Three new Lycopodium alkaloids from Huperzia carinata and Huperzia squarrosa

Eleven Lycopodium alkaloids with lycodine-type, lycopodine-type, and fawcettimine-related skeletons were isolated from the whole plants of Huperzia carinata (Desv. Ex. Poir.) Trevis and Huperzia squarrosa (G. Forst) Trevis (Huperziaceae). Among them, 8,15-dihydrohuperzine A (2), lycocarinatine A (3), and lycoposerramine U N-oxide (11) are new compounds. The structures of these new alkaloids were elucidated on the basis of 2D NMR correlations. Some of these isolated alkaloids were assayed for acetylcholinesterase (AChE) inhibitory activity.     

Exploring the molecular basis for selective cytotoxicity of lamellarins against human hormone-dependent T47D and hormone-independent MDA-MB-231 breast cancer cells

Abstract  

The common structural requirements for cytotoxicity of lamellarins against two human breast cancer cell lines were determined using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) techniques. Twenty lamellarins were selected to serve as the training set, whereas another group of six compounds were used as the test set. The best CoMFA and CoMSIA models for both cell lines yielded satisfactory predictive ability with r _cv² values in the range of 0.659–0.728. Additionally, the contour maps obtained from both the CoMFA and CoMSIA models agreed well with the experimental results and may be used in the design of more potent cytotoxic compounds for human breast cancers. Both analyses not only suggested structural requirements of various substituents around the lamellarin skeleton for their cytotoxic activity against both human breast cancer cell lines but also revealed the molecular basis for the differences between the saturated and unsaturated D-rings of the lamellarins.     

Synthesis of benzoindoloquinolizines via a Cu(I)-mediated C–N bond formation

An effective synthesis of the multi ring-fused benzoindoloquinolizines has been accomplished by Cu(I)-mediated and MW-assisted C–N_amide bond formation of benzo[a]quinolizin-4-ones. The deamination of tetrahydro-2H-pyrido[2,1-a]isoquinolines was also studied and was found to give benzoquinolizines. The benzo[a]quinolizin-4-ones were prepared based on the annulations of C-1 substituted 3,4-dihydroisoquinolines and azlactones.     

Synthesis of aryl α-keto esters via the rearrangement of aryl cyanohydrin carbonate esters

A facile synthesis of aryl α-keto esters is reported involving the rearrangement of aryl cyanohydrin carbonate esters induced by the α-carbanion to the nitrile group generated by LDA. However, under similar conditions, an o-benzyloxycyanohydrin carbonate ester rearranged via a domino reaction leading to 2-phenylbenzofuran-3-carboxylic acid.     

Cu(I)-mediated lactone formation in subcritical water: a benign synthesis of benzopyranones and urolithins A–C

Benzopyranones were successfully synthesized using Cu(I)-mediated C–O bond formation in subcritical water. A number of benzopyranone derivatives including polymethoxy benzopyranones, benzopyranopyridones, chromenoindolones, and furochromenones were synthesized in satisfactory yield. This methodology was further applied to synthesize the intestinal microbial metabolites, urolithins A, B, and C, which were found to exhibit potent antioxidant activity.     

Opioid modulation of GABA release in the rat inferior colliculus

Background  

The inferior colliculus, which receives almost all ascending and descending auditory signals, plays a crucial role in the processing of auditory information. While the majority of the recorded activities in the inferior colliculus are attributed to GABAergic and glutamatergic signalling, other neurotransmitter systems are expressed in this brain area including opiate peptides and their receptors which may play a modulatory role in neuronal communication.     

New mechanistic insight in the thermal helix inversion of second-generation molecular motors

The introduction of dibenzocyclohepten-5-ylidene as part of a unidirectional light-driven molecular motor allows a more complete picture of the pathway of thermal helix inversion to be developed. The most stable conformation is similar to that found in related motors in that it has, overall, an anti-folded structure with the substituent at the stereogenic centre adopting an axial orientation. Photochemical cis/trans isomerisation at -40 degrees C results in the formation of an isomer in a syn-folded conformation with the methyl group in an axial orientation. This contrasts with previous studies on related molecular rotary motors. The conformation of the higher energy intermediate typically observed for this class of compound is the anti-folded conformation, in which the methyl group is in an equatorial orientation. This conformation is available through an energetically uphill upper half ring inversion of the observed photochemical product. However, this pathway competes with a second process that leads to the more stable anti-folded conformation in which the methyl group is oriented axially. It has been shown that the conformations and pathways available for second-generation molecular motors can be described by using similar overall geometries. Differences in the metastable high-energy species are attributable to the relative energy and position on the reaction coordinate of the transition states. Kinetic studies on these new molecular motors thus provide important insights into the conformational dynamics of the rotation cycle.     

COX-1, COX-2 inhibitors and antifungal agents from Croton hutchinsonianus

Two new compounds, 3'-(4'-hydroxy-3',5'-dimethoxyphenyl)-propyl benzoate (1) and 3'-(4'-hydroxyphenyl)-propyl benzoate (3) together with known compounds, 3'-(4'-hydroxy-3'-methoxyphenyl)-propyl benzoate (2), poilaneic acid (4), farnesyl acetone (5) and 4-hydroxybenzaldehyde (6) were isolated and identified from the branches of Croton hutchinsonianus. Their structures were determined by spectroscopic methods. The three phenylpropyl benzoates (1-3) were found to exhibit antifungal activity against Candida albicans (IC(50) 5.36-11.41 microg/ml). Compounds 1-2 (IC(50) 2.11-4.95 microg/ml) exhibited potent but non-selective activity against the enzymes cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) whereas 3 (IC(50) 1.88 microg/ml) preferentially inhibited the enzyme COX-2.