1. Department of Pharmacology and Drug Toxicology, Faculty of Pharmacy, Medical University - Plovdiv, Bulgaria
3. Center of Excellence – Translational Research in Hematology, National Specialized Hospital for Active Treatment of Hematological Diseases, Sofia, Bulgaria.
4. Department of Pharmacognosy, Faculty of Pharmacy, Medical University-Sofia, Bulgaria
5. Section of Botany and Pharmacognosy, Department of Pharmaceutical Sciences, Faculty of Pharmacy, Medical University - Plovdiv, Bulgaria
6. Department of Pharmaceutical Technology and Biopharmaceutics, Faculty of Pharmacy, Medical University - Sofia, Bulgaria
7. Laboratory of Hematopathology and Immunology, National Specialized Hospital for Active Treatment of Hematological Diseases, Sofia, Bulgaria;
8. Department of Immunology, National Center of Infectious and Parasitic Diseases, Sofia, Bulgaria;
Background: Hyperatomarin is an acylphloroglucinol isolated from H. annulatum Moris subsp. annulatum, a species endemic for Sardinia and the Balkan Peninsula. Preliminary studies have shown antibacterial activity, serotonin re-uptake inhibition and cytotoxicity against tumor cell lines. In continuation of these studies we hereby report on the antiproliferative and proapoptotic potential of hyperatomarin against chemosensitive and resistant tumor cell lines and human umbilical vein endothelial cells (HUVECs).
Methods: The cytotoxic effects of hyperatomarin were tested in a panel of human tumor cell lines, including a multi-drug resistant model HL-60/Dox, using the MTT-dye reduction assay. The pro-apoptotic activity of hyperatomarin in HL-60 and KG-1 leukemic cells was investigated with a commercially available 'Cell Death Detection ELISA' kit. The effects of hyperatomarin on the cell cycle progression of KG-1 cells were studied by flow cytometric analysis following propidium iodide staining of cellular DNA. The angiostatic effects of the tested compound were evaluated in an in vitro angiogenesis assay using proliferating HUVECs.
Results: Hyperatomarin proved to be a potent cytotoxic and proapoptotic agent, against chemosensitive and multidrug resistant tumor cell lines, and human endothelial cells stimulated to proliferate by VEGF treatment. Hyperatomarin treatment was found to induce G1 arrest in KG-1 cells and to induce apoptotic DNA-fragmentation, presumably via activation of the caspase signaling cascade.
Conclusions: Our data indicate that hyperatomarin has multimodal activity targeting tumor cells and abnormally proliferating endothelial cells. On these grounds hyperatomarin could be considered a promising drug candidate with hybrid cytotoxic and angiostatic properties necessitating further detailed pharmacological evaluation as antineoplastic agent.
Key words: hyperatomarin, Hypericum annulatum Moris subsp. annulatum, acylphloroglucinols, cytotoxicity, apoptosis, antiangiogenic effects