Free radicals scavenging and hepatoprotective activities of the rwandese medicinal herb, Crassocephalum vitellinum and composition of the essential oil - Mukazayire, MJ; Faes, M; Allaeys, V; Tomani, JC; Buc Calderon, P; Chalchat, JC; Duez, P (Planta Medica, 2007)