Ken-ichi Nihei's research while affiliated with Tokyo University of Agriculture and Technology and other places

Publications (97)

Article
A highly symmetric dihydrofuran lignan, ribesin B (1), isolated from the leaves of Ribes nigrum, was synthesized via a process whereby the key step was a sequential Michael addition–carbocyclization. However, the NMR spectral features of the synthesized 1 were inconsistent with those of the natural product 1. Thus, the chemical synthesis of the iso...
Article
To develop novel tyrosinase inhibitors, resorcinol alkyl glucosides 7–12 were synthesized via the Wittig and/or Horner-Wadsworth-Emmons reactions with Koenigs-Knorr glycosylation as the key step. Half maximal inhibitory concentrations (IC50) of 35.9–0.39 µM were observed for 7–12 for the tyrosinase-catalyzed oxidation. Tyrosinase inhibitory activit...
Article
Tyrosinase-catalyzed L-tyrosine oxidation is a key step in melanogenesis, and intense melanin formation is often a problem in chemotherapies or food preservation. Methyl p-coumarate is isolated from fresh flower of medicinal plant, Trixis michuacana var longifolia (D. Dow) C., and it suppressed melanogenesis in cultured murine B16-F10 melanoma cell...
Article
Procedures for the deprotection of the 2-nitro-and 2,4-dinitrobenzenesulfonamides to give the corresponding primary amines were developed. The 2-Nitrobenzenesulfonyl group was effectively removed by HSCH 2 CH 2 OH/DBU or PhSH/Cs 2 CO 3 in DMF under mild conditions to give the corresponding primary amines in high to excellent yield. For removal of t...
Article
Full-text available
Venoms of solitary wasps are utilized for prey capture (insects and spiders), paralyzing them with a stinger injection to be offered as food for their larvae. Thus, the identification and characterization of the components of solitary wasp venoms can have biotechnological application. In the present study, the venom components profile of a solitary...
Article
Full-text available
Background: Solitary wasp venoms may be a rich source of neuroactive substances, since their venoms are used for paralyzing preys. We have been exploring bioactive constituents of solitary wasp venoms and, in this study, the component profile of the venom from a solitary scoliid wasp, Scolia decorata ventralis, was investigated through a comprehen...
Article
Purification of small peptide components in the venoms of the solitary sphecid wasps, Sphex argentatus argentatus and Isodontia harmandi, led to the isolation of several major peptides. Analysis of MS/MS spectra by MALDI-TOF/TOF revealed the sequence of a new peptide Sa112 (EDVDHVFLRF-NH2), which is structurally very similar to leucomyosupressin (p...
Article
Phloretin-4-O-β-D-glucopyranoside (1), isolated from Homalium stenophyllum, was synthesized for the first time through aldol condensation and Schmidt glycosylation reactions aiming to develop a novel hydrophilic tyrosinase inhibitor. However, the specific rotation of synthetic 1 was found to be negative and different from that reported for natural...
Article
Full-text available
The oxidation of 4-t-butylcatechol catalyzed by mushroom tyrosinase was inhibited by 4-bromobenzaldehyde, 4-chlorobenzaldehyde, 4-fluorobenzaldehyde, 4-cyanobenzaldehyde, and 4-nitrobenzaldehyde with 50% inhibitory concentrations of 114 μM, 175 μM, 387 μM, 822 μM, and 1846 μM, respectively. The inhibition kinetics were analyzed by Dixon plots, whic...
Article
Total synthesis of two arabidopyrones, iso-arabidopyl alcohol (1) and iso-arabidopic acid (2) isolated from Arabidopsis thaliana was achieved for the first time using Claisen condensation and Wittig reaction as the key steps. In addition, arabidopic acid (4) was synthesized from the methyl ester of arabidopyl alcohol (3). Thus, chemical synthesis o...
Article
Ants (Hymenoptera, Apocrita, Aculeata, Formicoidea) comprise a well-succeeded group of animals. Like bees and wasps, ants are mostly venomous, having a sting system to deliver a mixture of bioactive organic compounds and peptides. The predatory giant ant Dinoponera quadriceps belongs to the subfamily Ponerinae that includes one of the largest known...
Article
Ants (Hymenoptera, Apocrita, Aculeata, Formicoidea) comprise a well-succeeded group of animals. Like bees and wasps, ants are mostly venomous, having a sting system to deliver a mixture of bioactive organic compounds and peptides. The predatory giant ant Dinoponera quadriceps belongs to the subfamily Ponerinae that include one of the largest known...
Article
Apios isoflavone glucosides 1 and 2 were synthesized for the first time via Friedel–Crafts reaction, Bischler–Napieralski-type cyclization, and phase-transfer catalyzed glycosylation as the key steps. In addition, aglycones 4 and 5 and related natural isoflavone cajanin (6) were synthesized in short steps. Evaluation of the inhibitory activity of t...
Article
The recovery of useful components such as antioxidants from strawberry leaves would be desirable because this byproduct is usually disposed of as agricultural waste. In this study, strawberry leaves were extracted with supercritical carbon dioxide (sc-CO2) and the effects of various entrainers were evaluated under the following conditions: temperat...
Article
As a novel mushroom tyrosinase inhibitor, 4-methoxybenzonitrile (anisnitrile) was identified (IC 50 = 111.1 μM) with hyperbolic inhibition manner. The calculated αK i (166.3 μM) was larger than K i (66.5 μM) by Dixon plots, indicating that this nitrile acts as a competitive-noncompetitive mixed type inhibitor. Similarly, 4-isopropylbenzonitrile (cu...
Article
Resorcinol alkyl glucosides 7–12 were developed as novel tyrosinase inhibitors based on the structure of rhododendrin. These were synthesized from 2,4-dibenzyloxybenzaldehyde using either the Wittig or the Horner-Wadsworth-Emmons reaction with Koenigs-Knorr glycosylation as key steps. The tyrosinase inhibitory activity of 7–12 increased with the le...
Article
In this study, dihydrooxyresveratrol glucosides 3–6 were synthesized for the first time to the best of our knowledge by the Wittig reaction and Schmidt glycosylation as key steps for the purpose of developing novel hydrophilic tyrosinase inhibitors. Results obtained from inhibitory studies revealed 50% inhibitory concentration (IC50) values of 12.8...
Article
Isotachioside (1) and its related natural product 2 are isolated from Isotachis japonica and Protea neriifolia, respectively, and are categorized as analogs of arbutin (3), a tyrosinase inhibitor for practical use. Both of the natural products and several derivatives such as glucoside 4, xyloside 5, cellobioside 6, and maltoside 7 were synthesized...
Article
Full-text available
Background: Among the hymenopteran insect venoms, those from social wasps and bees - such as honeybee, hornets and paper wasps - have been well documented. Their venoms are composed of a number of peptides and proteins and used for defending their nests and themselves from predators. In contrast, the venoms of solitary wasps and bees have not been...
Article
Strawberries are one of the most popular fruits in Japan and they have a high antioxidant content. In this study, the contents in strawberry receptacles were extracted with supercritical carbon dioxide and entrainers. Using ethanol, acetone, and water as entrainers improved the antioxidant capacity and increased the amounts of total saccharides and...
Article
Full-text available
Hyperuricemia is recognized as an important risk factor for gout. High dietary intake of purine-rich foods such as meats and sea foods increases uric acid (UA) levels in the blood. Taxifolin present in Siberian larch and strawberries has been reported to possess health promoting activities including anti-oxidant effect. In this study, we examined a...
Article
Sonnerphenolic C (3), which was predicted in a redox product of epirhododendrin (1) isolated from Acer nikoense, was synthesized for the first time via the epimeric separation of benzylidene acetal intermediates as a key step. From a similar synthetic route, 1 was obtained concisely. As a result of their antioxidative evaluation, only 3 revealed po...
Article
Benzaldehyde inhibited the oxidation of 4-t-butylcatechol catalyzed by mushroom tyrosinase with an IC50 of 31.0 μM. The inhibition kinetics analyzed by Dixon plots indicated that it acts as a partial noncompetitive inhibitor. Further studies of several benzaldehydes, particularly those having a substitution at C-4, suggested that the partial inhibi...
Article
Dihydroresveratrol cellobioside and xylobioside, whose structure were designed based on that of naturally occurring melanogenesis-controlled agent dihydroresveratrol glucoside, were synthesized via Schmidt glycosylation as the key step. Both analogues stimulated melanogenesis with efficacies comparable to that of 8-methoxypsoralen, a well-known mel...
Article
Full-text available
Solitary wasps paralyze insects or spiders with stinging venom and feed the paralyzed preys to their larva. Accordingly, the venoms should contain a variety of constituents acting on nervous systems. However, only a few solitary wasp venoms have been chemically studied despite thousands of species inhabiting the planet. We have surveyed bioactive s...
Article
Rhododendrol derivatives 3-12 have been synthesized in six steps, including aldol condensation and/or trichloroacetimidate glycosylation as the key reactions. Each derivative showed effective inhibition of tyrosinase-catalyzed oxidation processes. In particular, a series of synthetic derivatives having an R-stereogenic center at C-2 proved to be mo...
Article
5-Pentadecatrienylresorcinol, isolated from cashew nuts and commonly known as cardol (C15:3), prevented the generation of superoxide radicals catalysed by xanthine oxidase without the inhibition of uric acid formation. The inhibition kinetics did not follow the Michelis-Menten equation, but instead followed the Hill equation. Cardol (C10:0) also in...
Article
Dihydroresveratrol glucoside 1 isolated from Camellia oleifera and its xyloside derivative 2 were synthesized for the first time in 5 steps from TBS-protected aldehyde 4. Natural product 1 is a potent melanogenesis inhibitor in B16F0 melanoma cells (approximately 40 fold more potent than kojic acid). In contrast, the synthetic product 2 stimulates...
Article
The stereochemistry of inuloidin (1), which was a sesquiterpenoid that was characterized as a plant growth inhibitory substance from Heterotheca inuloides, was investigated. The modified Mosher's method coupled with a total synthetic study using osmium oxidation and Burgess dehydration as key steps were performed to clarify the stereochemistry of 1...
Article
The concise synthesis of rhododendrol glycosides 3-8, which are novel derivatives of (+)-epirhododendrin (1) and (-)-rhododendrin (2), has been achieved in six steps from benzaldehyde 9. The key reactions include aldol condensation and trichloroacetimidate glycosylation. From biological studies, it has been determined that synthetic derivatives of...
Article
Full-text available
Xanthine oxidase inhibitors may serve as therapeutic agents for hyperuricaemia and/or oxidative stress. From our continuing investigation, we proposed that some inhibitors for reactions catalyzed by xanthine oxidase consisted of a head portion and a tail portion and that each portion had different functions for inhibition. In a previous study on th...
Article
The absolute stereochemistry of altersolanol A (1) was established by observing a positive exciton couplet in the circular dichroism (CD) spectrum of the C3,C4-O-bis(2-naphthoyl) derivative 10 and by chemical correlations with known compound 8. Before the discussion, the relative stereochemistry of 1 was confirmed by X-ray crystallographic analysis...
Article
A large quantity of quercetin was characterized from a local dish, known as maniçoba in Pará, Brazil. The fresh leaf of Manihot esculenta Crantz (Euphorbiaceae), a principal ingredient for maniçoba, was found to contain a large amount of rutin or quercetin 3-O-rutinoside which was completely hydrolyzed to quercetin during cooking processes. Antioxi...
Article
Full-text available
Four novel peptides were isolated from the venoms of the solitary eumenine wasps Eumenes rubrofemoratus and Eumenes fraterculus. Their sequences were determined by MALDI-TOF/TOF (matrix assisted laser desorption/ionization time-of-flight mass spectrometry) analysis, Edman degradation and solid-phase synthesis. Two of them, eumenitin-R (LNLKGLIKKVAS...
Article
Bibenzyl glycosides 1-6 were synthesized from 2,4-dihydoxybenzaldehyde and xylose, glucose, cellobiose or maltose. The key steps in the synthesis were the Wittig reaction and trichloroacetimidate glycosylation. Tests for tyrosinase inhibitory activity showed that all were significantly active, indicating that they are unique hydrophilic tyrosinase...
Article
Water-soluble proteins in avian corneas were profiled by two-dimensional electrophoresis and identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Comparative protein profiling of avian and mammalian corneas revealed five major protein spots specifically detected in avian species. These proteins were identified...
Article
In the present HPLC-based analysis of the isoflavone profile of groundnut (Apios americana Medik) tubers, we identified a major peak that did not correspond to any known isoflavones. A water extract of groundnut tubers prepared at 4°C showed the major and genistin peaks, whereas that prepared at 45°C did not yield these peaks but showed a peak for...
Article
Procedures for the deprotection of the 2-nitro- and 2,4-dinitrobenzenesulfonamides to give the corresponding primary amines were developed. The 2-Nitrobenzenesulfonyl group was effectively removed by HSCH2CH2OH/DBU or PhSH/Cs2CO3 in DMF under mild conditions to give the corresponding primary amines in high to excellent yield. For removal of the 2,4...
Article
Acyl-CoA thioesterase II (TesB), which catalyzes hydrolysis of acyl-CoAs to free fatty acids and CoA, is involved in 3-hydroxyalkanoic acid production in Escherichia coli. Effects of genetic replacement of tesB with Saccharomyces cerevisiae acyl-CoA thioesterase gene PTE1 on 3-hydroxyalkanoic acid production from oleic acid through β-oxidation were...
Article
Full-text available
A series (C 1 to C 16) of alkyl gallates was tested for their antioxidant activity for food protection and human health. One molecule of alkyl gallate, regardless of alkyl chain length, scavenges six molecules of 1,1-diphenyl-2-picrylhydrazyl (DPPH). Alkyl gallates inhibited the linoleic acid peroxidation catalyzed by soybean lipoxygenase-1 (EC 1.1...
Article
Full-text available
To assess the digestion and assimilation of gelatin and gelatin hydrolysates, the in situ absorption of typical hydroxyproline-containing dipeptides, Pro-Hyp, Hyp-Gly, Ser-Hyp Ala-Hyp, and pentadecapeptide, (Pro-Hyp-Gly)(5), was investigated in the rat small intestine. During vascular perfusion after the injection of Hyp-Gly, Pro-Hyp and (Pro-Hyp-G...
Article
Two novel cucurbitane glycosides, wilbrandisides A and B were isolated as sweet-taste substances from the root of Wilbrandia species (Cucurbitaceae) along with seven known cucurbitane glycosides. Their structures were determined by spectroscopic means, including two-dimensional NMR experiments. Their sweet-taste properties were evaluated by a human...
Article
Spiroleptosphol B (2), spiroleptosphol C (3), norleptosphol C (4) and hydroleptosphol (5) were isolated from ascomycete Leptosphaeria doliolum. Detailed (1)H and (13)C NMR spectral analyses revealed these were structural analogues of spiroleptosphol (1) which we have recently isolated from the same fungi. Spiroleptosphol B (2) carried an unpreceden...
Article
In order to develop water soluble tyrosinase inhibitors, bibenzyl xyloside 1 isolated from Chlorophytum arundinaceum (liliaceae), and its derivatives 2 and 3 were synthesized by using Wittig reaction and trichloroimidate glycosylation procedure as key steps. Xylosides 1-3 showed potent tyrosinase inhibitory activity with IC(50)s of 1.6, 0.43, and 0...
Article
On the basis of antibacterial anacardic acids, 6-pentadecenylsalicylic acids, isolated from the cashew apple, Anacardium occidentale L. (Anacardiaceae), a series of 6-alk(en)ylsalicylic acids were synthesized and tested for their antibacterial activity against Streptococcus mutans ATCC 25175. Among them, 6-(4',8'-dimethylnonyl)salicylic acid was fo...
Article
The antimicrobial activities of anethole, anisic acid, and eugenol characterized from aniseed were tested against 18 organisms including both bacteria and yeasts. As far as their minimum inhibitory concentration (MIC) values were compared, they are nearly comparable but act in different ways. For example, anethole was noted to be effective against...
Article
Tannic acid isolated from a unique natural medicine Gallae Rhois showed insect growth inhibitory activity against the pink bollworm Pectinophora gossypiella larvae in an artificial diet feeding assay. Gallic acid isolated from the same source also inhibited the growth of P. gossypiella larvae but much weaker compared to tannic acid. In addition, ta...
Article
A series of anacardic acid analogues possessing different side chains viz. phenolic, branched, and alicyclic were synthesized and their antibacterial activity tested against methicillin-resistant Staphylococcus aureus (MRSA). The maximum activity against this bacterium occurred with the branched side-chain analogue, 6-(4',8'-dimethylnonyl)salicylic...
Article
Full-text available
In searching for tyrosinase inhibitors from plants using L-3,4-dihydroxyphenylalanine (L-DOPA) as a substrate, quercetin was found to be partially oxidized to the corresponding o-quinone under catalysis by mushroom tyrosinase (EC 1.14.18.1). Simultaneously, L-DOPA was also oxidized to dopaquinone and both o-quinones were further oxidized, respectiv...
Article
Novel cyclic thiopeptides, cyclothiazomycins B1 (1) and B2 (2), were isolated from Streptomyces sp. A307 as potent hyphal swelling inducing substances. They are stable in the solid state but slowly isomerize with one another in solution. Degradation experiments and spectroscopic analyses disclosed that they comprise unique tricyclic structures each...
Article
A series of aliphatic (2E)-alkenals and alkanals from C5 to C13 were tested for their antibacterial activity against Salmonella choleraesuis ssp choleraesuis ATCC 35640. The activity against this food-borne bacterium is correlated with the hydrophobic alkyl chain length from the hydrophilic aldehyde group. (2E)-Dodecenal (C12) was most effective ag...
Article
Biological activities of 2alpha-substituted 1alpha,25-dihydroxyvitamin D3 analogues were evaluated in vitro. Their binding affinity was examined with calf thymus cytosolic vitamin D receptor (VDR) and rat plasma vitamin D-binding protein (DBP). In addition, the transcriptional activity of the analogues was measured using a rat 25-hydroxyvitamin D3-...
Article
A large quantity of quercetin was characterized from a local dish known as maniçoba in Pará, Brazil. The fresh leaf of Manihot esculenta Crantz (Euphorbiaceae), a principal ingredient for maniçoba, was found to contain a large amount of rutin or quercetin 3-O-rutinoside which was completely hydrolyzed to quercetin during cooking processes. Antioxid...
Article
An efficient and versatile synthesis of acylpolyamine spider toxins of all structural types classified by extensive MS analysis has been achieved. By using 2-nitrobenzenesulfonamide as an effective activating and/or protecting group (the Nosyl strategy), the naturally occurring toxins 1–8 corresponding to Types A–F were concisely synthesized in hig...
Article
A series (C1-C12) of alkyl gallates was examined for their effects on the activity of xanthine oxidase. Octyl (C8), decyl (C10), and dodecyl (C12) gallates competitively inhibited uric acid formation generated by xanthine oxidase, and the inhibition increased upon increasing the alkyl chain length. Interestingly, neither menthyl nor bornyl gallates...
Article
Two novel limonoids, musidunin (1) and musiduol (2), were isolated from a methanol extract of Croton jatrophoides by bioassay-guided fractionation. Their structures were established by extensive NMR experiments. Interestingly, A,B-seco limonoid 1 contains a unique acetal annulation of A, A', and B' rings. Both limonoids exhibited antifeedant activi...
Article
We analyzed the effect of the acylpolyaminetoxin JSTX-3 on the epileptogenic discharges induced by perfusion of human hippocampal slices with artificial cerebrospinal fluid lacking Mg2+ or N-methyl-D-aspartate. Hippocampi were surgically removed from patients with refractory medial temporal lobe epilepsy, sliced in the surgical room and taken to th...
Article
The Joro spider toxin (JSTX-3), derived from Nephila clavata, has been found to block glutamate excitatory activity. Epilepsy has been studied in vitro, mostly on rat hippocampus, through brain slices techniques. The aim of this study is to verify the effect of the JSTX-3 on the epileptiform activity induced by magnesium-free medium in rat CA1 hipp...
Article
Three new A-seco limonoids, zumketol (1), zumsenin (2), and zumsenol (3), were isolated from a methanol extract of Croton jatrophoides by bioassay-guided fractionation, and their structures were determined by NMR analysis. The alpha-ketol 1 may be biosynthesized via the intramolecular acyloin condensation of a dicarboxylate intermediate.
Article
This is the first report for secondary metabolites in an African medicinal plant, Pachyelasma tessmannii (Leguminosae). Four novel saponins, pachyelasides A-D, were isolated from the methanol extract of the root bark by using recycling HPLC. These compounds showed molluscicidal activity (LD(50) < or =8.0 mug/mL) against the South American snail, Bi...
Article
Four possible stereoisomers of 3-hydroxy-4-methyltetradecanoic acid were enantioselectively synthesized by using Sharpless epoxidation and a subsequent epoxide-ring opening reaction with trimethylaluminum as the key steps. The absolute configuration of the beta-oxyacid component of antifungal cyclodepsipeptides W493 A and B was consequently determi...
Article
p-Coumaric acid (4-hydroxycinnamic acid) and methyl p-coumarate (methyl 4-hydroxycinnamate) inhibit the oxidation of L-tyrosine catalyzed by mushroom tyrosinase. However, both were oxidized as monophenol substrate analogues at an extremely slow rate. This oxidation was significantly accelerated as soon as catalytic amounts (0.01 mM) of L-3,4-dihydr...
Article
Quercetin was oxidized as a substrate catalyzed by mushroom tyrosinase to the corresponding o-quinone and subsequent isomerization to p-quinone methide type intermediate; followed by the addition of water on C-2 yielding a relatively stable intermediate, 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone. In the presence of a catalytic a...
Article
A series of alkyl 3,4-dihydroxybenzoates (protocatechuates) was synthesized, and their fungicidal activity against Saccharomyces cerevisiae was assayed using a 2-fold serial broth dilution method. Nonyl and octyl 3,4-dihydroxybenzoate were noted to be the most effective against this yeast with the minimum fungicidal concentration of 12.5 microg/mL...
Article
Aliphatic (2E)-alkenals and alkanals characterized from the fresh leaves of the coriander Coriandrum sativum L. (Umbelliferae) were found to possess bactericidal activity against Salmonella choleraesuis ssp. choleraesuis ATCC 35640. (2E)-Dodecenal (C(12)) was the most effective against this food-borne bacterium with the minimum bactericidal concent...
Article
Two novel A-seco limonoids, dumnin and dumsenin, were isolated from the methanolic extract of Croton jatrophoides by bioassay-guided fractionation, and the structures were determined by nuclear magnetic resonance, circular dichroism, and mass spectrometry experiments. These compounds showed potent antifeedant activity (PC(50) <or= 2.0 microg/mL) ag...
Article
Octyl gallate inhibited soybean lipoxygenase-1 (EC 1.13.11.12, type I) with an IC(50) of 1.3 microM. The inhibition of the enzyme by octyl gallate is a slow and reversible reaction without residual activity. The inhibition kinetics analyzed by Lineweaver-Burk plots indicates that octyl gallate is a competitive inhibitor, and the inhibition constant...
Article
Arbutin, hydroquinone-O-beta-D-glucopyranoside (1) was found to inhibit the oxidation of l-tyrosine (monophenolase activity) catalyzed by mushroom tyrosinase. However, arbutin itself was oxidized as a monophenol substrate at an extremely slow rate, and this oxidation was accelerated as soon as catalytic amounts (0.01 mM) of l-3,4-dihydroxyphenylala...
Article
Hydroquinone was found to alter agglutination of Streptococcus mutans induced by sucrose. The newly formed agglutination product produced by hydroquinone does not kill this cariogenic bacterium and the formation is reversible. The agglutination altering activity of hydroquinone seems to be specific for strains of S. mutans. As a result, hydroquinon...
Article
The antibacterial activity of a series of alkyl gallates (3,4,5-trihydroxybenzoates) against Gram-positive bacteria was tested using a broth dilution method. All of the Gram-positive bacteria tested were susceptible to alkyl gallates, and this activity was found to correlate with the alkyl chain length. The antibacterial activity of alkyl gallates...
Article
Chamaecin (2-hydroxy-4-isopropylbenzaldehyde) was synthesized and tested for its tyrosinase inhibitory activity. It partially inhibits the oxidation of L-3,4-dihydroxyphenylalanine (L-DOPA) catalyzed by mushroom tyrosinase with an IC(50) of 2.3 microM. The inhibition kinetics analyzed by Dixon plots found that chamaecin is a mixed type inhibitor. T...
Article
The synergistic effects of 6-alk(en)ylsalcylic acids, also known as anacardic acids, in combination with methicillin against Staphylococcus aureus ATCC 33591 (MRSA) was investigated. The double bond in C15-anacardic acids is not essential in eliciting the antibacterial activity but is associated with increasing the activity. The synergistic effects...
Article
Full-text available
Several tetra-substituted 2,5-dihydrofuran lignans have been prepared using a sequential Michael addition-carbocyclization with palladium as the catalyst. The synthetic compounds were evaluated against trypomastigote forms of Trypanossoma cruzi and the higher activity for diastereoisomeric compounds could be correlated to the trans configuration of...
Article
This study investigated the effect of a series of naturally occurring aliphatic (2E)-alkenals against Salmonella choleraesuis subsp. choleraesuis ATCC 35640 and evaluated their antibacterial action. A homologous series of aliphatic (2E)-alkenals from C5-C13 were tested for their antibacterial activity against Salm. Choleraesuis. The antibacterial a...
Article
The structural and antibacterial activity relationship of 6-alk(en)ylsalicylic acids, also known as anacardic acids, was investigated against Gram-positive bacteria, emphasizing the methicillin resistant Staphylococcus aureus ATCC 33591 (MRSA) strain. The unsaturation in the alkyl side chain is not essential in eliciting activity but is associated...