NON-TRADITIONAL EXAMINATION: A STUDY TO IMPROVE ACADEMIC AND RESEARCH PERFORMANCE OF UNDERGRADUATE ORGANIC CHEMISTRY STUDENTS#

An investigation of conducting a presentation examination instead of a classical written examination method on academic and research performance of undergraduate chemistry students was performed at the University of Texas-Pan American. The results suggest that chemistry students do much better in the presentation examination compared to the written examination at the advanced organic chemistry course. But, the performances of the students in the lower level courses are mixed. However, students do much better in research work when presentation examination was conducted

STEREOSELECTIVITY OF PHTHALIMIDO β-LACTAMS FORMATION: SYNTHESIS OF 3-AMINO β-LACTAMS THROUGH A FACILE DEPROTECTION REACTION

Synthesis of amino β-lactams is a crucial objective because of the medicinal properties associated with them and the products derived from of them. Stereocontrolled synthesis of phthalimido β-lactams is performed and cis and trans-phthalimido β-lactams are deprotected with ethylene diamine (and other reagents) to amino β-lactams of diverse structures in excellent yield. This reaction is also conducted under solventless conditions to afford identical products

Effect of polygodial and its direct derivatives on the mammalian Na+/K+-ATPase activity

The sesquiterpene polygodial is an agonist of the transient receptor potential vanilloid 1 (TRPV1). Our group recently reported the synthesis and anticancer effects of polygodial and its derivatives, and showed that these compounds retain activity against apoptosis- and multidrug-resistant cancer cells. Herein, we tested the inhibitory effect of these compounds on the activity of the enzyme Na+/K+-ATPase (NKA) from kidney (α1 isoform) and brain (α2 and α3 isoforms) guinea pig extracts. Polygodial (1) displayed a dose-dependent inhibition of both kidney and brain purified NKA preparations, with higher sensitivity for the cerebral isoforms. Polygo-11,12-diol (2) and C11,C12-pyridazine derivative (3) proved to be poor inhibitors. Unsaturated ester (4) and 9-epipolygodial (5) inhibited NKA preparations from brain and kidney, with the same inhibitory potency. Nevertheless, they did not achieve maximum inhibition even at higher concentration. Comparing the inhibitory potency in crude homogenates and purified preparations of NKA, compounds 4 and 5 revealed a degree of selectivity toward the renal enzyme. Kinetic studies showed a non-competitive inhibition for Na+ and K+ by compounds 1, 4 and 5 and for ATP by 1 and 4. However, compound 5 presented a competitive inhibition type. Furthermore, K+-activated p-nitrophenylphosphatase activity of these purified preparations was not inhibited by 1, 4 and 5, suggesting that these compounds acted in the initial phase of the enzyme's catalytic cycle. These findings suggest that the antitumor action of polygodial and its analogues may be linked to their NKA inhibitory properties and reinforce that NKA may be an important target for cancer therapy.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Polygodial and ophiobolin a analogues for covalent crosslinking of anticancer targets

In a search of small molecules active against apoptosis-resistant cancer cells, including glioma, melanoma, and non-small cell lung cancer, we previously prepared α,β-and γ,δ-unsatu-rated ester analogues of polygodial and ophiobolin A, compounds capable of pyrrolylation of primary amines and demonstrating double-digit micromolar antiproliferative potencies in cancer cells. In the current work, we synthesized dimeric and trimeric variants of such compounds in an effort to discover compounds that could crosslink biological primary amine containing targets. We showed that such compounds retain the pyrrolylation ability and possess enhanced single-digit mi-cromolar potencies toward apoptosis-resistant cancer cells. Target identification studies of these in-teresting compounds are underway.SCOPUS: ar.jinfo:eu-repo/semantics/publishe