[Steroid furostanol glycosides: a new class of natural adaptogenes (review)].

The present review summarizes experimental data revealed while studying the mechanism of the adaptogenic effect of furostanol glycosides (FG) extracted from Dioscorea deltoidea Wall cell culture under the conditions of biotic stress in tomato plants Lycopersicon esculenium Mill. induced by the gall nematode Meloidogyne incognita Kofoid et White. Comparison of changes in isoprene content (phytosterines, tomatin, and carotenoids) and in the rate of oxidative processes in the leaves and roots of intact and treated plants evidence that FG cause nonspecific defense reactions resulting in the formation of systemic acquired resistance. This formation is presented by the enhancement in photosynthetic apparatus pigment fund, pigments of the violaxanthin cycle in particular, by activation of processes related to POL, and by increase in peroxidase activity-enzyme of antioxidant protection.

[Adaptogenic effects of furostanol glycosides of Dioscorea deltoidea wall on oxidative processes in tomato plants in biotic stress].

The effect of furostanol glycosides of cell culture of Dioscorea deltoidea Wall on oxidative processes in tomato plants subjected to invasion with the gall nematode Meloidogyne incognita Kofoid et White was studied. We showed that furostanol glycosides induce a nonspecific defensive response in plants. Exposure of cell membranes to furostanol glycosides cause rearrangements in fatty acids resulting in the formation of conjugated dienes, which makes molecules thermodynamically more stable under stress conditions. The study of changes in the activity of peroxidases of intact plants and plants affected with the nematode, which were treated with furostanol glycosides, showed that the protective effect of the guaiacol-dependent peroxidase is more long-term than the effect of the benzidine-dependent peroxidase.

[Interaction between structure of plant steroids and their effect on phytonematodes]. / Vzaimosviaz' mezhdu stroeniem rastitel'nym steroidov i ikh deistviem na fitonematod.

The effects of certain plant steroids of the groups of furostanol glycosides, glycoalkaloids, and alpha-ecdysone on growth and development of phytoparasitic nematodes were studied. It was shown using an experimental system including tomato, Lycopersicon esculentum Mill., and root-knot nematode, Meloidogyne incognita Kofoid et White, that steroid molecule had significant nematicidic activity if it contained a carbohydrate moiety and an additional heterocycle in the steroid core. The maximum nematicidic activity is inherent in glycosides containing chacotriose as the carbohydrate moiety of the molecule. Some compounds tested in this work could be used for protecting plants against phytoparasitic nematodes.

[Photosynthetic pigments of tomato under conditions of biotic stress and effects of furostanol glycosides]. / Fotosinteticheskie pigmenty rastenii tomatov v usloviiakh bioticheskogo stressa i deistvie na nikh furostanolovykh glikozidov.

Adaptogenic effect of furostanol glycosides (FG) on biosynthesis of photosynthetic pigments in tomato plants (Lycopersicon esculentum Mill.) were studied under conditions of biotic stress caused by root-knot nematode (Meloidogyne incognita Kofoid et White). Treatment of plants with 5 x 10(-4) M FG was accompanied by an increase in the rate of biosynthesis of pigments (particularly, chlorophyll b and carotenoids), which was observed against the background of a decrease in the relative contribution of beta-carotene and an increase in the relative contribution of pigments of violaxanthin cycle (VXC) to the overall pool of carotenoids. It was suggested that FG stimulated phytoimmunity by shifting metabolism of carotenoids toward enhanced biosynthesis of VXC pigments. These pigments play a protective role and facilitate stabilization of photosynthetic apparatus, which is particularly important under stress conditions.

[Role of isoprenoid compounds in plant adaptation to biogenic stress caused by parasitic nematodes]. / Rol' izoprenoidnykh soedinenii v adaptatsii rasteni k biogennomu stressu, vyzbannomu paraziticheskimi nematodami.

Parasitic nematodes are considered as a biogenic stress factor in plants. The effects of various plant isoprenoids, including mono-, sesqui-, di-, and triterpenoids, sterols, and steroid glycosides, on parasitic nematodes are reviewed. Certain isoprenoids can be placed in the class of natural plant adaptogens.

A new alternative non-mevalonate pathway for isoprenoid biosynthesis in eubacteria and plants.

Data concerning the discovery of an alternative non-mevalonate pathway for isoprenoid biosynthesis leading to isopentenyl diphosphate formation are reviewed. This pathway has been discovered in experiments with several eubacteria producing triterpenoids of the hopane series. 13C-labeled acetate, glucose, and triose phosphates were used as precursors. The 13C-labeling patterns in isoprenoids were studied by 13C-NMR spectrometry. In eubacteria the universal C5 precursor--isopentenyl diphosphate--did not appear to form via the classical acetate/mevalonate pathway, but via a novel glyceraldehyde 3-phosphate/pyruvate pathway. It is postulated that the condensation of the C2 unit formed as a result of pyruvate decarboxylation with the C3 unit (glyceraldehyde 3-phosphate) and the next transposition leads to the formation of the branched C5 precursor--isopentenyl diphosphate. In Scenedesmus obliquus not only all plastid isoprenoids (carotenoids and prenyl side chains of chlorophylls and plastoquinone-9) were formed via this novel pathway, but also the non-plastid cytoplasmic sterols. In higher plants the plastid isoprenoids were formed via the glyceraldehyde 3-phosphate/pyruvate pathway, while the cytoplasmic sterols were formed via the acetate/mevalonate pathway.

[Composition and biological activity of steroid glycosides from a suspended culture of Dioscorea deltoidea Wall cells]. / Sostav i biologicheskaia aktivnost' steroidnykh glikozidov iz suspenzionnoi kul'tury kletok Dioscorea deltoidea Wall.

Two major steroid spirostanol glycosides (oligospirostanosides): deltoside (melting point, 296 degrees C, [alpha]D10:-90.8 degrees C (c 5.0,Py) and dioscine (melting point, 285-285 degrees C, [alpha]D10:-106.5 degrees C (c 5.0, Py) and a minor glycoside diosgenin-3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranoside were isolated form cell suspensions of Discorea deltoidea after fermentation with beta-glucosidase. The cell suspensions contained these glycosides as the furostanol analogs (oligofurostanosides) deltoside, protodioscine, and delta 5-furosten-3 beta,22,26-triol-3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D- glucopyranoside. The native oligofurostanosides isolated from D. deltoidea cell suspensions have a high biological activity and can be used as phytobiostimulators in medicine, veterinary, and agriculture.

[Successes in studying the physiological activity of terpenoids and steroids]. / Uspekhi v izuchenii fiziologicheskoi aktivnosti terpenoidov i steroidov.

Data concerning the structure and function of prenyl proteins and peptides of fungi and animals are reviewed. There exist proteins that are posttranslationally modified by thioether-linked farnesyl- or geranylgeranyl groups; the modification affects the cysteine residue near the C-terminus. Prenylation increases hydrophobicity and is expected to promote protein binding to membrane lipids or other hydrophobic proteins. Isopentenyl-adenylated proteins mediate isoprenoid control over DNA synthesis and are involved in regulation of cell proliferation in animals. Sterols of fungi and plants play a role in regulation of the membrane structure as well as in proliferation. The significance biologically active terpenoids for biotechnology, medicine, and agriculture is discussed.

[Steroid saponins from the rhizomes of Dioscorea caucasica Lipsky]. / Steroidnye saponiny iz kornevishch dioskorei kavkazskoi Dioscorea caucasica Lipsky.

Deltonin or diosgenin-3-0-alpha-L-rhamnopyranosyl-(1----2)-[beta-D- glucopyranosyl-(1----4)-]-beta-D-glucopyranoside, m. p. 282 degrees, [alpha] 20(546): -96.4 degrees (c 1, pyridine) and a new oligospirostanoside beta-D-glucopyranosyl-(1----3'' Glcp)-deltonin, m. p. 242-243 degrees, [alpha]20(546): -63.7 degrees (c 1, pyridine) were isolated from rhizomes of Dioscorea caucasica.

[Action of the steroid glycoside deltonin on the bacterial membranes of Micrococcus lysodeikticus]. / Deistvie steroidnogo glikozida del'tonina na bakterial'nye membrany Micrococcus lysodeikticus.

A slight detergent-like effect of steroid glycoside deltonine from Dioscorea deltoidea on the bacterial membranes of Micrococcus lysodeikticus was detected which resulted in the breaking of the osmotic barrier of protoplasts and in the loss from the membranes of small fragments containing the dehydrogenases of the respiratory chain but without cytochromes. These small fragments still retained the membrane structure.

[Fungiotoxic properties of steroid saponins from the rhizomes of deltoid dioscorea]. / Izuchenie fungitoksicheskikh svoistv steroidnykh saponinov iz kornevishch dioskorei del'tovidnoi

Experiments were carried to test the fungitoxic effect of steroid glycosides--deltoside and deltonine--(representatives of spiro and furostanol saponins) on the growth of conidia F. solani and zoospores Ph. infestans. Both saponins inhibited the growth of test-objects in a different degree. A correlation between the membranolytic effect of the tested compounds on the mobile envelope-free zoospores of F. solani and their capacity to form cholesterol complexes was established. There was no direct relationship between the degree of fungal toxicity and membranolytic activity of the compounds.

[Isolation and properties of saponins from rhizomes of Dioscorea deltoidea Wall]. / Vydelenie i svoistva saponinov iz kornevishch Dioscorea deltoidea Wall

From the rhizome D. deltoidea a new trisaccharide of diosgenine has been isolated. This compound is diosgenine-3 (alpha-L-rhamnopyranosyl (1-->2gl)-beta-D-glucopyranosyl-(1-->4 gl)-beta-D-glucopyranoside. This trisaccharide has been termed deltonine. The rhizome D. deltoidea has also displayed furostanolic tetrasaccharide which is a mixture of delta5-furostene-3beta, 22, 26-triol-3beta-deltotrioside-26beta-D-glucopyranoside and its alkoxyderivative. This tetrasaccharide has been termed deltoside. The rhizome has also small quantities of diosgenine-3-beta-D-glucopyranosyl (1-->4)-beta-D-glucopyranoside.