Natural Toxicants in Foods

Acetylenes and Psoralens

“…Food plants that produce LFCs in their utilized plant parts are listed in Table 5.2 and include important vegetables such as carrots, celery, celeriac, parsnip and parsley of the Apiaceae and various citrus plants of the Rutaceae. The LFCs found in the utilized parts of Apiaceae food plants are primarily psoralen (79), xanthotoxin (81), bergapten (91) and isopimpinellin (93) of which celery, parsnip and parsley appear to contribute to the highest intake of psoralens, as these important vegetables are known to produce relatively high amounts of LFCs in their edible parts (Beier and Nigg 1992). The structural variation of the psoralens found in utilized parts of citrus species is much larger than those found in Apiaceae food plants.…”

“…The biological activities of LFCs are extremely diverse, due to their ability to intercalate into RNA (Talib and Banerjee 1982) and in particular DNA (Parsons 1980;Beier and Nigg 1992) where they form covalent bonds in the presence of UVA light (320-400 nm). The photoreaction of LFCs with DNA is the final result of a multistage process.…”

“…Because LFCs are potent photoactive compounds, they have been used clinically to treat human skin disorders such as skin depigmentation (vitiligo), psoriasis, mycosis fungoides, polymorphous photodermatitis and eczema. About 40 mg of psoralen (79) administered orally combined with UVA light is normally referred to as PUVA therapy, but other psoralens such as xanthotoxin (81) are also frequently used in PUVA treatment (Beier and Nigg 1992;Pathak and Fitzpatrick 1992). PUVA treatment controls excess cell division in the skin by virtue of its ability to damage DNA.…”

“…A number of studies have demonstrated that concentrations of LFCs used for medical treatment are carcinogenic, mutagenic and photodermatitic. For example PUVA therapy has caused papillomas, keratoanthomas and squamous cell carcinomas in mice (Hannuksela et al 1986), and there are strong indications that PUVA has resulted in photocarcinogenicity in humans (Stern et al 1979;Young, 1990); and furthermore PUVA therapy has been linked to genital cancer in men (Beier and Nigg 1992).…”

Ethnobotany, Volatile Oils and Secretion Tissues of Werneria Poposa from Argentina

“…These drugs are subjected to investigation in the search for new biodynamic compounds with renewed rigor. A common belief is that plant remedies are naturally superior to synthetic drugs and that they are not harmful to human beings (Beier, 1992).…”