Quantitative structure-property relationship modeling of beta-cyclodextrin complexation free energies

CODESSA-PRO was used to model binding energies for 1:1 complexation systems between 218 organic guest molecules and beta-cyclodextrin, using a seven-parameter equation with R2 = 0.796 and Rcv2 = 0.779. Fragment-based TRAIL calculations gave a better fit with R2 = 0.943 and Rcv2 = 0.848 for 195 data points in the database. The advantages and disadvantages of each approach are discussed, and it is concluded that a combination of the two approaches has much promise from a practical viewpoint.     

Structure-activity relationship of new octaethylporphyrin-based benzochlorins as photosensitizers for photodynamic therapy

An in vitro and in vivo structure-activity relationship study was carried out on a series of benzochlorins with variable lipophilicity. The structural features evaluated in this study include the length of the alkyl or fluoroalkyl groups attached to the six-member exocyclic ring either by an ether or by a carbon-carbon bond. In preliminary in vitro (radiation-induced fibrosarcoma [RIF] cells) and in vivo screening (C3H mice, bearing RIF tumors), all Zn (II) benzochlorins were found to be effective. However, benzochlorins bearing alkyl groups with carbon-carbon bonds showed enhanced efficacy compared with the related alkyl ether analogs. A comparative intracellular localization study of the newly synthesized benzochlorins with Rhodamine-123 indicated that the effective photosensitizers localize in mitochondria, and a displacement study with PK11195 showed their partial affinity for the peripheral benzodiazepine receptor (PBR). Interestingly, compared with the Zn(II) benzochlorin that was found to be quite effective in vivo, the corresponding free-base analog produced less photosensitizing activity and was found to localize in lysosomes. A comparative study with dansyl-proline confirmed the binding of the effective benzochlorins to Site II of human serum albumin (HSA). However, no direct correlation was observed between the binding constant values (to HSA or to PBR) of benzochlorins and their photosensitizing ability.     

On the aromaticity of porphin

We have undertaken a study of the bromination of porphin. We have learned contrary to literature reports, that bromine (in chloroform) attacks porphin preferentially at the meso position and that bromination of this meso monobromoporphin produces a single dibromo product, namely 5, 15-dibromoporphin. Our results are interpreted in terms of the aromaticity of the different peripheral carbon atoms.     

Quantitative modeling of dielectrophoretic traps

We present quantitative modeling software for simulating multiple forces acting on a single particle in a microsystem. In this paper, we focus on dielectrophoretic (DEP) trapping of single cells against fluid flow. The software effectively models the trapping behavior for a range of particles including beads, mammalian cells, viruses, and bacteria. In addition, the software can be used to reveal useful information about the DEP traps - such as multipolar DEP force effects, trap size-selectivity, and effects from varying the flow chamber height. Our modeling software thus serves as a predictive tool, enabling the design of novel DEP traps with superior performance over existing trap geometries. In addition, the software can evaluate a range of trap dimensions to determine the effects on trapping behavior, thus optimizing the trap geometry before it is even fabricated. The software is freely available to the scientific community at: .     

A normal mode analysis of free base porphin

The in-plane vibrational modes of free base porphin have been calculated. The results are compared to high resolution single-site fluorescence spectra and a tentative assignment of some experimental i.r. vibrational frequencies is made. The importance of the peripheral hydrogen atoms in vibronic analyses of porphins is discussed.     

Quantum-chemical study of nh tautomerism in porphin

Calculations of the hypersurface of the adiabatic potential which determines the movement of NH protons in the centre of the porphin molecule are carried out by the CNDO/2 method. Simultaneous displacements of two NH protons and the displacement of only one proton are considered. The barrier heights for NH tautomerism in these two cases are evaluated, as well as the frequencies of NH vibrational modes for a porphin molecule of D_2h symmetry. The data obtained indicate that shifts of the central protons from one nitrogen atom to another occur almost independently of each other, and the degenerate rearrangement A → B proceeds in a stepwise way, via the intermediate isomer C with adjacent disposition of NH protons (see Fig. 1). The role of tunnelling through the barrier in this process is emphasized. The electronic absorption spectra of the two porphin isomers of D_2h and C_2v symmetry are calculated using the CNDO/S method.     

Antiviral properties of photosensitizers

Abstract— We have studied the antiviral properties of three different groups of photo-sensitizers, viz. (i) various furyl compounds; (ii) β-carboline alkaloids; (iii) thiophenes and their acetylene derivatives. In general the antiviral potency of the furyl compounds correlated with their ability to produce DNA photoadducts. Among the naturally occurring β-carboline alkaloids, harmine was considerably more potent (in the presence of long wavelength UV radiation, UVA) than several other harmane-related compounds. Slight alterations in chemical structure had profound effects on their antiviral activities. Harmine was shown to inactivate the DNA-virus murine cytomegalovirus (MCMV) by inhibiting viral gene expression, although other targets may also exist. Several eudistomins, carboline derivatives isolated from a tunicate, were also photoactive against viruses. Various plant thiophenes and polyacetylenes were studied in detail. These compounds also required UVA for antiviral activity, and some of them were extremely potent against viruses with membranes, e.g. α-terthienyl, which showed significant activity at only 10^-5μg/ml. When MCMV had been treated with α-terthienyl plus UVA, the virus retained its integrity and penetrated cells normally; but the virus did not replicate. More than 30 additional thiophenes have recently been evaluated, including many synthetic ones, and some of these are even more potent than a-terthienyl. We believe that certain thiophenes possess potential therapeutic value and should be tested against model virus infections in animals.     

Synthesis of tetra(4-sulfonatophenyl)porphin derivatives

Corresponding sulfonamides were obtained by the action of ammonia and amines on tetra(4-sulfonatophenyl)porphin fluorides and chlorides. Their structure was confirmed by IR, PMR, and electronic spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 770–772, June, 1988.     

The lowest quartet state of copper porphin: Zeeman experiments at 4.2 K

Zeeman experiments in a magnetic field of 75 kG on copper porphin in a single crystal of n-octane prove the lowest metastable state to be a quartet as predicted by Gouterman and colleagues. In zero magnetic field this quartet is split into two degenerate pairs, the ±$\text{1}\text{2}$ components lying at about 0.7 cm^?1 higher energy than the ±$\text{3}\text{2}$ components.     

一阶导数差示脉冲极谱法测定氢氯噻嗪的研究

本研究了一阶导数差示脉冲极谱法用于氢氯噻嗪及其制剂的定量分析。在０．００２ｍｏｌ／Ｌ盐酸－０．００２ｍｏｌ／Ｌ氯化钾底液中，于０．０５０Ｖ（ｖｓ．Ａｇ／ＡｇＣｌ）处出现良好的一阶导数极谱峰，氢氯噻嗪浓度在０～６．０×１０＾－４ｍｏｌ／Ｌ范围内，与峰高呈线性关系，检测限为４．０×１０＾－９ｍｏｌ／Ｌ。方法操作简便、快速、灵敏、结果准确。