Studies on terpenoids and steroids—2 : Structures of two new tri- and tetra-oxygenated D:A-friedo-oleanan triterpenes from kokoona zeylanica

The two D:A-friedo-oleanane triterpenes kokzeylanol and kokzeylanonol isolated from the inner bark of Kokoona zeylanica have been characterized as 6β,27-dihydroxy-D:A -friedo-olean-3-one and 6β,27-dihydroxy-D:A-friedo-olean-3,21-dione, respectively, by the deoxygenation of their 27-acetoxy derivatives using lithium-ethylenediamine reduction coupled with spectroscopic and irradiation methods. Kokzeylanonol represents the first tetra-oxygenated D:A-friedo-oleanane triterpene obtained from a nautral source. Significance of some of these D:A-friedo-oleananes in the biosynthesis of quinonoid triterpenes in Celastraceae is discussed.     

One-pot Multicomponent Synthesis,Spectroscopy, Crystal Structures and Theoretical Calculations of 3-Cyano-4-(4-hydroxy-3-methoxyphenyl)-6-phenyl-2(1H)-pyridinone and 3-Cyano-4-chlorophenyl-6-(4-tolyl)-2(1H)-pyridinone

Pyridinone derivatives are of great interest in medicinal chemistry where they were found to be potent to various diseases. Their metal complexes added more value to their applications. Here, we have synthesized two 2-pyridinone derivatives(3-cyano-4-(4-hydroxy-3-methoxyphenyl)-6-phenyl-2(1 H)-pyridinone and 3-cyano-4-chlorophenyl-6-(4-tolyl)-2(1 H)-pyridinone) using one-pot multicomponent system. They were well characterized using spectroscopic techniques like nuclear magnetic resonance(NMR-1 H 13 C), Fourier transform infrared(FT-IR) and UV/Vis spectroscopy. The final structures were determined using single-crystal X-ray diffraction technique which helps us to determine their geometries. Density functional theory(DFT) and time-dependent density functional theory(TD-DFT) with suitable basis-sets of calculations have correctly simulated these spectroscopic parameters. The intramolecular charge transfer(ICT) of both substrates has been discussed using natural bond orbital(NBO) technique. Molecular electrostatic potential(MEP) surfaces showed their reactive locations for intermolecular charge transfer. Compared to p-nitroaniline(pNA), both substrates were shown to have substantial molecular hyperpolarizability.     

The effect of oblateness in the perturbed restricted three-body problem

In this paper the restricted three-body problem is generalized in the sense that the effects of oblateness of the three participating bodies as well as the small perturbations in the Coriolis and centrifugal forces are considered. The existence of equilibrium points, their linear stability and the periodic orbits around these points are studied under these effects. It is found that the positions of the collinear points and y-coordinate of the triangular points are not affected by the small perturbations in the Coriolis force. While x-coordinate of the triangular points is neither affected by the small perturbations in the Coriolis force nor the oblateness of the third body. Furthermore, the critical mass value and the elements of periodic orbits around the equilibrium points such as the semi-major and the semi-minor axes, the angular frequencies and corresponding periods may change by all the parameters of oblateness as well as the small perturbations in the Coriolis and centrifugal forces. This model could be applicable to send satellite or place telescope in stable regions in space.     

Plant‐supported silver nanoparticles: Efficient,economically viable and easily recoverable catalyst for the reduction of organic pollutants

Ginger rhizome powder was used for the synthesis of supported metallic nanoparticle catalysts. A simple and novel adsorption method was used for the synthesis of silver nanoparticles loaded on ginger powder (Ag/GP), copper on ginger powder (Cu/GP) and nickel on ginger powder (Ni/GP). Among these, Ag/GP showed selective reduction of methyl orange and was used for further reactions. The prepared nanomaterials were characterized through X‐ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, fourier transform infrared spectroscopy and energy‐dispersive X‐ray spectroscopy. The prepared Ag/GP catalyst was employed in the catalytic reduction of 4‐nitrophenol (4‐NP), 2‐nitrophenol (2‐NP), rhodamine B, methyl red and congo red. Ag/GP showed excellent catalytic reduction activity, the rate constants being 1.26 × 10^?3 and 2.38 × 10^?3 s^?1 for 2‐NP and 4‐NP, respectively. The turnover frequency reached 1.06 min^?1 for 2‐NP and 1.16 min^?1 for 4‐NP when using the Ag/GP catalyst. The prepared Ag/GP catalyst demonstrated outstanding activity for the degradation of a mixed solution of dyes. Also, stability and reusability of the prepared catalyst were investigated, which showed outstanding reusability up to five times and was stable up to five days.     

Eu luminescence in La5Si2BO13 with apatite related structure and magnetic studies in Ln5Si2BO13 (Ln=Gd, Dy)

Eu³⁺ photoluminescence is studied in La₅Si₂BO₁₃ with apatite related structure. La_5−xEu_xSi₂BO₁₃ [x=0.05, 0.1, 0.3, 0.5, 0.7, 1.0, 2.0] compositions are synthesized. The emission results shows that Eu³⁺ ions occupy two different cationic sites viz., La(1) and La(2). The increase in the intensity of ⁵D₀-⁷F₀ line with increasing Eu³⁺ content shows the preferential occupancy of Eu³⁺ in La(2) site due to the existence of short La(2)-O(4) (free oxide ion) bond. The observation of antiferromagnetic interactions in Gd and Dy analogues supports the structural features elucidates from photoluminescence studies.     

The intersection seam between the 11A′ and 21A′ states of ozone

The intersection seam between the two lowest ¹A^′ states of ozone has been determined. The potential energy surfaces and the seam are calculated and discussed in perimetric coordinates which exhibit the full three-dimensional symmetry. The seam is shown to form a closed curve which crosses the C _{2 v} -restricted coordinate planes at six points. Three of these correspond to the previously determined intersection, the starting point of the present search. The other three correspond to highly repulsive regions on the potential energy surface where two atoms approach each other to within two-thirds of the O₂ bond length. At the former three points both states have ¹ A ₁ symmetry, but at the latter three points one state has ¹ A ₁ symmetry whereas the other has ¹ B ₂ symmetry. Consequently, there exist three additional branches of the intersection seam between these two states. Each of these branches lies entirely in one C _{2 v} -restricted coordinate plane and connects to the previously discussed C _s -seam at one point. The existence of a further intersection seam is established. A novel method for determining intersection points is described. Received: 10 January 1996 / Accepted: 2 January 1997     

Pharmacological Justification for the Medicinal Use of Plumeria rubra Linn. in Cardiovascular Disorders

Plumeria rubra (L.) is a traditional folkloric medicinal herb used to treat cardiovascular disorders. The present investigation was methodically planned to investigate the pharmacological foundations for the therapeutic effectiveness of P. rubra in cardiovascular illnesses and its underlying mechanisms. Ex vivo vaso-relaxant effects of crude leaf extract of P. rubra were observed in rabbit aorta ring preparations. Hypotensive effects were measured using pressure and force transducers connected to the Power Lab data acquisition system. Furthermore, P. rubra displayed cardioprotective properties in rabbits when they were exposed to adrenaline-induced myocardial infarction. In comparison to the intoxicated group, the myocardial infarction model showed decreased troponin levels, CK-MB, LDH, ALT, ALP, AST, and CRP, as well as necrosis, apoptosis, oedema, and inflammatory cell enrollment. P. rubra has revealed good antioxidant properties and prolonged the noradrenaline intoxicated platelet adhesion. Its anticoagulant, vasorelaxant, and cardioprotective effects in both in vivo and ex vivo investigations are enabled by blocking L-type calcium channels, lowering adrenaline, induced oxidative stress, and tissue tear, justifying its therapeutic utility in cardiovascular disorders.