Elderberry oil-cake “Sambucus Ebulus” – natural immune stimulant Albena Durakova, Adelina Vasileva, Velichka Yanakieva, Hristo Kalaydzhiev, Zhivka Goranova and Milena Temelkova BIO Web Conf., 170 (2025) 01010 Published online: 01 April 2025 DOI: 10.1051/bioconf/202517001010