Two xanthones and two rotameric (3→8) biflavonoids from the Cameroonian medicinal plant Allanblackia floribunda Oliv. (Guttiferae) - Mountessou, BY G; Tchamgoue, J; Dzoyem, J P; Tchuenguem, R T; Surup, F; Choudhary, M I; Green, I R; Kouam, F S (Tetrahedron Lett, 2018)