Design, synthesis, and anti-inflammatory activity both in vitro and in vivo of new betulinic acid analogues having an enone functionality in ring A - Honda, T; Liby, K T; Su, X; Sundararajan, C; Honda, Y; Suh, N; Risingsong, R; Williams, C R; Royce, D B; Sporn, M B; Gribble, G W (Bioorg Med Chem Lett, 2006)