Lookup NU author(s): Dr Kirsten Brandt
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Through epidemiological investigations it is well known that a high consumption of vegetables and fruits protect against certain types of cancer and other important diseases (Greenvald et al. 2001; Kris-Etherton et al. 2002; Maynard et al. 2003; Gundgaard et al., 2003; Trichopoulou et al. 2003). In order to explain the health promoting effects of fruit and vegetables focus has primarily been on vitamins, minerals and antioxidants, but still we do not know which components are responsible for these effects of food plants. One of the possible explanations is the hypothesis that plants contain other bioactive compounds that provide benefits for health, even though they are not essential nutrients (Brandt et al. 2004). Plants contain a great number of different secondary metabolites, many of which display biological activity and are used in plant defence against e.g., insects, fungi and other microorganisms. Many bioactive substances with known effects on human physiology and disease have been identified through studies of plants used in e.g., traditional medicine. Some of these compounds occur also in food plants, although many of these bioactive compounds are normally considered undesirable in human food due to their “toxic” effects. However, a low daily intake of these “toxins” may be an important factor in the search for an explanation of the beneficial effects of fruit and vegetables on human health (Brandt et al. 2004). The acetylenes and linear furanocoumarins (psoralens) are examples of bioactive secondary metabolites that have been considered undesirable in plant foods due to their “toxic” effects. Some acetylenes are known to be potent skin sensitizers and irritants, and to be neurotoxic in high concentrations, but have also been shown to have a pronounced selective cytotoxic activity against various cancer cells. Due to their role in plant defence many acetylenes and psoralens are considered as natural pesticides or in some cases phytoalexins since their formation is often induced in plants as a response to outer stimuli. Psoralens are photoactivated secondary metabolites that have been used since ancient times to treat human skin disorders. However, the use of these furanocoumarins in medicine has been associated with increased incidence of skin cancer, and a number of studies have also demonstrated that the furanocoumarins can be carcinogenic, mutagenic, photodermatitic and to have reproductive toxicity. Although many acetylenes and psoralens are toxic when ingested in very high amounts, they may have beneficial effects in low concentrations, and hence could explain some of the beneficial effects of the food plants where they appear. This chapter highlights the present state of knowledge on the occurrence of naturally occurring acetylenes and psoralens in the edible parts of more or less common food plants, including their biochemistry, bioactivity, and possible relevance for human health.
Author(s): Christensen LP, Brandt K
Editor(s): Crozier, A; Clifford, M; Ashihara, H
Publication type: Book Chapter
Publication status: Published
Book Title: Plant Secondary Metabolites: Occurence, Structure and Role in the Human Diet
Place Published: Oxford
Library holdings: Search Newcastle University Library for this item