Toshitake Tamura

Karounidiol [D:C-friedo-oleana-7,9(11)-diene-3α,29-diol] and its 3-o-benzoate: novel pentacyclic triterpenes from Trichosanthes kirilowii. X-Ray molecular structure of karounidiol diacetate

Spectroscopic data were used to propose a probable structure for karounidiol [D:C-friedo-oleana-7,9(11)-diene-3α,29-diol] and its 3-benzoate, triterpenes isolated from the seeds of Trichosanthes kirilowii(Cucurbitaceae). The structure of the skeleton was proved by conversion of the natural product into multiflora-7,9(11)-dien-3βol [D:C-friedo-oleana-7,9(11)-dien-3β-ol], a known synthetic compound. The configuration at C-20 was determined by X-ray analysis of karounidiol diacetate after an attempt to obtain this information by chemical correlation with naturally occurring 3α-hydroxy-D:C-friedo-oleana-7,9(11)-dien-29-oic acid had failed. N.m.r. evidence and the results of the X-ray analysis indicate that the configuration at C-20 of the latter compound and of two structurally related natural products {bryocoumaric acid [3α-(p-hydroxycinnamoyl)-D:C-friedo-oleana-7,9(11)-dien-29-oic acid] and bryonolic acid (3β-hydroxy-D:C-friedo-olean-8-en-29-oic acid)} was wrongly assigned: all three have a 20β-carboxy configuration (i.e. they are the -30-oic acids according to the usual convention).

Tirucalla-5,24-dien-3β-ol [(13α,14β,17α,20S)-lanosta-5,24-dien-3β-ol] and three other Δ5-unsaturated tirucallanes from the roots of Bryonia dioica Jacq.: the first naturally occurring C-10 methylated tetracyclic triterpene alcohols with a Δ5-monounsaturated skeleton

Four novel triterpene alcohols with a Δ5-unsaturated tirucallane-type skeleton, i.e. tirucall-5-en-3β-ol, tirucalla-5,24-dien-3β-ol, 24-methyltirucalla-5,24(241)-dien-3β-ol and (24S)-24-methyltirucalla-5,25-dien-3β-ol, have been isolated from the roots of Bryonia dioica Jacq. (Cucurbitaceae). The structures have been determined by spectroscopic and chromatographic methods. These compounds are the first examples of naturally occurring C-10 methylated triterpenes with a Δ5-monounsaturated skeleton.

(22Z,24S)-Stigmasta-5,22,25-trien-3β-ol and other novel sterols from Clerodendrum scandens: first report of the isolation of a cis-Δ22-unsaturated sterol from a higher plant

(22Z,24S)-Stigmasta-5,22,25-trien-3β-ol was isolated from Clerodendrum scandens(Verbenaceae). It is only the second example of a naturally occurring Z-Δ22-unsaturated sterol. Four other novel sterols were isolated from the same source, viz.(24S)-5α-stigmast-25-en-3β-ol, (22E,24S)-5α-stigmasta-22,25-dien-3β-ol, 24-methylergosta-5,25-dien-3β-ol, and (24S)-14α-methyl-5α-stigmasta-9(11),25-dien-3β-ol. All structures were determined by chemical and spectroscopic methods.

Widespread occurrence of syn-alkane-6,8-diols in the flowers of the compositae

Ten tabular- and eight ligulate-flowers and seven flower-heads from twenty-two species of Compositae were investigated for their alkanediol constituents. All of the flowers contained alkanediols in small amounts suggesting their widespread occurrence in these flowers. Twelve alkanediols were identified as syn(R,S and/or S,R)-C(21)-, C(23)-, C(25)-, and C(27)--C(35)-alkane-6,8-diols among which syn-hentriacontane-6,8-diol occurred abundantly in many of the flowers.

24S-Chirality of 24-alkylsterols possessing a Δ25-double bond from Polypodium formosanum

Abstract Twenty-one components of the 4,4-dimethyl-, 4-methyl- and 4-demethylsterol fractions of the rhizomes and aerial parts of Polypodium formosanum were identified, including both epimers at C-24 of 24-methylcholest- 5-en-3β-ol. All other 24-alkylsterols were sterically pure. NMR data show that all nine 24-alkyl-Δ25- sterols from this plant have the 24S/β-configuration. Four of these sterols, viz. 24-methyl-25-dehydrocycloartanol, 24-ethyl-25-dehydrocycloartanol, 24-methyl-25-dehydrolophenol and 24-ethyl-25-dehydrolophenol have been misidentified in the literature (they were reported to have the 24R/α-configuration). 24S-Methyl-31-norlanosta-8,25-dien-3β- ol seems to be a novel sterol.

Cycloartane triterpenoids from the aerial part of Bryonia dioica.

A novel triterpenoid isolated from the non-saponifiable lipid of the aerial part extract of white bryony (Bryonia dioica) was established to be 3beta-hydroxy-27-norcycloartan-24-one based on spectroscopic methods. Isolation and identification of other known cycloartane triterpenoids and sterols also are described.