Embelin (2,5-Dihydroxy-3-undecyl-p-benzoquinone) for Photodynamic Therapy: Study of Their Cytotoxicity in Cancer Cells

Abstract

Photodynamic therapy (PDT) involves the use of photochemical reactions mediated through the interaction of photosensitizing agent for the treatment of malignant tumor. The present study was carried out to evaluate the photosensitizing potential of embelin isolated from Embelia ribes. For PDT study, cells were grouped into four groups. Two types of control were used, one with Ehrlich's ascites carcinoma (EAC) cells alone (group 1) and one which received the illumination alone (group 2). Group 3 contains cells treated with different concentrations of embelin for 1 h at 37 °C. Another set of cells (group 4) after treatment with different concentrations of embelin was illuminated in ice for 4 min with a 1000-W halogen lamp. To study the mechanism of cell death, the following parameters such as reactive oxygen species (ROS), caspase-3, lactate dehydrogenase (LDH), and thiobarbituric acid reactive substances (TBARS) were analyzed both in the absence and presence of light after the treatment of embelin. PDT study clearly indicated that embelin alone recorded no cytotoxicity, but for light treatment alone with the different concentrations of embelin, there was a significant induction of cytotoxicity in a concentration-dependent manner. Level of ROS and LDH increased in cells treated with embelin. Moreover, caspase-3 also increased which clearly indicated that cell death is through caspase-dependent apoptosis. This is the first report on PDT, a novel modality, using embelin for cancer therapy in vitro. The novelty of the study depends on the fact that cytotoxicity was produced by the synergistic effect of the embelin and light.

Embelin’s Versatile Photochemistry Makes It a Potent Photosensitizer for Photodynamic Therapy

“…All these possibilities provide different modes of action of embelin as a potent photosensitizer, which has already been shown in in vitro studies targeting malignant tumor cells . The toxicity of embelin was indeed elevated upon irradiation suggesting increased reactivity by virtue of photochemical reactions.…”

“…21−24 All these possibilities provide different modes of action of embelin as a potent photosensitizer, which has already been shown in in vitro studies targeting malignant tumor cells. 25 The toxicity of embelin was indeed elevated upon irradiation suggesting increased reactivity by virtue of photochemical reactions. In addition, embelin has been found to be useful for the photochemical generation of silver and gold nanostructures for photothermal therapy, 26 underpinning its rich photochemistry.…”

The Application of Embelin for Cancer Prevention and Therapy

“…Embelin may also be used with photodynamic therapy (PDT), which employs photochemical reactions mediated via interaction with a photosensitizing agent for treating malignant tumors. Embelin in combination with PDT increased ROS accumulation in Ehrlich ascites carcinoma cells and induced apoptosis [ 112 ]. Similarly, in A549 lung-cancer cells, embelin can induce ROS activation and subsequently lead to the induction of apoptosis [ 113 ].…”

Embelin-Induced Phosphatidylserine Translocation in the Erythrocyte Cell Membrane

“…Embelin (2,5-dihydroxy-3-undecyl-1,4-benzoquinone), a phytochemical isolated from Embelia ribes [1], has antihelminthic [2], contraceptive [2], anti-inflammatory [3][4][5][6] and anticancer [1][2][3][4][6][7][8][9][10][11] potency, as well as photosensitizing [1] and radiation sensitizing [12] property. Embelin has further been shown to decrease cardiac injury following experimental myocardial infarction [13] and to protect cells against UVB-induced oxidative damage [14], but to aggravate the encephalopathy following neonatal hypoxia-ischemia [15].…”