fungal metabolism of steroidal glycosides of Easter lily (Lilium longiflorum Thunb.) by the plant pathogenic fungus, Botrytis cinerea

Botrytis cinerea Pers. Fr. is a plant pathogenic fungus and the causal organism of blossom blight of Easter lily (Lilium longiflorum Thunb.). Easter lily is a rich source of steroidal glycosides, compounds which may play a role in the plant-pathogen interaction of Easter lily. Five steroidal glycosides, including two steroidal glycoalkaloids and three furostanol saponins, were isolated from L. longiflorum and evaluated for fungal growth inhibition activity against B. cinerea, using an in vitro plate assay. All of the compounds showed fungal growth inhibition activity; however, the natural acetylation of C-6' of the terminal glucose in the steroidal glycoalkaloid, (22R,25R)-spirosol-5-en-3β-yl O-α-L-rhamnopyranosyl-(1→2)-[6-O-acetyl-β-D-glucopyranosyl-(1→4)]-β-D-glucopyranoside (2), increased antifungal activity by inhibiting the rate of metabolism of the compound by B. cinerea. Acetylation of the glycoalkaloid may be a plant defense response to the evolution of detoxifying mechanisms by the pathogen. The biotransformation of the steroidal glycoalkaloids by B. cinerea led to the isolation and characterization of several fungal metabolites. The fungal metabolites that were generated in the model system were also identified in Easter lily tissues infected with the fungus by LC-MS. In addition, a steroidal glycoalkaloid, (22R,25R)-spirosol-5-en-3β-yl O-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranoside (6), was identified as both a fungal metabolite of the steroidal glycoalkaloids and as a natural product in L. longiflorum for the first time.     

Isolation and Caenorhabditis elegans lifespan assay of flavonoids from onion

The main flavonoids were isolated from three selected onion cultivars. Three phenolic compounds were obtained by reverse-phase HPLC, and their structures were elucidated by multiple NMR measurements. There were two known compounds, quercetin and quercetin 3'-O-β-D-glucopyranoside (Q3'G), and one novel compound, quercetin 3-O-β-D-glucopyranoside-(4→1)-β-d-glucopyranoside (Q3M), which was identified in onion for the first time. These flavonoids were found to be more abundant in the onion peel than in the flesh or core. Their antioxidative activities were tested using the DPPH method, and their antiaging activities were evaluated using a Caenorhabditis elegans lifespan assay. No direct correlation was found between antioxidative activity and antiaging activity. Quercetin showed the highest antioxidative activity, whereas Q3M showed the strongest antiaging activity among these flavonoids, which might be related to its high hydrophilicity.     

Spectroscopic identification and antioxidant activity of glucosylated carotenoid metabolites from Cydonia vulgaris fruits

Carotenoid metabolites are common plant constituents with significant importance for the flavor and aroma of fruits. Three new carotenoid derivatives, (2E,4E)-8-hydroxy-2,7-dimethyl-2,4-decadiene-1,10-dioic acid 1-O-beta-D-glucopyranosyl ester (1), (2Z,4E)-8-beta-D-glucopyranosyloxy-2,7-dimethyl-2,4-decadiene-1,10-dioic acid (3), and 3,9-dihydroxymegastigmast-5-ene-3-O-[beta-D-glucopyranosyl-(1-->6)]-beta-D-glucopyranoside (5), as well as three known compounds, have been isolated from the ethanolic extract of peels of Cydonia vulgaris, the fruit of a shrub belonging to the same family as the apple. All the compounds were identified by spectroscopic techniques, especially 1D and 2D NMR. Antioxidant activities of all the isolated metabolites were assessed by measuring their ability to scavenge DPPH radical and superoxide radical (O2*-) and to induce the reduction of Mo(VI).     

Antioxidant activity of prune (Prunus domestica L.) constituents and a new synergist

Ethanol extract of prune was separated into hexane-soluble and H(2)O-soluble fractions, and the H(2)O-soluble fraction was further separated into a methanol (MeOH) eluate and an H(2)O eluate by Diaion HP-20 column chromatography. The MeOH eluate exhibited the strongest antioxidant activity among the separated fractions evaluated by oxygen radical absorbance capacity (ORAC). Further purification of the MeOH eluate led to isolation of a novel compound, 4-amino-4-carboxychroman-2-one, together with four known compounds (p-coumaric acid, vanillic acid beta-glucoside, protocatechuic acid, and caffeic acid), structures of which were identified by NMR and MS analyses. The ORAC values of these isolated compounds showed 0.15-1.43 units (micromol of Trolox equiv)/micromol, and the new compound showed a remarkable synergistic effect on caffeoylquinic acid isomers. The antioxidant activity of the MeOH eluate was highly dependent on the major prune components, caffeoylquinic acid isomers, with a contribution from the new synergist.     

Triterpene saponins from the roots of Medicago hybrida

Fourteen triterpene saponins (1-14) have been isolated from the roots of Medicago hybrida and their structures elucidated by FAB-MS and NMR analysis. Two of them are new compounds and were identified as hederagenin 3-O-[alpha-L-rhamnopyranosyl(1-->2)-beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl]-28-O-beta-D-glucopyranoside (7) and oleanolic acid 3-O-[beta-D-galactopyranosyl(1-->2)-beta-D-glucuronopyranosyl]-28-O-[alpha-L-rhamnopyranosyl(1-->4)-beta-D-glucopyranoside] (14). Seven saponins being mono- and bidesmosides of hederagenin (1, 5, 6, 9), one bidesmoside of bayogenin (2), and two bidesmosides of 2beta,3beta-dihydroxyolean-12-en-23-al-28-oic acid (11) and oleanolic acid (13) are known compounds but not previously reported as saponin constituents of Medicago, whereas five other saponins, being mono- and bidesmosides of medicagenic acid (3, 4, 8, 10, 12), and one monodesmoside of hederagenin (8) have been previously isolated from other Medicago species. The presence of 2beta,3beta-dihydroxyolean-12-en-23-al-28-oic acid might represent an interesting intermediate in the biosynthesis of these substances.