Cycloartane and oleanane saponins from Egyptian Astragalus spp. as modulators of lymphocyte proliferation - Verotta, L; Guerrini, M; El-Sebakhy, N A; Assad, A M; Toaima, S M; Radwan, M M; Luo, Y D; Pezzuto, J M (Planta Med, 2002)