Steroidal sapogenins. LVIII. Steroidal sapogenins from the Joshua tree

The Joshua tree,Yucca brevifolia, is distributed over parts of Arizona, California, Nevada, and Utah. A study of its steroidal sapogenins showed that the leaves contain practically none; the wood, small amounts of smilagenin; the seeds high amounts of hecogenin and tigogenin.     

Sapogenins of Yucca glauca seed pods

From the fruiting pods of Yucca glauca Nutt. devoid of seeds the following sapogenins have been isolated and identified: neo-tigogenin, hecogenin, gitogenin, manogenin, Δ⁹-manogenin and sarsasapogenin. A small amount of a material believed to be Δ²-desoxysarsasapogenin was also isolated and is apparently an artifact arising from the hydrolysis and extraction procedure. Manogenin and Δ⁹-manogenin have not been previously detected in Y. glauca, and Δ⁹-manogenin has not been reported in any Yucca species.     

Effect of chemical mutagens on steroidal sapogenins in Trigonella species

A two- to four-fold increase in the steroidal sapogenins (diosgenin and tigogenin) was observed in the plants and seeds obtained from seeds of T. corniculata and T. foenum-graecum treated with low concentrations of chemical mutagens (EMS, MMS and NaN₃). However, a decrease in their levels was recorded at high concentrations of the mutagens.     

Micropropagation and field performance of Yucca valida

Yucca valida is an important potential source of steroidal saponins closely related to Yucca schidigera, the species that is commercially exploited from the wild as a source of steroidal extracts. Neither of the species has been domesticated mainly because of their slow growth and long life span before harvesting. Here, we report a micropropagation method to generate isogenic or clonal lines for plantation purposes. Seventeen clonal lines were propagated and evaluated over a period of 26 months in an experimental plantation and compared with the performance of plants from seeds. The large variability found between the plants derived from seeds is manifested in the differences observed between the different clonal lines; however, these present a much smaller internal coefficient of variation than the one observed in the population of plants derived from seeds. Some clonal lines perform in a superior manner indicating that a process of selection and cloning can generate lines of fast growing individuals for plantations that can satisfy the demand for these materials without putting a natural resource at risk.     

Acyl-CoA: cholesterol acyltransferase inhibitory activity of ginseng sapogenins, produced from the ginseng saponins.

Ginseng sapogenins were produced from ginseng saponins, isolated from Korean ginseng roots. Ginseng saponins very mildly inhibited acyl-CoA:cholesterol acyltransferase (ACAT) in vitro, however, the sapogenins showed strong inhibitory activity on microsomal ACAT. Therefore, the sapogenins will be one of key ingredients of ginseng affected a lowering of the serum total cholesterol level.     

Infertile seeds ofYucca schottii: A beneficial role for the plant in the yucca-yucca moth mutualism?

Summary The yucca-yucca moth interaction is a classic case of obligate mutualism. Female moths pollinate and oviposit in the gynoecium of the flower; however, maturing larvae eat a fraction of the developing seeds. We studied within-fruit distributions of four seed types (fertile, infertile, eaten and uneaten seeds) in order to evaluate costs and benefits in aYucca schottii population in southeastern Arizona. We focused on how the spatial arrangement of seeds affected larval behaviour and, hence, the costs of the mutualism to the yucca. Infertile seeds were distributed throughout both infested and uninfested locules. Additionally, moth larvae feeding in a single locule preferred fertile seeds and even avoided infertile seeds and left the fruit significantly more often when they encountered infertile seeds. We suggest that, regardless of the cause of infertile seeds, they function as blocking units within seed locules and therefore reduce seed predation by moth larvae. We also suggest that, together with certain other fruit traits, the presence of infertile seeds promotes the evolutionary stability of this pollination mutualism.     

Sapogenins of Yucca glauca seeds

From the seeds of Yucca glauca Nutt., sarsasapogenin. markogenin. tigogenin. neo-tigogenin. neo-gitogenin, hecogenin and gloriogenin have been isolated and identified. Sarsasapogenin was the predominant sapogenin. Markogenin and gloriogenin have not been reported in leaves, roots or rhizomes of this species before. Small amounts of a sapogenin believed to be either diosgenin or yamogenin were also detected.     

Protective effect of ginseng sapogenins against 2,2'-azobis (1-aminopropane) dihydrochloride (AAPH)-induced LLC-PK₁ cell damage

The effect of ginseng sapogenins, aglycone parts of ginsenosides, against oxidative damage by radical generator, 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH), in renal epithelial LLC-PK(1) cells was investigated to identify the structural characteristics of sapogenins to have renoprotective effects. Of the tested sapogenins, Δ(20(21))-protopanaxatriol showed the strongest protective effect against the AAPH-induced LLC-PK(1) cell damage. Based on the structure and stronger activity of Δ(20(21))-protopanaxatriol than the other sapogenins, the hydroxyl group in C-6 and double bond in C-20(21) position were important for renoprotective effect of sapogenin against oxidative stress.     

CELL WALL CONFORMATION IN DRY SEEDS IN RELATION TO THE PRESERVATION OF STRUCTURAL INTEGRITY DURING DESICCATION

Internal tissues of mature air-dry seeds, prepared anhydrously for observation with the scanning electron microscope, exhibit cell wall structure which is different from that observed in aqueously fixed (hydrated) seed tissues. In a wide range of dry seeds observed (six members of the Cucurbitaceae, two species of Yucca, Hibiscus esculentus, Phaseolus vulgaris, and Helianthus annuus) cell walls exhibit a unique collapsed structure. The manner of cell wall collapse is characteristic for a given species and ranges from a highly regular folding pattern in the Cucurbitaceae to random wrinkling of the walls in Hibiscus. Evidence suggests that the regular patterns of wall folding may result from a mechanism located in the cell wall. Wall collapse in dry seeds is explained as a means of coordinating wall and protoplasmic shrinkage during desiccation and is thought to be essential for preserving the structural integrity of the tissue by conserving intercellular communication and plasmalemma-cell wall association. Implications of these observations may relate to retention of viability in seeds.     

Pollen dispersal in Yucca filamentosa (Agavaceae): the paradox of self-pollination behavior by Tegeticula yuccasella (Prodoxidae)

We investigated pollen dispersal in an obligate pollination mutualism between Yucca filamentosa and Tegeticula yuccasella. Yucca moths are the only documented pollinator of yuccas, and moth larvae feed solely on developing yucca seeds. The quality of pollination by a female moth affects larval survival because flowers receiving small amounts of pollen or self-pollen have a high abscission probability, and larvae die in abscised flowers. We tested the prediction that yucca moths primarily perform outcross pollinations by using fluorescent dye to track pollen dispersal in five populations of Y. filamentosa. Dye transfers within plants were common in all populations (mean ± 1 SE, 55 ± 3.0%), indicating that moths frequently deposit self-pollen. Distance of dye transfers ranged from 0 to 50 m, and the mean number of flowering plants between the pollen donor and recipient was 5 (median = 0), suggesting that most pollen was transferred among near neighbors. A multilocus genetic estimate of outcrossing based on seedlings matured from open-pollinated fruits at one site was 94 ± 6% (mean ± 1 SD). We discuss why moths frequently deposit self-pollen to the detriment of their offspring and compare the yucca-yucca moth interaction with other obligate pollinator mutualisms in which neither pollinator nor plant benefit from self-pollination.     

Immunomodulatory effects of two sapogenins 1 and 2 isolated from Luffa cylindrica in Balb/C mice

Two Triterpenoids (sapogenins 1 and 2) isolated from Luffa cylindrica were subjected to immunomodulatory activity in male Balb/c mice. Mice were treated with three doses of sapogenins 1 and 2 (10, 30 and 100 mg/kg) and levamisole (2.5 mg/kg) used as a standard reference drug for 15 days. Immune responses to T-dependent antigen SRBCs were observed using parameters like HA, PFC, DTH, lymphocyte proliferation and phagocytosis. As regards these parameters, sapogenins 1 and 2 elicited a significant increase in the HA, PFC and DTH response at dose 10 mg/kg (P<0.01) and 100 mg/kg (P<0.001), respectively. Sapogenins 1 and 2 also showed significant dose-dependent decrease and increase in lymphocyte proliferation assay and phagocytic activity of macrophages. Overall, sapogenins 1 and 2 showed dose relative immunostimulatory effect on in vivo immune functions in mice.     

Saponins of two alfalfa cultivars

A saponin mixture was separated from the forage of DuPuits and Lahontan cultivars of Medicago sativa and found to contain about 30 saponins. Glucose, galactose, xylose, arabinose and rhamnose, were the principal sugars; the sapogenins comprised soyasapogenols A and B, lucernic acid, medicagenic acid together with four unidentified but related triterpenoids. Medicagenic acid was the predominant sapogenin of the DuPuits cultivar, whereas soyasapogenot A was prominent in Lahontan saponins. Galactose was found in the saponins of monocarboxylic or nonacidic sapogenins but was absent in those containing dicarboxylic sapogenins, such as medicagenic acid.     

黄精属植物甾体皂苷的分子进化及其化学分类学意义

在植物化学研究的基础上,按分子的氧化水平将黄精属植物的甾体皂苷元分为5个等级,通过对不同氧化水平之间分子进化规律的分析,讨论黄精属植物甾体皂苷元分子进化与形态特征的相关性。结果表明,较原始的类群通常含有氧化水平较低的甾体皂苷,如：互叶系（Ser. Alternifolia）;而氧化水平较高的甾体皂苷类型则大多存在于较进化的类群中,如：轮叶系（Ser. Verticillata）。这一植物化学分类学的观点有助于黄精属植物的系统分类。     

Investigations on the content of steroidal alkaloids and sapogenins withinSolanum sect.Solanum ( = sect.Morella) (Solanaceae)

Plant material of 55 strains from 32 species ofSolanum sect.Solanum ( = sect.Morella) has been investigated for the content of steroidal alkaloids and sapogenins. The leaf-extracts of all species contain diosgenin resp. tigogenin or both together in considerable amount. On the contrary the characteristic steroidal alkaloid solasodine was absent in these samples. For 29 species the presence of steroidal sapogenins has been proved for the first time. In unripe fruits, however, solasodine could be detected in most of the species examined. New occurences of solasodine are reported for seven further species. These chemical results may contribute to a better comprehension of the difficult genusSolanum.—Ontogenetic studies on different organs ofS. atriplicifolium show the relationship between accumulation of steroidal compounds and plant maturity.     

Morphogenesis in Yucca schidigera Roezl. Root Organ Cultures

Root development in suspension cultures of Yucca schidigerawas light-mediated. The green cultures consisted of roots, smalltissue aggregates and suspension cells. Roots possessed an apicalmeristem with a root cap, meristematic region and region ofdifferentiating tissues. Phloem, xylem vessels and tracheidsoccurred in discrete polyarch vascular bundles. Xylary wallthickening was reticulate, and endodermis and pericycle werepresent. Roots of intact Y. schidigera plants had a similardistribution of vascular tissues. Dark-grown cultures were cream-colouredand contained only lobed tissue aggregates and suspension cells. Yucca schidigera Roezl., tissue cultures, morphogenesis, root organ, light/dark     

THE TUBERS,SAPOGENINS, AND VIRUS RESISTANCE OF DIOSCOREA SPECIES HYBRIDS

Dioscorea species differ in sapogenin content, tuber size and shape, and virus resistance. The amount and type of sapogenins in tubers of F₁ hybrids among four sapogenin-bearing and one other Dioscorea species were determined chromatographically. Characteristics of the tuber and resistance to a virus were observed and compared to those of the parents. The presence of particular sapogenins appeared to be a dominant trait modified by minor genes from either parent. Other traits appeared to be determined by many genes. Heterosis was expressed in some hybrids by superior yields and excellent virus tolerance. Some of the hybrids could be used as clonal varieties, but none contained the desired keto sapogenins except in mixtures with diosgenin.     

Furostanol saponins from Yucca gloriosa L. rhizomes

Two new and one known furostanol saponins were isolated from the rhizomes of Yucca gloriosa. The structures of the isolated compounds were established by detailed spectroscopic analysis (1D-, 2D NMR, ESI-MS, HR-MALDI-MS). The glycosidic profile of Y. gloriosa in comparison to that of Yucca schidigera, the well known commercial source of saponins, is briefly discussed. The similarity between the two species regarding the high steroidal content suggests that it might be possible to use Y. gloriosa for the same applications as Y. schidigera.     

Triterpenoids of Colletia spinosissima

The neutral components from the stems of Colletia spinosissima Gmel. include lupenone, sitosterol lupeol, daucosterine. Acid hydrolysis of the glycoside fraction afforded ethyl sinapate and two homologous degradation products from the corresponding sapogenins. Mild hydrolysis of the glycoside fraction afforded the intact sapogenins, which have been tentatively assigned the structures (VIIb) and (VIIIb). The chemistry of the latter compounds has been explored.     

Genetic consequences of specialization: yucca moth behavior and self-pollination in yuccas

Reciprocal specialization in interspecific interactions, such as plant-pollinator mutualisms, increases the probability that either party can have detrimental effects on the other without the interaction being dissolved. This should be particularly apparent in obligate mutualisms, such as those that exist between yucca and yucca moths. Female moths collect pollen from yucca flowers, oviposit into floral ovaries, and then pollinate those flowers. Yucca moths, which are the sole pollinators of yuccas, impose a cost in the form of seed consumption by the moth larvae. Here we ask whether there also is a genetic cost through selfish moth behavior that may lead to high levels of self fertilization in the yuccas. Historically, it has been assumed that females leave a plant immediately after collecting pollen, but few data are available. Observations of a member of the Tegeticula yuccasella complex on Yucca filamentosa revealed that females remained on the plant and oviposited in 66% of all instances after observed pollen collections, and 51% of all moths were observed to pollinate the same plant as well. Manual cross and self pollinations showed equal development and retention of fruits. Subsequent trials to assess inbreeding depression by measuring seed weight, germination date, growth rate, and plant mass at 5 months revealed significant negative effects on seed weight and germination frequency in selfed progeny arrays. Cumulative inbreeding depression was 0.475, i.e., fitness of selfed seeds was expected to be less than half that of outcrossed seeds. Single and multilocus estimates of outcrossing rates based on allozyme analyses of open-pollinated progeny arrays did not differ from 1.0. The discrepancy between high levels of behavioral self-pollination by the moths and nearly complete outcrossing in mature seeds can be explained through selective foreign pollen use by the females, or, more likely, pollen competition or selective abortion of self-pollinated flowers during early stages of fruit development. Thus, whenever the proportion of pollinated flowers exceeds the proportion that can be matured to ripe fruit based on resource availability, the potential detrimental genetic effects imposed through geitonogamous pollinations can be avoided in the plants. Because self-pollinated flowers have a lower probability of retention, selection should act on female moths to move among plants whenever moth density is high enough to trigger abortion. Received: 18 March 1996 \Accepted: 30 July 1996     

Variation in the costs and benefits of mutualism: the interaction between yuccas and yucca moths

Summary Yucca moths are both obligate pollinators and obligate seed predators of yuccas. I measured the costs and net benefits per fruit arising for eight species of yuccas from their interaction with the yucca moth Tegeticula yuccasella. Yucca moths decrease the production of viable seeds as a result of oviposition by adults and feeding by larvae. Oviposition through the ovary wall caused 2.3–28.6% of ovules per locule to fail to develop, leaving fruit with constrictions, and overall, 0.6–6.6% of ovules per fruit were lost to oviposition by yucca moths. Individual yucca moth larvae ate 18.0–43.6% of the ovules in a locule. However, because of the number of larvae per fruit and the proportion of viable seeds, yucca moth larvae consumed only 0.0–13.6% of potentially viable ovules per fruit. Given both oviposition and feeding effects, yucca moths decreased viable seed production by 0.6–19.5%. The ratio of costs to (gross) benefits varied from 0% to 30%, indicating that up to 30% of the benefits available to yuccas are subsequently lost to yucca moths. The costs are both lower and more variable than in a similar pollinator-seed predator mutualism involving figs and fig wasps.There were differences between species of yuccas in the costs of associating with yucca moths. Yuccas with baccate fruit experienced lower costs than species with capsular fruit. There were also differences in costs between populations within species and high variation in costs between fruit within populations. High variability was the result of no yucca moth larvae being present in over 50% of the fruit in some populations, while other fruit produced up to 24 larvae. I present hypotheses explaining both the absence and high numbers of larvae per fruit.