Toosendanin relatives, trypanocidal principles from Meliae Cortex.

Africa Trypanosomiasis remains a serious health problem, but the approved drugs for this disease are so few that novel trypanocidal compounds are demanded. In search for trypanocidal principles from medicinal plants, we found MeOH extracts of Meliae Cortex with potent activity through the screening from about 300 kinds of methanolic extract. By bioassay-guided fractionation from this extract through the liquid-liquid partition and subsequent chromatographic technique using silica gel and ODS, finally we disclosed toosendanin (1) and its relatives as active principles.

Inhibitor for FcεRI expression on mast cell from Verbasucum thapsus L.

We found out 2',3'-dihydroxypuberulin from South American medicinal plant, V. thapsus L., as a candidate of an anti-allergic lead which inhibits the expression of high-affinity receptor of IgE (FcεRI) on the surface of mast cells.

Oenothein B, dimeric hydrolysable tannin inhibiting HCV invasion from Oenothera erythrosepala.

The envelope proteins of the hepatitis C virus (HCV), E1 and E2, have been revealed to be essential for invasion of HCV. Thus, we were engaged in the search for the inhibitors against HCV invasion through the assay system using the model virus expressing recombinant HCV envelopes, E1 and E2. Now, we disclosed dimeric hydrolysable tannin oenothein B (1) from MeOH extract of Oenothera erythrosepala as an active principle for inhibition of HCV invasion and its potency was almost the same as that of monomeric hydrolysable tannin, tellimagrandin I (2).

Six new acylated anthocyanins from red radish (Raphanus sativus).

Six new acylated anthocyanins (1-6) were isolated along with the three known congeners (7-9) from the fresh roots of red radishes (Raphanus sativus L.) cultivated by our group. Their chemical structures were elucidated by spectroscopic properties.

Concise synthesis of 5,6-dihydrovaltrate leading to enhanced Rev-export inhibitory congener.

The concise synthesis of 5,6-dihydrovaltrate (2), the bioisostere of valtrate (1) showing anti-HIV activity by inhibition for nuclear export of Rev, has been achieved from the commercially available iridoid genipin (3). Analysis of steric influence of the substituents linked to the three hydroxyl groups was conducted by the synthesized three analogs (2a-2c). Consequently, attenuation of steric hindrance around the epoxy portion was revealed to enhance inhibitory potency for Rev-export.

Inhibitors for expression of IgE receptor on human mast cell from Puerariae Flos.

Bioassay-guided separation of the extract of the medicinal plant, Puerariae Flos, disclosed the two isoflavones tectorigenin (1) and genistein (2) as the inhibitors for expression of IgE receptor (FcepsilonRI), the key molecule triggering the allergic reactions, on human mast cells. As a result of analysis of structure-activity relationship of the naturally occurring and synthesized isoflavones, 7-O-methyl glycitein (11) was disclosed as the more potent inhibitor than tectorigenin (1). These isoflavone ingredients suppressed expression of FcepsilonRI more potently than the active flavonoids found previously.

Prenylcoumarin with Rev-export inhibitory activity from Cnidii Monnieris Fructus.

By use of the fission yeast expressing the model fusion protein comprised of GST, SV40 T antigen NLS, GFP, and Rev-NES in the bioassay, the prenylcoumarin osthol (1) was disclosed as the new Rev-export inhibitor from the MeOH extract of Cnidii Monnieris Fructus. Furthermore, 1 was also found to inhibit export the genuine Rev in HeLa cells by indirect fluorescent antibody technique. By the competitive experiment using the biotinylated probe 3, osthol (1) was revealed to inhibit nuclear export of Rev through a NES non-antagonistic mode.

Halogenated analogs of 1'-acetoxychavicol acetate, Rev-export inhibitor from Alpinia galanga, designed from mechanism of action.

In the course of search for the robust analogs of 1'-acetoxychavicol acetate (ACA, 1), the Rev-export inhibitor from the medicinal plant Alpinia galanga, we clarified formation of the quinone methide intermediate ii to be essential for exerting the inhibitory activity of 1. Based on this mechanism of action, the rational design from the MO calculation of the conclusive activation energy to ii resulted in the four halogenated analogs with more potent activity than ACA (1). In particular, the difluoroanalog 20d exhibited approximately four-fold potent activity as compared with 1.

Bioisostere of valtrate, anti-HIV principle by inhibition for nuclear export of Rev.

Rational design by the MO calculation disclosed 5,6-dihydrovaltrate (2) as the bioisostere of valtrate (1), the Rev-export inhibitor with anti-HIV activity. The synthesis of 2 was accomplished by ingenious use of asymmetric Diels-Alder reaction and stereoselective epoxidation associated with the adjacent hydroxyl group. Because of similar biological potency to 1, the analog 2 should be recognized as a promising scaffold for new anti-HIV agents with an unprecedented mechanism of action, inhibition for nuclear export of Rev protein, in the conventional remedy.

New inhibitors for expression of IgE receptor on human mast cell.

Exploration for inhibitors against expression of IgE receptor (Fc epsilonRI) on human mast cell, a significant trigger to acute and chronic allergic symptoms, disclosed epigallocatechin gallate (EGCG), epicatechin gallate, and gallocatechin gallate as active principles. Additionally, the anthocyanidin, delphinidin, and the flavone, tricetinidin, possessing a pyrogallol function were also revealed to suppress expression of Fc epsilonRI. Structure-activity relationship analysis among catechins, anthocyanidins, and flavones revealed the pyrogallol moiety to be crucial for biological potency.

Unprecedented NES non-antagonistic inhibitor for nuclear export of Rev from Sida cordifolia.

Bioassay-guided separation from the MeOH extract of the South American medicinal plant Sida cordifolia resulted in isolation of (10E,12Z)-9-hydroxyoctadeca-10,12-dienoic acid (1) as an unprecedented NES non-antagonistic inhibitor for nuclear export of Rev. This mechanism of action was established by competitive experiment by the biotinylated probe derived from leptomycin B, the known NES antagonistic inhibitor. Additionally, structure-activity relationship analysis by use of the synthesized analogs clarified cooperation of several functionalities in the Rev-export inhibitory activity of 1.

New anti-malarial phenylpropanoid conjugated iridoids from Morinda morindoides.

A new phenylpropanoid conjugated iridoid together with four known congeners was isolated from Morinda morindoides, used for the therapy of malaria traditionally in some African countries, as anti-malarial principles through bioassay-guided separation. Furthermore, their absolute stereostructures were unambiguously established by a combination of modified Mosher's method and chemical correlation.

Tellimagrandin I, HCV invasion inhibitor from Rosae Rugosae Flos.

By use of the model virus, expressing the HCV envelope proteins E1 and E2, bioassay guided separation of the MeOH extract from Rosa rugosa Thunb. disclosed tellimagrandin I (1) together with eugeniin (2) and casuarictin (3) as the potent HCV invasion inhibitors. Furthermore, structure-activity relationship analysis of some relative tannins including the synthesized analogs elucidated the partial structures crucial for potent activity of 1.

Anti-inflammatory properties of red ginger (Zingiber officinale var. Rubra) extract and suppression of nitric oxide production by its constituents.

Red ginger (Zingiber officinale var. Rubra) has been prescribed as an analgesic for arthritis pain in Indonesian traditional medicine. The surface color of the rhizome is purple because of the anthocyanidins in its peel.

New Rev-export inhibitor from Alpinia galanga and structure-activity relationship.

Bioassay-guided separation by use of the fission yeast expressing NES of Rev, an HIV-1 viral regulatory protein, disclosed 1'-acetoxychavicol acetate (ACA, 1) as a new inhibitor for nuclear export of Rev from the roots of Alpinia galanga. Both analysis for mechanism of action with biotinylated probe (2) and several synthesized analogs established crucial portions in 1 for Rev-export inhibitory activity.

Preparative high-performance liquid chromatography for the purification of natural acylated anthocyanins from red radish (Raphanus sativus L.).

Preparative high-performance liquid chromatography (HPLC) is applied to the purification of anthocyanins from raw extracts of red radish (Raphanus sativus L). For each separation, the chromatographic conditions are optimized to achieve an efficient purification in the shortest time. In addition, UV-vis characterization is carried out on all purified anthocyanins.

[Safety and structural analysis of polymers produced in manufacturing process of alpha-lipoic acid].

Alpha-Lipoic acid has recently been permitted for use in foodstuffs and is contained in tablets and capsules. Although alpha-lipoic acid is synthesized from adipic acid, the safety of polymers produced during the purification and drying processes has been an issue of concern. Hence, we examined the safety profiles of thermally denatured polymer (LAP-A) and ethanol-denatured polymer (LAP-B) produced in the manufacturing process of alpha-lipoic acid.

Kola acuminata proanthocyanidins: a class of anti-trypanosomal compounds effective against Trypanosoma brucei.

Human African trypanosomiasis is undergoing an alarming rate of recrudescence in many parts of sub-Saharan Africa. Yet, there is no successful chemotherapy for the disease due to a limited number of useful drugs, side effects and drawbacks of the existing medication, as well as the development of drug resistance by the parasite. Here we describe a new lead anti-trypanosomal compound isolated from Kola acuminata (Makasu).

Synthesis of a bioprobe for elucidation of target molecule of spongean anti-malarial peroxides.

The reactants of an anti-malarial peroxide having a 6-carbomethoxymethyl-3-methoxy-1,2-dioxane moiety treated with FeSO4 were analyzed. For mechanistic study of the anti-malarial peroxide, two biotinylated probes to elucidate the target molecules were designed and synthesized. The two synthesized probes showed potent anti-malarial activity, and one of them was proved to form an irreversible binding with protein in a model experiment.

New analogue of arenastatin A, a potent cytotoxic spongean depsipeptide, with anti-tumor activity.

Two analogues possessing steric hindered substituents on C-15 of arenastatin A (1), a potent cytotoxic spongean depsipeptide, were synthesized and shown to enhance stability in mouse serum. Notably, 15-tert-butylanalogue (6) with higher cytotoxicity exhibited in vivo anti-tumor activity through iv administration different from 1. Additionally, conformation analysis among the two analogues and arenastatin A (1) indicated that the torsion angle from C-14 to C-20 is a conclusive factor for the potent cytotoxicity of 1.

New anti-malarial peroxides with in vivo potency derived from spongean metabolites.

The structure-activity relationship of the anti-malarial substance 3 having a 6-carbomethoxymethyl-3-methoxy-1,2-dioxane structure was studied. The ester portion of the peroxide 3, showing little in vivo efficacy in malaria-infected mice in spite of the potent in vitro activity, was hydrolyzed in serum to afford an inactive free acid 4. The amide analogues (8 and 9) robust to mouse serum were disclosed to exhibit in vivo anti-malarial potency.

New semisynthetic quassinoids with in vivo antimalarial activity.

On the basis of a comparative analysis for stability in mouse serum between 15-O-acetylbruceolide and bruceolide 15-methyl carbonate, several 3,15-dialkyl carbonates of bruceolide were synthesized and their in vitro antimalarial activity was assessed. Methyl, ethyl, and isopropyl carbonates with pronounced in vitro activity were further evaluated for in vivo antimalarial potency. Both the methyl and ethyl carbonates significantly increased the life span of mice as compared with 3,15-di-O-accetylbruceolide and chloroquine.

Facilely accessible multidrug resistance modulator derived from sucrose.

Exploration for new MDR-modulators utilizing atractysucroses as scaffolds disclosed 2,3,4,3',4'-O-pentaisovalerylsucrose (9) as a readily accessible medicinal lead. This lead was prepared from sucrose in 65% total yield for three steps. In addition, compound 9 exhibited more potent MDR modulating activity than verapamil, a representative modulator of MDR mediated by P-gp.