Phillip J. Salisbury

Isolation and characterization of natural products from plant tissue cultures of Maytenus buchananii

Abstract Explants of Maytenus buchananii were induced to form a callus aid subsequently to form suspension cultures on a wide variety of media. Culture extracts showed cytotoxic activity, but examination by TLC did not indicate the presence of maytansine. Isolation of natural products from a large scale suspension culture led to the identification of polpunonic acid, sitosterol and the cytotoxic triterpene quinone-methides, tingenone and 22β-hydroxytingenone. Possible biosynthetic relationships of these and other triterpene quinone-methides are discussed.

The recycling air lift transfer fermenter for plant cells

SummarySuspension cultures of Triptergium wildordii require oxygen at a rate of 3.2 to 0.8 uL of oxygen/mg dry wt of cells/hr. A recycling air lift fermenter was developed in which the major volume of air required to lift the cells is recycled air. Sufficient new air is fed to meet the oxygen requirements of the cells. Such a fermenter design supports the growth of a large production of cells suitable for batch or continuous feeding.

An inducible hydrolase from Mortierella isabellina (basidiomycetes). The deacylation of (+)-usnic acid

Abstract An inducible enzyme catalysing the hydrolysis of (+)-usnic acid to (+)-2-desacetylusnic acid and acetic acid has been purified 150-fold from the mycelium of Mortierella isabellina grown in the presence of (+)-usnic acid. Purification was achieved by treatment with protamine sulfate, (NH 4 ) 2 SO 4 fractionation, negative adsorption on alumina Cγ gel and hydroxylapatite followed by chromatography on DEAE-cellulose and Sephadex G-200. The elution pattern from a Sephadex G-200 column indicated a MW of ca 7.6 × 10 4 for the enzyme. The apparent K m value for (+)-usnic acid at the pH optimum (pH 7) was 4.0 × 10 −5 M. The enzyme was specific for (+)-usnic acid and inactive towards (−)-usnic acid, (+)-isousnic acid or certain phloracetophenone derivatives. Its activity was enhanced in the presence of divalent metal ions such as Co 2+ , Ni 2+ , Mn 2+ , Mg 2+ and Zn 2+ .