The Characterisation of Hesperidin and Hesperetin, and their effects on glioma cell growth

Abstract

Glioblastoma (GB) is the most common and aggressive central nervous system (CNS) malignancy. Current treatment involves surgical resection followed by radiotherapy and chemotherapy with temozolamide (TMZ) and cisplatin. However, the median survival rate remains low (~15 months), due to the brain’s susceptibility to damage, drug resistance and ineffectiveness of surgical resections. Current studies have shown potential of phytochemicals in reducing the risk and prevention of cancers, due to their antioxidant properties. This study investigates the pharmacological effects of the flavonoids hesperidin and hesperetin on U87-MG and SVGp12 cells for cell viability, proliferation, cell cycle accumulation and apoptosis. Investigations were also undertaken into their radical scavenging and antioxidant capacity, and effects on ROS levels. The phytochemicals reduced U87-MG cell viability in a time- and dose-dependent manner, however it appeared that cisplatin treatment resulted in greater reductions in cell viability. The chosen compounds resulted in significantly greater decreases in SVGp12 cell viability in comparison to U87-MG cells (Hdin; U87-MG: 197 vs. SVGp12: 114M, p<0.05), (Htin; U87-MG: 157 vs. 84M; p<0.001). No significant effects were observed for cell proliferation (p>0.05). The phytochemicals resulted in G0/G1 accumulation within U87-MG cells, compared to G2/M with SVGp12 cells. The compounds resulted in a greater proportion of viable U87-MG cells, whereas SVGp12 cells saw a greater proportion of late apoptotic cells following treatment, with a significant difference with hesperidin (49.35  25.03% vs. 12.69  10.94%; p<0.05) and hesperetin (48hrs: 63.18  1.47% vs. 17.08  2.93%, p<0.01). Hesperidin and hesperetin showed little antioxidant capacity and radical scavenging abilities, with 24-hours required to see a significant effect. Hesperetin was shown to have a significantly lower radical scavenging ability than hesperidin (300M; 66.34  0 vs. 79.23  21.55%, p<0.001) (100M 38.42  0% vs. 64.23  19.06%, p<0.001). The phytochemicals resulted in increased ROS levels, following 6-hour incubation. By combining the phytochemicals with current treatment, a time- and dose-dependent effect was observed, with greater decreases in U87-MG viability, than cisplatin and TMZ alone. Significant effects occurred in SVGp12 cell lines, suggesting protective effects with combination treatment. The results from this study support the potential for hesperidin and hesperetin in GB treatment, with potential of combinations with cisplatin and TMZ, while providing protective effects in normal cells.