Kunihide Mihashi

Isolation of rhododaurichromanic acid B and the anti-HIV principles rhododaurichromanic acid A and rhododaurichromenic acid from Rhododendron dauricum

Abstract—Two novel chromane derivatives (1 and 2) and the known chromene (3) were isolated from the leaves and twigs of Rhodo-dendron dauricum. The absolute stereostructure of 1 was established by spectroscopic examination and X-ray crystallographic analysis. Theabsolute stereostructures of 2 and 3 were also confirmed by photochemical conversion of 3 into 1 and 2. Daurichromenic acid (3)demonstrated potent anti-HIV activity with an EC 50 value of 0.00567 mg/mL and therapeutic index (TI) of 3,710. Rhododaurichromanicacid A (1) also showed relatively potent anti-HIV activity with an EC 50 value of 0.37 mg/mL, and a TI of 91.9, whereas rhododaurichromanicacid B (1) displayed no anti-HIV activity. q 2001 Elsevier Science Ltd. All rights reserved. 1. IntroductionRhododendron dauricum is distributed in the northern partof China, eastern part of Siberia, and Hokkaido. The driedleaves of this plant are known in China as ‘Manshanfong,’and are used medicinally as an expectorant and totreat acute–chronic bronchitis.

Three chromone components from Aloe vera leaves

Abstract Three new chromone components, 8-C-glucosyl-7-O-methyl-(S)-aloesol, isoaloeresin D and aloeresin E were isolated from the leaves of Aloe vera. Their structures have been established from spectroscopic studies; the structures of 8-C-glucosyl-7-O-methyl-(S)-aloesol, isoaloeresin D and aloeresin E were shown to be 8-C-β- d - glucopyranosyl -2-[(S)-2- hydroxy]propyl-7-methoxy-5-methylchromone , 8-C-β- d -[2′-O-(E)-p- coumaroyl]glucopyranosyl -2-[(S)-2- hydroxy]propyl-7-methoxy-5-methylchromone and 8-C-β- d -[2′-O-(E)- cinnamoyl]glucopyranosyl -2-[(S)-2- hydroxy]propyl-7-methoxy-5-methylchromone , respectively. The inhibitory action of these compounds against tyrosine oxidation by mushroom tyrosinase was examined.

Guest-induced conformational change in a flexible host: mono-altro-β-cyclodextrin †

Mono-altro--cyclodextrin 1 ,a -cyclodextrin with one of the seven glucose units being configurationally changed to an altrose, is shown to be a flexible host undergoing a distinct conformational change within its altropyranose geometry upon intracavity inclusion of adamantanecarboxylate, thus representing an induced-fit model of binding rather than one following the rigid lock-and-key type pattern.

Flavone production in transformed root cultures of Scutellaria baicalensis Georgi

Abstract A flavone derivative 5,2′-dihydroxy-6,7,8,3′-tetramethoxyflavone identified by 1 H-, 13 C-NMR, FABMS, together with two known phenolics skullcapflavone I and acteoside ( 3 ), were isolated from Scutellaria baicalensis transformed roots (clone C) into which the β-glucuronidase gene had been integrated by the infection with Agrobacterium rhizogenes A13. Another clone of transformed roots (clone W) was also induced by infection with A. rhizogenes ATCC 15834 (wild type). Both clones C and W, cultured in phytohormone-free BF liquid medium, produced 3 at a high content (maximum; clone C: 1.81% and clone W: 2.96% of tissue dry weight) under the light and dark conditions. The contents of glucuronide-type flavonoids, such as baicalin and wogonin 7- O -glucuronide in clone W, were almost three times higher than those in clone C. Compound 3 , which was not detected in the intact plant roots, also accumulated in leaf (0.23% dry weight) and root (0.68% dry weight) parts of in vitro cultured plantlets.

Phenylpropanoid-substituted catechins from Castanopsis hystrix and structure revision of cinchonains

Abstract Two new and two known complex flavan-3-ols, containing an additional phenylpropanoid (C 6 –C 3 ) unit in the molecule, have been isolated from the leaves of Castanopsis hystrix . The structures including absolute stereochemistry were elucidated on the basis of spectroscopic evidence and also by synthesis. In addition, comparison of the CD spectral data of these compounds with those of previously known complex flavan-3-ols, cinchonains, has led to the revision of their structures.

Isolation and structures of aplykurodins a and b, two new isoprenoids from the marine mollusk aplysia kurodai

Abstract Two new isoprenoids, aplykurodins A and B, were isolated from the marine mollusk, Aplysia kurodai (Aplysiidae), and their structures were determined by chemical, spectral and X-ray crystallographic analyses.

Novel antiproliferative falcarindiol furanocoumarin ethers from the root of Angelica japonica.

Four novel antiproliferative furanocoumarin ethers of falcarindiol, named japoangelols A (8.5), B (7.2), C (7.4), and D (8.4), were isolated from the root of Angelica japonica together with panaxynol (0.3), falcarindiol (3.2), (9Z)-1,9-heptadecadiene-4,6-diyne-3,8,11-triol (2.2), and 8-acetoxyfalcarinol (3.2). Structures were established from the spectroscopic evidence, and the inhibitory activities (ED50, microgram/ml, shown in the parentheses) were evaluated using the MTT assay.

Polyacetylene glycosides from Pratia nummularia cultures

Two polyacetylene glycosides, lobetyol 9-O-glc(6)-(1)rha (pratialin-A) and lobetyol 9-O-glc(6)-(1)glc(6)-(1)glc (pratialin-B), were isolated from Pratia nummularia (Campanulaceae) callus and hairy root cultures and their chemical structures were determined by analysis of spectroscopic data. From the methanol extract of the hairy root cultures, together with the known polyacetylene constituents lobetyol, lobetyolin, and lobetyolinin, tryptophan was also isolated. This report is the first example of the isolation and structure elucidation of rutinoside (pratialin-A) and triglucoside (pratialin-B) derivatives of polyacetylene constituents.

Five chromones from Aloe Vera leaves

Abstract Five new chromone components were isolated from the gel of Aloe vera leaves. Their structures have been established as 8- C -glucosyl-noreugenin, 4′- O -glucosyl-isoaloeresin DI, 4′– O -glucosyl-isoaloeresin DII, 8- C -glucosyl-(2′- O -cinnamoyl)-7- O -methylaloediol A and 8- C -glucosyl-(2′- O -cinnamoyl)-7- O -methylaloediol B, from spectroscopic studies.

Antitumor agents 171. Cytotoxicities of lobatosides B, C, D, and E, cyclic bisdesmosides isolated from Actinostemma lobatum maxim

Abstract Cytotoxicities for lobatosides B—E and actinostemmosides B—F, isolated from Actinostemma lobatum , were evaluated against a panel of ca 60 human cancer cell lines. Lobatosides B—E ( 1–4 ) were cytotoxic (GI 50 ≤ 1 × 10 −4 M) against all tumor cell lines; 4 showed potent cytotoxicity especially against A-549, SK-MEL-5, and SW-620 cell lines with GI 50 values of 0.14, 0.14, and 0.36 μM, respectively.