Donald R. McPhail

The cytotoxic principles of Hyptis capitata and the structures of the new triterpenes hyptatic acid-A and -B

Abstract Bioassay-directed fractionation of a methanolic extract of Hyptis capitata has led to the isolation and characterization of five triterpene acids which include the new hyptatic acids -A and -B in addition to the known 2α-hydroxyursolic acid, tormentic acid and maslinic acid. Spectral data in conjunction with X-ray analysis of the methanol solvate of hyptatic acid-A established the structures of these compounds. Hyptatic acid-A and 2α-hydroxyursolic acid demonstrated significant in vitro cytotoxicity in human colon HCT-8 tumour cells.

STRUCTURE AND STEREOCHEMISTRY OF PSEUDOLAROLIDE-I, A NOVEL CYTOTOXIC PEROXYTRITERPENE DILACTONE FROM PSEUDOLARIX KAEMPFERI

A novel cytotoxic peroxytriterpene dilactone, pseudolarolide I, has been isolated from the seeds of Pseudolarix kaempferi, and its structure and stereochemistry have been established from spectral data in conjunction with a single-crystal X-ray analysis

Cytotoxic aporphines from artabotrys uncinatus and the structure and stereochemistry of artacinatine

Abstract The stem and stem bark of Artabotrys uncinatus afforded two cytotoxic aporphine alkaloids, liriodenine and atherospermidine, as well as a novel 11 -oxoaporphine, artacinatine, which is inactive. The structure of artacinatine was elucidated from spectral data in conjunction with a single-crystal X-ray analysis.

Kansuiphorin-C and -D, cytotoxic diterpenes from Euphorbia kansui

Abstract Two new cytotoxic diterpenes, kansuiphorin-C and -D, have been isolated from Euphorbia kansui . Their structures and stereochemistries have been established from spectral data in conjunction with X-ray crygtallographic analysis of the benzene solvate of kansuiphorin-C.

Structure and synthesis of murrapanine, a novel skeletal indole-naphthoquinone alkaloid and cytotoxic principal from Murraya paniculata var. omphalocarpa

Abstract A novel skeletal cytotoxic indole-naphthoquinone alkaloid, murrapanine, has been isolated from the root bark of Murraya paniculata var. omphalocarpa and its structure has been established from spectral data and single-crystal X-ray analysis; the synthesis of murrapanine from indole-3-aldehyde is also described.

X-ray structure of psiadiarabin, a flavone from Psiadia arabica

Abstract The chloroform extract of the aerial parts of Psiadia arabica yielded upon solvent partitioning and chromatography a new flavone with a tetraoxygenated ring B. Spectral and X-ray crystallographic data identified the compound, psiadiarabin, as 5,3′-dihydroxy-6,7,2′,4′,5′-pentamethoxyflavone.

Ghalakinoside, a cytotoxic cardiac glycoside from Pergularia tomentosa

Abstract The isolation and structural elucidation using spectroscopic methods and X-ray analysis of ghalakinoside, a novel cytotoxic cardiac glycoside, containing a doubly linked sugar substituent are reported. Calactin, another related glycoside was also isolated and its structure similarly established.

A flavone and diterpene from Psiadia arabica

Abstract The aerial parts of Psiadia arabica yielded two new constituents: a flavone, 5,7,3′-trihydroxy-2′,4′,5′-trimethoxyflavone, the structure of which was derived from spectral data and chemical derivatization, and a kaurane diterpene named psiadian, which was characterized unambiguously from its chemical and spectral data in conjunction with X-ray crystallography.

Structure and stereochemistry of pseudolarolide-H, a novel peroxy triterpene dilactone from Pseudolarix kaempferi

Pseudolarolide J (1), a novel nortriterpene lactone, has been isolated from the seeds of Pseudolarix kaempferi and structurally characterized from spectral data and X-ray crystallographic analysis.

Antitumor agents--CLI. Bis(helenalinyl)glutarate and bis(isoalantodiol-B)glutarate, potent inhibitors of human DNA topoisomerase II.

Evaluation of a number of cytotoxic antitumor sesquiterpene lactones and their derivatives has led to the discovery of bis(helenalinyl)glutarate (4) and bis(isoalantodiol-B)glutarate (10) as potent inhibitors of human-derived topoisomerase II. Unlike etoposide, which inhibits by preventing the DNA rejoining process, compounds 4 and 10 inhibit topoisomerase II without causing DNA breakage. The structure-activity relationships of 4, 10, and related compounds are discussed.