Three New Cytotoxic Acylspermidines from the Soft Coral,Sinularia sp.

Three new acylated spermidines and two known related compounds were isolated from the Okinawan soft coral, Sinularia sp. These compounds were N′,N″,N″-trimethylspermidines that are acylated by a methyl-branched unsaturated fatty acid. These acylspermidines showed potent cytotoxicity against human tumor cell lines at an IC₅₀ value of 17 ng/ml and the induction of apoptotic phenomena.     

Occurrence of steryl glycosides and acylated steryl glycosides in some marine algae

There is some controversy concerning the presence of steryl glycosides and acylated steryl glycosides in eucaryotic algae. These two classes of sterol compounds were investigated in species belonging to the three major groups of eucaryotic algae: green algae (Ulva gigantea, Cladophora rupestris), brown algae (Fucus vesiculosus, Ascophyllum nodosum), and red algae (Rhodymenia palmata, Porphyridium sp.). All these algae contain both steryl glycosides and acylated steryl glycosides. The sterol components of these compounds vary according to the alga but they are always the same as the free sterols of the alga in question. The most common sugar moiety is glucose. In the acylated steryl glycosides, the fatty acid is mainly palmitic acid. The percentage of these compounds (as a percentage of the total sterol content) is often low.     

Synthesis and analgesic activity of N,N'-dicarbonyltryptamines

5-Methoxytryptamine and L-tryptophan methyl ester were acylated with malonic acid, dimethyl malonate, or succinic anhydride to produce the corresponding N,N'-dicarbonyltryptamine derivatives. The analgesic activity was evaluated by the tail flick test. All of the compounds exhibited desirable analgesic potency. This result is consistent with that of N-(N-acetyl-L-tryptophanyl)-5-methoxytryptamine and confirmed that introducing substituted tryptamine into the amide chain of melatonin does enhance analgesic potency.     

Synthesis and Analgesic Activity of N,N'-Dicarbonyltryptamines

ABSTRACT

5-Methoxytryptamine and L-tryptophan methyl ester were acylated with malonic acid, dimethyl malonate, or succinic anhydride to produce the corresponding N, N'-dicarbonyltryptamine derivatives. The analgesic activity was evaluated by the tail flick test. All of the compounds exhibited desirable analgesic potency. This result is consistent with that of N-(N-acetyl-L-tryptophanyl)-5-methoxytryptamine and confirmed that introducing substituted tryptamine into the amide chain of melatonin does enhance analgesic potency.     

Microbial and chemical transformations of some 12,13-epoxytrichothec-9,10-enes.

Resting cells of Streptomyces griseus, Mucor mucedo, and a growing culture of Acinetobacter calcoaceticus when mixed with compounds related to 12,13-epoxytrichothec-9-ene-4beta,15-diacetoxy-3alpha-ol(anguidine) produced a series of derivatives that were either partially hydrolyzed or selectively acylated. These derivatives showed marked differences in activities as assayed by antifungal and tissue culture cytotoxicity tests.     

Microbial and chemical transformations of some 12,13-epoxytrichothec-9,10-enes.

Resting cells of Streptomyces griseus, Mucor mucedo, and a growing culture of Acinetobacter calcoaceticus when mixed with compounds related to 12,13-epoxytrichothec-9-ene-4beta,15-diacetoxy-3alpha-ol(anguidine) produced a series of derivatives that were either partially hydrolyzed or selectively acylated. These derivatives showed marked differences in activities as assayed by antifungal and tissue culture cytotoxicity tests.     

Polyacylated neohesperidosides from Geranium caespitosum: bacterial multidrug resistance pump inhibitors

Bioassay-directed fractionation for Staphylococcus aureus multidrug resistance efflux pump inhibitors resulted in isolation of novel acylated neohesperidosides from Geranium caespitosum. The more highly acylated compounds had no direct activity against S. aureus, but potentiated activity of the antibiotics berberine, rhein, ciprofloxacin and norfloxacin. Cellular concentrations of berberine were greatly increased in the presence of active esters.     

Design of weakly basic thrombin inhibitors incorporating novel P1 binding functions: molecular and X-ray crystallographic studies

To prepare weakly basic thrombin inhibitors with modified S1 anchoring groups, two series of compounds were synthesized by reaction of guanidine or aminoguanidine with acyl halides and N,N-disubstituted carbamoyl chlorides. pK(a) measurements of these acylated guanidines/aminoguanidines showed a reduced basicity, with pK(a) values in the range of 8.4-8.7. These molecules typically showed inhibition constants in the range of 150-425 nM against thrombin and 360-965 nM against trypsin, even though some bulky derivatives, such as N,N-diphenylcarbamoylguanidine/aminoguanidine and their congeners, showed much stronger thrombin inhibitory activity, with inhibition constants in the range of 24-42 nM. Unexpectedly, very long incubation times with both proteases revealed that aminoguanidine derivatives behaved as irreversible inhibitors. To assess the molecular basis responsible for the high affinity observed for these molecules toward thrombin, the crystal structure of the thrombin-hirugen-N,N-diphenylcarbamoylaminoguanidine complex has been solved at 1.90 A resolution. The structural analysis of the complex revealed an unexpected interaction mode with the protease, resulting in an N,N-diphenylcarbamoyl intermediate covalently bound to the catalytic serine as a consequence of its hydrolysis together with the release of the aminoguanidine moiety. Surprisingly, in this covalent adduct a phenyl group was found in the S1 specificity pocket, which usually recognizes positively charged residues. These findings provide new insights in the design of low basicity serine protease inhibitors.     

Flavonoids inBrassica nigra (L.) Koch,B. oleracea L.,B. campestris L. and their natural amphidiploids

Flavonoid analysis of the leaves inBrassica nigra, B. oleracea, B. campestris and their natural amphidiploids, led to the identification of 19 flavonol glycosides, including some acylated ones. These compounds were based on kaempferol, quercetin and isorhamnetin, except forB. oleracea, where no isorhamnetin glycosides were detected. Additive inheritance could normally be shown in the hybrids. Some considerations on the phylogenetic relationships within the group are expressed.     

Kinetic resolution of (±)-diethyl- and dibenzyl hydroxy(phenyl)methanephosphonates and their acyl derivatives with lipases

Abstract

A wide variety of commercially available lipases and microbial whole cells were tested for biotransformations of (±)-diethyl and dibenzyl hydroxyl(phenyl)methanephosphonates. Biocatalytic hydrolysis of acylated hydroxyphosphonates by whole cells of Bacillus subtilis gave optically active compounds with 95%ee _S. Enantioselectivities obtained when using commercially available enzymatic preparations were less satisfactory, leading to both compounds with an enantiomeric excess in the range 15 35%. Screening lipases for their ability to acylate these phosphonates or to hydrolyze their acylated derivatives enabled selection of enzymes and organisms suitable for use in both processes.     

Preventive effects of dietary cabbage acylated anthocyanins on paraquat-induced oxidative stress in rats

The preventive effects of acylated anthocyanins from red cabbage on paraquat-induced oxidative stress were determined in rats. Decreased food intake and body weight gain, and increased lung weight and atherogenic index by feeding the rats on a diet containing paraquat were clearly suppressed by supplementing acylated anthocynins to the paraquat diet. Paraquat feeding increased the concentration of thiobarbituric acid-reactive substances (TBARS) in liver lipids, and decreased the liver triacylglycerol level. These effects tended to be suppressed by supplementing acylated anthocynins to the paraquat diet. In addition, the catalase activity in the liver mitochondrial fraction was markedly decreased by feeding on the paraquat diet, this decrease being partially suppressed by supplementing the paraquat diet with acylated anthocyanins. An increase in the NADPH-cytochrome-P450-reductase activity in the liver microsome fraction by paraquat was suppressed by supplementing the paraquat diet with acylated anthocyanins. These results suggest that acylated anthocyanins from red cabbage acted preventively against the oxidative stress in vivo that may have been due to active oxygen species formed through the action of paraquat.     

Mass spectrometric analysis of GAP-43/neuromodulin reveals the presence of a variety of fatty acylated species

GAP-43 (neuromodulin) is a protein kinase C substrate that is abundant in developing and regenerating neurons. Thioester-linked palmitoylation at two cysteines near the GAP-43 N terminus has been implicated in directing membrane binding. Here, we use mass spectrometry to examine the stoichiometry of palmitoylation and the molecular identity of the fatty acid(s) attached to GAP-43 in vivo. GAP-43 expressed in either PC12 or COS-1 cells was acetylated at the N-terminal methionine. Approximately 35% of the N-terminal GAP-43 peptides were also modified by palmitate and/or stearate on Cys residues. Interestingly, a variety of acylated species was detected, in which one of the Cys residues was acylated by either palmitate or stearate, or both Cys residues were acylated by palmitates or stearates or a combination of palmitate and stearate. Depalmitoylation of membrane-bound GAP-43 did not release the protein from the membrane, implying that additional forces function to maintain membrane binding. Indeed, mutation of four basic residues within the N-terminal domain of GAP-43 dramatically reduced membrane localization of GAP-43 without affecting palmitoylation. These data reveal the heterogeneous nature of S-acylation in vivo and illustrate the power of mass spectrometry for identification of key regulatory protein modifications.     

Feeding responses of an oligophagous bean aphid, Megoura crassicauda, to primary and secondary substances in Vicia angustifolia

The feeding behaviour of the aphid Megoura crassicauda Mordivilko (Homoptera: Aphididae), which feeds selectively on plants in the genus Vicia (Fabaceae), was studied. The aphids deposited proteinaceous stylet sheaths intercellularly towards the phloem tissues of host plants. Similar stylet sheaths were formed on a Parafilm membrane when host‐specific acylated flavonoid glycosides [two 2″‐O‐(E)‐p‐coumaroyl esters of quercetin 3‐O‐diglycosides] present in the extracts of the narrow vetch, Vicia angustifolia L., were supplied in the solution covered by the membrane. In contrast, their corresponding deacyl analogues, present more abundantly in the host plant tissues, were not stimulatory, which suggested specificity in the structural requirements of the probing stimulants. While the aphids imbibed an artificial diet composed of primary nutrients (e.g., sucrose and amino acids) and produced a large quantity of honeydew, acylated flavonoids alone and non‐acylated flavonoids supplied with the nutrients more or less suppressed honeydew production. These findings implied that the acylated flavonoids serve as a cue to navigate the stylet sheath towards the phloem prior to sap‐sucking, whereas non‐acylated flavonoids may serve as a negative stimulus to refrain from sucking during tissue penetration before tapping the phloem, although the distribution of these compounds in the plant tissues remains unknown. Thus, the feeding behaviour of M. crassicauda appears to be controlled by multiple chemical stimuli in the process of the settling on its host plant.     

Evidence for reactivity of serine-74 with trans-4-(N,N-dimethylamino)cinnamaldehyde during oxidation by the cytoplasmic aldehyde dehydrogenase from sheep liver

A nucleophilic group in the active site of aldehyde dehydrogenase, which covalently binds the aldehyde moiety during the enzyme-catalyzed oxidation of aldehydes to acids, was acylated with the chromophoric aldehyde trans-4-(N,N-dimethylamino)cinnamaldehyde (DACA). Acyl-enzyme trapped by precipitation with perchloric acid was digested with trypsin, and the peptide associated with the chromophoric group was isolated and shown to be Gln-Ala-Phe-Gln-Ile-Gly-Ser-Pro-Trp-Arg. After redigestion with thermolysin, the chromophore was associated with the C-terminal hexaresidue part. If the chromophore is attached to this peptide, serine would be expected to bind the aldehyde and lead to the required acylated derivative. Differential labeling experiments were performed in which all free thiol groups on the acylated enzyme were blocked by carboxymethylation. The acyl chromophore was then removed by controlled hydrolysis and the protein reacted with [14C]iodoacetamide. No 14C-labeled tryptic peptides were isolated, suggesting that the sulfur of a cysteine cannot be the acylated residue in the precipitated acyl-enzyme.     

Acylated flavonol glycosides from the forage legume, Onobrychis viciifolia (sainfoin)

Ten acylated flavonol glycosides were isolated from aqueous acetone extracts of the aerial parts of the forage legume, Onobrychis viciifolia, and their structures determined using spectroscopic methods. Among these were eight previously unreported examples which comprised either feruloylated or sinapoylated derivatives of 3-O-di- and 3-O-triglycosides of kaempferol (3,5,7,4'-tetrahydroxyflavone) or quercetin (3,5,7,3',4'-pentahydroxyflavone). The diglycosides were acylated at the primary Glc residue of O-α-Rhap(1→6)-β-Glcp (rutinose), whereas the triglycosides were acylated at the terminal Rha residues of the branched trisaccharides, O-α-Rhap(1→2)[α-Rhap(1→6)]-β-Galp or O-α-Rhap(1→2)[α-Rhap(1→6)]-β-Glcp. Identification of the primary 3-O-linked hexose residues as either Gal or Glc was carried out by negative ion electrospray and serial MS, and cryoprobe NMR spectroscopy. Analysis of UV and MS spectra of the acylated flavonol glycosides provided additional diagnostic features relevant to direct characterisation of these compounds in hyphenated analyses. Quantitative analysis of the acylated flavonol glycosides present in different aerial parts of sainfoin revealed that the highest concentrations were in mature leaflets.     

New Acylated Flavonol Glycosides and a Phenolic Profile of Pritzelago alpina,a Forgotten Edible Alpine Plant

Thirteen acylated flavonoid glycosides, 1 – 13 , including eleven new congeners, 3 – 13 , were isolated from the aerial parts of Pritzelago alpina (Brassicaceae) by a combination of column chromatography on Sephadex LH‐20, and preparative and semi‐preparative HPLC. The structures were established by extensive NMR and MS experiments in combination with acid hydrolysis and sugar analysis by GC/MS. The new compounds were shown to be kaempferol and quercetin glycosides acylated for most of them by a branched short chain fatty acid or a hydroxycinnamic acid residue on the sugar portion. As shown by a HPLC‐DAD analysis of a MeOH extract, these compounds are the main phenolic constituents in the aerial parts of the plant.     

Pierisformotoxins A – D,Polyesterified Grayanane Diterpenoids from Pieris formosa and Their cAMP‐Decreasing Activities

Four highly acylated diterpenoids, designated as pierisformotoxins A–D ( 1 – 4 , resp.), along with 26 known compounds, were isolated from the flowers of Pieris formosa. Among them, pierisformotoxins A and B ( 1 and 2 , resp.) were new highly acylated grayanane diterpenoids, of which the five‐membered ring A has undergone an oxidative cleavage between C(3) and C(4), followed by lactonization, to give rise to a five‐membered lactone ring between C(3) and C(5), differing from the previously reported grayanane diterpenoids with a 5/7/6/5 ring system. Results of the cAMP‐regulation‐activity assay showed that pierisformotoxin C ( 3 ) at 10 μM (inhibitory ratio (IR): 10.1%) or 2 μM (9.8%), and pierisformotoxin B ( 2 ) at 50 μM (13.9%) significantly decreased the cAMP level in N1E‐115 neuroblastoma cells (p<0.05).     

Chlorine-containing iridoid and iridoid glucoside, and other glucosides from leaves of Myoporum bontioides

Sixteen compounds were isolated from the MeOH extract of leaves of Myoporum bontioides. The five compounds hitherto unknown, were elucidated to be a chlorine-containing iridoid, named myopochlorin, and an iridoid glucoside, an acylated iridoid glucoside, a linear acetogenin glucoside, and an acyclic monoterpene glucoside, named myobontiosides A-D, respectively, by means of spectroscopic analyses.     

Anti-influenza diarylheptanoids from the bark of Alnus japonica

This study to investigate anti-influenza components from the bark of Alnus japonica resulted in the isolation of two rare acylated diarylheptanoids, named oregonoyl A (5) and oregonoyl B (6), along with nine known compounds (1–4 and 7–11). Their structures were elucidated on the basis of extensive spectroscopic and chemical methods. Antiviral testing of compounds 1–11 against KBNP-0028 (H9N2) avian influenza virus showed that platyphyllone (10) was strongly active, and platyphyllonol-5-xylopyranoside (9) was moderately active against KBNP-0028 as compared with the positive control, zanamivir, respectively.     

Sulphuretin glycosides of Coreopsis mutica

The anthochlor complement of Coreopsis mutica has been determined. The compounds observed were all glycosidic derivatives of sulphuretin, being the mono- and di-glucosides and two new glucosidic derivatives acylated with caffeic acid.