Production of quinones by in vitro cultures of Dionaea and Streptocarpus species

Abstract

Quinones are a class of oxygen-containing secondary metabolites found chiefly in higher plants, fungi, bacteria and restricted in the animal kingdom to arthropods and echinoderms (Thompson 1971). In the plant, quinones, especially naphthoquinones, have been shown to function in allelopathy (juglone; Binder et al 1989), plant-insect interactions and plant-plant interactions (plumbagin; Kubo et al 1986, 1998, Spencer et al 1986, Ganapaty et al 2004). These quinones also have significant in vitro biological activities e.g. are antibacterial (Didry et al 1994), fungicidal and insecticidal (Kubo et al 1986). The main objective of this thesis was to establish a number of in vitro cultures to produce biologically active quinones. Two unrelated plant genera, Dionaea and Streptocarpus were used as source material. Dionaea muscipula Ellis, more commonly referred to as the Venus flytrap, is a carnivorous plant native to coastal North and South Carolina. Dionaea contains plumbagin (5- hydroxy, 2-methyl-1,4-naphthoquinone), an important naphthoquinone having a broad range of biological activities such as anticancer, antimicrobial, leishmanicidal, antimutagenic, piscicidal and insecticidal properties (Komaraiah et al 2002). Streptocarpus dunnii, also known as the Cape primrose, is native to South Africa and has been reported to contain a number of naphthoquinone and anthraquinone compounds (Inoue et al 1983). The main metabolite of this plant is the 1,2- naphthoquinone, dunnione, which has been subjected to a limited number of biological investigations. However, S. dunnii also produces other naphthoquinones, which have not yet been investigated biologically.