The distribution and phylogenetic significance of desmethylsterols inChenopodium andAtriplex: Coexistence of Δ7- and Δ5 -sterols

Twenty-one species in the Chenopodiaceae were analyzed for sterol composition. In ten of eleven species ofChenopodium, the major desmethylsterols were Δ⁷-sterols accompanied by lower proportions of Δ⁵-sterols. InC. fremontii this pattern was reversed. The sterol profiles of five species ofAtriplex were characterized by the coexistence of Δ⁷- and Δ⁵-sterols in ratios of 0.3∶1 to 0.4∶1. MaleAtriplex plants contained higher proportions of Δ⁵-sterols than femaleAtriplex plants. OneCeratoides and twoSalicornia species contained Δ⁵-sterols as their predominant sterols.     

Diversity of sterol biosynthetic capacity in the caryophyllidae

The order Caryophyllales, along with its two associated orders, the Polygonales and Plumbaginales, comprise the angiosperm subclass Caryophyllidae. We have now characterized the sterol compositon of 231 members of this subclass. This includes 210 species and 21 cultivars in 108 genera within the 14 families of these three orders. From these data, clear differences in biosynthetic capability and putative relationships between taxa have been established. Members of the two monofamilial orders (Polygonales and Plumbaginales) contain Δ⁵-sterols in ratios typical of “main line” angiosperms. Members of families in the Caryophyllales contain Δ⁵-sterols, or Δ⁷-sterols or mixtures of Δ⁵- and Δ⁷-sterols. In the majority of species where Δ⁷-sterols are the dominant sterols produced, trace amounts to almost equal amounts of Δ⁵-sterols are also present. Replicate samples of many of these species have shown that the ratio of Δ⁵-sterols to Δ⁷-sterols in these species is stable over time and/or location. From these data, it appears that the conversion of Δ⁷-sterols to Δ⁵-sterols is highly regulated in the majority of species within this order. In these families, similarities in sterol composition correlate well with taxonomic relatedness. Relationships between these taxa with respect to biosynthetic capability can now be postulated. Based on a paper presented at the Symposium on Plant and Fungal Sterols: Biosynthesis, Metabolism and Function, held at the AOCS Annual Meeting, Baltimore, Maryland, April 1990.     

Sterol compositions of seeds and mature plants of family cucurbitaceae

The sterol fractions of the unsaponifiable lipids obtained from 32 seed and mature plant (leaves and stems, pericarp of the fruit, and roots) materials from the 12 generaApodanthera, Benincasa, Citrullus, Coccinea, Cucumis, Cucurbita, Gynostemma, Lagenaria, Luffa, Momordica, Sechium andTrichosanthes, of the family Cucurbitaceae were investigated by gas liquid chromatography (GLC) on an OV-17 glass capillary column. Among the 23 sterols with Δ⁵-, Δ⁷- and Δ⁸-skeletons identified by GLC, the Δ⁷-sterols were found to be the major sterols of most of the Cucurbitaceae investigated. The seed materials contained 24-ethyl-Δ⁷-sterols possessing Δ²⁵-bonds, i.e. 24-ethylcholesta-7,25-dienol and 24-ethylcholesta-7,22,25-trienol, whereas the mature plant materials contained 24-ethyl-Δ⁷sterols without a Δ²⁵-bond, i.e. 24-ethylcholest-7-enol and 24-ethylcholesta-7,22-dienol, as the most predominant sterols, with a few exceptions. The isolation and identification of 24α-ethylcholesta-8(14),22-dienol from the aerial parts ofCucumis sativus also is described.     

Cooccurrence of C-24 alkylated Δ7- and Δ5-Sterols in the leaves ofBeta vulgarisin the leaves ofBeta vulgaris

The 4-desmethylsterols from the leaves ofBeta vulgaris are a mixture of Δ⁷-sterols (71%) and Δ⁵-sterols (29%). The Δ⁷-sterols isolated are spinasterol (24α-ethylcholesta-7,22-dien-3β-ol; 45%), 22-dihydrospinasterol (24α-ethylcholest-7-en-3β-ol; 24%), and avenasterol (24-ethylcholesta-7,24(28)-dien-3β-ol; 1.5%). The Δ⁵-sterols isolated are sitosterol (24α-ethylcholest-5-en-3β-ol; 15%), 24ζ-ethylcholesta-5,22-dien-3β-ol (7.5%), and 24ζ-methylcholest-5-en-3β-ol (7%).     

Sterols of cucurbitaceae: The configurations at C-24 of 24-Alkyl-Δ5-,Δ7- and Δ8-sterols

The major sterols of the seeds ofBenincasa cerifera, Cucumis sativus, Cucurbita maxima, C. pepo andTrichosanthes japonica and of the mature plant tissues (leaves and stems) ofCitrullus battich, Cucumis sativus andGynostemma pentaphyllum of the family Cucurbitaceae were 24-ethyl-Δ⁷-sterols which were accompanied by small amounts of saturated and Δ⁵-and Δ⁸-sterols. The 24-ethyl-Δ^7,22,Δ^7,25(27) and Δ^7,22,25(27)-sterols constituted the predominant sterols for the seed materials, whereas the 24-ethyl-Δ⁷ and Δ^7,22-sterols were the major ones for the mature plant tissues. The configurations of C-24 of the alkylsterols were examined by high resolution¹H NMR and¹³C NMR spectroscopy. Most of the 24-methyl- and 24-ethylsterols examined which lack a Δ²⁵⁽²⁷⁾-bond (i.e., 24-methyl-, 24-methyl-Δ²²-, 24-ethyl- and 24-ethyl-Δ²² sterols) were shown to occur as the C-24 epimeric mixtures in which the 24α-epimers predominated in most cases. The 24-ethylsterols which possess a Δ²⁵⁽²⁷⁾ (i.e., 24-ethyl-Δ²⁵⁽²⁷⁾-and 24-ethyl-Δ^7,22,25(27)-sterols) were, on the other hand, composed of only 24β-epimers. The Δ⁸-sterols identified and characterized were four 24-ethyl-sterols: 24α-and 24β-ethyl-5α-cholesta-8,22-dien-3β-ol, 24β-ethyl-5α-cholesta-8,25(27)-dien-3β-ol and 24β-ethyl-5α-cholesta-8,22,25(27)-trien-3β-ol. This seems to be the first case of the detection of Δ⁸-sterols lacking a 4-methyl group in higher plants, and among the four Δ⁸-sterols the latter two are considered to be new sterols. The probable biogenetic role of the Δ⁸-sterols and the possible biosynthetic pathways leading to the 24α- and 24β-alkylsterols in Cucurbitaceae are discussed.     

The lipids of the common house cricket,Acheta domesticus L. III. Sterols

Sterols constitute 1.95% of the total extractable lipids ofAcheta domesticus L., of which 18% are esterified. The free sterols consist of cholestane-3β-ol (0.5%), Δ⁵-cholestene-3β-ol (83.5%), Δ⁷-cholestene-3β-ol (2.3%) Δ^5,7-cholestadiene-3β-ol (3%), Δ^5,22-cholestadiene-3β-ol (4%), Δ^5,7,22-cholestatriene-3β-ol (0.2%), campestane-3β-ol (0.03%), Δ⁵-campestene-3β-ol (1.0%), Δ⁷-campestene-3β-ol (trace), Δ^5,7-campestadiene-3β-ol (0.2%), stigmastane-3β-ol (0.09%), Δ⁵-stigmastene-3β-ol (2.1%), Δ⁷-stigmastene-3β-ol (0.04%), Δ^5,7-stigmastadiene-3β-ol (0.4%), Δ^5,22-stigmastadiene-3βol (0.1%). The same sterols are present in the esterified sterol fraction. Δ⁷-Sterols and Δ^5,7-sterols are present in significantly larger amounts in the esterified fraction than in the free sterol fraction. By a comparison with the sterols of the cricket food, it is clear thatA. domesticus is capable of removing methyl and ethyl groups from C-24 of sterols of the campestane and stigmastane type. The ability to introduce a Δ⁷ double bond into saturated and Δ⁵-sterols is indicated, and it is suggested that Δ⁷-sterols of the C₂₇, C₂₈, and C₂₉ sterol series may be intermediates in the conversion of Δ⁵-sterols to Δ^5,7-sterols. Associate Professor, Department of Chemistry, University of Michigan, Ann Arbor, Mich.; Alfred P. Sloan Foundation Fellow, 1968–68. Public Health Service Predoctoral Fellow, 1968–67.     

Effect of host sterols on the sterol composition and virulence of a nuclear polyhedrosis virus ofHeliothis zea

The type of sterol in the diet ofHeliothis zea affected not only the sterol composition of the insect larva but also the virulence and/or sterol composition of a single-nucleocapsid nuclear polyhedrosis virus (HzSNPV). This baculovirus, which was purified by differential and sucrose density gradient centrifugation, had a sterol content of 40 ng per 10⁶ polyhedra. When the sterol composition of HzSNPV was characterized by gas liquid chromatography, reversed phase-high performance liquid chromatography, mass spectrometry, proton nuclear magnetic resonance spectrometry and/or ultraviolet spectroscopy, the sterols in the virus were similar to those of the host. The HzSNPV isolated from larvae fed Δ_{5_}, Δ_{0_} or Δ_5,7-sterols contained primarily cholesterol, cholestanol or 7-dehydrocholesterol, respectively. Changes in the sterol composition of HzSNPV affected its LD₅₀, but not LT₅₀, in larvae containing Δ₅-sterols. The LD₅₀ of virus isolated from larvae containing Δ_{0_}, Δ_{5_} and Δ₇-sterols decreased from 275,423 to 32,359 to 5,012 polyhedra/larva, respectively. The latter virus was also more virulent than the one that was isolated from larvae containing Δ_5,7-sterol and had an LD₅₀ of 58,884 polyhedra/larva. In contrast, the LD₅₀ of an HzSNPV (Sandoz, Inc.) containing Δ₅-sterol was not affected by the presence of Δ_{5_}, Δ_{0_} or Δ_5,7-sterols in the tissues of the host (1,413; 1,288 and 355 polyhedra/larva, respectively). The results of this study indicate that the sterol composition ofH. zea can affect the sterol composition of HzSNPV and therefore may affect the ability of this biological control agent to control its economically important insect host.     

Changes in Δ5- and Δ7-sterols during germination and seedling development ofCucurbita maximaduring germination and seedling development ofCucurbita maxima

While seeds ofCucurbita maxima contain both Δ⁵- and Δ⁷-sterols, the former, which have been described earlier, now have been found to disappear during germination. This suggests that a function exists for the Δ⁵-compounds only in the early part of the life cycle ofC. maxima, unlike most of the other higher plants studied. In contrast to the Δ⁵-sterols, the level of Δ⁷-sterols increased during germination as well as during seedling development and maturation. The period of transition between germination and seedling development appeared to be of special importance in terms of sterol changes. This period represented a surge of sterol biosynthesis with an ontogenetic shift in sterol composition from approximately equal amounts of 24α- and 24β-ethyl stereochemistry to a predominance of the former. The sterol composition of the mature plants included only about 5% of the 24β-ethylsterols. The configurational relationships were demonstrated by high resolution¹H-NMR. The sterols of the mature plants were: 25(27)-dehydrochondrillasterol, 24β-ethyl-25(27)-dehydrolathosterol, avenasterol, spinasterol, 22-dihydrospinasterol and 24ξ-methyllathosterol. Based on the changes which occurred in the relative amounts of the Δ⁷-sterols, it did not appear that the Δ⁵-components were being converted to their Δ⁷-analogs. A portion of this work was presented at the meeting of the American Oil Chemists' Society in May, 1985 in Philadelphia.     

Review of chemical syntheses of 7-keto-Δ<Superscript>5</Superscript>-sterols

Steroids bearing ketone functionality at carbon-7 are found commonly in nature, and the most prevalent of these are the 7-keto-Δ⁵-sterols. These substances have diverse biological properties and are present in biological samples and food products. For the purpose of studying this class of oxysterols, many chemical methods, involving the chemical oxidation of Δ⁵-sterols to the corresponding 7-keto-Δ⁵-sterols derivatives have been developed to produce these compounds. We have undertaken a review and evaluation of chemical methods for the synthesis of these compounds and have endeavored to enhance one of these procedures to yield products for chemical and biological investigations.     

Sterols of the spongeTethya amamensis: Occurrence of (24E)-24-ethylidenecholesta-5,7-dienol, (24E)-24-propylidenecholesta-5,7-dienol,and (24Z)-24-propylidenecholesta-5,7-dienol

The spongeTethya amamensis, collected from Kagoshima Bay, Japan, contained at least 24 sterols, including Δ⁵-sterols (82.2% of total sterols) and Δ^{5, 7}-sterols (17.8%). The predominant sterols were cholesterol (29.0%), cholesta-5,22-dienol (13.8%), 24-methylcholesta-5,22-dienol (10.9%), 24-methylenecholesterol (8.3%), 24-methylcholesta-5,7,22-trienol (6.8%), 24-ethylcholest-5-enol (6.1%), and isofucosterol *4.1%). Combined gas liquid chromatography-mass spectrometry suggested the presence of 3 uncommon sterols, (24E)-24-ethylidenecholesta-5,7-dienol, (24E)-24-propylidenecholesta-5,7-dienol, and (24Z)-24-propylidenecholesta-5,7-dienol as minor components. The sterols ofT. amamensis also contained small amounts of 24-norcholesta-5,7,22-trienol and (24Z)-24-ethylidenecholesta-5,7-dienol.     

Developmental regulation of sterol biosynthesis inCucurbita maxima L.

Twenty-two sterols were identified by capillary gas chromatography and capillary gas chromatography/mass spectroscopy inCucurbita maxima grown under green-house conditions. Both whole plants and individual tissues (leaves, stems, roots, cotyledons, flowers) were analyzed at weekly intervals during the 12-week development of the plant. In whole plants, sterol accumulation parallels plant growth except for a period in the mid-life cycle where there is a reduction in the amount of sterol accumulated on a total sterol/plant and mg sterol/g dry wt basis. This reduction in the amount of sterol is coincident with the visual onset of flowering. During development, the percent contribution of each class of sterol (Δ^5_, Δ^7_, Δ^0_-sterols) remains relatively constant. However, the percent contribution of an individual sterol species varies depending on the tissue examined and the developmental period selected for analysis. While the young plant (<2 weeks) possesses elevated levels of sterols with the Δ²⁵⁽²⁷⁾-double bond, the trend was toward a reduction in the amounts of these sterols with development. Leaves and stems accumulate large quantities of 24ζ-ethyl-5α-cholesta-7,22-dien-3β-ol (7,22-stigmastadienol) and 24ζ-ethyl-5α-cholest-7-en-3β-ol (7-stigmastenol), while roots accumulate only 7,22-stigmastadienol as their principal sterol. Male flowers and roots were found to contain elevated levels of Δ^5_-sterols.     

Inhibition of C28 and C29 phytosterol metabolism by N,N-dimethyldodecanamine in the nematodecaenorhabditis elegans

Effects on the metabolism of campesterol and stigmasterol inCaenorhabditis elegans were investigated using N,N-dimethyldodecanamine, a known inhibitor of growth, reproduction and the Δ²⁴-sterol reductase of this nematode. 7-Dehydrocholesterol was the predominant sterol (51%) ofC. elegans grown in stigmasterol-supplemented media, whereas addition of 25 ppm amine resulted in a large decrease in the relative percentage of 7-dehydrocholesterol (23%) and the accumulation of a substantial proportion (33%) of Δ²⁴-sterols (e.g., cholesta-5,7,24-trienol) and Δ^22,24-sterols (e.g., cholesta-5,7,22, 24-tetraenol) but yielded no Δ²²-sterols. Dealkylation of stigmasterol byC. elegans proceeded in the presence of the Δ²²-bond; reduction of the Δ²²-bond occurred prior to Δ²⁴-reduction. Addition of 25 ppm amine to campesterol-supplemented media altered the sterol composition ofC. elegans by increasing the percentage of unmetabolized dietary campesterol from 39 to 60%, decreasing the percentage of 7-dehydrocholesterol from 26 to 12%, and causing the accumulation of several Δ²⁴-sterols (6%).C. elegans also was shown to be capable of dealkylating a Δ²⁴⁽²⁸⁾-sterol as it converted 24-methyl-enecholesterol to mostly 7-dehydrocholesterol. The proposed role of 24-methylenecholesterol as an intermediate between campesterol and 7-dehydrocholesterol was supported by the results.     

Dominance of Δ7-sterols in the family caryophyllaceaein the family caryophyllaceae

The predominant 4-desmethylsterols from the leaves of 12 species in 11 genera of the family Caryophyllaceae are 24-ethyl-Δ⁷-sterols. In eight species,Scleranthus annus L.,Paronychia virginica Spreng.,Lychnis alba Mill.,Silene cucubalus Wibel,Dianthus armeria L.,Gypsophilia paniculata L.,Saponaria officinales L. andMyosoton aquaticum (L.) Moench, the major sterols are spinasterol (24α-ethylcholesta-7,22E-dien-3β-ol) and 22-dihydrospinasterol (24α-ethylcholest-7-en-3β-ol), with spinasterol at more than 60% of the desmethylsterol in the latter six species. Both 24α-and 24β-ethyl-Δ⁷-sterols are present in two species,Minuartia caroliniana Walt. andSpergula arvensis L., which possess 24β-ethylcholesta-7,25(27)-dien-3β-ol and 24β-ethylcholesta-7,22E,25(27)-trien-3β-ol as well as spinasterol and 22-dihydrospinasterol.Cerastium arvense L.,C. vulgatum L. andArenaria serpyllifolia L. possess 24-alkyl-Δ⁵ and Δ⁷-sterols. These three species synthesize sitosterol (24α-ethylcholest-5-en-3β-ol), 24ζ-methylcholest-5-en-3β-ol, spinasterol, 22-dihydrospinasterol and the stanols, sitostanol (24α-ethyl-5α-cholestan-3β-ol) and 24ζ-methyl-5α-cholestan-3β-ol. Avenasterol (24-ethylcholesta-7,24(28)Z-dien-3β-ol) was also isolated from five species. Sterol biosynthetic capability may be a useful characteristic in examining the taxonomic relatedness of plants in the Caryophyllaceae.     

Diversity of sterol composition in the family chenopodiaceae

The predominant 4-desmethylsterols from the leaves of 13 species in eight genera of the family Chenopodiaceae are 24α-ethylsterols. In four species,Chenopodium ambrosioides L.,C. rubrum L.,Salicornia europaea L. andS. bigelovii Torr., the C-22(23) double bond is introduced into more than 70% of the 24α-ethylsterols producing spinasterol (24α-ethylcholesta-7,22E-dien-3β-ol) in the first two species and mixtures of spinasterol and stigmasterol (24α-ethylcholesta-5,22E-dien-3β-ol) in the latter species. The saturated side chain analogues predominate with more than 70% of the 24α-ethylsterols in eight species.Salsola kali L.,Suaeda linearis (Ell.) Moq.,Kochia scoparia (L.) Roth., andBassia hirsute (L.) Aschers. synthesize sitosterol (24α-ethylcholest-5-en-3β-ol), andAtriplex arenaria Nutt.,C. album L.,C. urbicum L. andC. leptophyllum Nutt. possess mixtures of sitosterol and 22-dihydrospinasterol (24α-ethylcholest-7-en-3β-ol). Sitostanol (24α-ethyl-5α-cholestan-3β-ol) was isolated fromSuaeda linearis as an 18% component of the total 4-desmethylsterol and in lesser amounts from four other species. In all species synthesizing 24-ethyl-Δ⁵-sterols, a 24ξ-methylcholest-5-en-3β-ol was also present at 1.0–20% of the total 4-desmethylsterol. Avenasterol [24-ethylcholesta-7,24(28)Z-dien-3β-ol], isofucosterol [24-ethylcholesta-5,24(28)Z-dien-3β-ol), cholesterol (cholest-5-en-3β-ol) and 24ξ-methyl-5α-cholestan-3β-ol also were isolated from several species. Species in the family Chenopodiaceae and the type genusChenopodium may be categorized into one of three groups based on sterol biosynthesis: the Δ⁷-sterol producers; the Δ⁵-sterol producers, and those producing mixtures of both Δ⁷- and Δ⁵-sterols in relatively fixed percentage compositions.     

Characterization of sterols in refined borage oil by GC-MS

Borage oil sterols were isolated by TLC and characterized using GC and GC-MS. Several diunsaturated Δ⁵-sterols, some of them not previously recorded in vegetable oils, were found. Of these, 24-methylcholesta-5,23-dienol and 24-ethylcholesta-5,23-dienol could be useful markers for borage oil. Two other diunsaturated Δ⁵-sterols that are rarely found in vegetable oils, 24-methylcholesta-5,24(25)-dienol and 24-ethylcholesta-5,24(25)-dienol, were identified. The diunsaturated C-24(28)-sterol, isofucosterol, was also found, as well as the monounsaturated Δ⁵-sterols campesterol and sitosterol. These are normally present in vegetable oils, which makes them unsuitable as markers for borage oil.     

The phylogenetic distribution of sterols in tracheophytes

The sterols of nine mature plant species in seven families ranging from the subphylum Lycopsida through the Filicopsida and the classes Gymnospermae and Angiospermae in the Pteropsida were structurally and stereochemically defined. Two plant categories were found. In the first, comprised byDryopteris (Thelypteris) noveboracensis, Polystichum acrostichoides, Dennstaedtia punctilobula, Osmunda cinnamomea, Ginkgo biloba, Cucurbita pepo, andKalmia latifolia, 24α-alkylsterols were dominant and were composed principally of 24α-ethylcholesterol (sitosterol) or (inCucurbita pepo) 24α-ethyllathosterol and itstrans-22-dehydro derivative (spinasterol). Depending on the species, small amounts of 24α-ethyl-trans-22-dehydrocholesterol (stigmasterol), 24α-methylcholesterol (campesterol), 24β-methylcholesterol (dihydrobrassicasterol, always less than campesterol), cholesterol, lathosterol, 24α-ethyllathosterol, 24ξ-methyllathosterol,trans-24-ethylidenelathosterol (Δ⁷-avenasterol), and (tentatively identified) 24-ethyl-24(25)-dehydrolathosterol were present.Spinacea oleracea was also confirmed as belonging to Category I, and, except as described in what follows, Category I represents all other configurationally investigated vascular plants. The second category of plants contained only 24β-ethylsterols. Only one species (Kalanchoe daigremontiana) belonging to the family Crassulaceae was found, but one other (the genusClerodendrum in the family Verbenaceae) is already known.K. daigremontiana contained 25(27)-dehydroclionasterol (clerosterol) and 25(27)-dehydroporiferasterol. The primitiveLycopodium complanatum was intermediate between Categories I and II; the sterols with a 24-C₂-group had only the 24α-configuration (sitosterol with some stigmasterol), but the principal sterols with a 24-C₁-group (ergosterol and dihydrobrassicasterol) possessed the 24β-configuration.C. pepo seeds, which are already known to contain principally 24β-ethylsterols, contrast sharply with our finding that tissue (pericarp of the fruit) from the mature plant contains only 24α-ethylsterols. This apparent evolutionary recapitulation (Category II to I) during development coupled with statistical dominance of Category II plants among the algae and fungi and of Category I plants in the Tracheophytes, and the existence of an intermediate type in the species examined from the lower Tracheophyte (Lycopsida) lead logically to the conclusion that the 24α-alkyl structure, especially 24-α-ethyl-Δ⁵-sterols (sitosterol and the much rarer stigmasterol) constitutes the most highly evolved type of 24-alkylsterol. By inference from our knowledge of biosynthesis, corroborated by the spectrum of sterols found here, the pathway [through Δ²⁴⁽²⁵⁾-sterol] leading to 24α-alkylsterol appears to be higher than the pathway [through Δ²⁵⁽²⁷⁾-sterols] which leads to 24β-alkylsterols. The sterols of these and other plants were also found amenable to classification according to their nuclear unsaturation (Δ⁵, A; Δ⁷, B; and Δ^5,7, C). Tracheophytes of Category A have been most frequently encountered, butC. pepo was shown to be of Category B throughout its ontogeny. While no Tracheophytes of pure Category C have been discovered,L. complanatum was shown to be of the mixed A-C-Type. Based on these facts and ideas, some previously suggested lines of botanical evolution are examined. The chemical data fail to verify a line from Magnoliales to theCucurbitaceae, from Magnoliales through Theales to Ericales, nor from Ranales to Saxifragales. However, they are consonant with a relationship between Cucurbitaceae and Theales and between Rosales and Lamiales. Triterpenoids found in various of the families studied included cycloartenol and friedelin. The spectroscopic properties of the latter are described.     

The role of phytosterols in host plant utilization by cactophilicDrosophila

The Cactus-Drosophila Model System of the Sonoran Desert consists of four endemic species ofDrosophila (D. mojavensis, D. nigrospiracula, D. mettleri andD. pachea) and five species of columnar cacti (agria, organpipe, saguaro, cardón and senita). Extensive collection records indicate that each cactus species has only one species ofDrosophila as the primary resident. The elimination of six of the twenty possible random combinations ofDrosophila species and cactus species can be attributed directly to phytosterols.Drosophila pachea has a strict requirement for Δ⁷-sterols such as 7-cholestenol and 7-campestenol. Since Δ⁷-sterols are found only in senita cactus,D. pachea cannot use agria, organpipe, saguaro or cardón as host plants. The lipid fractions of agria and organpipe are chemically similar and contain high concentrations of several 3β,6α-dihydroxysterols. Larval viability tests using chemical constitutents of organpipe cactus demonstrate that the sterol diols are toxic toD. nigrospiracula but not to the resident, species,D. mojavensis. Agria and organpipe are therefore unsuitable as host plants forD. nigrospiracula. These results suggest that phytosterols play a major role in determining host plant utilization by cactophilicDrosophila in the Sonoran Desert. Deceased.     

Sterols,methylsterols, and triterpene alcohols in threeTheaceae and some other vegetable oils

The unsaponifiables from threeTheaceae (Camellia japonica L.,Camellia Sasanqua Thunb., andThea sinensis L.) oils and alfalfa, garden balsam, and spinach seed oils and shea fat were separated into four fractions: sterols, 4-methylsterols, triterpene alcohols, and less polar compounds by thin layer chromatography. While the sterol fraction was the major one for the unsaponifiables from alfalfa and spinach seed oils, the triterpene alcohol fraction was predominant for the unsaponifiables from all other oils. The sterol, 4-methylsterol, and triterpene alcohol fractions were analyzed by gas chromatography. All the sterol fractions were alike in their compositions, consisting exclusively of Δ⁷-sterols, such as α-spinasterol and Δ⁷-stigmastenol as predominant components together with Δ⁷-avenasterol and 24-methylcholest-7-enol. Obtusifoliol, gramisterol (occasionally accompanied with cycloeucalenol), and citrostadienol, together with several other unidentified components, were found in the 4-methylsterol fractions from all of the oils except shea fat. The 4-methylsterol fraction from shea fat showed a characteristic composition containing a large proportion of unidentified components which had relative retention time greater than that of citrostadienol, while no citrostadienol was detected. β-Amyrin, lupeol, and butyospermol were major components of the triterpene alcohol fractions from most of the oils, but the fraction from spinach seed oil contained cycloartenol and 24-methylene-cycloartanol as predominant components. There is a close similarity in the compositions of unsaponifiables (sterols, 4-methylsterols, and triterpene alcohols) of the threeTheaceae oils. Two sterols, α-spinasterol and Δ⁷-stigmastenol, and five triterpene alcohols were isolated from tea seed oil. Moreover, five unidentified components beside parkeol, butyrospermol, α-amyrin, and lupeol were isolated from the triterpene alcohol fraction of shea fat.     

4-Desmethylsterols from the marine bivalveMacoma balthica

4-Desmethylsterols fromMacoma balthica L. were investigated by gas chromatography and gas chromatography/mass spectrometry after isolation by argentation and column chromatography. Twenty-three Δ⁰- and Δ⁵-sterols with saturated and unsaturated side chains were identified. It is suggested that sterols inM. balthica are derived from dietary sources. The great diversity of minor 4-desmethylsterols is likely to be due to their role as intermediates in the metabolism of dietary sterols.     

Differences in Sterol Composition between Male and Female Gonads of Dominant Limpet Species

The present study demonstrated here for the first time that there are statistically significant differences in sterol composition between male and female gonads of the dominant limpets Cellana grata and Cellana toreuma, which are intertidal gastropods. Among 11 different sterols identified in this study, unusually high levels (11.2–19.8% of total sterols) of the Δ⁸-sterols 5α-cholest-8-en-3β-ol (zymostenol) and 5α-cholesta-8,24-dien-3β-ol (zymosterol), which have never been reported in aquatic invertebrate gonads, were present in only the male gonads.