PURPOSE: Telomeres are specialized DNA-protein complexes found at the ends of eukaryotic chromosomes. In normal somatic cells these become shorter with each cell division and appear to control their replicative lifespan. However almost all tumours show activation of the enzyme telomerase, a specialised reverse transcriptase/DNA polymerase, that can add new telomeric repeats to the ends of chromosomes and this appears to be a key factor in the cell immortalization process.
Lipocalins are a family of proteins characterized by a conserved eight-stranded ?-barrel structure with a ligand-binding pocket. They perform a wide range of biological functions and this functional multiplicity must relate to the lipid partner involved. Apolipoprotein D (ApoD) and its insect homologues, Lazarillo (Laz) and neural Lazarillo (NLaz), share common ancestral functions like longevity, stress resistance and lipid metabolism regulation, coexisting with very specialized functions, like courtship behavior.
BACKGROUND: Metabolism of energy nutrients by the mitochondrial electron transport chain (ETC) is implicated in the aging process. Polymorphisms in core ETC proteins may have an effect on longevity. Here we investigate the cytochrome b (cytb) polymorphism at amino acid 7 (cytbI7T) that distinguishes human mitochondrial haplogroup H from haplogroup U. PRINCIPAL FINDINGS: We compared longevity of individuals in these two haplogroups during historical extremes of caloric intake.
BACKGROUND: R-etomidate possesses unique desirable properties but potently suppresses adrenocortical function. Consequently, efforts are being made to define structure-activity relationships with the goal of designing analogues with reduced adrenocortical toxicity. The authors explored the pharmacological impact of modifying etomidate's chiral center using R-etomidate, S-etomidate, and two achiral etomidate analogues (cyclopropyl etomidate and dihydrogen etomidate).
From 9-substituted DHA, several new artemisinin-derived C-10 acetal ethers and esters were prepared with either a 9-fluoro or a 9-sulfonyl substituent. The very strong inductive electron-withdrawing C-9 substituent is shown to retard considerably C-10 ionization (acid-promoted etherification) of 9-fluoro-DHA and 9-sulfonyl-DHA.
The selective oxyfunctionalization of isolated sp(3) C-H bonds in complex molecules represents a formidable challenge in organic chemistry. Here, we describe a rational, systematic strategy to expedite the development of P450 oxidation catalysts with refined regio- and stereoselectivity for the hydroxylation of remote, unactivated C-H sites in a complex scaffold.
Malaria continues to be a difficult disease to eradicate largely because of the widespread populations it affects and the resistance that malaria parasites have developed against once very potent therapies. The natural product artemisinin has been a boon for antimalarial chemotherapy, as artemisinin combination therapy (ACT) has become the first line of chemotherapy.
Artemisinin (ART) and its derivatives artesunate (AS), dihydroartemisinin (DHA) are a group of drugs containing a sesquiterpene lactone used to treat malaria. Previously, AS was shown to not have antibacterial activity but to significantly increase the antibacterial activities of ?-lactam antibiotics against E. coli. Herein, molecular docking experiments showed that ART, AS and DHA could dock into AcrB very well, especially DHA and AS; both DHA and AS had the same docking pose.
AIM: To study the chemical constituents of the rhizome of Matteuccia struthiopteris (L.) The constituents were separated and purified by column chromatography with normal Todaro. METHODS: phase silica gel and Sephadex LH-20. Their structures were identified on the basis of physical and spectral data (MS, NMR, HMBC and HMQC).
Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
R-(+)-Pulegone is a natural monoterpene obtained from the essential oils of a variety of plants. It is used in flavouring agents, perfumery and aromatherapy. In this work, a study of the molecular structure and the infrared and Raman spectra of this chemical is presented. Theoretical calculations reveal the existence of two conformers depending on the position of the methyl group (axial and equatorial), being the equatorial conformer the most stable.