A study on Turmeric (Curcuma longa L.): Multifunctional agents for the management of oxidative damage, neurodegeneration and cancer

The rhizome of Curcuma longa L, (turmeric, curcumin) has been widely used in therapeutic purposes for acne, heal wound, prevent skin damage, reduce cholesterol, treat diabetes, and control blood pressure. From this point of view, this research was aimed to investigate its biological properties including antioxidant, anticancer and neuroprotective properties of the turmeric rhizomes. The rhizomes of turmeric were extracted with methanol-MeOH and distilled water-dH2O, and subjected to various assays. Neuroprotective potentials of the extracts were tested through enzyme inhibitory assays on acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), which are closely linked to pathogenesis of Alzheimer's disease. Their anticancer activities were evaluated using MTT assay against A549, MCF-7, HeLa human cancer cells, and non-tumorous HUVECs. In vitro methods including 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), ferric reducing antioxidant power (FRAP), and cupric ion reducing capacity (CUPRAC) were performed to reveal antioxidant capacities of the extracts. Total polyphenolic compositions of the extracts were also identified spectrophotometrically. The turmeric extracts were found to have rich polyphenolic quantities, particularly the MeOH-extract possessed higher total polyphenolic contents than the dH2O-extract. The extracts demonstrated the remarkable inhibition on both of the cholinesterase enzymes even at the lowest concentration (100μg mL−1). Moreover, they showed higher enzyme inhibition against AChE, comparing with that of BChE enzyme. In general, a significant correlation was observed between the total antioxidant capacities and neuroprotective potentials of the extracts from turmeric rhizomes. As for the anticancer activity, the extracts were found as a natural anticancer agent with the IC50 values ranged from 13.01±0.16 to 26.72±1.04 μg mL−1. In the light of the findings of the presented research, it is clearly concluded that turmeric is an important natural source to fight oxidative stress related diseases, with its excellent cholinesterase-inhibiting properties; strong antioxidant capacities as well as remarkable anticancer activities.