Cholinesterase inhibitors fromSargassumandGracilaria gracilis: Seaweeds inhabiting South Indian coastal areas (Hare Island, Gulf of Mannar)

Abstract

Dementia is a chronic progressive mental disorder, which adversely affects memory, thinking, comprehension, calculation and language. Some of the commonest forms of dementia are Alzheimer's disease, Parkinsonism, Dementia with Lewy Bodies and Myasthenia gravis. All these disorders are related to abnormalities in the central cholinergic system, which shows a decline in acetylcholine level. Cholinesterase (ChE) inhibitors are one of the novel strategies used for the symptomatic treatment of neurological disorders like dementia. In the course of screening new ChE inhibitors from marine sources, about 11 seaweeds, which have wide pharmaceutical applications, were collected from Hare Island, Gulf of Mannar, Tamilnadu, India. Methanolic extracts of the seaweeds were assessed for ChE inhibitory activity under in vitro conditions. Kinetic parameters IC(50), K(i) and V(max) were also analysed. The results showed that 3/11 seaweeds showed 50% inhibition for both ChEs (using acetylthiocholine iodide and butyrylthiocholine iodide as substrate) at concentrations of 2 mg mL(-1) (Gracilaria gracilis, Sargassum, Cladophora fasicularis for ChE with acetylthiocholine iodide as substrate and Gracilaria gracilis, Gracilaria edulis, Sargassum for ChE with butyrylthiocholine iodide as substrate) and 4/11 showed no inhibitory activity. Inhibitory activity of seaweed extracts was compared with standard drug donepezil. Enzyme kinetic analysis showed that algal extracts exhibited mixed type inhibition (partially non-competitive inhibition).

The marine halophytes Carpobrotus edulis L. and Arthrocnemum macrostachyum L. are potential sources of nutritionally important PUFAs and metabolites with antioxidant, metal chelating and anticholinesterase inhibitory activities

“…Compounds that inhibit ChE not only increase ACh levels, but also prevent the formation of β -amyloidal plaques, thereby having a key role in the prevention of neuronal death due to infl ammation caused by AD (Giacobini 2004 ). In addition, ChEIs activate α -secretase, which acts on the β -amyloid precursor protein preventing the formation of β -amyloid plaques (Natarajan et al 2009 ). The ChEI properties of C .…”

Natural products as a source of Alzheimer's drug leads

“…sp., was a more potent AChE inhibitor than galantamine ( 15 ) in vitro , 170 so could be of interest for further study. Extracts from the sponge Topsentia ophiraphidites 171 and the seaweeds Gracilaria gracilis , 172 G. edulis , Ulva reticulata , Hypnea valentiae and Padina gymnospora 173 also inhibit AChE but identification of the compounds responsible and any therapeutic potential requires further study.…”

Acetylcholinesterase Inhibitory and Antioxidant Properties of Thai Vegetables

“…The use of natural antioxidants play an essential role in the prevention of diseases caused by oxidative stress due to the antioxidants can scavenge free radicals and inhibit lipid peroxidation [12]. Therefore, one of the AD therapeutics is especially related to phytotherapy through the use of natural antioxidants to minimize oxidative imbalance [10].…”