A new bioactive steroidal saponin, furcreastatin, from the plant Furcraea foetida

Microbial and plant secondary metabolites were screened for compounds that are selectively cytotoxic to mutant p53-expressing mouse fibroblasts. As a result, furcreastatin, a novel steroidal saponin, was isolated from an EtOH extract of the leaves of Furcraea foetida. Furcreastatin consisted of hecogenin as the aglycone and a hexasaccharide containing D-galactose, L-rhamnose and four D-glucose residues. The structure was determined to be (3 beta,5 alpha,25R)- 3-hydroxyspirostan-12-one 3-O-[alpha-L-Rhap-(1-->4)-beta-D-Glcp-(1-->3)-?beta-D-Glcp-(1-->3) -beta-D- Glcp-(1-->2)?-beta-D-Glcp-(1-->4)-beta-D-Galp] by extensive NMR spectroscopic studies. Furcreastatin decreased the viability of mutant p53-over-expressing cells with an ED50 of 4.0 micrograms/mL, and decreased that of the parental cell-line with an ED50 of 9.6 micrograms/mL.     

蒺藜甾体皂甙元化学成分研究

从蒺藜(Tribulus terrestris)的氯仿部位分离得到8个已知的甾体皂甙元类化合物,运用光谱分析方法鉴定分别为：tigogenin(1),hecogenin(2),pregna 4,16 diene-3,12,20-trione(3),hecogenin acetate(4),25(R)-spirostan-4-ene-3,12-dione(5),25(R)-spirostan-3,12-dione(6),25(R)-spirostan-3,6,12-trione(7),gitogenin(8)。其中化合物3,5,6为首次从该植物中分得。     

The bile acid composition of gastric contents from neonates with high intestinal obstruction.

The study was designed to identify 'atypical' bile acids in gastric contents from three neonates with high intestinal obstruction on the basis that this was likely to represent a rich source of primary bile acids. Cholic acid was the major component, and related 'atypical' bile acids included its C-3 and C-7 oxidation products, its 3 beta-epimer and 2 beta- and 6 alpha-hydroxylation products. Allocholic acid was the only 5 alpha-cholanic acid derivative identified. 7 alpha, 12 alpha-Dihydroxy-3-oxochol-4-en-24-oic acid was found in all three specimens and might be an intermediate in a biosynthetic pathway from cholesterol to cholic acid in which side-chain oxidation precedes at least some of the nuclear changes. Side-chain-hydroxylated derivatives of trihydroxycoprostanic acid were also detected and these may represent intermediates in biosynthetic pathways from cholesterol to cholic acid via 5 beta-cholestan-3 alpha, 7 alpha, 12 alpha-triol. The most abundant bile acid of this type was (25 epsilon)-3 alpha, 7 alpha, 12 alpha, 25-tetrahydroxy-5 beta-cholestan-26-oic acid, which suggested that C-25 hydroxylation may be an important step in the shortening of the C8 side chain of the cholestane triol to the C5 side chain of cholic acid in the neonatal period. Bile acids lacking a substituent at C-12 included chenodeoxycholic acid, its C-3 and C-7 oxidation products, its 3 beta-epimer and its 6 alpha-hydroxylation product (hyocholic acid).     

The catabolism of cholesterol in vitro. Formation of 3α,7α,12α-trihydroxy-5β-cholestanoic acid from cholesterol by rat liver

1. Both 25-d- and 25-l-3alpha,7alpha,12alpha-trihydroxy-5beta-cholestanoic acid were isolated from the gall-bladder bile of Crocodylus niloticus. 2. The catabolism of cholesterol to 25-d- and 25-l-3alpha,7alpha,12alpha-trihydroxy-5beta-cholestanoic acid respectively was studied by using a rat liver preparation in vitro. The results show that rat liver can metabolize cholesterol to both forms of 3alpha,7alpha,12alpha-trihydroxy-5beta-cholestanoic acid. However, a preference was noted for the formation from [4-(14)C]cholesterol of 3alpha,7alpha,12alpha-trihydroxy-5beta-cholestanoic acid (25-d), which was isolated from the incubations with a specific radioactivity about four times that of 3alpha,7alpha,12alpha-trihydroxy-5beta-cholestanoic acid (25-l). 3. The results indicate that 3alpha,7alpha,12alpha-trihydroxy-5beta-cholestanoic acid is a normal intermediate in the biosynthesis of bile acids from cholesterol in the rat.     

Structural and biosynthetic studies of a principal bile alcohol, 27-nor-5beta-cholestane-3alpha,7alpha,12alpha,24,25-pentol, in human urine

The stereochemistry at C-24 and C-25 of 27-nor-5beta-cholestane-3alpha,7alpha,12alpha,24 ,25-pentol, a principal bile alcohol in human urine, and its biosynthesis are studied. Four stereoisomers of the C(26)-24,25-pentols were synthesized by reduction with LiAlH(4) of the corresponding epoxides prepared from (24S)- or (24R)-27-nor-5beta-cholest-25-ene-3alpha, 7alpha,12alpha,24-tetrol. The stereochemistries at C-25 were deduced by comparison of the C(26)-24,25-pentols with the oxidation products of (24Z)-27-nor-5beta-cholest-24-ene-3alpha,7alpha, 12alpha-triol with osmium tetraoxide. On the basis of this assignment, the principal bile alcohol excreted into human and rat urine was determined to be (24S,25R)-27-nor-5beta-cholestane-3alpha,7alpha, 12alpha,24,25-pentol, accompanied by a lesser amount of (24R, 25R)-isomer. To elucidate the biosynthesis of the C(26)-24,25-pentol, a putative intermediate, 3alpha,7alpha, 12alpha-trihydroxy-27-nor-5beta-cholestan-24-one, derived from 3alpha,7alpha, 12alpha-trihydroxy-24-oxo-5beta-cholestanoic acid by decarboxylation during the side-chain oxidation of 3alpha,7alpha, 12alpha-trihydroxy-5beta-cholestanoic acid, was incubated with rat liver homogenates. The 24-oxo-bile alcohol could be efficiently reduced to yield mainly (24R)-27-nor-5beta-cholestane-3alpha,7alpha, 12alpha,24-tetrol. If a 25R-hydroxylation of the latter steroid occurs, it should lead to formation of (24S,25R)-C(26)-24,25-pentol. Now it has appeared that a major bile alcohol excreted into human urine is (24S,25R)-27-nor-5beta-cholestane-3alpha,7alpha, 12alpha, 24, 25-pentol, which might be derived from 3alpha,7alpha, 12alpha-trihydroxy-27-nor-5beta-cholestan-24-one via (24R)-27-nor-5beta-cholestane-3alpha, 7alpha,12alpha,24-tetrol.     

Etoposide: a new approach to the synthesis of 4-O-(2-amino-2-deoxy-4,6-O-ethylidene-beta-D-glucopyranosyl)-4'-O- demethyl-4-epipodophyllotoxin

Synthesis of 3-O-acetyl-2-benzyloxycarbonylamino-2-deoxy-4,6-O-ethylidene- alpha-(7 alpha) and-beta-D-glucopyranose (7 beta) and their 3-O-chloroacetyl analogues (11 alpha and 11 beta) are described. Condensation (BF3-etherate, ethyl acetate, -20 degrees) of 7 alpha with 4'-O-benzyloxycarbonyl-4'-O-demethyl-4-epipodophyllotoxin (8) afforded mainly the beta-glycoside 9 beta (alpha, beta-ratio 1:9). Condensation of 11 alpha beta with 8 or the 4'-O-chloroacetyl analogue 13 gave mainly the 4-O-(2-benzyloxycarbonylamino-3-O-chloroacetyl-2-deoxy-4,6-O-ethyl idene-beta-D- glucopyranosyl)-epipodophyllotoxin 12 beta or 15 beta. Glycosidation of podophyllotoxin (14) with 11 alpha beta (during which the aglycon epimerized at C-4 under the action of BF3-etherate) afforded alpha- (16 alpha) and beta-glycoside (16 beta) in the ratio 1:5. Removal of the chloroacetyl groups from 12 beta, its alpha analogue 12 alpha, and 15 beta gave the 4-O-(2-benzyloxycarbonylamino-2-deoxy-4,6-O-ethylidene-alpha-(17 alpha) and -beta-D-glucopyranosyl)-4'-O-demethyl-epipodophyllotoxins (17 beta and 20 beta), respectively. Hydrogenolysis of the benzyloxycarbonyl groups then gave 4-O-(2-amino-2-deoxy-4,6-O-ethylidene-alpha- (18 alpha) and -beta-D-glucopyranosyl)-4'-O-demethyl-4-epipodophyllotoxin (18 beta). Reductive alkylation of 18 beta and 18 alpha afforded the 2"-deoxy-2"-dimethylamino-etoposide 3 and its alpha analogue 19 alpha.     

Chiral separation of pheniramine-like 3-phenyl-3-heteroarylpropylamines by CE and HPLC methods

Analytical CE and HPLC methods were developed for the chiral separation of halogen-substituted 3-phenyl-3-(2-pyridyl)propylamines 1-4 (1: 3-(4-fluorophenyl) approximately, 2: 3-(3,4-difluorophenyl) approximately, 3: 3-(4-chlorophenyl) approximately, 4: 3-(3,4-dichlorophenyl) approximately ), 3-(4-fluorophenyl)-3-(2-thiazolyl)propylamine (5), and 3-(4-fluorophenyl)-3-(1-benzylimidazol-2-yl)propylamine (6), which are building blocks for the preparation of very potent arpromidine-type histamine H(2) receptor agonists. All amines were enantioseparated by CE with resolutions of at least 1.8 using alpha-, beta-, or gamma-cyclodextrin (CD) as chiral selectors. With heparin as buffer additive for CE the optical antipodes of 1-4 and 6 were separated with resolutions > or = 1.8. On RP-18 columns the separation of the (+)-(S)-acetylmandelic acid amides of racemic 2 (R = 0.9, alpha = 1.07) and the thioureas prepared by addition of 6 to 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl isothiocyanate (R = 2.0, alpha = 1.20) was successful, whereas the diastereomeric ureas prepared from 3 and (+)-(S)-1-(1-naphthyl)ethyl isocyanate could not be resolved. Separation of the diastereomeric isoindoles prepared from 1-5, o-phthaldialdehyde and 2,3,4,6-tetra-O-acetyl-1-thio-beta-D-glucopyranoside was achieved on a RP-18 phase (R > or = 0.4, a > or = 1.02). Direct separation of the enantiomers of 3 and 4 was achieved on a Cyclobond I column (R > or = 0.9, alpha > or = 1.07). alpha- and beta-CD were also useful as mobile phase additives for HPLC (3 and 4: RP-18 column, beta-CD, R > or = 0.4, alpha > or = 1.03; 3: RP-18 column, alpha-CD: R = 0.5, alpha = 1.04).     

Two new pregnanone derivatives with strong cytotoxic activity from Pachysandra axillaris

Two new, bioactive, pregnane-based natural products, pachysanonin (= 3beta,11alpha,12beta)-12-acetoxy-3-(dimethylamino)-11-[(3,4-dimethylpent-3-enoyl)oxy]pregnan-20-one; 1) and pachysanone (= (11alpha,12beta)-12-acetoxy-11-[(3,4-dimethylpent-3-enoyl)oxy]pregnan-3,20-dion; 2) have been isolated from Pachysandra axillaris. Their structures were determined by spectroscopic methods, and, in the case of 2, by single-crystal X-ray crystallography (Figure). Compound 2 showed significant antitumor activity against Lewis lung carcinoma (LCC) tumor cells, with an IC50 value of 0.020+/-0.006 microg/ml, which is equal or even lower than those of the well-known natural antitumor agents harringtonine (0.02), homoharringtonine (0.15), and adriamycin (0.06 microg/ml; positive control).     

Novel P450(17alpha) inhibitors: 17-(2'-oxazolyl)- and 17-(2'-thiazolyl)-androstene derivatives

Twelve 17-(2'-oxazolyl)- and 17-(2'-thiazolyl)-androsta-5,16-diene derivatives were designed and synthesized from 3 beta-acetoxy-pregna-5,16-dien-20-one (1b) as inhibitors of 17 alpha-hydroxylase-C(17,20)-lyase (P450(17 alpha)). Potent inhibitors of this enzyme could be of value as treatment of prostate cancer. Two substituents (methyl and phenyl) were introduced either at their 4'- or 5'-position in order to investigate their structure-activity relationship. Due to the 16,17-double bond, 17-thiazoles were generally obtained in low yield. The pharmacological results showed that the compounds containing 17-(2'-oxazolyl) (14c) and 17-(2'-thiazolyl) (8c) (41.5%) demonstrated reasonable inhibition against P450(17 alpha). Their 3-acetate (13c and 7c) were less potent than their 3-OH counterparts. The introduction of a phenyl or methyl group generally decreased inhibitory activity. Surprisingly, 17-(5'-methyl-2'-thiazolyl) (12a) was the most potent compound in this series and was almost as potent as L-39, which has good antitumor activity.     

Covalent structure of collagen. Amino acid sequence of an arthritogenic cyanogen bromide peptide from type II collagen of bovine cartilage

Bovine articular type II collagen was prepared by limited pepsin digestion, differential salt fractionation and carboxymethylcellulose chromatography. Cyanogen bromide digestion of purified type II collagen alpha chains yielded twelve distinct peptides designated CB1-12. The peptide alpha 1(II)-CB11 was isolated by carboxymethylcellulose chromatography and Sephadex G-75S gel filtration. Automated Edman degradation together with chymotrypsin, thermolysin and trypsin digestion enabled identification of its complete amino acid sequence. Compared with type I and type III collagen, the data show similarity with alpha 1(I)-CB8 and alpha 1(III)-CB6-1-8-10-2 peptides, respectively. The peptide is located within residues 124-402 of the alpha 1(II) collagen chain and with its identification, now extends the known amino acid sequence of bovine type II cartilage collagen to 660 amino acid residues including alpha 1(II)-CB1-2-6-12-11-8-10 (partial). This corresponds to alpha 1(I)-CB0-1-2-4-5-8-3-7 (partial; 1-660) and alpha 1(III)-CB3A-3B-3C-7-6-1-8-10-2-4-5 (partial; 1-660) of bovine alpha 1(I) and alpha 1(III) collagen chains.     

Facile synthesis of 12-carboxamido-11-spirostenes via palladium-catalyzed carbonylation reactions

12-Carboxamido- and 12-carboxyl-11-spirostenes were synthesized from the corresponding 12-iodo-11-ene derivative in palladium-catalyzed carbonylation reactions under mild reaction conditions. The synthesis of the iodo-alkene substrate is based on the transformation of the 12-keto derivative (hecogenin) to hydrazone, which was treated with iodine in the presence of a base (1,1,3,3-tetramethyl guanidine). While various 12-carboxamides were synthesized in moderate to high yields by using simple alkyl/arylamines or amino acid methylesters as N-nucleophiles, low yields can be achieved with alcohols as O-nucleophiles. The homogeneous carbonylation reactions tolerate the 3-hydroxy substituent and the spiroacetal moiety.     

Competitive inhibitors of rabbit hepatic microsomal steroid 12 alpha-hydroxylase

The sterols 7 alpha-hydroxycholest-4-en-3-one (I) and 5 alpha-cholestane-3 alpha,7 alpha-diol (II) are competitive inhibitors for rabbit hepatic microsomal preparations of steroid 12 alpha-hydroxylase with apparent Ki values of 56 and 93 microM, respectively. To ascertain the optimum structure for a substrate with maximal enzymic activity, nine sterols or steroidal acids containing the 7 alpha-hydroxy-4-en-3-one or 3 alpha,7 alpha-dihydroxy-5 alpha configuration were prepared and studied as inhibitors with enzyme preparations in the presence of NADPH, oxygen and appropriate cofactors. Although each of these compounds exhibited competitive inhibition, the best inhibitor for sterol (I) was 7 alpha,25-dihydroxycholest-4-en-3-one (IV) (Ki 36 microM). Steroidal acids (3-oxo-7 alpha-hydroxychol-4-enoic acid and 3-oxo-7 alpha-hydroxy-4-cholene-24-carboxylic acid) were poor inhibitors (Ki 1080 and 654 microM, respectively). For sterol (II) the best inhibitors were sterol (IV) (Ki 35 microM) and 5 alpha-cholestane-3 alpha,7 alpha,25-triol (VIII) (Ki 45 microM). The 12 alpha-hydroxylated products of sterols (I) and (IV) were less tightly bound to the enzyme (Ki 88 and 98 microM, respectively) in the presence of sterol (II). Allochenodeoxycholic acid (Ki 495 microM) was not a good inhibitor for sterol (II). 12 alpha-Hydroxylated products of sterols (IV) and (VIII) were isolated from larger scale incubations, separated by HPLC and identified by mass spectrometry.     

21beta-Hydroxy-oleanane-type triterpenes from Hippocratea excelsa

Stem bark of Hippocratea excelsa afforded six pentacyclic triterpenes, five oleanane and one ursane types. They were identified as 11beta,21beta-dihydroxy-olean-12-ene-3-one (2), 3alpha,11alpha,21beta-trihydroxy-olean-12-ene (3), 3alpha,21beta-dihydroxy-11alpha-methoxy-olean-12-ene (4), 3alpha,21beta-dihydroxy-olean-9(11),12-diene (5), 3alpha,21beta-dihydroxy-olean-12-ene (6) and 3alpha,21beta-dihydroxy-11alpha-methoxy-urs-12-ene, isolated as its diacetate derivative (7), as well as 3alpha,21beta-dihydroxy-olean-12-ene (1) previously isolated from the root bark. The known alpha- and beta-amyrin, oleanoic and ursolic acids, trans-polyisoprene, and the ubiquitous beta-sitosterol were also isolated. Structures were elucidated on the basis of spectroscopic analyses, including homo- and heteronuclear correlation NMR experiments (COSY, ROESY, HSQC and HMBC) and comparison with literature data. The antigiardial activity of compounds 2-5 was not significant.     

Vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF) expression during induced luteolysis in the bovine corpus luteum

Angiogenic factors, like vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF), and their receptors, are strongly regulated during the development of bovine corpus luteum (CL). The aim of this study was to investigate real-time changes of these factors in luteal tissue of cows (n = 4-5 per group) in the mid-luteal phase (day 8-12) after intramuscular injection of the PGF2alpha-analog Cloprostenol. Before (control) and 2, 4, 12, 48, and 64 hr after prostaglandin (PG) injection, CL were collected by transvaginal ovariectomy. RT-PCR for VEGF, VEGF-receptor type 1 (VEGF-R1), VEGF-R2, acidic FGF (FGF-1), basic FGF (FGF-2), and FGF-receptor (FGF-R) was performed. Additionally, the protein concentration for VEGF was determined. The mRNA expression of VEGF and its two receptors (VEGF-R1 and -R2) was significantly downregulated during structural luteolysis (after 12 hr). VEGF protein concentration already significantly declined 2 hr after PGF2alpha. Surprisingly FGF-1 and FGF-2 were significantly and maximally upregulated during functional luteolysis (until 12 hr). Furthermore, FGF-R mRNA was significantly upregulated at 2 hr after PGF2alpha, when compared with the control group. During structural luteolysis, the expression of FGFs and their receptors was not significantly different from control, except FGF-2 mRNA, which was downregulated at 64 hr. We conclude that the cessation of VEGF-support for the CL plays a role during structural luteolysis, whereas FGFs seem to have a major impact on functional luteolysis. The possible role of these growth factors could be a transient counter-regulation of luteolysis, but also an involvement in preventing inflammatory reactions during luteal regression.     

Side chain hydroxylations in bile acid biosynthesis catalyzed by CYP3A are markedly up-regulated in Cyp27-/- mice but not in cerebrotendinous xanthomatosis.

The accumulation of various 25-hydroxylated C(27)-bile alcohols in blood and their excretion in urine are characteristic features of cerebrotendinous xanthomatosis (CTX) a recessively inherited inborn error of bile acid synthesis caused by mutations in the mitochondrial sterol 27-hydroxylase (CYP27) gene. These bile alcohols may be intermediates in the alternative cholic acid side chain cleavage pathway. The present study was undertaken to identify enzymes and reactions responsible for the formation of these bile alcohols and to explain why Cyp27(-/-) mice do not show CTX-related abnormalities. Microsomal activities of 5beta-cholestane-3alpha,7alpha,12alpha-triol 25- and 26-hydroxylases, 5beta-cholestane-3alpha,7alpha,12alpha,25-tetrol 23R-, 24S-, and 27-hydroxylases and testosterone 6beta-hydroxylase, a marker enzyme for CYP3A, in Cyp27(-/-) mice livers were markedly up-regulated (5.5-, 3.5-, 6.5-, 7.5-, 2.9-, and 5.4-fold, respectively). In contrast, these enzyme activities were not increased in CTX. The activities of 5beta-cholestane-3alpha,7alpha,12alpha-triol 25- and 26-hydroxylases and 5beta-cholestane-3alpha,7alpha,12alpha,25-tetrol 23R-, 24R-, 24S-, and 27-hydroxylases were strongly correlated with the activities of testosterone 6beta-hydroxylase in control human liver microsomes from eight unrelated donors. Troleandomycin, a specific inhibitor of CYP3A, markedly suppressed these microsomal side chain hydroxylations in both mouse and human livers in a dose-dependent manner. In addition, experiments using recombinant overexpressed human CYP3A4 confirmed that these microsomal side chain hydroxylations were catalyzed by a single enzyme, CYP3A4. The results demonstrate that microsomal 25- and 26-hydroxylations of 5beta-cholestane-3alpha,7alpha,12alpha-triol and microsomal 23R-, 24R-, 24S-, and 27-hydroxylations of 5beta-cholestane-3alpha,7alpha,12alpha,25-tetrol are mainly catalyzed by CYP3A in both mice and humans. Unlike Cyp27(-/-) mice, CYP3A activity was not up-regulated despite marked accumulation of 5beta-cholestane-3alpha,7alpha,12alpha-triol in CTX.     

Stemodane and stemarane diterpenoid hydroxylation by Mucor plumbeus and Whetzelinia sclerotiorum

Incubation of stemodin (1) with Mucor plumbeus ATCC 4740 resulted in the formation of 2alpha,6beta,13-trihydroxystemodane (2), 2alpha,3beta,13-trihydroxystemodane (3), 2alpha,11beta,13-trihydroxystemodane (4) and 2alpha,13,14-trihydroxystemodane (5), while stemodinone (7) afforded 6alpha,13-dihydroxystemodan-2-one (8) and 6alpha,12alpha,13-trihydroxystemodan-2-one (9). Metabolites obtained from the bioconversion of stemarin (11) were 8,13,19-trihydroxystemarane (12) and 2alpha,13,19-trihydroxystemarane (13). 19-N,N-Dimethylcarbamoxy-13-hydroxystemarane (14) was not transformed by the fungus. Stemodin (1) was incubated with Whetzelinia sclerotiorum ATCC 18687 to produce 2alpha,7beta,13-trihydroxystemodane (6) and 2alpha,11beta,13-trihydroxystemodane (4). Stemodinone (7) was converted to 7beta,13-dihydroxystemodan-2-one (10). Compounds 2, 4, 9, 10, 12 and 13 have not been previously reported.     

Metabolism of bile alcohols in the perfused rabbit liver.

The mechanism and sequence of side chain hydroxylation of cholesterol in bile acid synthesis was studied in the isolated perfused rabbit liver. A comparison was made between the importance of 26- and 25-hydroxylation in cholic acid biosynthesis in the rabbit. The formation of [G-3H]cholic acid was observed when the liver was perfused with 5beta-[G-3H]cholestane-3alpha, 7alpha-diol, 5beta-[G-3H]cholestane-3alpha, 7alpha-12alpha-triol, and 5beta-[G-3H]cholestane-3alpha, 7alpha, 26-triol. No [G-3H]chenodeoxycholic acid was detected in the bile. These findings indicate that potential precursors of chenodeoxycholic acid were hydroxylated at position 12alpha either subsequent to or before hydroxylation of the cholesterol side chain. In addition, no other intermediates (tetrahydroxy or pentahydroxy bile alcohols) were found in the bile when these compounds were perfused in the liver. Bile acid precursors were detected in bile when the rabbit liver was perfused with 5beta-[24-14C]cholestane-3alpha, 7alpha, 25-triol. The 5beta-[24-14C]cholestane-3alpha, 7alpha, 25-triol was hydroxylated in the liver at the 12alpha position to yield the corresponding 5beta-cholestane-3alpha, 7alpha, 12alpha, 25-tetrol. The tetrol was further metabolized to a series of pentols (5beta-cholestane-3alpha, 7alpha, 12alpha, 22, 25-pentol; 5beta-cholestane-3alpha, 7alpha, 12alpha, 23, 25-pentol; 5beta-cholestane-3alpha, 7alpha, 12alpha, 24, 25-pentol; and 5beta-cholestane-3alpha, 7alpha, 12alpha, 25, 26-pentol). The major bile acid obtained from the perfusion of the 5beta-cholestane-3alpha, 7alpha, 25-triol was cholic acid. The experiments indicated that in the rabbit liver 12alpha-hydroxylation can occur after hydroxylation of the cholesterol side chain at either C-25 (5 beta-cholestane-3alpha, 7alpha, 25-triol) or C-26 (5beta-cholestane-3alpha, 7alpha-26-triol). Apparently, the rabbit can form cholic acid via the classical 26-hydroxylation pathway as well as via 25-hydroxylated intermediates.     

Biotransformation of cadina-4,10(15)-dien-3-one and 3alpha-hydroxycadina-4,10(15)-diene by Curvularia lunata ATCC 12017

Cadina-4,10(15)-dien-3-one (1) was metabolised by Curvularia lunata ATCC 12017 in two different growth media to give three metabolites, one of which, 12-hydroxycadina-4,10(15)-dien-3-one (4), was new. Incubation of 3alpha-hydroxycadina-4,10(15)-diene (2) with the fungus produced three new analogues, namely, (4S)-1alpha,3alpha-dihydroxycadin-10(15)-ene (5), 3alpha,14-dihydroxycadina-4,10(15)-diene (6) and 3alpha,12-dihydroxycadina-4,10(15)-diene (7).     

Adenosine suppresses alpha(4)beta(7) integrin-mediated adhesion of T lymphocytes to colon adenocarcinoma cells

The interaction of T lymphocytes with tumor cells, a key step in the antitumor immune response, is suppressed by adenosine, a nucleoside produced at increased levels within the hypoxic tumor environment. We have explored the mechanism by which adenosine interferes with the lymphocyte:tumor cell interaction. The adhesion of anti-CD3-stimulated T cells to syngeneic MCA-38 mouse colon adenocarcinoma cells did not involve LFA-1 (alpha(L)beta(2)) or VLA-5 (alpha(5)beta(1)). However, antibodies against either lymphocyte alpha(4) or beta(7) (but not beta(1)) integrin subunits, or against VCAM-1 on the tumor cells, significantly suppressed adhesion, showing that the recognition of MCA-38 cells by T cells is strongly dependent upon the association of alpha(4)beta(7) on the effector cells with VCAM-1 on the tumor targets. This association is modulated by adenosine: The ability of adenosine to suppress T cell adhesion to MCA-38 cells was lost if alpha(4)beta(7) was functionally blocked with anti-alpha(4) antibodies (i) prior to or (ii) during the adhesion assay or if (iii) alpha(+)(4) cells were depleted from the T lymphocyte population. The binding of T cells to fibronectin through alpha(4)beta(1) was not suppressed by adenosine. We conclude that adenosine partially inhibits the interaction of T lymphocytes with tumor cells by blocking the function of integrin alpha(4)beta(7).     

Sterols and triterpenes in cell culture of Hyssopus officinalis L

Cell suspension cultures from hypocotyl-derived callus of Hyssopus officinalis were found to produce two sterols i. e. beta-sitosterol (1) and stigmasterol (2), as well as several known pentacyclic triterpenes with an oleanene and ursene skeleton. The triterpenes were identified as oleanolic acid (3), ursolic acid (4), 2alpha,3beta-dihydroxyolean-12-en-28-oic acid (5), 2alpha,3beta-dihydroxyurs-12-en-28-oic acid (6), 2alpha,3beta,24-trihydroxyolean-12-en-28-oic acid (7), and 2alpha,3beta,24-trihydroxyurs-12-en-28-oic acid (8). Compounds 5-8 were isolated as their acetates (6, 8) or bromolactone acetates (5, 7).