Hydroalcoholic extracts from wheat sprouts, white tea, Morinda citrifolia and fermented papaya were analysed to determine their reducing power and antioxidant activity. The results show that the micromoles of potassium ferricyanide reduced by a quantity of extract corresponding to 1 g of the various dehydrated starting tissues are: 12.91+/-0.83 (wheat sprouts), 10.66+/-1.22 (M. citrifolia), 17.06+/-1.24 (white tea), and 1.05+/-0.09 (fermented papaya). In addition the results show a strong oxygen superoxide scavenging activity in the extracts from white tea, M. citrifolia and wheat sprouts. The activity of the fermented papaya extract is the lowest. The thin-layer chromatography and UV spectrophotometry of the extracts show in each source a mixture of antioxidant compounds probably belonging to the families of reducing glycosides and polyphenols. The chromatographic pattern of the antioxidant compounds and the UV spectrum are quite different in the various sources.