Biosynthesis of bisorbicillinoid in Trichoderma sp. USF-2690; evidence for the biosynthetic pathway,via sorbicillinol,of sorbicillin,bisorbicillinol, bisorbibutenolide,and bisorbicillinolide

An incorporation study of [1-(13)C] and [1,2-(13)C2] labeled sodium acetates into sorbicillinol 1 established a ring closure system between C-1 and C-6 and the positions that were oxidized and/or methylated on a hexaketide chain. Subsequent investigations, using 13C-labeled 1 prepared from [1-(13)C] labeled sodium acetate, clearly demonstrated that both bisorbicillinol 2 and sorbicillin 6 incorporated 13C-labeled 1 into their carbon skeletons. 13C-labeled bisorbicillinols 2 derived from [1-(13)C]- and [2-(13)C]-labeled sodium acetates clearly indicate that these were on the biosynthetic route from 1 to bisorbibutenolide (bislongiquinolide) 3 and bisorbicillinolide 4 via 2 as a branching point in the fungus.     

Biosynthesis of Bisorbicillinoid in Trichoderma sp. USF-2690; Evidence for the Biosynthetic Pathway,via Sorbicillinol,of Sorbicillin,Bisorbicillinol, Bisorbibutenolide,and…

An incorporation study of [1-¹³C] and [1,2-¹³C₂] labeled sodium acetates into sorbicillinol 1 established a ring closure system between C-1 and C-6 and the positions that were oxidized and/or methylated on a hexaketide chain. Subsequent investigations, using ¹³C-labeled 1 prepared from [1-¹³C] labeled sodium acetate, clearly demonstrated that both bisorbicillinol 2 and sorbicillin 6 incorporated ¹³C-labeled 1 into their carbon skeletons. ¹³C-labeled bisorbicillinols 2 derived from [1-¹³C]- and [2-¹³C]-labeled sodium acetates clearly indicate that these were on the biosynthetic route from 1 to bisorbibutenolide (bislongiquinolide) 3 and bisorbicillinolide 4 via 2 as a branching point in the fungus.     

New chemical constituents from the endophyte Streptomyces species LR4612 cultivated on Maytenus hookeri

From solid cultures of the biologically important endophyte Streptomyces species LR4612, cultivated on Maytenus hookeri, four new and two known compounds were isolated. The new compounds were identified as (2S*,3S*)-5-amino-3-hydroxy-5-oxopentan-2-yl 3-(formylamino)-2-hydroxybenzoate (1), N-[(3R*,4R*)-3-amino-3,4-dihydro-4-methyl-2,6-dioxo-2H,6H-1,5-benzodioxocin-10-yl]formamide (2), (5beta,6alpha)-6,11-dihydroxyeudesmane (3), and 5-(6,7-dihydroxy-6-methyloctyl)furan-2(5H)-one (4); the known compounds were elucidated as sorbicillin (5) and N-acetyltyramine (6). The structures were established by HR-ESI-MS and in-depth NMR analyses.     

The novel pyrimidine and purine derivatives of l-ascorbic acid: synthesis, one- and two-dimensional 1H and 13C NMR study, cytostatic and antiviral evaluation

The syntheses of the novel C-5 substituted pyrimidine derivatives of l-ascorbic acid containing free hydroxy groups at C-2' (6-10) or C-2' and C-3' (11-15) positions of the lactone ring are described. Debenzylation of the 6-chloro- and 6-(N-pyrrolyl)purine derivatives of 2,3-O,O-dibenzyl-l-ascorbic acid (16 and 17) gave the new compounds containing hydroxy groups at C-2' (18) and C-2' and C-3' (19 and 20). Z- and E-configuration of the C4'C5' double bond and position of the lactone ring of the compounds 6-9 were deduced from their one- and two-dimensional (1)H and (13)C NMR spectra and connectivities in NOESY and HMBC spectra. Compounds 15 and 18 showed the best inhibitory activities of all evaluated compounds in the series. The compound 15 containing 5-(trifluoromethyl)uracil showed marked inhibitory activity against all human malignant cell lines (IC(50): 5.6-12.8 microM) except on human T-lymphocytes. Besides, this compound influenced the cell cycle by increasing the cell population in G2/M phase and induced apoptosis in SW 620 and MiaPaCa-2 cells. The compound 18 containing 6-chloropurine ring expressed the most pronounced inhibitory activities against HeLa (IC(50): 6.8 microM) and MiaPaCa-2 cells (IC(50): 6.5 microM). The compound 20 with 6-(N-pyrrolyl)purine moiety showed the best differential inhibitory effect against MCF-7 cells (IC(50): 35.9 microM).     

Design, synthesis, inhibitory activity, and SAR studies of hydrophobic p-aminosalicylic acid derivatives as neuraminidase inhibitors

A series of hydrophobic p-aminosalicylic acid derivatives containing a lipophilic side chain at C-2 and an amino or guanidine at C-5 were synthesized and evaluated for their ability to inhibit neuraminidase (NA) of influenza A virus (H3N2). All compounds were synthesized in good yields starting from commercially available p-aminosalicylic acid (PAS) using a suitable synthetic strategy. These compounds showed potent inhibitory activity against influenza A NA. Within this series, six compounds, 11, 12, 13e, 16e, 17c, and 18e, have the good potency (IC(50)=0.032-0.049 microM), which are compared to Oseltamivir (IC(50)=0.021 microM) and could be used as lead compounds in the future.     

Cytotoxic labdane alkaloids from an ascidian Lissoclinum sp.: isolation, structure elucidation, and structure-activity relationship

Four labdane alkaloids, haterumaimides N-Q (1-4), were isolated from an ascidian Lissoclinum sp. and their structures were elucidated by chemical and spectral analyses. Investigation of the structure-activity relationships of haterumaimides J-K, N-Q, and 14 related compounds suggested that the presence of hydroxyl groups at C-6, C-7, C-12, and C-18, a chlorine atom at C-2, and an imido NH in ring C should be essential for cytotoxicity against P388 cells.     

Penicacids A-C, three new mycophenolic acid derivatives and immunosuppressive activities from the marine-derived fungus Penicillium sp. SOF07

Three new mycophenolic acid derivatives, penicacids A-C (1-3), together with two known analogues, mycophenolic acid (MPA, 4) and 4'-hydroxy-MPA (5), were isolated from a fungus Penicillium sp. SOF07 derived from a South China Sea marine sediment. The structures of compounds 1-3 were elucidated on the basis of MS and NMR ((1)H, (13)C, HSQC and HMBC) data analyses and comparisons with the known compounds. Structure-activity relationship studies of compounds 1-5 focused on inosine-monophosphate dehydrogenase inhibition revealed that hydroxylation at C-4', methylation at C-7-OH, dual hydroxylation at C-2'/C-3' double bond of MPA diminished bioactivity whereas glucosyl hydroxylation at C-4' correlated to bioactivity comparable to that observed for MPA.     

Sesquiterpenoids from the endophytic fungus Trichoderma sp. PR-35 of Paeonia delavayi

A new bisabolane-type sesquiterpene, trichoderic acid (1), and a new acorane-type sesquiterpene, 2β-hydroxytrichoacorenol (2), along with three known compounds, cyclonerodiol (3), cyclonerodiol oxide (4), and sorbicillin (5), were isolated from the culture broth of Trichoderma sp. PR-35, an endophytic fungus isolated from Paeonia delavayi. Their structures were elucidated on the basis of their IR, MS, and 1D- and 2D-NMR analyses. The antibacterial and antifungal activities of 1-5 towards various types of bacteria and fungi were tested. Most of the compounds showed moderate or weak antimicrobial activities in an agar-diffusion assay.     

Synthesis,metabolism and in vitro cytotoxicity studies on novel lavendamycin antitumor agents

A series of lavendamycin analogues with two, three or four substituents at the C-6, C-7 N, C-2′, C-3′ and C-11′ positions were synthesized via short and efficient methods and evaluated as potential NAD(P)H:quinone oxidoreductase (NQO1)-directed antitumor agents. The compounds were prepared through Pictet–Spengler condensation of the desired 2-formylquinoline-5,8-diones with the required tryptophans followed by further needed transformations. Metabolism and toxicity studies demonstrated that the best substrates for NQO1 were also the most selectively toxic to NQO1-rich tumor cells compared to NQO1-deficient tumor cells.     

Synthesis and structure-activity relationships of taxuyunnanine C derivatives as multidrug resistance modulator in MDR cancer cells

A series of new generation taxoids bearing a bulky group on different positions such as C-2, C-5, C-7, C-9, C-10 or C-14 were obtained by chemical modifications and biotransformation of taxuyunnanine C (1) and its analogs, 4, 5, and 10. Compounds 3, 5, 6, 8, and 9a showed significant activity toward calcein accumulation in MDR 2780AD cells. The most effective compound 9a with a cinnamoyloxy group at C-14 and a hydroxyl group at C-10 was actually efficient for the cellular accumulation of the anticancer agent, vincristine, in MDR 2780AD cells. The enhancing effects of 6 and 9a for taxol, adriamycin, and vincristine were at the same levels as those of verapamil toward MDR 2780AD cells. Thus, compounds 6 and 9a can modulate the multidrug resistance of cancer cells. The cytotoxicity (IC(50)) of the compounds was examined against human normal cell line, WI-38, and cancer model cell lines, VA-13 and HepG2. Since compounds 6 and 8 had no cytotoxicity, they were expected to be lead compounds of MDR cancer reversal agents. On the contrary, compounds 3, 5, and 9a showed cell growth inhibitory activity toward VA-13 and/or HepG2 as well as accumulation activity of calcein and/or vincristine in MDR 2780AD and they were expected to be lead compounds of new-type anticancer agents.     

Structural studies on sulfated oligosaccharides derived from the carbohydrate-protein linkage region of chondroitin 6-sulfate proteoglycans of shark cartilage. II. Seven compounds containing 2 or 3 sulfate residues.

Shark cartilage proteoglycans bear predominantly chondroitin 6-sulfate. After exhaustive protease digestion, reductive beta-elimination and subsequent chondroitinase ABC digestion, 13 hexasaccharide alditols were obtained from the carbohydrate-protein linkage region and six of them contain 0 or 1 sulfate and/or 1 phosphate residue (Sugahara, K., Ohi, Y., Harada, T., de Waard, P., and Vliegenthart, J. F. G. (1992) J. Biol. Chem. 267, 6027-6035). The other seven compounds, which represent approximately 60% of the isolated linkage hexasaccharides, were analyzed by chondroitinase ACII digestion in conjunction with high performance liquid chromatography and by 500-MHz one- and two dimensional 1H NMR spectroscopy. All seven compounds have the following conventional structure in common. [formula: see text] Two disulfated compounds have an O-sulfate on C-6 of the Gal-2 residue attached to xylitol in combination with an O-sulfate on C-4 or on C-6 of the GalNAc residue. The third disulfated compound has O-sulfate on C-6 of Gal-2, and also on C-6 of Gal-3. Two of the trisulfated compounds also have O-sulfate on C-6 of both Gal-2 and Gal-3 with in addition sulfate on C-6 or C-4 of GalNAc. The other two trisulfated compounds have O-sulfate on C-6 of Gal-2 and on C-4 of Gal-3 in conjunction with sulfate on C-6 or C-4 of GalNAc.     

Syntheses of stable isotope-labeled 6 beta-hydroxycortisol, 6 beta-hydroxycortisone,and 6 beta-hydroxytestosterone

A method is described for the preparation of two types of multi-labeled 6 beta-hydroxycortisol containing either five deuterium atoms at C-19 methyl and C-1 methylene or four 13C atoms at C-1, C-2, C-4, and C-19 in addition to the five deuterium atoms for use as analytical internal standards for gas chromatography-mass spectrometry (GC-MS). BMD derivatives of [1,1,19,19,19-2H(5)]cortisone and [1,2,4,19-13C(4),1,1,19,19,19-2H(5)]cortisone (cortisone-2H(5)-BMD and cortisone-13C(4),2H(5)-BMD) were first synthesized via indan synthon method starting from optical active 11-oxoindanylpropionic acid and labeled isopropenyl anion ([1,1,3,3,3-2H(5)]- or [1,3-13C(2),1,1,3,3,3-2H(5)]isopropenyl anion). The labeled isopropenyl anion was prepared from commercially available [1,1,1,3,3,3-2H(6)]- or [1,3-13C(2),1,1,1,3,3,3-2H(6)]acetone. Ultraviolet (UV) irradiated autoxidation at C-6 position of 3-ethyl-3,5-dienol ether derivatives of the labeled cortisone-BMDs gave 6 beta-hydroxy-[1,1,19,19,19-2H(5)]cortisone-BMD and 6 beta-hydroxy-[1,2,4,19-13C(4),1,1,19,19,19-2H(5)]cortisone-BMD, respectively, as a mixture of 6 beta- and 6 alpha-epimers in a ratio of 4:1. Separation of 6 beta- and 6 alpha-epimers by thin-layer chromatography (TLC) and subsequent hydrolysis of the BMD group at C-17 gave pure labeled 6 beta-hydroxycortisone. After protecting the keto group at C-3 of the labeled 6 beta-hydroxycortisone-BMD as semicarbazone, reduction of 11-keto group with NaBH(4) and subsequent removal of the C-3 and C-17 protecting groups gave 6beta-hydroxy-[1,1,19,19,19-2H(5)]cortisol (6 beta-hydroxycortisol-2H(5)) and 6 beta-hydroxy-[1,2,4,19-13C(4),1,1,19,19,19-2H(5)]cortisol (6 beta-hydroxycortisol-13C(4),2H(5)), respectively, as a mixture of 6 beta- and 6 alpha-epimers (6 beta:6 alpha=4.4:1). The isotopic compositions of 6 beta-hydroxycortisol-2H(5) and 6 beta-hydroxycortisol-13C(4),2H(5) were 90.9 and 92.1 at.%, respectively. Furthermore, 6 beta-hydroxy-[1 alpha,16,16,17 alpha-2H(4)]testosterone was synthesized by the UV irradiated autoxidation at C-6 position of 3-ethyl-3,5-dienol ether derivative of deuterium-labeled testosterone ([1 alpha,16,16,17 alpha-2H(4)]testosterone) obtained by using catalytic deuteration and hydrogen-deuterium exchange reactions.     

Dammarane-type glycosides from Gynostemma pubescens

Triterpene saponins 1-8 were isolated from the aerial parts of Gynostemma pubescens. Among them, compounds 1-4, 8 possess carboxylic groups at both C-21 and C-29, 5 contains a carboxylic group at C-21 and an aldehyde function at C-29, whereas 6 and 7 contain carboxylic groups at C-21 and hydroxymethylene groups at C-29. Their structural elucidation was accomplished by extensive spectroscopic methods including application of 1D (1H, (13)C, (13)C DEPT) and 2D NMR experiments (HMQC, HMBC, HSQC), HRESIMS analysis, as well as by chemical degradation.     

Regioselective synthesis of 1I,1II,5I,5II,6I,6I,6II,6II-2H8-cellobiose

Partially deuteriated 1,5,6,6-(2)H(4)-d-glucose and 1(I),1(II),5(I),5(II),6(I),6(I),6(II),6(II)-(2)H(8)-d-cellobiose were synthesized in high yields and on a large scale from d-glucose. (2)H enrichment at C-5 and C-6 of each glucopyranosyl unit in excess of 85% and 90%, respectively, was realized by (1)H-(2)H exchange in (2)H(2)O containing deuteriated Raney Ni. Nucleophilic addition of LiAlD(4) to 5,6,6-(2)H(3)-2,3,4,6-tetra-O-benzyl-d-gluconolactone led to a 98% (2)H enrichment at C-1. Deuteriated cellobiose is of interest as building block for the synthesis of a model compound of cellulose I.     

Steroidal carbonitriles as potential aromatase inhibitors

Estrogens, responsible for the growth of hormone-dependant breast cancer are biosynthesized from androgens involving aromatase enzyme in the last rate limiting step. Inhibition of aromatase is an efficient approach for the prevention and treatment of breast cancer. Novel 4-phenylthia derivatives (2, 3 and 7) have been synthesized as aromatase inhibitors. The synthesized compounds (2, 3 and 7) exhibited noticeable enzyme inhibiting activity. Kinetics study of these compounds (2, 3, and 7) showed negligible inhibition of the enzyme under conditions conducive for irreversible inhibition of the enzyme. Introduction of unsaturation at C-4, C-1 & 4 or C-4 & 6 (compounds 5, 9 and 11) was observed to not be an effective strategy for entrancing aromatase inhibiting activity in 17-oxo-16β-carbonitrile derivatives. The D-seco derivatives (13-15 and 17) having unsaturation at C-4, C-1 & 4 or C-4 & 6 along with carbonitrile function in ring-D showed complete loss of aromatase inhibiting activity.     

Structural investigation of a fucoidan containing a fucose-free core from the brown seaweed, Hizikia fusiforme

A fucoidan, obtained from the hot-water extract of the brown seaweed, Hizikia fusiforme, was separated into five fractions by DEAE Sepharose CL-6B and Sepharose CL-6B column chromatography. All five fractions contained predominantly fucose, mannose and galactose and also contained sulfate groups and uronic acid. The fucoidans had MWs from 25 to 950 kDa. The structure of fraction F32 was investigated by desulfation, carboxyl-group reduction, partial hydrolysis, methylation analysis and NMR spectroscopy. The results showed that the sugar composition of F32 was mainly fucose, galactose, mannose, xylose and glucuronic acid; sulfate was 21.8%, and the MW was 92.7 kDa. The core of F32 was mainly composed of alternating units of -->2)-alpha-D-Man(1--> and -->4)-beta-D-GlcA(1-->, with a minor portion of -->4)-beta-D-Gal(1--> units. The branch points were at C-3 of -->2)-Man-(1-->, C-2 of -->4)-Gal-(1--> and C-2 of -->6)-Gal-(1-->. About two-thirds of the fucose units were at the nonreducing ends, and the remainder were (1-->4)-, (1-->3)- and (1-->2)-linked. About two-thirds of xylose units were at the nonreducing ends, and the remainder were (1-->4)-linked. Most of the mannose units were (1-->2)-linked, and two-thirds of them had a branch at C-3. Galactose was mainly (1-->6)-linked. The absolute configurations of the sugar residues were alpha-D-Manp, alpha-L-Fucp, alpha-D-Xylp, beta-D-Galp and beta-D-GlcpA. Sulfate groups in F32 were at C-6 of -->2,3)-Man-(1-->, C-4 and C-6 of -->2)-Man-(1-->, C-3 of -->6)-Gal-(1-->, C-2, C-3 or C-4 of fucose, while some fucose had two sulfate groups. There were no sulfate groups in either the GlcA or xylose residues.     

Generation of anti-factor Xa active, 3-O-sulfated glucosamine-rich sequences by controlled desulfation of oversulfated heparins.

In the framework of a project aimed at generating heparin-like sulfation patterns and biological activities in biotechnological glycosaminoglycans, different approaches have been considered for simulating the alpha(1-->4)-linked 2-O-sulfated L-iduronic acid (IdoA2SO(3))-->N,6-O-sulfated D-glucosamine (GlcNSO(3)6SO(3)) disaccharide sequences prevalent in mammalian heparins. Since the direct approach of sulfating totally O-desulfated heparins, taken as model compounds for C-5-epimerized sulfaminoheparosan (N-deacetylated, N-sulfated Escherichia coli K5 polysaccharide), preferentially afforded heparins O-sulfated at C-3 instead than at C-2 of the iduronate residues, leading to products with low anticoagulant activities, the problem of re-generating a substantial proportion of the original IdoA2SO(3) residues was circumvented by performing controlled solvolytic desulfation (with 9:1 v/v DMSO-MeOH) of extensively sulfated heparins. The order of desulfation of major residues of heparin GlcN and IdoA and of the minor one D-glucuronic acid was: GlcNSO(3)>GlcN6SO(3)>IdoA3SO(3) congruent with GlcA2SO(3) congruent with GlcN3SO(3)>IdoA2SO(3) congruent with GlcA3SO(3). Starting from a 'supersulfated' low-molecular weight heparin, we obtained products with up to 40% of iduronate residues O-sulfated exclusively at C-2 and up to 40% of their glucosamine residues O-sulfated at both C-6 and C-3. Upon re-N-sulfation, these products displayed an in vitro antithrombotic activity (expressed as anti-factor Xa units) comparable with those of current low-molecular weight heparins.     

Structure determination by 1H NMR spectroscopy of (sulfated) sialylated N-linked carbohydrate chains released from porcine thyroglobulin by peptide-N4-(N-acetyl-beta-glucosaminyl)asparagine amidase-F

The N-linked carbohydrate chains of porcine thyroglobulin were released by peptide-N4-(N-acetyl-beta-glucosaminyl)asparagine amidase-F (PNGase-F). The resulting oligosaccharides were fractionated by a combination of fast protein liquid chromatography and high performance liquid chromatography and analyzed by 500-MHz 1H NMR spectroscopy. The major acidic compounds are mono- and disialylated, fucosylated diantennary compounds terminated with alpha(2-6)-linked sialic acid on the Man alpha(1-3) branch. The Man alpha(1-6) branch shows a large heterogeneity. It can be terminated with Man-4', GlcNAc-5', or Gal-6', whereas the Gal-6' residue may be extended with Gal alpha(1-3), NeuAc alpha(2-3), or Sia alpha (2-6). In the major structures 8% of alpha(2-6)-linked sialic acid was found as NeuGc instead of NeuAc. The main compounds have sulfated homologues bearing a sulfate group (6-20%) at C-3 of Gal-6' or at C-6 of GlcNAc-5 as follows. [formula: see text]     

Tomoeones A-H, cytotoxic phloroglucinol derivatives from Hypericum ascyron

Phloroglucinol derivatives tomoeones A-H (1-8) and three known compounds were isolated from leaves of Hypericum ascyron. Their structures were established based on spectroscopic analyses. They are all acylphloroglucinol derivatives possessing a spiro skeleton with geminal isoprenyl groups and a monoterpene moiety, and they are stereoisomers to each other at C-4 and C-13. They appear to be a class of phloroglucinol derivatives. Cytotoxicities of the isolated phloroglucinol derivatives against human tumor cell lines, including multidrug-resistant (MDR) cancer cell lines, were evaluated. Tomoeone F (6) demonstrated significant cytotoxicity against KB cells with an IC50 value of 6.2 microM. Compound 6 was also cytotoxic against MDR cancer cell lines (KB-C2 and K562/Adr), which was more potent than doxorubicin.