Secondary Metabolites of Plants

Orchid phytochemicals that have been studied include alkaloids, bibenzyls, phenanthrenes, stilbenoids, phenols, flavonoids, anthocyanins and polysaccharides. Many of these compounds exhibit antioxidant, anti-inflammatory, antimicrobial, antihelminthic, anticoagulant, antidiabetic and lipid-lowering properties. Some compounds are cytotoxic, prevent angiogenesis and tumour spread and promote programmed cell death of cancer cells. Some compounds protect nerve cells against chemicals and oxygen deprivation (stroke), promote nerve cell regeneration, protect the skin from ultraviolet damage, protect the liver against poisons such as carbon tetrachloride, prevent calcium loss from bone and enhance foetal lung maturation. This chapter provides a short account of the characteristics of the various groups of compounds, including their properties.