This review deals with recent application of the electrochemical reaction on organic synthesis reported by our group. A low-valent nickel complex [Ni (PPh3)4] was prepared from NiCl2 (PPh3)2 in the presence of PPh3 by electrochemical reduction. Its reactivity was the same as that of the complex generated from NiCl2 (PPh3)2 in the presence of PPh3 by Zn-reduction. Anodic oxidation of lactams afforded important intermediates for the synthetic organic chemistry. Using this procedure, β-lactams with substituents on nitrogen provided oxidation products of exo- and endo-cyclic carbon α to nitrogen. 4-Acetoxy-β-lactams could be synthesized from β-lactams having no substituents on nitrogen in CH3CN-AcOH. The same compounds were obtained from 4-carboxy-β-lactams in the presence of AcONa in CH3CN-AcOH by electrochemical oxidation.
6A, 6X-Di-O-(tert-butyldimethylsilyl)-α- or -β-cyclodextrins (CDs) were prepared by reaction of α- or β-CD with tert-butyldimethylsilyl chloride in pyridine. Their three positional isomers were each isolated by high-performance liquid chromatography, and characterized by 13C-nuclear magnetic resonance spectroscopy and by conversion to the known compounds, di-O-mesitylenesulfonates of α-CD and di-O-toluenesulfonates of β-CD.
Through respective administrations of [1-14C] acetate, [3-14C] phenylalanine and [7-14C]-benzoic acid to Swertia japonica, it was proved that the biphenylcarboxylic acid moiety of the strongly bitter secoiridoid glucosides, amarogentin and amaroswerin existing in the plant, is biosynthesized from 3 units of acetates and 3-hydroxybenzoic acid formed from phenylalanine via benzoic acid.
When human cancer cell (JTC-26) was subjected to aqueous extracts of some crude drugs for a long time, its drug resistance against the cancer cell decreased. However, the cancer cell with decreased resistance recovered its proliferative power completely when cultured without the addition of the specimens. This revealed that the drug resistance-decreasing action or cytostatic action was entirely reversible. On the other hand, chemical anticancer agents increased cancer cell resistance, but the cancer cell did not recover itself and then perished when damage was given to it to a certain extent. Normal cell showed no decrease in resistance to the aqueous extracts.
A Chinese herbal medicinal prescription, Kanbaku-taiso-to, was studied for the inhibitory activity of adenosine 3', 5'-cyclic monophosphate (cAMP) phosphodiesterase. The effect for the inhibitory activity of cAMP phosphodiesterase in combination with constituent crude drugs and difference in kind of crude drugs of the prescription were studied. The inhibitory activity of the prescriptions which were combined with low protein content wheat were higher than that with high protein content wheat.
Mao-to, a Chinese herbal medicinal prescription was studied for the inhibitory activity of adenosine 3', 5'-cyclic monophosphate (cAMP) phosphodiesterase. The inhibitory activity for this enzyme depended mainly on Ephedra herb and Glycyrrhiza in this prescription. Apricot kennel acted as a mitigatory component for Ephedra herb in cAMP phosphodiesterase inhibitory test. In ephedrine and the related compounds the inhibitory activity of cAMP phosphodiesterase was not shown.
The pharmacokinetics of pranoprofen, 2-(5H- benzopyrano [2, 3-b] pyridin-7-yl) propionic acid (I) in humans were examined. 1-O-Acylglucuronide of I (II) and its isomer (III) were isolated from the human urine after oral administration of I. The stability of II was tested in order to establish the suitable conditions for the storage and handling of biological samples. Maximum stability of II was found at pH 3-4. Unchanged drugs, II and III were detected in the human plasma after oral administration of I. Plasma concentrations of these compounds reached the maximum at 1-2 h after the administration and thereafter decreased biphasically. From the urinary sample, 1-O-acylglucoside of I (IV) was detected in addition to unchanged drugs, II and III. Within 24 h after dosing, 1.3, 84.0, 7.0 and 0.6% of the dose were excreted as I, II, III and IV, respectively and the total urinary excretion amounted to 92.9% in term of unchanged drug.
By the immersion method with a polarizing microscope a principal agent phenytoin was identified from its 10 times trituration containing vehicles such as lactose and starch. A particle size distribution of phenytoin crystals in its trituration was determined by observing one of the habit parameters b from all the detectable particles of phenytoin under a microscope in a suspension of an immersion oil, nD : 1.555, in which phenytoin crystals having key refractive indexes, n1 : 1.606, n2 : 1.631, were clearly detectable from other vehicles. By the similarity of crystal habits in the same lot the particle size distribution of phenytoin crystals in its trituration was calculated from the values of observed parameter b and average values of habit coefficients, T (√(ab/c)) : 2.004, L (b/a) : 2.545, which were obtained from some previously identified phenytoin crystals.