Naotoshi Yoshida

Taxuspines A ∼ C, new taxoids from Japanese yew Taxus cuspidata inhibiting drug transport activity of P-glycoprotein in multidrug-resistant cells

Abstract Three new taxoids, taxuspines A ∼ C (1 ∼ 3), possessing different skeletons from usual taxane diterpenoids consisting of a 6/8/6-membered ring system have been isolated together with known taxoids (4 ∼ 12) from stems of the Japanese yew Taxus cuspidata Sieb. et Zucc. and the structures elucidated on the basis of spectroscopic data. Most of the taxoids increased cellular accumulation of vincristine in multidrug-resistant tumor cells, while taxol (12) did not show such an activity. The taxoids (1 ∼ 11) showed no or weak cytotoxicity and among them, 2 and 6 reduced appreciably CaCI2-induced depolymerization of microtubules. These results suggest that some taxoids may be useful for overcoming multidrug resistance in tumor cells.

Complanadine A, a new dimeric alkaloid from Lycopodium complanatum

Abstract A new dimeric alkaloid with a lycodine-type skeleton, complanadine A ( 1 ), has been isolated from the club moss Lycopodium complanatum , and the structure including the absolute stereochemistry was elucidated on the basis of spectroscopic data.

Cephalezomines A–F, Potent Cytotoxic Alkaloids from Cephalotaxus harringtonia var. nana

Six new alkaloids, cephalezomines A–F (1–6), have been isolated together with known related alkaloids 7–16 from the leaves of Cephalotaxus harringtonia var. nana and the structures were elucidated by spectroscopic data and chemical methods. Cephalezomines A–F (1–6) showed potent cytotoxicity against tumor cells.

Taxuspines E ∼ H and J, new taxoids from the Japanese yew Taxus cuspidata

Abstract Five new taxoids, taxuspines E ∼ H and J (1 ∼ 5), have been isolated together with known taxoids (6 ∼ 23) containing a series of taxol-related compounds (15 ∼ 20) from stems and leaves of the Japanese yew Taxus cuspidata Sieb. et Zucc. and the structures elucidated on the basis of spectroscopic data. The structures and cytotoxicity of these taxoids (1 ∼ 23) are described.

Daphnezomines C, D, and E, new alkaloids with an N-oxide moiety from Daphniphyllum humile

Abstract Three new alkaloids containing an N-oxide moiety, daphnezomines C (1), D (2), and E (3), have been isolated from the stems of Daphniphyllum humile, and the structures including relative stereochemistry were elucidated on the basis of spectroscopic data.

New Picrotoxinin-type and Dendrobine-type Sesquiterpenoids from Dendrobium Snowflake ‘Red Star’

Two new picrotoxinin-type sesquiterpenes, flakinins A (1) and B (2), and three new dendrobine-type sesquiterpene alkaloids, mubironines A (3), B (4), and C (5), have been isolated from the whole plants of Dendrobium Snowflake ‘Red Star’ (Orchidaceae). Their stereostructures were elucidated by 2D NMR data and chemical means.

Daphnezomines H, I, J, and K, New Daphnilactone-type and Yuzurimine-type Alkaloids from Daphniphyllum humile

Daphnezomines H (1), I (2), J (3), and K (4), four new alkaloids possessing a daphnilactone-type (1 and 2) or a yuzurimine-type skeleton (3 and 4) have been isolated from the leaves (1), stems (2) and fruits (3 and 4) of Daphniphyllum humile, respectively, and the structures including relative stereochemistry were elucidated on the basis of spectroscopic data.

Sesquiterpenoids from petasites fragrans

Abstract Chemical analysis of Petasites fragrans yielded the eremophilane type of sesquiterpenes: petasol, isopetasol, S-petasin, neo-S-petasin, and a mixture of petasol derivatives, with caffeic acid methyl ester and a mixture of phytosterols. Their structures were elucidated by chemical and spectroscopic methods.

Senepodine A, a novel C22N2 alkaloid from Lycopodium chinense

A new C 2 2 N 2 Lycopodium alkaloid, senepodine F (1), consisting of a decahydroquinoline and a quinolizidine ring has been isolated together with senepodines A (2) and E (3) from the club moss Lycopodium chinense. The relative stereochemistry of 1 was determined by NOESY correlations for a deacetylated derivative.

Camtschatcanidine, an alkaloid from Fritillaria camtschatcensis

Abstract From the hydrolysed glycoalkaloid fraction from bulbs of mature Fritillaria camtschatcensis in addition to already reported alkaloids a new solanidanine alkaloid, 22 R ,25 S -solanid-5-ene-3β,27-diol (camtschatcanidine), was isolated and its structure elucidated by spectral analysis and its conversion to solanidine. Also veralkamine was identified from the same plant.