Antioxidant activity of α and β-amyrin isolated from Myrcianthes pungens leaves

Abstract

Brazil has a great variety of native plants which could be explored and among them guabiju (Myrcianthes pungens) stands out. Thus, this study consisted of isolating pentacyclic triterpenes, α and β-amyrin from guajibu leaves, and determine the antioxidant activity.The leaves were dried, pulverized and submitted to a dynamic maceration process with ethanol 96° GL, concentrated to obtain crude leaf extract (CLE). CLE was eluted with dichloromethane until total depletion, resulting in a dichloromethane fraction (FRDicl) which was concentrated and analyzed by GC/MS and NMR. The result of the chemical analysis revealed the presence of pentacyclic triterpenes of oleanane (β-amyrin), and ursane (α-amyrin) groups. The β-carotene bleaching method revealed a high antioxidant activity for the CLE as well as for FRDicl. The antioxidant protection equivalent to the trolox was of 137 and 129%, respectively at 500 µg/mL. The antioxidant potential of FRDicl can be explained by the presence of α and β-amyrins.     

Anti-inflammatory,analgesic and molecular docking studies of Lanostanoic acid 3-O-α-D-glycopyranoside isolated from Helichrysum stoechas

Helichrysum stoechas has been conventionally used as herbal tea due to its anti-inflammatory, antioxidant, antimicrobial and diuretic activities. Ethanolic extract of the aerial parts of the plant (HSE) afforded a lanostane triterpenoid glycoside. The isolated compound was characterized as Lanostan-3β-olyl-26-oic acid 3-O-α-D-glycopyranoside (HS-01) with the help of UV, IR, ¹H, ¹³C NMR and MS spectroscopic techniques. HSE (at 100 and 200 mg/kg doses) and the isolated compound, HS-01 (at 10 mg/kg dose) has been investigated for anti-inflammatory and analgesic activities against chemically challenged experimental animal. Both the HSE as well as HS-01 showed a substantial decline in paw volume when compared with the relevant control groups (p < 0.01 & p < 0.001). The HSE and HS-01 also confirms a significant prolongation of the paw licking or jumping towards the Eddy’s hot plate and reduction in quantity of writhes after the introduction of acetic acid in mice (p < 0.01 & p < 0.001). In order to have a better understanding of the binding interactions of HS-01 at molecular level, docking studies were performed with various macromolecular drug targets using AutoDock 4.2 and AutoDock Vina 1.1. Both programs predicted Galectin-3 as most favorable target for HS-01 followed by iNOS, whereas TNFα and COX-2 were among less favorable. Therefore, HS-01 could be developed as suitable therapy against inflammation and associated disorders.     

β,β-Difluoro analogs of α-oxo-β-phenylpropionic acid and phenylalanine

A simple three-step procedure converted the readily accessible (2-bromo-1,1-difluoroethyl)arenes (2) into α-aryl-α,α-difluoroacetaldehydes (1). Subsequent hydrocyanation, hydrolysis, oxidation and again hydrolysis afforded β-aryl-β,β-difluoro-α-oxopropionic acids (3). Reductive amination transformed the oxoacids 3 into a separable mixture of α-hydroxyacids 11 and racemic β,β-difluoro-β-phenylalanine derivatives (4). Enantiomerically pure β,β-difluorophenylalanine (l-4a) was obtained when α,α-difluoro-α-phenylacet-aldehyde (1a) was condensed with homochiral 1-phenylethylamine, hydrogen cyanide added to the resulting imine, the diastereomeric mixture thus produced hydrolyzed to the carboxamides (15) which were found to be separable by fractional crystallization or chromatography. The pK_a values of the β-aryl-β,β-difluoroalanines (4) were measured and biological profile of the latter probed. 3-(4-Chlorophenyl)-3,3-difluoro-2-oxopropionic acid (4c) proved to be a potent (K_i 27 μM) and selective inhibitor of arogenate dehydratase, a key enzyme catalyzing the last step of the phenylalanine biosynthesis.     

Facile syntheses of fluorine-containing α,β-unsaturated acids and esters from 2-trifluoromethylacrylic acid

Various types of fluorine-containing α,β-unsaturated acids and their esters were synthesized from 2-trilfuoromethylacrylic acid as a sole starting material.     

Synthesis and antitumor activity of derivatives of 23-hydroxybetulinic acid

A series of natural product 23-hydroxybetulinic acid derivatives were prepared.In the preparation of mono-O-benzoyl ester derivative,it was observed that benzoyl group migrated from 3-O-to 23-O-position during the detritylation.     

Selective extraction of uranium from uranium–beryllium ore by acid leaching

Journal of Radioanalytical and Nuclear Chemistry - Both uranium and beryllium are very important strategic metals and have been applied to many fields, such as nuclear industries, atomic energy,...     

Facile access to α,β-dehydroalanine and α,β-dehydroamino butyric acid derivatives from DL-serines and threonines

Not only α,β-dehydroamino acids are important constituents for a number of bioactive peptides in nature, but also they are important building blocks for a variety of synthetic amino acids in organic synthesis. Methods to prepare dehydroamino acids have been reported extensively in the literature; however, efficient and convenient protocols are still required. Here we have developed a convenient method to prepare dehydroalanine (ΔAla) and dehydroamino butyric acid (ΔAbu) derivatives derived from DL-serines and DL-threonines, respectively. 4-Toluenesulfonyl chloride (TsCl) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) were employed in this procedure, which carried out activation of hydroxyl group and β-elimination in one pot. Because it is convenient and easy to handle, this method will attract the attention of synthetic chemists.     

A new dihydrobenzofuran lignan and potential α-glucosidase inhibitory activity of isolated compounds from Mitrephora teysmannii

A new dihydrobenzofuran lignan, (2R,3S)-2-(3′,4′-dimethoxyphenyl)-5-(3-hydroxypropyl)-7-methoxy-2,3-dihydrobenzofuran-3-methyl acetate, named as mitredrusin (1), was isolated from the leaves of Mitrephora teysmannii (Annonaceae) together with 12 known compounds including a related dihydrobenzofuran lignan: (?)-3′,4-di-O-methylcedrusin (2), four polyacetylenic acids: 13(E)-octadecene-9,11-diynoic acid (3), 13(E),17-octadecadiene-9,11-diynoic acid (4), octadeca-9,11,13-triynoic acid (5) and octadeca-17-en-9,11,13-triynoic acid (6), five lignans: (?)-eudesmin (7), (?)-epieudesmin (8), (?)-phillygenin (9), magnone A (10) and forsythialan B (11) and two megastigmans: (3S,5R,6S,7E,9R)-7-megastigmene-3,6,9-triol (12) and annoionol A (13). The chemical structures of these compounds were established on the basis of their 1-D and 2-D NMR spectroscopic data. All compounds were evaluated for their α-glucosidase inhibitory activity. Among these isolates, polyacetylenic acids 3 and 4 showed more than 20-fold much higher activity compared with that of the antidiabetic drug acarbose.     

Selective Phosphorylation of α,β-Unsaturated Carbonyl Compounds

Abstract

Elaboration of effective methods of selective phosphorylation of α,β-unsaturated carbonyl compounds containing simultaneously C[dbnd]C and C[dbnd]O bonds, which may compete with each other or react consistently one after another, is one of the most complex problems in the modern organophosphorus synthesis. On the basis of our previous systematic investigations of kinetics and mechanism of the Pudovik and Abramov reactions in the series of α,β-unsaturated carbonyl compounds we have suggested three possible ways to solve this problem: a) soft reaction conditions, regulated by solvent, catalyst and temperature; b) interface catalysis; c) metallocomlex catalysis (reaction in the coordination sphere of transition metal).     

Synthesis and photo activity of phenylazonaphthalene peptide nucleic acid monomers

Phenylazonaphthalene peptide nucleic acid （PNA） monomers were successfully synthesized, and their photoisomerization was examined. The new PNA monomers showed reversible trans-cis isomerization with UVand visible light irradiation, which might be the foundation of photo-regulating the hybridization between PNA containing phenylazonaphthalene unit and DNA. Simultaneously, the fluorescence of the new PNA monomers might make them especially useful as structural probes.     

Potent α-glucosidase inhibitory activity of compounds isolated from the leaf extracts of Uvaria hamiltonii

Abstract

The phytochemical investigation of the leaf extracts of Uvaria hamiltonii (Annonaceae) led to the isolation and identification of ten compounds including a new seco-cyclohexene (1) together with nine known compounds (2–10). Their structures were elucidated by intensive analysis by spectroscopic methods and comparisons of their spectroscopic data with those of compounds reported in the literature. Compounds 2, 8, and 9 showed potent α-glucosidase inhibitory activity with the IC₅₀ values ranging from 2.6–7.1?µM.     

Preparation and antibacterial activity of aromatic derivatives of β-aminopropionic and γ-aminobutyric acid

Ten aromatic derivatives of β-aminopropionic acid and γ-aminobutyric acid were prepared.Their compositions and structures were identified by elemental analysis,IR,and 1H NMR.They have been examined for their antibacterial action against Staphylococcua aurens and Escherichia coli.These compounds showed higher activity than the aromatic derivatives of ct-amino acid which were reported previously.The general conclusion to be drawn is that the distance between amino and carboxylic group in these molecules could affect their antibacterial activity.Furthermore,those compounds with p-methyl substituent in phenyl ring exhibit higher activity than the others,and all the compounds exhibit higher activity against Escherichia coli and against Staphylococcua aureus.     

Synthesis and antitumor activity of heterocyclic acid ester derivatives of 20S-camptothecins

A series of heterocyclic acid esters of camptothecins as new compounds had been synthesized by acylation method,their in vitro and in vivo antitumor activities were evaluated.The cytotoxic results showed that 6 possessed the best efficacy on six human cancer cell lines in the six classes of CPTs' derivatives.In vivo testing results indicated that 9 had better antitumor activity against mouse liver carcinoma H_(22) than topotecan.     

The structure and13C NMR spectra of mannitol oligo-β-d-glucopyranosides isolated from the brown seaweedChorda filum (L.) Lam

1-O-β-d-Glucopyranosyl-d-mannitol, 1,6-di-O-glucopyranosyl-d-mannitol, 1-O-β-gentiobiosyl-d-mannitol, 1-O-β-gentiobiosyl-6-O-β-d-glucopyranosyl-d-mannitol, and 1-O-β-d-gentiotriosyl-d-mannitol were isolated from the brown seaweedChorda filum and the assignment of signals in their¹³C NMR spectra was performed. Comparative analysis of the oligosaccharide composition and the structure of laminarans from seven brown algae demonstrates that the oligosaccharides are not always fragments of the corresponding laminarans. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1817–1820, October, 1993.     

Trichloroisocyanuric acid mediated one-pot synthesis of 3,5-diarylisoxazoles from α,β-unsaturated ketones

A facile one-pot synthesis of 3,5-diarylisoxazoles from α,β-unsaturated ketones and hydroxylamine hydrochloride is reported. The reaction is efficiently promoted by trichloroisocyanuric acid (TCCA) to afford the desired products, mostly in high yields and in relatively short time. The mild nature of the synthesis and short reaction time are notable advantages of the developed protocol. This protocol is effective towards various substrates having different functionalities.     

Synthesis of novel β2,2-amino acid from D-mannose and attempted synthesis of peptides from the amino acid

The study describes the synthesis of new α,α-disubstituted β-amino acid (β^2,2-Caa) and attempts the synthesis of peptides from it. The β^2,2-Caa was prepared from D-(+)-mannose, using crossed aldol and Cannizzaro reactions.     

Iron-catalyzed hydroaminocarbonylation of alkynes: Selective and efficient synthesis of primary α,β-unsaturated amides

α,β-Unsaturated primary amides are important intermediates and building blocks in organic synthesis. Herein, we report a ligand-free iron-catalyzed hydroaminocarbonylation of alkynes using NH₄HCO₃ as the ammonia source, enabling the highly efficient and regioselective synthesis of linear α,β-unsaturated primary amides. Various aromatic and aliphatic alkynes are transformed into the desired linear α,β-unsaturated primary amides in good to excellent yields. Further studies show that using NH₄HCO₃ as the ammonia source is key to obtain good yields and selectivity. The utility of this route is demonstrated with the synthesis of linear α,β-unsaturated amides including vanilloid receptor-1 antagonist TRPV-1.     

Synthesis and anti-α-glucosidase activity evaluation of betulinic acid derivatives

In this article, a series of betulinic acid derivatives (3a ～ 3u, 4a ～ 4e) were synthesized through a stepwise structure optimization and evaluated for their anti-α-glucosidase activities. All synthesized derivatives exhibited stronger anti-α-glucosidase activities (IC₅₀: 0.56 ± 0.05 ～ 3.99 ± 0.23 μM) than betulinic acid (IC₅₀: 7.21 ± 0.58 μM) and acarbose (IC₅₀: 611.45 ± 15.51 μM). Compound 3q presented the outstanding inhibitory activity (IC₅₀: 0.56 ± 0.05 μM), which was ～ 1100 time stronger than that of acarbose. Compound 3q was revealed as a reversible and noncompetitive α-glucosidase inhibitor by inhibitory mechanism assay. Fluorescence spectra, 3D fluorescence and CD spectra results showed that the interaction of compound 3q with α-glucosidase caused the conformational and secondary structure content change of α-glucosidase. Finally, the molecular docking simulated the interaction between compound 3q with α-glucosidase and the physicochemical parameter was assessed using SwissADME software.