Synthesis, characterization and Cu(2+) triggered selective fluorescence quenching of Bis-calix[4]arene tetra-triazole macrocycle.

A novel fluorescent bis-calix[4]arene macrocycle 9 incorporating metal-binding pockets was successfully prepared. The structure of macrocycle 9 and its precursors were characterized via EI-MS, MALDI-TOF-MS, ESI-MS, (1)H NMR, (13)CNMR, 2D NMR, and X-ray crystallography. The macrocycle 9 displayed selective fluorescence quenching after interacting with Cu(2+) in the presence competing metal cations including Mg(2+), Ca(2+), Ba(2+), Ag(+), Zn(2+), Ti(4+),Cd(2+), Hg(2+), Pb(2+), In(3+), La(3+), Cr(3+), Ni(2+), Sb(3+), V(5+), Fe(3+), Co(2+), Sn(2+), Sn(2+), and Tl(+).

A cyclic peptide accelerates the loading of peptide antigens in major histocompatibility complex class II molecules.

Major histocompatibility complex (MHC)-loading enhancers (MLE) have recently attracted attention because of their ability to enhance the efficacy of peptide immunotherapeutics. As small molecular weight compounds, they influence the loading of peptides in MHC molecules by converting them from a non-receptive to a receptive state. Herein, we report a 14-mer cyclic peptide 1 (CP-1) as a new class of MLE-peptide.

Brine shrimp lethality assay 'an effective prescreen': microwave-assisted synthesis, BSL toxicity and 3DQSAR studies-based designing, docking and antitumor evaluation of potent chalcones.

Context: In the course of searching potential antitumor agents from a library of chalcones synthesized under microwave irradiations, the brine shrimp lethality (BSL) assay and a 3D structure-activity relationship (3DQSAR) studies were followed by the antitumor evaluation of most potent analogues.

Objective: The objective of the current study was to effectively use the BSL assay for the identification of potential cytotoxic analogues from a set of compounds.

Methods: We applied the comparative molecular field analysis (CoMFA) and devised 3DQSAR on 33 synthesized chalcones leading to prediction of five related compounds with improved activity.

Hepatoprotection by chemical constituents of the marine brown alga Spatoglossum variabile: a relation to free radical scavenging potential.

Context: In the course of searching hepatoprotective agents from natural sources, the protective effect of chemical constituents of the marine brown alga Spatoglossum variabile Figaro et DE Notar (Dictyoaceae) against CCl₄-induced liver damage in Wistar rats was investigated. The compounds were first investigated for in vitro radical scavenging potential and were also tested for β-glucuronidase inhibition to further explore the relationship between hepatoprotection and antiradical potential.

Methods: The compounds cinnamic acid esters 1 and 2 and aurone derivatives 3 and 4 were first investigated for in vitro radical scavenging potential against 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH), and superoxide anion radicals.

Characterization of structural features controlling the receptiveness of empty class II MHC molecules.

MHC class II molecules (MHC II) play a pivotal role in the cell-surface presentation of antigens for surveillance by T cells. Antigen loading takes place inside the cell in endosomal compartments and loss of the peptide ligand rapidly leads to the formation of a non-receptive state of the MHC molecule. Non-receptiveness hinders the efficient loading of new antigens onto the empty MHC II.

Free radical scavenging phenylethanoid glycosides from Leucas indica Linn.

A new phenylethanoid glycoside, 2-(3,4-dihydroxyphenyl)-ethyl-O-alpha-L-rhamnopyranosyl-(1 --> 3)-O-alpha-L-rhamnopyranosyl-(1 --> 6)-4-O-E-feruloyl-beta-D-glucopyranoside (3-O-methyl poliu-moside, 1) along with five known phenylethanoid glycosides (2-6) were isolated from the aerial parts of Leucas indica Linn. The structure of compound 1 has been elucidated on the basis of spectral data. Compounds 1-6 exhibited significant antioxidant activity in 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical assay method.

Syntheses and biological activities of chalcone and 1,5-benzothiazepine derivatives: promising new free-radical scavengers, and esterase, urease, and alpha-glucosidase inhibitors.

A series of 2,4-diaryl-2,3,4,5-tetrahydro- (36-40) and 2,4-diaryl-2,3-dihydro-1,5-benzothiazepines (25-35) have been synthesized from the corresponding chalcones 1-24. Both the benzothiazepines and chalcones were evaluated as DPPH free-radical scavengers and as inhibitors of cholinesterases, urease, and alpha-glucosidase. Compounds 2, 5, 6, 7, 10, 13, 18, 21, 36a, 37a, 37b, and 39a showed significant cholinesterase inhibiting activities.

Bioactive constituents from Boswellia papyrifera.

Phytochemical investigation of the stem bark extract of Boswellia papyrifera afforded two new stilbene glycosides, trans-4',5-dihydroxy-3-methoxystilbene-5-O-{alpha-L-rhamnopyranosyl-(1-->2)-[alpha-L-rhamnopyranosyl-(1-->6)]-beta-D-glucopyranoside (1), trans-4',5-dihydroxy-3-methoxystilbene-5-O-[alpha-L-rhamnopyranosyl-(1-->6)]-beta-D-glucopyranoside (2), and a new triterpene, 3alpha-acetoxy-27-hydroxylup-20(29)-en-24-oic acid (3), along with five known compounds, 11-keto-beta-boswellic acid (4), beta-elemonic acid (7), 3alpha-acetoxy-11-keto-beta-boswellic acid (8), beta-boswellic acid (9), and beta-sitosterol (10). The stilbene glycosides exhibited significant inhibition of phosphodiesterase I and xanthine oxidase. The triterpenes (3-9) exhibited prolyl endopeptidase inhibitory activities.

Isotamarixen - a new antioxidant and prolyl endopeptidase-inhibiting triterpenoid from Tamarix hispida.

A new pentacyclic triterpenoid, 3alpha-(3",4"-dihydroxy- trans-cinnamoyloxy)- D-friedoolean-14-en-28-oic acid ( 1) has been isolated along with two known compounds, rhamnocitrin ( 2) and isorhamnetin ( 3) from the aerial parts of Tamarix hispida Willd. Compound 1 was found to be a potent antioxidant. In addition, compounds 1 - 3 showed significant inhibitory activity against prolylendopeptidase (PEP).

Highly oxygenated triterpenes from the roots of Atropa acuminata.

Two new oleanane triterpenes; 2alpha,3alpha,24-trihydroxyolean-12-ene-28,30-dioic acid ([structure: see text]) and 2alpha,3alpha,24,28-tetrahydroxyolean-12-ene ([structure: see text]) have been isolated from the roots of Atropa acuminata. Anti-oxidant p-hydroxyphenethyl trans-ferulate ([structure: see text]), beta-sitosterol-3-O-beta-D-glucopyranoside ([structure: see text]) and oleanolic acid ([structure: see text]) have also been reported for the first time from this species. The structures were determined by spectroscopic studies including 2D-NMR.