A cutaneous gel preparation containing an extract from Solanum incanum with potential antineoplastic activity. SR-T100 gel contains high amounts of the steroidal alkaloid glycoside solamargine. Solamargine is able to upregulate expression of tumor necrosis factor receptors 1 (TNFR1) and 6 (TNFRSF6 or Fas), and their signaling adaptors TNFR1-associated death domain, and Fas-associated death domain. In addition, this agent is able to upregulate expression of apoptosis promoter Bax, and suppress the expression of the anti-apoptotic proteins Bcl-xL and Bcl-2. Altogether, this induces apoptosis in tumor cells and may lead to an inhibition of tumor cell proliferation.