Neuroprotective effects of Cyperus rotundus on SIN-1 induced nitric oxide generation and protein nitration: Ameliorative effect against apoptosis mediated neuronal cell damage

) radicals react together and form neurotoxicperoxynitrite anion (ONOO ) which is a short-lived oxidantspecies (Xie et al., 2002). ONOO is also a potent nitrating agentwhich is capable of attacking and modifying proteins, lipids, DNAas wellasdepletingantioxidantdefences.Ithasbeenreportedthatthe interaction of proteins with ONOO oxidizes tryptophan,cysteine, methionine and can nitrate tyrosine residues to form 3-nitro-L-tyrosine (3-NT) and protein carbonyl groups thus blockingtyrosine phosphorylation, modifying protein conformation andenhancing proteolysis/fragmentation (Kelm et al., 1997). ONOOformation also induces cell damage by oxidative and apoptoticstimuli and has been implicated in several pathological conditionssuch as diabetic nephropathy, cardiac arrest, neurodegenerative,neuromuscular disorders, hypoxia, amyotrophic lateral sclerosis,Alzheimers and Parkinsons disorders and in aging (Torreilles et al.,1999; Szabo´ et al., 2007). In an earlier study Sharma and Ebadi(2003) had demonstrated the SIN-1 induced formation of alpha-synuclein in SK-N-SH dopaminergic neurons, which is the markerobserved in Parkinson’s and Alzheimers. In another study Pal et al.(2004) described that SIN-1 induces neuronal death by liberationof intracellular zinc as well as overactivation of potassiumchannels. Ashki et al. (2008) had reported that SIN-1 inducesreversible conduction deficits within axons of the spinal cordwhich mimics reversible and non-reversible neurologic deficitsfollowing neurotrauma.Cyperus rotundus (CR) locally known as ‘musta’, belongs tocyperaceaefamilyandisawelldocumentedtraditionalmedicinalherb. It grows naturally throughout tropical, sub-tropical andtemperate regions and is widespread in India. The bioactivechemical constituents of this herb are essential oils, oligomericflavonoids, terpenoids, sesquiterpenes, sitosterol, cyperene,cyperol, valencene, nootkatene, ascorbic acid and polyphenols(Sonwa and Ko¨nig, 2001; Tsoyi et al., 2011). The herb is widelyused as an analgesic, nervinetonic,nootropic,sedative,antispas-modic, antimalarial, to relieve diarrhea, and stomach disorders