Background: Nerium oleander L. (syn. Nerium indicum Mill, Nerium odorum Aiton) belongs to the family Apocynaceae. It is used for its anti-inflammatory, anti-diabetic, anti-cancer and hepatoprotective activities in traditional medicine. Previous pharmacognostic studies suggested that 70 % hydro-methanolic extracts of oleander possess potent free radical scavenging and anti-inflammatory activities, both of which are helpful against hepatotoxicity.
Methods: Hydro-methanolic extracts of oleander stem and root were evaluated for their hepatoprotective activities in acute CCl4 intoxicated mouse through in vitro and in vivo studies. Silymarin was used as positive reference. Antioxidant enzymes, pro-inflammatory markers and liver enzymatic and biochemical parameters were studied. The extracts were further chemically characterized using Fourier Transform Infrared (FTIR) spectroscopy and Gas chromatography-mass spectrometry (GC-MS).
Results: CCl4 toxicity caused fatty liver formation by increase of relative liver weight (32.53 g) compared to control group (16.08 g). The elevated liver enzymatic and biochemical parameters due to CCl4 toxicity were considerably normalized by the extracts treatment under both in vivo and in vitro models. Oleander stem (NOSE) and root (NORE) extracts increased the reduced hepatic catalase activity 27.37 and 25.25 %, whereas peroxidase activity was increased 18.19 and 22.78 %, respectively. The extent of lipid peroxidation was significantly (p < 0.01) lowered 20.76 % (NOSE) and 21.12 % (NORE) compared to CCl4 group. The levels of pro-inflammatory tumor necrosis factor-α (TNF-α) was lowered 71.33 % (NOSE) and 61.60 % (NORE). Histopathological study demonstrated substantial reduction of hepatocellular necrosis, fatty infiltration, sinusoidal dilation, bile duct proliferation, vascular congestion, leukocyte infiltration in the silymarin and extract treated groups. Furthermore, various bioactive compounds were identified in the extracts such as apocynin, tocopherol, squalene, vanillin, isoeugenol, amyrin, lupeol etc.
Conclusion: The present study provided convincing evidence that oleander extracts possess potent hepatoprotective capacity which was primarily governed by its antioxidant and anti-inflammatory activities. The collegial bioactivities of the phytochemicals may be accredited behind the hepatoprotective activity of oleander.
Keywords: Hepatoprotective; Inflammation; Liver; Nerium; Oxidative stress; Xenobiotic.