Shin-ichiro Kurimoto

New α-glucosides of caffeoyl quinic acid from the leaves of Moringa oleifera Lam.

Two new caffeoyl quinic acid α-glucosides, together with three known caffeoyl quinic acids and five known flavonoid glucosides, were isolated from the leaves of Moringa oleifera Lam. The structures of the new compounds were elucidated as 4-O-(4′-O-α-d-glucopyranosyl)-caffeoyl quinic acid (1) and 4-O-(3′-O-α-d-glucopyranosyl)-caffeoyl quinic acid (2) by spectroscopic analyses.

A C14-polyacetylenic glucoside with an α-pyrone moiety and four C10-polyacetylenic glucosides from Mediasia macrophylla

Polyacetylenic glucosides (1-5) were isolated from the MeOH extract of Mediasia macrophylla, and their structures were established by spectroscopic analyses. Compounds 2-4 were the first examples of C(10)-polyacetylenic glucosides found in the family Umbelliferae, while compound 1 was a unique polyacetylenic glucoside possessing an alpha-pyrone moiety.

Conjugates of a secoiridoid glucoside with a phenolic glucoside from the flower buds of Lonicera japonica Thunb.

Secoiridoid glucosides, including two conjugates with a phenolic and two conjugates with a nicotinic acid derivative (3 and 4), together with seven known secoiridoid derivatives, were isolated from flower buds of Lonicera japonica. The structures were elucidated by spectroscopic analyses. Anti-influenza activities of six isolated compounds were also evaluated by plaque assay and neuraminidase inhibitory assay.

Acylated neo-clerodanes and 19-nor-neo-clerodanes from the aerial parts of Scutellaria coleifolia (Lamiaceae)

Scutefolides A1 and A2, two acylated neo-clerodanes with a 19,18-γ-lactone, scutefolides B1, B2 and C, three 19-nor-neo-clerodanes, together with scutefolides D, E1, E2 and F, four neo-clerodanes, were isolated from the EtOAc-soluble fraction of the aerial parts of Scutellaria coleifolia. Their structures were established on the basis of spectroscopic analysis. The absolute configurations of four of these compounds were elucidated by the CD exciton chirality method. Cytotoxic activities of scutefolides D-F against four cancer cell lines (KB, A549, HeLa, and MCF7) were also evaluated, but they were inactive.

Triterpenoids from the fruits of Azadirachta indica (Meliaceae).

Four new triterpenoids, indicalilacols A-D (1-4), were isolated from the MeOH extract of the fruits of Azadirachta indica, including a new 19(10→9β)abeo-tirucallane derivative, two new tirucallane-type triterpenoids, and a new euphane-type triterpenoid, along with three known tirucallane-type triterpenoids. Their structures were elucidated on the basis of spectroscopic analyses. The absolute configuration of 2 was elucidated by the chemical conversion of 2 into 21-oxo-melianodiol 24,25-acetonide. Compounds 2, 6-8 exhibited moderate cytotoxicity against three human cancer cell lines, including multidrug-resistant (MDR) cancer cells (KB-C2). Although compound 5 was not cytotoxic against any of the tested cancer cell lines, 5 showed cytotoxicity against KB-C2 cells in the presence of 2.5 μM colchicine, suggesting that 5 might have an MDR-reversal effect.

New 29-nor-cycloartanes with a 3,4-seco- and a novel 2,3-seco-structure from the leaves of Sinocalycanthus chinensis.

Eight new triterpenoids, including sinocalycanchinensins A-E (1-5) with a 3,4-seco-29-nor-cycloartane skeleton, sinocalycanchinensin F (6) possessing a novel 2,3-seco-29-nor-cycloartane skeleton, and 29-nor-cycloartanes, sinocalycanchinensins G and H (7 and 8), have been isolated from the leaves of Sinocalycanthus chinensis. Their structures were elucidated on the basis of spectroscopic examinations. The cytotoxicities of the isolated new triterpenes against a panel of human cancer cell lines, including multi-drug resistant (MDR) cancer cell lines, were also evaluated. Compound 5 demonstrated enhanced cytotoxicity against MDR KB cells in the presence of colchicine, although all the compounds showed moderate or no cytotoxicities.

Four new glucosides from the aerial parts of Mediasia macrophylla

As part of our chemical studies on the medical plants in Uzbekistan aimed at searching for new drug leads, we have examined the aerial parts of Mediasia macrophylla. This has resulted in the isolation of four new glucosides, together with 30 known compounds. The structures of new compounds were elucidated as (1′S)-(4-hydroxyphenyl) ethane-1′,2′-diol 2′-O-β-glucopyranoside (1), 3-(4′-methoxyphenyl)-propanol 1-O-β-glucopyranoside (2), 2-methoxy-3-hydroxy-5-(E)-propenyl-phenol 1-O-β-glucopyranoside (3), 1-O-angeloyl-β-glucopyranose (4), on the basis of spectral analysis.

Coleifolides A and B, Two New Sesterterpenoids from the Aerial Parts of Scutellaria coleifolia H.Lév.

Coleifolides A and B (1 and 2), two new sesterterpenoids with a β‐methyl‐α,β‐unsaturated‐γ‐lactone moiety, were isolated from the aerial parts of Scutellaria coleifolia H.Lév. (Lamiaceae), together with three known compounds. Their structures were elucidated by NMR and MS examinations. Coleifolides A and B were concluded to be partially racemic compounds by the HPLC analysis using a chiral column or introduction of chiral derivatizing agents. The absolute configuration of the major isomer was determined by analyses of the CD spectrum as well as NMR data of (R)‐ and (S)‐2‐NMA derivatives. Coleifolides A and B are structurally similar to manoalide derivatives, previously isolated from marine sponges, and appear to be the first examples of this type of compounds being isolated from higher plants.

Studies on medicinal plants of Yunnan province: Constituents of Gentiana rigescens

We have been investigating traditional herbal medicines used by ethnic minority groups in Yunnan province, China, aimed at searching seed compounds for drug development. Gentiana rigescens (Gentianaceae) is a medicinal folk plant used for hepatitis and cholecystitis by the Yi ethnic minority group. We have examined the MeOH extracts of the aerial parts and roots of G. rigescens, which has resulted in the isolation of ten new secoiridoid derivatives (1 – 10). The structure elucidation of these compounds will be presented.