L. A. Anderson

St John's wort (Hypericum perforatum L.): a review of its chemistry, pharmacology and clinical properties

The chemical composition of St. Johns wort has been well‐studied. Documented pharmacological activities, including antidepressant, antiviral, and antibacterial effects, provide supporting evidence for several of the traditional uses stated for St Johns wort. Many pharmacological activities appear to be attributable to hypericin and to the flavonoid constituents; hypericin is also reported to be responsible for the photosensitive reactions that have been documented for St. Johns wort. With regard to the antidepressant effects of St Johns wort, hyperforin, rather than hypericin as originally thought, has emerged as one of the major constituents responsible for antidepressant activity. Further research is required to determine which other constituents contribute to the antidepressant effect.

Ethnopharmacology and western medicine

The contribution of plants to western medicine is briefly considered using alkaloids as examples of one class of pharmacologically active natural product. Plants and plant products are present in 14 of the 15 therapeutic categories of pharmaceutical preparations which are currently recommended to medical practitioners in the U.K. and they form an important part of our health-care system in the western world. There is considerable scope for new drug discovery from traditional medicines which are used throughout the world and some recent developments are commented upon and conclusions are made.

Antiplasmodial activity of Artemisia annua plant cell cultures.

Extracts of Artemisia annua cultures have been assessed for in vitro activity against the malarial parasite Plasmodium falciparum. Callus and suspension cells and medium were analysed and examined for their activity at different stages of growth and development. Time-course experiments were carried out to investigate the influence of various basal media, plant growth regulators and light on both growth and possible artemisinin production. Two active fractions were obtained but artemisinin was not detected.

In vitro cultures of Cinchona species : Precursor feeding of C. ledgeriana root organ suspension cultures with L-Tryptophan.

The uptake of l-[methylene-14C]-tryptophan from culture medium into root organs of Cinchona ledgeriana and the subsequent incorporation of the radiolabel into quinine and quinidine is reported. In addition, feeding unlabelled l-tryptophan at levels of 500mg/l to the cultures results in a 5-fold increase in the yields of both quinoline alkaloids.

Studies on Ailanthus altissima cell suspension cultures: precursor feeding of L-[methylene-14C]tryptophan and L-tryptophan

The uptake of L-[methylene 14C]-tryptophan from culture medium and the subsequent incorporation of the radiolabel into canthin-6-one, 1-hydroxycanthin-6-one and 1-methoxycanthin-6-one has been demonstrated in cell suspension cultures of Ailanthus altissima. Efficient incorporation has been shown to depend significantly on the time of feeding. Furthermore, feeding of L-tryptophan, at levels of 500 mg/l resulted in improved alkaloid yields, particularly when fed during the lag phase of the growth cycle.

Investigation of Cinchona leaf alkaloids by high-performance liquid chromatography

Abstract A high-performance liquid chromatographic (HPLC) system has been developed for the separation of thirteen Cinchona alkaloids. This system separates into two distinct groups the quinoline alkaloids, which are found predominantly in Cinchona bark, nd the indole alkaloids, which have been found to predominate in the leaves of one species. HPLC has been used to examine the alkaloid content of four plantation samples of Cinchona leaves obtained from different parts of the world. All four samples were found to contain different proportions of alkaloids and although the cinchophyllines were the major alkaloids found in two samples of Cinchona ledgeriana, quinoline alkaloids were also present. However, quinoline alkaloids were the major alkaloids of Cinchona succirubra from Thailand and C. succirubra × C.ledgeriana from Guatemala. In addition, quinamine and 3-epiquinamine were present in the four leaf samples investigated.

Studies on Ailanthus altissima cell suspension cultures. The effect of basal media on growth and alkaloid production.

Time-course experiments have been carried out to investigate the relationship between growth and alkaloid accumulation in A. altissima cell suspension cultures. Results indicate that the type of basal medium, viz. Murashige and Skoog, Linsmaier and Skoog, Schenk and Hildebrandt or Gamborgs B5, has a significant influence on both growth and alkaloid production.

Separation of heteroyohimbine and oxindole alkaloids by reversed-phase high-performance liquid chromatography

Abstract The separation of nine heteroyohimbine and eight oxindole alkaloids has been investigated by using reversed-phase high-performance liquid chromatography. The behaviour of these seventeen alkaloids has been compared with the separations obtained on silica gel thin-layer chromatography plates. Whereas the sequence of separation on adsorbent layers can be rationalised, at a molecular level, by assessing the ability of nitrogen lone-pair electrons to hydrogen bond with silanol hydroxyl groups, no clear pattern emerges from the results of the reversed-phase high-performance liquid chromatographic separations. Although some alkaloids exhibit the expected reversed-phase behaviour, other alkaloids follow the same sequence of elution as found on adsorption systems.

Studies on Ailanthus altissima cell suspension cultures. Uptake of L-[methyl-14C]methionine and incorporation of label into 1-methoxycanthin-6-one

Time-course studies of the uptake of L-[methyl 14C]-methionine have shown rapid uptake by Ailanthus altissima cells when fed at weekly stages throughout the growth cycle. The radio-label from [14C]-methionine was shown to be incorporated into 1-methoxycanthin-6-one with the highest level of incorporation being achieved with cells fed late in the growth phase.

Alkaloids from Macoubea guianensis seeds.

From the seeds of Macoubea guianensis (Apocynaceae), mixtures of the antipodes of two indole alkaloids, vincadifformine and vincadine, have been isolated; in the first the (+)- and in the second the (-)-isomer predominated.