Evaluation of the Antioxidant Capacity, Antimicrobial and Antiproliferative Potential of Fir (Abies alba Mill.) Honeydew Honey Collected from Gorski kotar (Croatia).

The paper examines the antiproliferative, antimicrobial and antioxidative effects of fir (Abies alba Mill.) honeydew honey from mountain region of Croatia (Gorski kotar) as a potential replacement for standard antibiotics and chemotherapeutic agents. Cell viability, annexin V assay and flow cytometry analysis served to analyse the antiproliferative effect on, apoptosis induction in and cell death of cancer cell lines: HeLa, MCF-7, SW620, CFPAC-1, MIA PaCa-2 and normal diploid human fibroblasts (BJ). Antimicrobial activity was tested against Staphylococcus and Acinetobacter strains by agar well diffusion and microdilution assays. The DPPH˙ assay determined the radical scavenging activity, while mathematical models helped to evaluate the kinetic data of DPPH˙ inhibition. Antiproliferative effect on all tested cell lines and the prominent effect on normal diploid human fibroblasts (BJ), colorectal adenocarcinoma (SW620, metastatic) and breast epithelial adenocarcinoma (MCF-7, metastatic) was observable. The mechanisms of antiproliferative effect included accumulation of cells in the sub-G1 phase in all tested cells and induction of apoptosis in SW620 and MCF-7 cells predominantly. The antibacterial assays showed that antibiotic-resistant strains of both bacteria, including multi-resistant strain A. baumannii ATCC® BAA-1605™, were sensitive to all tested honey samples. Radical scavenging assay suggests that antioxidants present in the honey possess different radical suppressing abilities and that they react at different rates with radicals, thereby causing two steps of reaction. The results of the study indicate that Croatian fir honeydew honey has a therapeutic potential due to the strong biological activity and can serve to protect human health.