Recently, considerable attention has been focused on dietary and medicinal phytochemicals that inhibit, reverse or retard diseases caused by oxidative and inflammatory processes. Vernonia amygdalina is a perennial herb belonging to the Asteraceae family. Extracts of the plant have been used in various folk medicines as remedies against helminthic, protozoal and bacterial infections with scientific support for these claims. Phytochemicals such as saponins and alkaloids, terpenes, steroids, coumarins, flavonoids, phenolic acids, lignans, xanthones, anthraquinones, edotides and sesquiterpenes have been extracted and isolated from Vernonia amygdalina. These compounds elicit various biological effects including cancer chemoprevention. Garcinia kola (Guttiferae) seed, known as "bitter kola", plays an important role in African ethnomedicine and traditional hospitality. It is used locally to treat illnesses like colds, bronchitis, bacterial and viral infections and liver diseases. A number of useful phytochemicals have been isolated from the seed and the most prominent of them is the Garcinia bioflavonoids mixture called kolaviron. It has well-defined structure and an array of biological activities including antioxidant, antidiabetic, antigenotoxic and hepatoprotective properties. The chemopreventive properties of Vernonia amygdalina and Garcinia biflavonoids have been attributed to their abilities to scavenge free radicals, induce detoxification, inhibit stress response proteins and interfere with DNA binding activities of some transcription factors.
Keywords: Garcinia kola; Vernonia amygdalina; antioxidants; chemoprevention; epivernodalol; kolaviron.