(RS)-CPP br Materials and methods br Results br

Materials and methods
Results
Discussion The present study clearly demonstrates anti-oxidant potential of A. calamus extracts as shown by inhibition of generation of free radicals, protection of DNA and mitochondria from oxidative damage as revealed by different in vitro assays and prevention of stress induced loss of anti-oxidant capacity through in vivo assay. Reactive oxygen species (ROS) including superoxide radicals, hydroxyl radicals, hydrogen peroxide and singlet oxygen are often generated as products of biological reactions or derived from exogenous factors. The ROS play an important role in cell metabolism including energy production, phagocytosis and intercellular signaling [25] and damage (RS)-CPP when present in excess. However, antioxidants scavenge the ROS to prevent their deleterious effects. There are enzymatic and non-enzymatic mechanisms that maintain a balance in the oxidant and antioxidant activities. However, imbalance between oxidant and antioxidant systems leads to oxidative stress which results in the variety of pathological effects such as DNA damage, carcinogenesis and various degenerative disorders such as cardiovascular diseases, aging and neuro-degenerative diseases [1,2]. Many plants were used for antioxidant activity for instance, Acacia auriculiformis, Aegle marmelos, Campanula alliariifolia, Dimocarpus Longan, Gracilaria changii, Hyphaene thebaica, Kappaphycus alvarezii, Mangifera indica, Parmelia saxatilis, Rosmarius officinalis, etc. reported to have anti-oxidant property [26]. The Indian medicinal herb, A. calamus, is a time tested and easily available herb in Asian region. Methanol [27,28], ethanol and hydro-alcoholic [29] extracts of A. calamus are known to possess antioxidant activity as determined by DPPH method. In these studies only total antioxidant activity (DPPH method) was demonstrated whereas other scavenging activities and DNA and mitochondria protective effects, if any were not considered. The present study demonstrates that anti-oxidant property of A. calamus is due to combined effects of different anti-oxidant mechanisms. Due to complex nature of phytochemicals a single method can not evaluate antioxidant activity of herbs. There are several ways antioxidants act i.e. by donating hydrogen to radicals, metal chelating ability, free radical scavenging activity, reducing power, and quenching singlet oxygen. But unfortunately, most of the assay methods measure any one of these activities. Hence, multiple antioxidant methods are required to reach the conclusion. DPPH method is a stable free radical system and a very sensitive way to determine the in vitro antioxidant activity of plant extracts [30]. The efficacies of anti-oxidants are often associated with their ability to scavenge stable free radicals. The petroleum ether and benzene extracts of A. calamus showed a higher free radical scavenging activity compared to other extracts in the present study in DPPH assay, indicating their potent anti-oxidant property. The DPPH assay also suggested that the A. calamus contained compounds that are capable of donating hydrogen to a free radical in order to remove odd electron, which is responsible for the radical\'s reactivity. Superoxide anion is an oxygen-centered radical with selective reactivity and it is produced by a number of enzyme systems in auto-oxidation reactions and by non-enzymatic electron transfers that univalently reduce molecular oxygen. Here, benzene extract showed higher superoxide radical scavenging activity compared to other extracts. The probable mechanism of scavenging the superoxide ions is inhibition of generation of superoxide radicals in the in vitro reaction mixture. The hydroxyl radical is highly reactive oxygen radical formed from the reactions of various hydroperoxides with transition metal ions. It attacks proteins, DNA, polyunsaturated fatty acids in membranes [31], abstracts hydrogen atoms from membrane lipids [32] and brings about peroxidic reaction of lipids. Hydroxyl radicals may cause fragmentation of sugar in DNA and DNA strand breaks [33]. The benzene extract of A. calamus caused inhibition of generation of hydroxyl radicals and the process was enhanced with increasing concentration of extracts and it caused maximum inhibition with low concentration compared to other extracts in the present experiment.