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The antifungal properties of saponin mixtures from alfalfa (Medicago sativa L.) tops and roots, the corresponding mixtures of prosapogenins from tops, and purified saponins and sapogenins against the causal agent of rice blast Pyricularia oryzae isolates are presented. In vitro experiments highlighted a range of activities, depending upon the assayed metabolite. The antifungal effects of the most promising prosapogenin mixture from alfalfa tops were confirmed by means of in planta tests using three different Italian cultivars of rice (Oryza sativa L. ssp. japonica), known to possess high, medium, and low blast resistance. The evidenced antifungal properties of the tested metabolites allowed some considerations on their structure-activity relationship. Results indicate that prosapogenins are active compounds to prevent the fungal attack of P. oryzae on different rice cultivars. Therefore, if properly formulated, these substances could represent a promising and environmentally friendly treatment to control rice blast.

Five new compounds, 16,23,29-trihydroxy-3-oxo-olean-12-en-28-oic acid (1), 4,23,29-trihydroxy-3,4-seco-olean-12-en-3-oate-28-oic acid (2), 3β,6β,23-trihydroxyolean-12-en-28-oic acid 28-O-β-D-glucopyranoside (3), 3-O-[2,3-di-O-acetyl-α-L-arabinopyranosyl]hederagenin 28-O-α-L-rhamnopyranosyl-(1→4)-β-D-glucopyranosyl-(1→6)-β-D-glucopyranoside (4), and 3-O-[3,4-di-O-acetyl-α-L-arabinopyranosyl]hederagenin 28-O-α-L-rhamnopyranosyl-(1→4)-β-D-glucopyranosyl-(1→6)-β-D-glucopyranoside (5), as well as 10 known compounds (6-15), were isolated from the stem bark of Kalopanax pictus. Compounds 1-5 and 7-14 inhibited TNFα-induced NF-κB transcriptional activity in HepG2 cells in a dose-dependent manner, with IC50 values ranging from 0.6 to 16.4 μM. Furthermore, the transcriptional inhibitory function of these compounds was confirmed on the basis of decreases in COX-2 and iNOS gene expression in HepG2 cells. The structure-activity relationship of the compounds with respect to anti-inflammatory activity is also discussed.

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.

Hederacoside C, alpha-hederin, and hederagenin are saponins of dry extracts obtained from the leaves of ivy (Hedera helix L.). Internalization of beta(2)-adrenergic receptor-GFP fusion proteins after stimulation with 1 microM terbutaline was inhibited by preincubation of stably transfected HEK293 cells with 1 microM alpha-hederin for 24 h, whereas neither hederacoside C nor hederagenin (1 microM each) influenced this receptor regulation. After incubation of A549 cells with 5 nM Alexa532-NA, two different diffusion time constants were found for beta(2)AR-Alexa532-NA complexes by fluorescence correlation spectroscopy. Evaluation of the autocorrelation curve revealed diffusion time constants: tau(bound1) = 1.4 +/- 1.1 ms (n = 6) found for receptor-ligand complexes with unrestricted lateral mobility, and tau(bound2) = 34.7 +/- 14.1 ms (n = 6) for receptor-ligand complexes with hindered mobility. The distribution of diffusion time constants was 24.3 +/- 2.5% for tau(bound1) and 8.7 +/- 4.3% for tau(bound2) (n = 6). A549 cells pretreated with 1 microM alpha-hederin for 24 h showed dose-dependent alterations in this distribution with 37.1 +/- 5.5% for tau(bound1) and 4.1 +/- 1.1% for tau(bound2). Simultaneously, the level of Alexa532-NA binding was significantly increased from 33.0 +/- 6.8 to 41.2 +/- 4.6%. In saturation experiments, alpha-hederin did not influence the beta(2)-adrenergic receptor density (B(max)), whereas the K(D) value for Alexa532-NA binding decreased from 36.1 +/- 9.2 to 24.3 +/- 11.1 nM. Pretreatment of HASM cells with alpha-hederin (1 microM, 24 h) revealed an increased intracellular cAMP level of 13.5 +/- 7.0% under stimulating conditions. Remarkably, structure-related saponins like hederacoside C and hederagenin did not influence either the binding behavior of beta(2)AR or the intracellular cAMP level.

The reinvestigation of saponin composition from Medicago arabica from Italy allowed the detection of nineteen (1-19) saponins. All of them were purified by reverse-phase chromatography and their structures elucidated by spectroscopic and spectrometric (1D and 2D NMR; ESI-MS/MS) and chemical methods. Fourteen were known saponins, previously found in other plants including other Medicago species. They have been identified as glycosides of oleanolic acid, 2beta,3beta-dihydroxyolean-12-en-28-oic acid, hederagenin, bayogenin and soyasapogenol B. Five saponins, identified as 3-O-[-alpha-L-arabinopyranosyl(1--2)-beta-D-glucuronopyranosyl]-30-O-beta-D-glucopyranosyl 2beta,3beta,30-trihydroxyolean-12-en-28-oic acid (1), 3-O-[alpha-L-arabinopyranosyl(1--2)-beta-D-glucuronopyranosyl]-30-O-[beta-D-glucopyranosyl] 3beta,30-dihydroxyolean-12-en-28-oic acid (2), 3-O-[beta-D-glucuronopyranosyl]-30-O-[alpha-L-arabinopyranosyl(1--2)-beta-d-glucopyranosyl] 2beta,3beta,30-trihydroxyolean-12-en-28-oic acid (3), 3-O-[beta-D-glucuronopyranosyl]-30-O-[alpha-L-arabinopyranosyl(1--2)-beta-D-glucopyranosyl] 3beta,30-dihydroxyolean-12-en-28-oic acid (4) and 3-O-[beta-D-glucuronopyranosyl]-30-O-[beta-D-glucopyranosyl] 2beta,3beta,30-trihydroxyolean-12-en-28-oic acid (5), are reported here as new natural compounds. These new saponins, possessing a hydroxy group at the 30-methyl position of the triterpenic skeleton, have never been previously found in the genus Medicago.

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.

Six new saponins, five lupanes (1-5) and one oleanane (6), along with 11 known saponins, were isolated from the roots of Pulsatilla koreana. The structures of the new saponins were found to be 23-hydroxy-3beta-[(O-alpha-L-rhamnopyranosyl-(1--2)-O-[O-beta-D-glucopyranosyl-(1--4)]-alpha-L-arabinopyranosyl)oxy]lup-20(29)-en-28-oic acid (1), 23-hydroxy-3beta-[(O-beta-D-glucopyranosyl-(1--3)-O-alpha-L-rhamnopyranosyl-(1--2)-alpha-L-arabinopyranosyl)oxy]lup-20(29)-en-28-oic acid (2), 3beta-[(O-alpha-L-rhamnopyranosyl-(1--2)-O-[O-beta-D-glucopyranosyl-(1--4)]-alpha-L-arabinopyranosyl)oxy]lup-20(29)-en-28-oic acid (3), 3beta-[(O-beta-D-glucopyranosyl-(1--3)-O-alpha-L-rhamnopyranosyl-(1--2)-alpha-L-arabinopyranosyl)oxy]lup-20(29)-en-28-oic acid (4), 23-hydroxy-3beta-[(O-beta-D-glucopyranosyl-(1--4)-alpha-L-arabinopyranosyl)oxy]lup-20(29)-en-28-oic acid (5), and hederagenin 3-O-beta-D-glucopyranosyl-(1--4)-beta-D-glucopyranosyl-(1--3)-alpha-L-rhamnopyranosyl-(1--2)-alpha-L-arabinopyranoside (6). Their structures were determined on the basis of 1D and 2D NMR ((13)C NMR, (1)H NMR, (1)H-(1)H COSY, HMQC, and HMBC) methods, FABMS, and hydrolysis. All isolated compounds were evaluated for their cytotoxic activity against A-549 human lung carcinoma cells.

Eight major triterpene saponins have been isolated from the aerial parts of Medicago arabica and their structures elucidated by FAB-MS and NMR analysis. Three of them are new compounds and are identified as 3-O-(alpha-L-arabinopyranoside) bayogenin, 3-O-(alpha-L-arabinopyranosyl), 28-O-(beta-D-glucopyranoside) bayogenin, and 3-O-[alpha-L-arabinopyranosyl(1-->2)-beta-D-glucuronopyranosyl], 28-O-beta-D-glucopyranoside 2-beta-hydroxyoleanolic acid. Two saponins, identified as 3-O-(alpha-L-arabinopyranoside) hederagenin and 3-O-(alpha-L-arabinopyranosyl), 28-O-(beta-D-glucopyranoside) hederagenin are known compounds but not previously reported as saponin constituents of Medicago species, while three other saponins, being mono- and bidesmosides of hederagenin, have been previously isolated from roots of M. sativa.

Two new triterpene saponins (8 and 9) and seven previously reported triterpene saponins (1-7) based upon oleanolic acid or hederagenin, along with two known lignans, (+)-pinoresinol (10) and beta-peltatin (11), were isolated from a saponin fraction prepared from the MeOH extract of the roots of Pulsatilla chinensis. The structures of the new saponins were determined by spectroscopic analysis, including 2D NMR spectroscopic techniques, and the results of hydrolytic cleavage. The isolated compounds and some derivatives were evaluated for their cytotoxic activity against HL-60 human leukemia cells.

Five new oleanane-type glycosides (1-5), along with two known triterpene saponins, were isolated from the roots of Pulsatilla patens var. multifida (Ranunculaceae). The structures of the new triterpene saponins were elucidated as 3-O-beta-D-glucopyranosyl(1-->2)-beta-D-galactopyranosyl hederagenin 28-O-beta-D-glucopyranosyl ester (1), hederagenin 3-O-[beta-D-glucopyranosyl(1-->2)][beta-D-glucopyranosyl(1-->6)]-beta -D-galactopyranoside (2), 3-O-beta-D-glucopyranosyl bayogenin 28-O-alpha-L-rhamnopyranosyl(1-->4)-beta-D-glucopyranosyl(1-->6)-beta -D-glucopyranosyl ester (3), 3-O-beta-D-glucopyranosyl(1-->2)-beta-D-galactopyranosyl oleanolic acid 28-O-alpha-L-rhamnopyranosyl(1-->4)-beta-D-glucopyranosyl(1-->6)-beta -D-glucopyranosyl ester (4), and 3-O-[beta-D-glucopyranosyl(1-->2)][beta-D-glucopyranosyl(1-->6)]-beta -D-galactopyranosyl hederagenin 28-O-alpha-L-rhamnopyranosyl(1-->4)-beta-D-glucopyranosyl(1-->6)-beta -D-glucopyranosyl ester (5). Structure elucidation was accomplished by 1D and 2D NMR (HMQC, HMBC, and ROESY) methods, FABMS, and hydrolysis.

Seven triterpenoid saponins were isolated from the seeds of Chenopodium pallidicaule (Chenopodiaceae). Of these compounds, four were identified as known saponins of oleanolic acid and phytolaccagenic acid. The other three compounds, named 1−3, are new saponins. The structures of these saponins were determined to be: (1) hederagenin 3-O-[α-l-arabinopyranosyl-(1→3)-β-d-glucuronopyranosyl]-28-O-β-d-glucopyranoside; (2) phytolaccagenic acid 3-O-[β-d-glucopyranosyl-(1→4)-β-d-glucopyranosyl]-28-O-β-d-glucopyranoside; and (3) phytolaccagenic acid 3-O-[β-d-glucopyranosyl-(1→4)-β-d-glucopyranosyl-(1→4)-β-d-glucopyranosyl]-28-O-β-d-glucopyranoside. All structures were elucidated by chemical and spectroscopic methods. Keywords: Canihua; Chenopodium pallidicaule; chenopodiaceae; South American crop; triterpene glycosides; 1H NMR, 13C NMR, 2D NMR

An investigation of Serjania salzmanniana for biologically active substances has led to the isolation of two novel saponins, salzmannianoside A (3-O-[[beta-D- glucopyranosyl-(1-->4)]-[alpha-L-rhamnopyranosyl-(1-->2)]-alpha-L- arabinopyranosyl] gypsogenin) [3] and salzmannianoside B (3-O-[[beta-D-glucopyranosyl-(1-->4)]-[alpha-L- arabinopyranosyl-(1-->3)-alpha-L-rhamnopyranosyl-(1-->2)] -alpha-L-arabinopyranosyl] hederagenin) (4). Two known saponins, pulsatilla saponin D (3-O-[[beta-D- glucopyranosyl-(1-->4)]-[alpha-L-rhamnopyranosyl-(1-->2)]-alpha-L- arabinopyranosyl] hederagenin) (1) and 3-O-[[beta-D-glucopyranosyl-(1-->4)]-[alpha-L-rhamnopyranosyl-(1-->2)]-a lpha-L- arabinopyranosyl] oleanolic acid (2) were also isolated from this plant. The structures of 3 and 4 were elucidated by FABMS and 2D NMR techniques. All these four saponins were mollusicidal, causing 70-100% mortality at 10 ppm against Biomphalaria alexandrina, a vector of Schistosoma mansoni in the Nile Valley. The saponins also showed antifungal activity against Cryptococcus neoformans and Candida albicans at minimal inhibitory concentrations of 8 and 16 micrograms/mL, respectively.

Reversed-phase high-performance liquid chromatography (HPLC) has been successfully applied to the determination of saponins in alfalfa root and aerial parts. It was shown that a single extraction of saponins with 30% MeOH followed by SPE C 18 Sep-Pak cleanup permits 91 and 96% recoveries from roots and aerial parts, respectively. The mostabundant saponins in roots were medicagenic acid glycosides substituted at the C3 position with glucuronic acid or glucose and hederagenin glycoside. The aerial parts contained mainly medicagenic acid glycosides substituted with glucuronic acid at C3, zanhic acid tridesmoside, and soyasaponin I

Quinoa is a hardy and nutritious South American food crop. Before consumption, aqueous extraction of quinoa seeds is necessary to remove bitter principles that have never been completely characterized. Guided by a brine shrimp lethality bioassay and a simple taste for bitterness, aqueous extracts of the whole seeds were fractionated chromatographically in an attempt to isolate the toxic/bitter principles. These undesirable compounds appear to be a mixture of saponins whose acidic hydrolysis gave oleanolic acid and hederagenin (3:1) as the only detectable saponin aglycons by GC/MS analysis. One of these saponins (quinoside A) has been identified as a tetraglycoside of hederagenin; the proposed structure (1) is named olean-12-ene-28-oic acid, 3,23-bis(O-beta-D-glucopyranosyloxy)-O-beta-D-glucopyranosyl-(1 leads to 3)-O-alpha-L-arabinopyranosyl ester (3 beta,4 alpha).

A new triterpenoid saponin, patrinia saponin H3 (3), was isolated from the aerial parts of Patrinia scabiosaefolia Fisch. and determined to be 3-O-beta-D-glucopyranosyl(1--3)-alpha-L-rhamnopyranosyl (1--2)-alpha-L-arabinopyranosyl hederagenin 28-O-alpha-L-rhamnopyranosyl (1--4)-beta-D-glucopyranosyl(1--6)-beta-D-glucopyranosyl ester on the basis of NMR and FAB MS experiments and acid hydrolysis.