Abstract
Barringtonia racemosa leaf water extract (BLE) had been shown to have high gallic acid (GA) content and BLE has been postulated to have anti-proliferative effects towards colorectal cancer. This study aims to further investigate the mechanism underlying the anti-proliferative effect of BLE in Caco-2 cells and to determine if GA is responsible for the observed effects. Both BLE and GA inhibited Caco-2 cells in a dose-dependent manner. Cells exposed to IC50 concentration of BLE and GA showed reduced antioxidant activities. GA-treated Caco-2 cells experienced higher oxidative stress compared to cells treated with BLE. Both BLE and GA significantly up-regulated the expression of SLC2A1. BLE but not GA, significantly down-regulated the expression of ADH4. Meanwhile, GA but not BLE, significantly up-regulated AKRIB10 and GLO1 but significantly down-regulated HAGH. Alterations in gene expression were coupled with changes in extracellular glucose and pyruvate levels. While BLE decreased intracellular pyruvate, GA did the opposite. Both intracellular and extracellular D-lactate were not affected by either BLE or GA. GA showed more pronounced effects on apoptosis while BLE irreversibly reduced cell percentage in the G0/G1 phase. In conclusion, this study demonstrates the multiple-actions of BLE against Caco-2 cells, potentially involving various polyphenolic compounds, including GA.
Highlights
Barringtonia racemosa (L.) Spreng is a medicinal plant belonging to the Lecythideceae family that is commonly found throughout Eastern Africa, Polynesia, Africa and Asia including Malaysia[1]
Barringtonia racemosa leaf water extract (BLE) in μg/ml that corresponded to 20% (IC20) and BLE IC50 were found to be at 69.1 ± 3.2 μg/ ml and 325.5 ± 12.8 μg/ml respectively while gallic acid (GA) IC20 and GA IC50 were found to be at 3.7 ± 0.1 μg/ml and 10.6 ± 0.6 μg/ml respectively
BLE IC20, BLE IC50, GA IC20 and GA IC50 were selected for further analyses
Summary
Barringtonia racemosa (L.) Spreng is a medicinal plant belonging to the Lecythideceae family that is commonly found throughout Eastern Africa, Polynesia, Africa and Asia including Malaysia[1]. Studies on various parts of B. racemosa have demonstrated its biological activities that includes antibacterial[3], antifungal[4], antioxidant[5], anti-inflammatory[6] and anti-cancer[7,8,9]. Initial analysis performed by our group indicated that the leaf water extract of B. racemosa (BLE) had the highest polyphenolic and ascorbic acid content as well as antioxidant activities amongst various extracts prepared in solvents of different polarities, including water, ethanol, ethyl acetate and hexane[10]. In the present study we applied biochemical and molecular approaches to investigate the effects of BLE on the antioxidant status and anti-proliferation of colorectal cancer cells Caco-2. We investigated the potential role of the glycolytic pathway as one of the possible mechanisms responsible for the anti-proliferative effects of BLE. The result in this study may elucidate more information on the action mechanism of BLE against colorectal cancer cells
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