Momoyo Ichimaru

Structure-activity relationships of quaternary protoberberine alkaloids having an antimalarial activity.

Abstract Seventeen quaternary protoberberine alkaloids related to berberine 1 were tested for antimalarial activity in vitro against Plasmodium falciparum and structure-activity relationships are proposed. The activity of the protoberberine alkaloids was influenced by the type of the oxygen substituents on rings A, C and D and the position of the oxygen functions on ring D. The position of the oxygen functions on ring D and the type of the oxygen substituents at the C-13 position (ring C) strongly influenced the activity. Shifting the oxygen functions at C-9 and C-10 to C-10 and C-11 on ring D resulted in a significant increase in the activity. Compounds bearing a methylenedioxy function at C-2 and C-3 (ring A) or C-9 and C-10 (ring D) showed higher activity than those which have methoxy groups at the same positions. Introduction of a methoxy group into the C-1 position (ring A) decreased the activity. Replacement of a hydroxy group at C-2 or C-3 (ring A) by a methoxy group led to a reduction in the activity. Displacement of a hydroxy function at C-13 (ring C) by the oxygen substituents such as OMe, OEt, OCOOEt, and OCON(Me) 2 reduced the activity. In the same replacement at C-9 (ring D), the activity depended upon the type of the oxygen function. Six protoberberines displayed more potent activity than berberine 1 . The activity decreased in the order: 10 , 11 , 17 and 18 > 7 and 8 > 1 .

New isoflavones from Belamcandae Rhizoma

Four new isoflavones (iristectrigenin A-7-glucoside (2), 8-hydroxytectrigenin (5), 8-hydroxyiristectrigenin A (6), and 8-hydroxyirigenin (7–1) have been isolated from Belamcandae Rhizoma (the rhizome of Belamcanda chinensis), along with nine known compounds: tectridin (1), tectrigenin-4′-glucoside (3), astragalin (4), irilin D (7–2), isotectrigenin (8), tectrigenin (9), iristectrigenin B (10), hispiludin (11–1), and irigenin (11–2). The structures of 2, 5, 6 and 7–1 were determined by spectroscopic methods, including high-resolution mass spectrometry (HR-MS), proton nuclear magnetic resonance (1H-NMR), carbon-13 NMR (13C-NMR), and various two-dimensional (2D)-NMR techniques.

Acyclic triterpenoids from Ekebergia capensis

Abstract From the dried bark of Ekebergia capensis, two novel acyclic triterpenoids, 2,3,22,23-tetrahydroxy-2,6,10,15,19,23-hexamethyl-6,10,14,18-tetracosatetraene and 2-hydroxymethyl-2,3,22,23-tetrahydroxy-6,10,15,19,23-pentamethyl-6,10,14,18-tetracosatetraene were isolated, along with known cyclic triterpenoids. The structures of these two new triterpenoids were determined by spectroscopic and chemical methods.

Guinesine-A, -B and -C: new sulfur containing insecticidal alkaloids from Cassipourea guianensis

Abstract New sulfur containing insecticidal alkaloids, guinesine-A ( 1a ), -B ( 1b ) and -C ( 1c ) have been isolated from the bark of Cassipourea guianensis and their structures determined by spectroscopic studies and X-ray analyses.

Chemical studies on the roots of Uvaria welwitschii

A chemical investigation of the chloroform extract of the roots of Uvaria welwitschii (Annonaceae), an African traditional medicine taken for stomach ache, led to the isolation of eight new compounds, named welwitschins A–H (1–8), together with five known compounds (9–13). The structural elucidation by spectroscopic studies of the compounds isolated is described. All new compounds were flavonoids having a 2-hydroxy-3,4,6-trimethoxyphenyl moiety in the A-ring, and unsubstituted phenyl in the B-ring. Four of them (1–4) were monomeric flavonoids while the others (5–8) were dimeric flavonoids. The cytotoxicity of the isolated compounds against human promyelocytic leukemia HL-60 cells was investigated.

Tropane alkaloids from Erythroxylum emarginatum

A tropane alkaloid, anhydroecgonine methyl ester N-oxide (2), was isolated for the first time as a naturally occurring compound, with anhydroecgonine methyl ester (1) from the bark of Erythroxylum emarginatum. Compound 1 was also isolated from the twigs. Their structures were elucidated mainly by spectroscopic methods.

A Semicontinuous Assay of Inhibition of Cyclic-AMP Phosphodiesterase by Benzo[c]phenanthridine Alkaloids

Abstract An HPLC apparatus to trace the reaction semicontinuously was devised and applied to the kinetic study of an enzyme reaction. From the thermostated solution in which the reaction proceeds continuously, an aliquot of the solution was removed and submitted to HPLC automatically and repeatedly. Thus, the change of concentrations of reactant and/or product was determined at a definite short interval. The inhibitory action of cyclic-/ P phosphodiesterase (PDE) by several benzo[c]phenenthridine alkaloids was examined. From 1/S–1/V (Lineweaver-Burk plot) sanguinarine and chelerythrine, which were both potent bacteriocidal alkaloids, were found to strongly inhibit PDE competitively. Kinetic parameters of the enzyme reaction such as Michaelis constant and inhibition constants were obtained.

Absolute configurations of two acyclic triterpenoids from Ekebergia capensis

Abstract The absolute configurations of two acyclic triterpenoids 1 and 2, previously isolated from the bark of Ekebergia capensis (Meliaceae) have been determined by the modified Moshers method.

Chapter 5 Histochemistry of Alkaloids

Publisher Summary This chapter reviews various biological and biochemical investigations, using histochemical and other techniques, of plants from five families. The chapter describes apparatus and methods for histochemical chromatography and its application to plant and animal tissues. Morphological and histological studies of plants have contributed to not only comparative study of plant species in taxonomy but also to biological, physiologic, and ecologic sciences. The alkaloids in the tissues and cells are detected as colored liquid, crystals, or precipitates by staining the section with alkaloid reagents and viewing with a microscope. A new technique to modify a conventional method of histochemistry, referred to as histochemical chromatography (HC) is developed. After removing cell components such as crystals, oil droplets, and colored liquid from tissue sections with an aspiratoscope, chemical analysis is accomplished by gas chromatography (GC), high-pressure liquid chromatograpy (HPLC), and gas chromatography–mass spectrometry (GC–MS). Morphology and histology in combination with pharmacognosy, pharmaceutics, pharmacology, physiology, genetics, and chemistry have contributed much to distinguish useful plants from non-useful ones, to develop more useful plants by modem hybridization techniques, and to obtain important organic chemicals, medicines, and dyes from various organs or the entire plant.