Free radicals are an atom or groupof atoms that has at least one unpaired electron and is therefore unstable andhighly reactive. The propagation of free radicals can bring about many adversereactions leading to extensive tissue damage (Cotran et al., 1999; Yu et al.,1992). Antioxidants may offer resistance against oxidative stress by scavengingthe free radicals. Antioxidants are compounds that can reduce or inhibits theoxidation of lipids or other molecules by inhibiting the initiation orpropagation of oxidative chain reactions. The antioxidant activity of thecompounds is mainly due to their redox properties in absorbing and neutralizingfree radicals, quenching singlet and triplet oxygen or decomposing peroxides (Stahl and Sies, 2005).In the present study, the free radical scavenging and antioxidantpotential of Mosinone-A was assessed by subjecting the radicals andoxidants namely DPPH, ABTS+, H2O2, NO-and OH•.
The Mosinone-A exhibited strong radical scavenging activityagainst DPPH+, ABTS+, H2O2-,OH• and Fe2+ assay.Many studies have been reported on the use of medicinal plants as radicalscavengers (Pham et al., 2011).Mosinone-A exhibited strong reducing power and free radical scavengingeffect on free radical, hydroxyl, superoxide and hydrogen peroxide radicals.Ascorbic acid is a very good reducing agent and free radicalscavenger. It is also reported to prevent the damage to RBC membrane byinteracting with superoxide and hydroxyl radical (Beyer, 1994). DPPH is arelatively stable free radical and usually used as a substrate to evaluate theantioxidant assay. This assay determinesthe ability of Mosinone-A to reduce DPPH radical to the corresponding hydrazineby converting the unpaired electrons to paired ones (Sreejayam and Rao, 1996).
- Thesis Statement
- Structure and Outline
- Voice and Grammar
Antioxidants and other radical scavenger can act by converting the unpairedelectrons to paired ones. The maximum concentration (50?M) of Mosinone-Aexhibited the highest percentage of inhibition which indicates that Mosinone-Acauses reduction of DPPH radical in a strohometric manner.ABTS assay is based on theinhibition of the absorbance of the radical cation ABTS+, which hasa characteristic long wavelength absorption spectrum (Sanchez-Moreno, 2002).ABTS, a protonated radical has characteristic absorbance maximum at 734nm whichdecreases with the scavenging of proton radicals (Mathew and Abraham, 2004).The results obtained imply the activity of the Mosinone-A either by inhibitingor scavenging the ABTS+ radicals.
Superoxide anion is produced frommolecular oxygen due to oxidative enzymes (Sainani et al., 1997) of body by nonenzymatic reaction such as auto-oxidation by catecholamines (Hemmani andParihar, 1998). Superoxide anionradical is one of the strongest reactive oxygen species among the free radicalscould be generated and it also has the ability to change to other harmfulreactive oxygen species and free radicals within the living cells (Yen, 1995).The probable mechanism of scavenging the superoxide anions may be due toinhibitory effect of the Mosinone-A towards generation of superoxides in the invitro reaction mixture.The hydroxyl radical(OH-) thus produced may attack the sugar of DNA bases causing sugarfragmentation, base loss and DNA strand breakage (Halliwell, 1994). Thisradical has the capacity to induce carcinogenesis, mutagenesis and whichrapidly initiates lipid peroxidation (Rajesh et al., 2008).
From the present results, it is inferred that theMosinone-A have better hydroxyl radical scavenging activity as reflected interms of percentage inhibition. Nitric oxide (NO) is a reactive free radicalproduced by phagocytes and endothelial cells, to yield more reactive speciessuch as peroxy nitrite which can be decomposed to OH radical. Excess concentration of NO isassociated with several diseases (Ialenti etal., 1993). Oxygen reacts with the excess nitric oxide to generate nitriteand peroxynitrite anions which acts as free radicals.
The level of nitric oxide was significantlyreduced in this study by the effect of Mosinone-A indicating the free radicalsscavenging properties in a concentration dependent manner.In the reducing powerassay, the presence of antioxidants in the sample results in the reduction ofFe3+ to Fe 2+ by donating an electron. The amount of Fe2+can then be monitored by measuring the formation of perl’s blue at 700nm.
Increasing absorbance indicates anincrease in reductive ability by the Mosinone-A. From the above results,it can be concluded that Mosinone-A showed the most potent in vitro antioxidantactivity with high percentage inhibition. This may be attributed to thepresence of acetogenein and tetra hydro furan portion in the molecules whichprobably play a role as an effective free radical scavenger and have aneffective anticancer agent.