Anti-angiogenic effect of ALS-L1023, an extract of Melissa officinalis L., on experimental choroidal neovascularization in mice

Background: The effect of ALS-L1023, an extract of Melissa officinalis L. (Labiatae; lemon balm) leaves, on experimental choroidal neovascularization (CNV) in mice was evaluated. Methods: C57BL/6 mice were given either vehicle or ALS-L1023 daily via oral gavage for 3weeks (days 0-21). CNV was induced by rupturing Bruch's membrane using laser photocoagulation (day 7). Two weeks after laser injury (day 21), the CNV lesions were evaluated by an examination of choroidal flat mounts using fluorescein-labelled dextran, immunofluorescence staining with isolectin B4 and fluorescence angiography. The effects of ALS-L1023 on endothelial cell tube formation and the expression of phosphorylated extracellular signal-regulated kinase 1/2 were evaluated using human umbilical vein endothelial cells. Results: The extent of CNV was reduced by ALS-L1023. Mice treated with 100 and 200mg/kg/day of the material exhibited 44.3 and 68.1% reductions in the extent of CNV lesions, respectively, compared to the vehicle group (P<0.001). The size of the isolectin B4-labelled area was also significantly decreased in the ALS-L1023-treated groups (P<0.001). On fluorescein angiography, ALS-L1023-treated mice exhibited significantly less leakage of fluorescent material than did vehicle-treated mice. ALS-L1023 decreased vascular endothelial growth factor-induced human umbilical vein endothelial cell tube formation in a dose-dependent manner. The expression of phosphorylated extracellular signal-regulated kinase 1/2 was suppressed by ALS-L1023. Conclusions: The laser-induced CNV in mice can be inhibited by ALS-L1023. Therefore, it may have therapeutic potential for the treatment of diseases involving CNV.