Biological activities and distribution of plant saponins.

Aging is an inevitable universal biological process, which can be characterized by a general decline in physiological function with the accumulation of diverse adverse changes and increased probability of death. Among several theories, oxidative stress/free radical theory offers the best mechanistic elucidation of the aging process and other age -related phenomenon. In the present paper , we discuss the aging process and have focused on the importance of some reliable markers of oxidative stress which may be used as biomarkers of the aging process.

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Markers of Oxidative Stress in Erythrocytes and Plasma During Aging in Humans

Polyphenolic compounds in cranberries have been investigated to determine their role in protection against cardiovascular disease and some cancers. Extracts of whole fruit were assayed for radical-scavenging activity and tumor growth inhibition using seven tumor cell lines. Selective inhibition of K562 and HT-29 cells was observed from a methanolic extract in the range of 16-125 microg/mL. Radical-scavenging activity was greatest in an extract composed primarily of flavonol glycosides. Seven flavonol glycosides were isolated and purified from whole fruit for further evaluation; the anthocyanin cyanidin 3-galactoside was also purified for comparison with the flavonoids. Three flavonol monoglycosides were newly identified by (13)C NMR as myricetin 3-alpha-arabinofuranoside, quercetin 3-xyloside, and 3-methoxyquercetin 3-beta-galactoside (isorhamnetin); the other four isolated were the previously identified myricetin 3-beta-galactoside, quercetin 3-beta-galactoside, quercetin 3-alpha-arabinofuranoside, and quercetin 3-alpha-rhamnopyranoside. These compounds were evaluated for 1,1-diphenyl-2-picrylhydrazyl radical-scavenging activity and ability to inhibit low-density lipoprotein oxidation in vitro. Most of the flavonol glycosides showed antioxidant activity comparable or superior to that of vitamin E; cyanidin 3-galactoside showed activity superior to that of the flavonoids as well as vitamin E or Trolox in both antioxidant assays.

Antioxidant activities and antitumor screening of extracts from cranberry fruit (Vaccinium macrocarpon).

Evolution of rosmarinic acid biosynthesis.

Fenugreek (Trigonella foenum-graecum) is used as a spice, vegetable and a medicinal plant. Since antioxidant properties have been linked to health benefits of natural products, such properties were studied in germinated fenugreek seeds which are considered to be more beneficial than dried seeds. Different fractions of the germinated seeds were used to determine their antioxidant potential at different levels. The assays employed were ferric reducing antioxidant power, radical scavenging by 1,1-diphenyl-2-picrylhydrazyl, ferrylmyoglobin/2,2'-azobis-3-ethylbenzthiazoline-6-sulfonic acid, pulse radiolysis, oxygen radical absorbance capacity and inhibition of lipid peroxidation in mitochondrial preparations from rat liver. An aqueous fraction of fenugreek exhibited the highest antioxidant activity compared with other fractions. As the quantity of phenolic and flavonoid compounds can be related to antioxidant activity, the contents from these extracts were measured. HPLC analysis was carried out to detect polyphenols, flavonoids and other components. This study reveals significant antioxidant activity in germinated fenugreek seeds which may be due partly to the presence of flavonoids and polyphenols.

Antioxidant properties of germinated fenugreek seeds

Fractionation of a methanolic extract of the leaves of Anthurium versicolor has resulted in the isolation of two main fractions, I and II. Both the extract and the fractions were assayed for their radical-scavenging activity by means of an in vitro test (bleaching of the stable 1,1-diphenyl-2-picrylhydrazyl radical) and showed a significant radical-scavenging effect. Subsequent chromatographic fractionation of the most active fraction, II, has led to the isolation and characterization, as major constituents, of four new flavone glycosides, acacetin 6-C-[α-l-rhamnopyranosyl-(1→3)-β-d-glucopyranoside] (1), acacetin 6-C-[β-d-xylopyranosyl-(1→6)-β-d-glucopyranoside] (2), acacetin 6-C-[β-d-apiofuranosyl-(1→3)-β-d-glucopyranoside] (3), and acacetin 8-C-[α-l-rhamnopyranosyl-(1→3)-β-d-glucopyranoside] (4), as well as vitexin (apigenin-8-C-β-d-glucopyranoside) and rosmarinic acid. The structures of 1−4 were determined using spectroscopic methods.

Phenolic Constituents and Antioxidant Activity of an Extract of Anthurium versicolor Leaves

Determination of the threshold odor concentration of main odorants in essential oils using gas chromatography–olfactometry incremental dilution technique

The isolation of seven triterpenoid saponins (1−7) is reported, among them three new natural products (1−3), together with three new ionol-derived glycosides (8−10) from the MeOH extract of the leaves of Amaranthus caudatus (Amaranthaceae). All structures were elucidated by spectroscopic methods, including the concerted application of one-dimensional (1H, TOCSY, 13C, and 13C DEPT NMR) and two-dimensional NMR techniques (DQF−COSY, HSQC, HMBC, ROESY). A comparative study of seeds and leaves has been also carried out. Keywords: Amaranthus caudatus; Amaranthaceae; leaves; food source; triterpenoid saponins; ionol glycosides; 1H and 13C NMR analysis

Studies on the Constituents of Amaranthus caudatus Leaves: Isolation and Structure Elucidation of New Triterpenoid Saponins and Ionol-Derived Glycosides

Susana Abdo

Papers

Phenolic Constituents and Antioxidant Activity of an Extract of Anthurium versicolor Leaves

Determination of the threshold odor concentration of main odorants in essential oils using gas chromatography–olfactometry incremental dilution technique

Studies on the Constituents of Amaranthus caudatus Leaves: Isolation and Structure Elucidation of New Triterpenoid Saponins and Ionol-Derived Glycosides

Isolation and structural characterization of glycosides from an anti-angiogenic extract of Monnina obtusifolia H.B.K.

Fungitoxic metabolites from Erigeron apiculatus.