Effect of Blanching Pomegranate Seeds on Physicochemical Attributes, Bioactive Compounds and Antioxidant Activity of Extracted Oil

This study investigated the effect of blanching pomegranate seeds (PS) on oil yield, refractive index (RI), yellowness index (YI), conjugated dienes (K232), conjugated trienes (K270), total carotenoid content (TCC), total phenolic compounds (TPC) and DPPH radical scavenging of the extracted oil. Furthermore, phytosterol and fatty acid compositions of the oil extracted under optimum blanching conditions were compared with those from the oil extracted from unblanched PS. Three different blanching temperature levels (80, 90, and 100 °C) were studied at a constant blanching time of 3 min. The blanching time was then increased to 5 min at the established optimum blanching temperature (90 °C). Blanching PS increased oil yield, K232, K270, stigmasterol, punicic acid, TPC and DPPH radical scavenging, whereas YI, β-sitosterol, palmitic acid and linoleic acid were decreased. The RI, TCC, brassicasterol, stearic acid, oleic acid and arachidic acid of the extracted oil were not significantly (p > 0.05) affected by blanching. Blanching PS at 90 °C for 3 to 5 min was associated with oil yield, TPC and DPPH. Blanching PS at 90 °C for 3 to 5 min will not only increase oil yield but could also improve functional properties such as antioxidant activity, which are desirable in the cosmetic, pharmaceutical, nutraceutical and food industries.

Obtusifoliol related steroids from Euphorbia sogdiana with cell growth inhibitory activity and apoptotic effects on breast cancer cells (MCF-7 and MDA-MB231)

From the aerial parts of Euphorbia sogdiana Popov, obtusifoliol (1) and two related steroids (2-3) have been isolated and characterized along with a known cycloartane derivative (4). The chemical structure of the obtusifoliol-related compounds, obtained by 1D and 2D NMR, and MS measurements, have been determined as: 3β,7α-dihydroxy-4α,14α-dimethyl-5α-ergosta-8,24(28)-diene-11-one (2) and 3β-hydroxy-4α,14α-dimethyl-5α-ergosta-8,24(28)-diene-1-one (3). Compound 2 has been previously isolated from Euphorbia chamaesyce while compound 3 was never reported before. The isolated compounds 1-4 were subjected to cytotoxic tests on the breast cancer cells, MCF-7 and MDA-MB231. Further pharmacological tests on the more active compounds 2 and 3 indicated their action to be related to cell growth inhibitory activity and apoptotic effects on the tested cells.

Structure Revision of (22E)-24-Methylcholesta-8(14),22-diene- 3β,5α,6β,7α-tetraol from the Marine-Derived Fungus Penicillium sp

Careful reexamination of the published ¹H- and ¹³C-NMR spectral data of (22E)-24-methylcholesta-8(14),22-diene-3β,5α,6β,7α-tetraol (1), isolated from the marine-derived fungus Penicillium sp., indicates that, in reality, the compound is 5α,6α-epoxy-(22E,24R)-24-methylcholesta-8(14),22-diene-3β,7α-diol (5).

New Bioactive Semisynthetic Derivatives of 31-Norlanostenol and Obtusifoliol from Euphorbia officinarum

Fifteen semisynthetic terpenoid derivatives from the major latex components of Euphorbia officinarum have been evaluated against the insect pest Spodoptera littoralis, two species of protozoan parasites, Trypanosoma cruzi and Leishmania infantum, and also against insect Sf9 and mammalian CHO cells to test their selective cytotoxicity. Our results showed that 40% of the test substances were postingestive toxicants to S. littoralis. All the tested derivatives had cytotoxic effects on insect-derived Sf9 cells, whereas mammalian CHO cells were affected by a lower number of compounds (47%). Furthermore, 87% of the test compounds had antiparasitic effects on both L. infantum and T. cruzi, with some of them being selective parasite toxicants.

Anti-Tumor and Immune Enhancing Activities of Rice Bran Gramisterol on Acute Myelogenous Leukemia

Background

Acute myelogenous leukemia (AML) is a cancer of the blood that most commonly affects human adults. The specific cause of AML is unclear, but it induces abnormality of white blood cells that grow rapidly and accumulate in bone marrow interfering with the production and functions of the normal blood cells. AML patients face poor prognosis and low quality of life during chemotherapy or transplantation of hematopoietic stem cells due to the progressive impairment of their immune system. The goal of this study is to find natural products that have the potential to delay growth or eliminate the abnormal leukemic cells but cause less harmful effect to the body’s immune system.

Methods and Findings

The unsaponified fraction of Riceberry rice bran (RBDS) and the main pure compound, gramisterol, were studied for cytotoxicity and biological activities in WEHI-3 cells and in the leukemic mouse model induced by transplantation of WEHI-3 cells intraperitoneally. In the in vitro assay, RBDS and gramisterol exerted sub-G1 phase cell cycle arrest with a potent induction of apoptosis. Both of them effectively decreased cell cycle controlling proteins (cyclin D1 and cyclin E), suppressed cellular DNA synthesis and mitotic division, and reduced anti-apoptosis Bcl-2 protein, but increased apoptotic proteins (p53 and Bax) and activated caspase-3 enzyme in the intrinsic cell death stimulation pathway. In leukemic mice, daily feeding of RBDS significantly increased the amount of immune function-related cells including CD3⁺, CD19⁺, and CD11b⁺, and elevated the serum levels of IFN-γ, TNF-α, IL-2, and IL-12β cytokines, but suppressed IL-10 level. At the tumor sites, CD11b⁺ cells were polarized and became active phagocytotic cells. Treatment of mice normal immune cells with gramisterol alone or a combination of gramisterol with cytokines released from RBDS-treated leukemic mice splenocytes culture synergistically increased pSTAT1 transcriptional factor that up-regulated the genes controlling cell survival and function. Phosphorylation of STAT1 was absent in WEHI-3. Instead, similar treatments significantly decreased pSTAT3 signaling that regulates transcription of genes controlling tumor growth and proliferation.

Conclusions

Rice bran gramisterol possesses a promising anti-cancer effect against a tumor of white blood cells and induces the production of anti-cancer immune-related cytokines. Gramisterol induces cell cycle arrest and apoptosis via suppression of pSTAT3 signaling control of tumor cells’ growth and progression. Gramisterol increased IFN-γ production and prevented the dysfunctional immune system of leukemic mice by enhancing pSTAT1 transcription signal controlling proliferation and functions of hematopoietic cells in the spleen. Together with IFN-γ, gramisterol efficiently facilitates leukemic mice immune system modulation leading to improvement of the AML condition. Administration of RBDS containing gramisterol potentiates immune recovery of leukemic mice and extends their survival. This finding encourages the medicinal application of rice bran gramisterol as a palliative treatment or an alternative agent for future drug development against AML.

(1)H and (13)C NMR assignments for two new steroids from the coral Chromonephthea sp

Two new steroids isolated from EtOH extracts of the South China Sea soft coral Chromonephthea sp. were identified. One-dimensional (1D) and two-dimensional (2D) NMR experiments including COSY, HSQC, HMBC and NOESY were used for the determination of their structure.

Sinugrandisterols A-D, trihydroxysteroids from the soft coral Sinularia grandilobata

Four new trihydroxysteroids, sinugrandisterols A-D (1-4), have been isolated from the CH(2)Cl(2)-soluble fraction of the EtOH extract of Sinularia grandilobata. The structures of these metabolites were determined on the basis of spectroscopic (IR, MS, and 1D and 2D NMR) analysis. The cytotoxicity of 1-4 toward a limited panel of cancer cell lines is also reported.

Steroidal constituents of rice (Rryza sativa) hulls with algicidal and herbicidal activity against blue-green algae and duckweed

Two new compounds, 14-methyl stigmast-9(11)-en-3alpha-ol-3beta-D-glucopyranoside (1) and cholest-11-en-3beta, 6beta, 7alpha, 22beta-tetraol-24-one-3beta-palmitoleate (2), along with the known compound beta-sitosteryl-3beta-D-glucopyranosyl-6'-linoleiate (3), were isolated from the methanolic extract of rice (Oryza sativa) hulls. The structures of the two new compounds were elucidated using one- and two-dimensional NMR in combination with IR, EI/MS, FAB/MS, HR-EI/MS and HR-FAB/MS. In bioassays with blue-green algae, Microcystis aeruginosa UTEX 2388 and duckweed, Lemna paucicostata Hegelm 381, the efficacy of bioactivity of the two new compounds linearly increased as the concentration increased from 0.3 to 300 IgM. Compared with momilactone A, compounds 1 and 2 showed similar and higher inhibitory activities against the growth of M. aeruginosa at a concentration of 300 microM. However, compound 2 was similar to momilactone A in inhibiting L. paucicostata growth at a concentration of 300 microM. As a result, compound 2 appears to have a strong potential for the environmentally friendly control of weed and algae that are harmful to water-logged rice.

[Study on the sterols from a brown alga endophytic fungus (NO. ZZF36) from the South China Sea]

Four sterols were isolated from a brown alga endophytic fungus NO. ZZF36 from the South China Sea. Their structures were identified as brassicaterol(2), ergosterol(2), ergosterol peroxide(3),7,22(E)-ergostadiene-beta,5alpha,6beta-triol(4) by spectroscopic methods.

Follicular sterol composition in gonadotrophin stimulated women with polycystic ovarian syndrome

This is the first study evaluating whether oocyte development and fertilization competence are related to intrafollicular concentration of cholesterol, meiosis-activating sterols and progesterone, after human chorionic gonadotrophin (HCG) administration of women with polycystic ovarian syndrome (PCOS). The concentration of follicular fluid meiosis-activating sterol (FF-MAS) significantly increased in the periovulatory period from 10-14 to 34-38 h after HCG administration, while the concentration of testis meiosis-activating sterol (T-MAS) decreased, suggesting a HCG-dependent inhibition of sterol Delta14-reductase. There was no correlation between follicular lanosterol, FF-MAS, T-MAS, and progesterone concentrations and the presence or absence of MII oocytes. Interestingly, free cholesterol level was significantly lower and FF-MAS/cholesterol and progesterone/cholesterol ratios significantly higher in follicles containing MII oocytes compared to follicles from which oocytes were not retrieved. Yet, fertilization and embryo quality did not correlate with follicular sterols. This knowledge should be beneficial for the implementation of protocols for in vitro maturation process, usually used in PCOS patients.

Nystatin-induced lipid vesicles permeabilization is strongly dependent on sterol structure

The selectivity of the antibiotic nystatin towards ergosterol compared to cholesterol is believed to be a crucial factor in its specificity for fungi. In order to define the structural features of sterols that control this effect, nystatin interaction with ergosterol-, cholesterol-, brassicasterol- and 7-dehydrocholesterol-containing palmitoyloleoylphosphocholine vesicles was studied by fluorescence spectroscopy. Variations in sterol structure were correlated with their effect on nystatin photophysical and activity properties. Substitution of cholesterol by either 7-dehydrocholesterol or brassicasterol enhance nystatin ability to dissipate a transmembrane K+ gradient, showing that the presence of additional double bonds in these sterols-carbon C7 and C22, plus an additional methyl group on C-24, respectively-as compared to cholesterol, is fundamental for nystatin-sterol interaction. However, both modifications of the cholesterol molecule, like in the fungal sterol ergosterol, are critical for the formation of very compact nystatin oligomers in the lipid bilayer that present a long mean fluorescence lifetime and induce a very fast transmembrane dissipation. These observations are relevant to the molecular mechanism underlying the high selectivity presented by nystatin towards fungal cells (with ergosterol) as compared to mammalian cells (with cholesterol).

Epoxidation and reduction of cholesterol, 1,4,6-cholestatrien-3-one and 4,6-cholestadien-3beta-ol

Many naturally occurring polyhydroxylated sterols and oxysterols exhibit potent biologic activities. This paper describes reagent and position selectivity of epoxidation and reduction of cholesterol derivatives. Cholesterol was reacted with m-chloroperoxybenzoic acid (m-CPBA) to form 5alpha,6alpha-epoxycholestan-3beta-ol, but in reaction with 30% H(2)O(2), it did not reacted. 1,4,6-cholestatrien-3-one was obtained from cholesterol and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone in dioxane. 1,4,6-cholestatrien-3-one was reacted with 30% H(2)O(2) and 5% NaOH in methanol to give 1alpha,2alpha-epoxy-4,6-cholestadien-3-one, which was stereoselectively reduced with NaBH(4) to form 1alpha,2alpha-epoxy-4,6-cholestadien-3beta-ol and reduced with Li metal in absolute ethanol to give 2-ethoxy-1,4,6-cholestatrien-3-one. And 1,4,6-cholestatrien-3-one was epoxidized with m-CPBA in dichloromethane to afford 6alpha,7alpha-epoxy-1,4-cholestadien-3-one, which was reacted with NaBH(4) to synthesize 6alpha-hydroxy-4-cholesten-3-one and reduced Li metal in absolute ethanol to form 2-ethoxy-1,4,6-cholestatrien-3-one, respectively. 1,4,6-cholestatrien-3-one was reduced with NaBH(4) in absolute ethanol to form 4,6-cholestadien-3beta-ol, which was reacted with 30% H(2)O(2) to leave original compound, but was reacted with m-CPBA to give 4beta,5beta-epoxy-6-cholesten-3beta-ol as the major product and 4beta,5beta-epoxy-6alpha,7alpha-epoxycholestan-3beta-ol as the minor product.

Enzymological properties of sterol-C4-methyl-oxidase of yeast sterol biosynthesis

Despite genes of the sterol methyl-oxidase component (SMO) of the sterol-C4-demethylation multienzymatic complex have been identified in a variety of organisms and the key role played by SMO in yeast sterol biosynthesis, the enzymological properties of yeast SMO have not been investigated. An enzymatic assay for measuring specifically sterol 4alpha-methyl-oxidase activity in Saccharomyces cerevisiae has been developed for the first time by using [14C]-4,4-dimethyl-zymosterol as substrate. It allowed enzymatically formed C4 mono- and di-demethylated products to be characterized as well as two novel C4-hydroxymethyl-zymosterol derivatives to be identified as immediate oxidative metabolites by the yeast 4,4-dimethyl-zymosterol 4alpha-methyl-oxidase (ScSMO). The properties of microsomal ScSMO have been established with respect to cofactor requirements and kinetics and the substrate selectivity examined with a number of 4,4-dimethyl- and 4alpha-methyl-sterols. Remarkably, ScSMO showed very low activity with 24-methylene-24-dihydrocycloartenol, the natural substrate of maize 4,4-dimethyl-sterol-C4-methyl-oxidase. Conversely, maize sterol-C4-methyl-oxidases showed extremely reduced activity with the natural substrate of ScSMO. The previously described antifungal agent, 6-amino-2-n-pentylbenzothiazole was shown to directly inhibit the microsomal ScSMO activity in vitro. The yeast system was more than 500 times more sensitive to this derivative than the maize systems. These distinct substrate specificities and inhibitor sensitivities between yeast and plant sterol-4alpha-methyl-oxidases probably reflect diversity in the structure of their active sites in relation to the distinct sterol biosynthetic pathways.

Alternative pathways of sterol synthesis in yeast. Use of C(27) sterol tracers to study aberrant double-bond migrations and evaluate their relative importance

Yeast produce traces of aberrant sterols by minor alternative pathways, which can become significant when normal metabolism is blocked by inhibitors or mutations. We studied sterols generated in the absence of the delta(8)-delta(7) isomerase (Erg2p) or delta(5) desaturase (Erg3p) by incubating three mutant strains of Saccharomyces cerevisiae with 5 alpha-cholest-8-en-3beta-ol, 8-dehydrocholesterol (delta(5,8) sterol), or isodehydrocholesterol (delta(6,8) sterol), together with the corresponding 3 alpha-3H isotopomer. Nine different incubations gave altogether 16 sterol metabolites, including seven delta(22E) sterols formed by action of the yeast C-22 desaturase (Erg5p). These products were separated by silver-ion high performance liquid chromatography (Ag(+)-HPLC) and identified by gas chromatography-mass spectrometry, nuclear magnetic resonance spectroscopy, and radio-Ag(+)-HPLC. When delta(8)-delta(7) isomerization was blocked, exogenous delta(8) sterol underwent desaturation to delta(5,8), delta(6,8), and delta(8,14) sterols. Formation of delta(5,8) sterol was strongly favored over delta(6,8) sterol, but both pathways are essentially dormant under normal conditions of sterol synthesis. The delta(5,8) sterol was metabolically almost inert except for delta(22) desaturation, whereas the delta(6,8) sterol was readily converted to delta(5,7), delta(5,7,9(11)), and delta(7,9(11)) sterols. The combined results indicate aberrant metabolic pathways similar to those in mammalian systems. However, delta(5,7) sterol undergoes only slight isomerization or desaturation in yeast, an observation that accounts for the lower levels of delta(5,8) and delta(5,7,9(11)) sterols in wild-type yeast compared to Smith-Lemli-Opitz individuals.

Relation between the molecular electrostatic potential and activity of some FF-MAS related sterol compounds

Follicular Fluid-Meiosis Activating Sterol (FF-MAS) is a compound important for maturation of gametes in mammals. Therefore, it may serve as a lead compound for a novel method of contraception. We studied the Molecular Electrostatic Potential of a series of active and inactive analogues of FF-MAS. We find that double bond configurations required for activity result in a local negative electrostatic potential which is larger as well as more dense compared to those of inactive molecules. We therefore hypothesize that the interaction energy of the double bond system of the MAS compounds with its receptor substantially contributes to the overall interaction energy. This notion is supported by interaction studies of the electrostatic potential originating from the double bonds in crystal structures of cholesterol and four MAS-derived Delta(8,14) structures synthesized and crystallized by us. In addition, we were able to derive a pharmacophore model that relates the local average ESP and its distance to the 3beta-OH oxygen atom to the activity of the molecules.

Plants steroid hormones, brassinosteroids: current highlights of molecular aspects on their synthesis/metabolism, transport, perception and response

Brassinosteroids (BRs) are plant steroids essential for normal growth and development and can be defined as steroids that carry an oxygen moiety at C-3 and additional ones at one or more of the C-2, C-6, C-22 and C-23 carbon atoms. BR biosynthesis and metabolism mutants have been obtained and the corresponding genes cloned. These include genes encoding 5alpha-reductase and cytochrome P450 enzymes, that are similar to enzymes associated with mammalian steroid synthesis. Perception and/or response mutants have also been identified via screening for altered sensitivity to BRs. Some of these mutants have been found to be defective in a leucine-rich repeat receptor kinase and in a component of a vacuolar ATPase. This review highlights the recent advances in unraveling BR synthesis/metabolism, transport, perception and response through the analysis of BR mutants.

Meiosis activating sterols (MAS) and fertility in mammals and man

In mammals two meiosis activating sterols (MAS) have been found to activate meiotic resumption in mouse oocytes, in vitro. FF-MAS (4, 4-dimethyl-5alpha-cholesta-8,14,24-triene-3beta-ol) was extracted from human preovulatory follicular fluid and T-MAS (4, 4-dimethyl-5alpha-cholest-8,24-diene-3beta-ol) from bull testicular tissue. Quite unexpected, these two sterols, which introduce the cholesterol biosynthetic pathway from lanosterol, may be locally acting substances with important physiological function for reproduction. FF-MAS and T-MAS are present in the preovulatory follicular fluid of different mammalian species and have the capacity to initiate resumption of meiosis in mouse oocyte cultured in the presence of hypoxanthine, a natural meiosis maturation inhibitor. FF-MAS is produced by the cumulus cells of intact oocyte-cumulus complexes upon FSH-stimulation and provides the oocyte with a go-signal for the resumption of meiosis. T-MAS constitutes the vast majority of MAS found in the mammalian testis and in the human ejaculate; in particular a high concentration is found in the spermatozoa. T-MAS may be produced by the spermatids and the presence of T-MAS in spermatozoa may suggest that T-MAS plays a role in fertilization by affecting the second meiotic division.J. Exp. Zool. (Mol. Dev. Evol.) 285:237-242, 1999.

Antitumor sterols from the mycelia of Cordyceps sinensis

Activity guided fractionations led to the isolation of two antitumor compounds 5 alpha,8 alpha-epidioxy-24(R)-methylcholesta-6,22-dien-3 beta-D-glucopyranoside and 5,6-epoxy-24(R)-methylcholesta-7,22-dien-3 beta-ol from the methanol extract of Cordyceps sinensis. Two previously known compounds, ergosteryl-3-O-beta-D-glucopyranoside and 22-dihydroergosteryl-3-O-beta-D-glucopyranoside were also isolated. The structures of hitherto unknown sterols were established by 1D and 2D NMR spectroscopic techniques with the former synthesized in order to confirm the identity of the sugar moiety by chemical correlation. The glycosylated form of ergosterol peroxide was found to be a greater inhibitor to the proliferation of K562, Jurkat, WM-1341, HL-60 and RPMI-8226 tumor cell lines by 10 to 40% at 10 micrograms/ml than its previously identified aglycone, 5 alpha,8 alpha-epidioxy-24(R)-methylcholesta-6,22-dien-3 beta-ol.

Mass spectrometry characterization of the 5alpha-, 7alpha-, and 7beta-hydroxy derivatives of beta-sitosterol, campesterol, stigmasterol, and brassicasterol

The 5alpha-hydroperoxides of beta-sitosterol, campesterol, stigmasterol, and brassicasterol were obtained by photooxidation of the respective sterols in pyridine in the presence of hematoporphyrine as sensitizer. The reduction of the hydroperoxides gives the corresponding 5alpha-hydroxy derivatives. The 7alpha- and 7beta-hydroperoxides of the sterols were obtained by allowing an aliquot of the 5alpha-hydroperoxides to isomerize to 7alpha-hydroperoxides, which in turn epimerize to 7beta-hydroperoxides. The reduction gave the corresponding 7alpha- and 7beta-hydroxy derivatives. The 5alpha-, 7alpha-, and 7beta-hydroxy derivatives of beta-sitosterol, campesterol, stigmasterol, and brassicasterol were identified by comparing thin-layer chromatography mobilities, specific color reactions, and mass spectral data with those of the corresponding hydroxy derivatives of cholesterol, which were synthesized in the same manner. The phytosterols had the same behavior to photooxidation as cholesterol and, moreover, the different phytosterols photooxidized at about the same rate. The mass spectra of the trimethylsilyl ethers of the hydroxy derivatives of the phytosterols investigated and of the corresponding hydroxy derivatives of cholesterol have the same fragmentation patterns and similar relative ion abundances.

Molecular diversity of sterol 14alpha-demethylase substrates in plants, fungi and humans

Metabolism of lanosterol (LAN), 24-methylene-24,25-dihydrolanosterol (24-methyleneDHL), dihydrolanosterol (DHL) and obtusifoliol (OBT) by purified human, plant (Sorghum bicolor) and fungal (Candida albicans) sterol 14alpha-demethylase (CYP51; P450(14DM)) reconstituted with NADPH cytochrome P450 reductases was studied in order to elucidate the substrate specificity and sterol stereo- and regio-structural requirements for optimal CYP51 activity. Both human and C. albicans CYP51 could catalyse 14alpha-demethylation of each substrate with varying levels of activity, but having slightly higher activity for their respective endogenous substrates in vivo, dihydrolanosterol for human CYP51 (Vmax = 0.5 nmol/min/nmol CYP51) and 24-methylene-24,25-dihydrolanosterol for C. albicans CYP51 (Vmax = 0.3 nmol/min/nmol CYP51). In contrast, S. bicolor CYP51 showed strict substrate specificity and selectivity towards its own endogenous substrate, obtusifoliol (Vmax = 5.5 nmol/min/nmol CYP51) and was inactive towards 14alpha-demethylation of lanosterol, 24-methylene-24,25-dihydrolanosterol and dihydrolanosterol. These findings confirm that the presence of the 4beta-methyl group in the sterol molecule renders the plant CYP51 incapable of 14alpha-demethylation thus revealing the strict active site conservation of plant CYP51 during evolution.

Silver ion high pressure liquid chromatography provides unprecedented separation of sterols: application to the enzymatic formation of cholesta-5,8-dien-3 beta-ol

We report that silver ion HPLC provides remarkable separations of C27 sterols differing only in the number or location of olefinic double bonds. This technique has been extended to LC-MS, analysis of purified components by GC, GC-MS, and 1H NMR, and to its use on a semipreparative scale. The application of this methodology for the demonstration of the catalysis, by rat liver microsomes, of the conversion of 7-dehydrocholesterol to cholesta-5,8-dien-3 beta-ol is also presented.

Identification and quantification of Tuber melanosporum Vitt. sterols

The sterol composition of Tuber melanosporum was examined by medium-pressure liquid and high-performance liquid chromatography, nuclear magnetic resonance spectroscopy, and mass spectrometry. Ergosterol (ergosta-5,7,22-trienol) and brassicasterol (ergosta-5,22-dienol) were identified as the major components (90%). Their quantities and their relative concentrations, probably good indicators for differentiating mature truffles from immature colored ones, were determined during the maturation of the fungus. The results show that the total quantity of sterols decreased with the age of the fungus, but that the ergosterol/brassicasterol ratio remained relatively constant.

New delta 8- and delta 8(14)-5 alpha,6 alpha-epoxysterols from the marine sponge Spongia officinalis

Six new delta 8- and delta 8(14)-5 alpha,6 alpha-epoxysterols (1-6) have been isolated from a collection of the Mediterranean sponge Spongia officinalis. The structures of the new metabolites, isolated as diacetate derivatives, have been determined by spectral analyses and an x-ray diffraction experiment performed on the diacetyl derivative of 1.

Phospholipid studies of marine organisms: 26. Interactions of some marine sterols with 1-stearoyl-2-oleoyl phosphatidylcholine (SOPC) in model membranes

The thermotropic behavior of multilamellar vesicles (MLV) composed of different mole fractions of various marine sterols and 1-stearoyl-2-oleoyl phosphatidylcholine (SOPC) was examined by differential scanning calorimetry (DSC), and was compared to pure SOPC as well as their mixtures with cholesterol. The marine sterols investigated were capable of interacting with the phospholipid bilayers. Upon addition of marine sterols, the apparent transition temperature (Tm) of SOPC decreased significantly. Desmosterol (cholesta-5,24-dien-3 beta-ol) had the least interaction with SOPC, as reflected by the larger delta H values of its mixtures with the phospholipid. Fucosterol (24-ethylcholesta-5,24(28)-dien-3 beta-ol) showed a non-linear trend as the mole percent of the sterol increased. Mixtures of sutinasterol (24R-24-ethyl-26,26-dimethylcholesta-7,25(27)-dien-3 beta-ol) with SOPC had similar enthalpy values to cholesterol. The shape of the SOPC/marine sterol endotherm and their delta H values were not identical when liposomes prepared by dialysis were compared to MLV.

Properties and structural requirements for substrate specificity of cytochrome P-450-dependent obtusifoliol 14 alpha-demethylase from maize (Zea mays) seedlings

The biochemical properties of cytochrome P-450-dependent obtusifoliol 14 alpha-demthylase (P-450OBT.14DM) from maize (Zea mays) seedlings were defined. In particular, the enzyme was shown by differential centrifugation to be localized in the endoplasmic reticulum. P-450OBT.14DM had an apparent Km of 160 +/- 5 microM and an apparent Vmax of 65 +/- 5 pmol/min per mg of protein for its best substrate, obtusifoliol. The substrate specificity of P-450OBT.14DM was thoroughly investigated by comparing the demethylation of obtusifoliol with that of a series of 15 natural or novel synthetic analogues of obtusifoliol. The results obtained clearly indicate that three distinct domains of the sterol substrate are governing obtusifoliol demethylation by P-450OBT.14DM. They revealed that (i) P-450OBT.14DM has probably a specific apolar binding site for the side chain, (ii) the delta 8-double bond is an absolute requirement for substrate demethylation and (iii) the 3-hydroxy group plays a critical role in the enzyme-substrate interaction. Interestingly the binding site, beyond the C-3 position, contains a cleft which cannot accommodate a 4 beta-methyl substituent present in lanosterol or eburicol, the precursors of 14-desmethylsterols respectively in mammals and yeast. This result indicates that P-450OBT.14DM is a novel constitutive cytochrome P-450 with a high degree of substrate and product specificity.