J.D. Phillipson

Polyphenolic compounds from Croton lechleri

The blood-red sap of Croton lechleri was found to contain proanthocyanidins as major constituents which accounted for up to 90% of the dried weight. In addition to (+)-catechin, (−)-epicatechin, (+)-gallocatechin, (−)-epigallocatechin and dimeric procyanidins B-1 and B-4, five novel dimers and trimers were isolated and characterized as catechin-(4α→8)- epigallocatechin, gallocatechin-(4α→8)-epicatechin, gallocatechin-(4α→6)-epigallocatechin, catechin-(4α→8)- gallocatechin-(4α→8)-gallocatechin and gallocatechin-(4α→8)-gallocatechin-(4α→8)-epigallocatechin. Higher oligomers were also obtained. A new procedure combining chemical degradation with 1H NMR spectroscopy has been developed for determination of the composition and molecular size of oligomeric/polymeric proanthocyanidins. The oligomers of the sap were shown to have the mean degree of polymerization of 4,5–6 and 6–7, respectively, and Mr up to 2130. The heterogeneity of the oligomers was clearly indicated by the presence of a variety of flavan-3-ols as extension and terminal units. An exceptionally high content of gallocatechin and epigallocatechin in the oligomers was observed.

Chorismate mutase in microorganisms and plants

The enzymology of chorismate mutase in plants and microorganisms is reviewed to include occurrence, gene-enzyme relationships, reaction mechanisms and details of active site studies.

Anthranilate synthase in microorganisms and plants

The enzymology of anthranilate synthase (EC 5.4.99.6) in microorganisms and plants is reviewed. Aminoacid sequences of the enzyme subunits in different species are compared, and the mechanism of reaction is discussed.

Diterpenes from Croton lechleri

Abstract The chloroform extract of Croton lechleri sap was chemically examined, and the major constituents characterized by mass and NMR spectroscopy. In addition to a number of known compounds, such as 1,3,5- trimethoxybenzene, 2,4,6-trimethoxyphenol, 3,4-dimethoxyphenol, 3,4-dimethoxybenzyl alcohol, 4-hydroxyphenethyl alcohol and its acetate, sitosterol, sitosterol-β- d -glucopyranoside and β-sitostenone, four diterpenoids were isolated from Croton lechleri bark, and two of them were found to be novel compounds possessing a clerodane skeleton. Their structures were unequivocally elucidated by extensive use of NMR spectroscopy. They were termed as crolechinol and crolechinic acid, respectively. The presence of these diterpenoids as minor constituents in the sap was confirmed by TLC profiles and NMR spectra.

Quaternisation and oxidation of strychnine and brucine during plant extraction

Abstract Use of CHCl 3 and CH 2 Cl 2 for the extraction of amines and alkaloids may easily lead to the formation of artifacts. CH 2 Cl 2 in particular reacts rapidly at laboratory temperature with strychnine and brucine forming quaternary salts. In connection with this, the TLC behaviour, NMR and MS properties of the chlorometho- and bromometho-halides and -picrates of strychnine and brucine are discussed. On standing, CHCl 3 solutions of strychnine yield not only a quaternary salt but also 16-hydroxystrychnine (pseudostrychnine) and strychnine N -oxide; brucine reacts similarly. When CH 2 Cl 2 and CHCl 3 are to be used for the extraction of amines or alkaloids, it is advisable to ascertain whether or not they leave the compounds chemically unchanged.

Clerodane diterpenoids from Croton lechleri

Abstract Further chemical examination of the constituents in the bark of Croton lechleri led to isolation of two new diterpenoidal compounds, korberin A and korberin B. Their structure was elucidated by 1 H and 13 C NMR spectroscopic methods, and they were shown to be diterpenoid lactones with the clerodane skeleton. Their antibacterial activity was tested using a direct bioautographic TLC assay.

Antirhine and antirhine metho-salt from the leaves of Strychnos camptoneura

Abstract The isolation of antirhine and antirhine metho-salt from the leaves of Strychnos camptoneura is described. The conformation of antirhine is discuss

Peptide and tetrahydroisoquinoline alkaloids from Euonymus europaeus

Abstract Three p -aryloxy macrocyclic peptide alkaloids frangulanine, franganine and frangufoline together with the 1-benzyltetrahydroisoquinoline alkaloid armepavine have been isolated from Euonymus europaeus native to Poland. These types of alkaloids are new to the Celastraceae and are of chemotaxonomic interest.

N-Oxides of the oxindole alkaloids, isorhynchophylline, rhynchophylline, rhynchociline and ciliaphylline

Abstract The N -oxides of isorhynchophylline, rhynchophylline, rhynchociline and ciliaphylline were prepared, for comparison with a new alkaloid from Mitragyna tubulosa .

In vitro conversion of morphine to its N-oxide in Papaver somniferum latex

Abstract Radio active morphine ( 14 C- and 3 H-labelled) was fed in vitro to freshly collected samples of capsules and stem latex of Papaver somniferum and it was shown that some of it was converted to radioactive N -oxide. Although metabolic activity and variation between samples of latex collected at different times were much less marked than those previously found using in vivo methods, the results do confirm that the isolated latex is a metabolically viable tissue.