Biomedical subjects
Publications and source records attributed to Kaoru Umehara.
From the leaves of Aspalathus linearis, 24 known compounds and a new one, aspalalinin (25), were isolated. The structures of the compounds were determined mainly based on spectral evidence. The absolute configuration of aspalalinin was presented on the basis of X-ray analysis. Each isolate was assessed for its estrogenic activity by an estrogen ELISA assay. Compounds 12, 15, and 24 showed the estrogenic activity.
From the rhizomes of Belamcanda chinensis, three new compounds, belalloside A (1), belalloside B (2), and belamphenone (3), along with 13 known compounds, resveratrol (4), iriflophenone (5), irisflorentin (6), tectorigenin (7), irilin D (8), tectoridin (9), iristectorin A (10), iristectorin B (11), hispiduloside, androsin, irigenin, iridin, and jaceoside, have been isolated and characterized. Isolates were evaluated for their cell proliferation stimulatory activity against the MCF-7 and T-47D human breast cancer cell lines. Along with 4, 5, 7, and 9, 3 was shown to stimulate not only MCF-7 but also T-47D human breast cancer cell proliferation.
While searching for new estrogenic compounds from the plant kingdom, we investigated an extract of the seeds of Cuscuta chinensis (Convolvulaceae) which showed potency for stimulating MCF-7 cell proliferation. A novel resin glycoside, cuscutic resinoside A ( 6) was isolated along with five known compounds from the extract. The structure was deduced from its spectral data as (11 S)-hydroxyhexadecanoic acid 11- O-alpha- L-(4- O-2 R,3 R-nilylrhamnopyranosyl)-(1-->2)- O-alpha- L-rhamnopyranosyl-(1,2-lactone) forming a unique 15-membered macrocyclic lactone. The compound significantly stimulated not only MCF-7 cell proliferation but also T47D human breast cancer cells at a concentration of 10 microM. Along with cuscutamine ( 1) and kaempferol ( 4), 6 was tested in the transient luciferase reporter assay and was found to have different luciferase inducing activity characteristics from the other compounds. These results suggest that 6 stimulated cancer cell proliferation by a different mechanism from 1 and 4.
Hairy root cultures of Pharbitis nil treated with CuSO4 and methyl jasmonate (MeJA) produced umbelliferone (1) and scopoletin (2) in the culture medium, and skimmin (3), a beta-D-glucopyranoside of 1, was isolated from the hairy roots. While 1 in the medium increased and reached a maximal level 16 h after the treatment with CuSO4, the amount of 3 in the hairy roots decreased, reaching a minimal level after 8 h, before recovering to a level higher than the basal level after 24 h and then continuously increasing. These observations suggest that 1 was released by the hydrolysis of 3. Umbelliferone (1) inhibited hairy root growth, while skimmin (3) did not. This result suggests that, after the release of 1 as a phytoalexin, the hairy roots glycosylated 1 for the detoxification and re-use of 3 as a source of phytoalexin.
Primary screening of antitumor-promoting activity using soft agar colony assays with JB6 cells was employed to isolate 22 compounds from Chaenomeles sinensis KOEHNE. These compounds were lyoniresinol-2a-O-alpha-L-rhamnopyranoside (1), lyoniresinol-2a-O-beta-D-glucopyranoside (2), aviculin (3), betulinic acid (4), betulin (5), 3-O-(E)-p-coumaroylbetulin (6), 3-O-(E)-caffeoylbetulin (7), 3-O-(Z)-p-coumaroylbetulin (8), 3-O-(E)-caffeoyllupeol (9), alphitolic acid (10), sorbikortal II (11), tormentic acid (12), euscaphic acid (13), corosolic acid (14), maslinic acid (15), erythrodiol (16), 1-beta-D-glucopyranosyloxy-3,4,5-trimethoxybenzene (17), avicularin (18), 7-O-beta-D-glucopyranosylkaempferol (19), 5-O-beta-D-glucopyranosylgenistein (20), 7-O-beta-D-glucopyranosylgenistein (21), epicatechin (22), and beta-sitosterol (23) and were identified using spectral data such as MS, (1)H- and (13)C-NMR. Compound 1, having a rhamnosyl group, showed greater activity than 2, having a glucosyl group, and 3, which was a bis-demethoxy derivative of 1. Betulinic acid (4), having a C-28 carboxyl group, 3-O-(E)-caffeoylbetulin (7), and tormentic acid (12) showed more potent activity than betulin (5), which has a C-28 hydroxymethyl group.
Prolyl endopeptidase (PEP, EC 3.4.21.26) has been proposed to play a role in degradation of proline-containing neuropeptides involved in the processes of learning and memory, e.g., vasopressin, substance P, and thyrotropin-releasing hormone (TRH). In the course of our search for bioactive constituents in medicinal plants, we studied the PEP inhibitory constituents of the roots of Lindera strychnifolia F. VILL and isolated two known tannins, epicatechin (1) and aesculitannin B (2), and four known sesquiterpenes, linderene (3), linderene acetate (4), linderalactone (5) and isolinderalactone (6) as inhibitors. On the inhibitory activities of six compounds against PEP from Flavobacterium meningosepticum and that from rat brain supernatant, compounds 1, 2 and 4 inhibited the enzyme from Flavobacterium more strongly than that from rat brain supernatant. However, compounds 3, 5 and 6 inhibited the enzymes from both origins to the same extent and furthermore, compound 6 was the strongest natural inhibitor against PEP from rat brain supernatant. The kinetic study of these inhibitors indicated that compounds 1, 2 are noncompetitive inhibitors and compounds 3-6 are competitive inhibitors. This is the first example of non-phenolic constituents showing significant competitive inhibitory activity being isolated from natural medicines.
The botulinum neurotoxin produced by Clostridium botulinum exhibits the strongest neurotoxicity, and causes botulism in mammals. We have found an inactivator for clostridial neurotoxins in black tea extract (thearubigin fraction) as a natural foodstuff. In this study, we have isolated and identified the inactivators. The activity against the neuromuscular blocking action of botulinus neurotoxin type A was examined in mouse phrenic nerve diaphram preparation. The purification procedure of the inactivators was as follows. Tea was extracted with aqueous acetone, and then filtrated and lyophilized. It was also extracted with n-hexane, chloroform, ethyl acetate, n-butylalchol and water, so the activity of the antidote was recognized to be in the n-butylalchol layer (named the thearubigin fraction). A two-step reversed phase HPLC was developed for the thearubigin fraction. Three flavonoids were found to have the major activity. The structural elucidation of the compounds by means of NMR spectrascopy revealed, kaempfenol-3-O-[glc-(6-1)-rha-(3-1)-glc];keampfetrin, kaempferol-3-O-[glc-(6-1)-rha];nicotiflorin and quercetin glycoside.