**3.8 Dyspepsia and gastric ulcer**

During a phase II clinical trial for peptic ulcer which was diagnosed with endoscopically in 45 subjects, given with 600 mg curcumin five times daily for 12 weeks, it was observed that ulcers were absent in 48% patients after 8 weeks, and in 76%

patients after 12 weeks. In remaining patients also within 1-2 weeks abdominal pain and other symptoms had decreased significantly [60].

### **3.9 Irritable bowel syndrome**

The most common symptoms of irritable bowel syndrome (IBS) are considered as altered bowel habits, abdominal pain, bloating etc.

After pilot study for eight week of IBS patients, it was found that 53% and 60% reduction in IBS prevalence. In post-study analysis, abdominal pain and discomfort scores were reduced by 22 and 25% [61].

### **3.10 Inflammatory bowel disease**

Ulcerative colitis (UC) and Crohn's disease (CD) are considered as two types of IBD, inflammatory bowel disease. In a pilot study performed in 2005, hematological, erythrocyte sedimentation rate (ESR) and biochemical blood analysis, C-reactive protein (CRP) (the latter two inflammatory indicators), sigmoidoscopy, and biopsy were all performed. The authors from this study concluded that curcumin plus standard therapy was more effective in maintaining remission than placebo plus standard UC treatment [62, 63].

#### **3.11 Neurological disorders**

Investigations on animal models for Alzheimer's disease (AD) was indicated a direct effect curcumin in reducing the amyloid pathology of AD.

Results have also shown that curcumin exhibited multiple effects in brain. Curcumin is considered as a future drug of therapy for the treatment of various neurological disorders including tardive dyskinesia, diabetic neuropathy and depression [64].

### **3.12 Antioxidant potential**

The two primary mechanisms as antioxidant and anti-inflammatory which explain the benefits of curcumin have proven for various pharmacological actions. Systemic marker of oxidative stress have been found to be improved due to presence of curcumin. Also, from previous literature, it had proven to increase serum activities of important antioxidants such as superoxide dismutase (SOD).

A recent data and analysis of randomized control studies related to the potential effect of supplementation with purified curcuminoids on various oxidative stress parameters had indicated a significant effect on plasma activities of SOD and catalase, as well as serum concentrations of glutathione peroxidase (GSH) and lipid peroxides. The activity of Curcumin on free radicals has been performed based upon many mechanisms. Many forms of free radicals are scavenged by Curcumin, including reactive oxygen and nitrogen species (ROS and RNS, respectively), and can also it was found to alter the activity of GSH, catalase, and SOD enzymes during the neutralization of free radicals and resulted in inhibition of ROS-generating enzymes such as lipoxygenase/cyclooxygenase and xanthine hydrogenase/oxidase. In addition to this, curcumin is considered as a lipophilic compound that makes it an effective scavenger of peroxyl radicals, hence can be effective as a chain-breaking antioxidant [65–71].

Antioxidant activity of the turmeric is evaluated by performing DPPH radical scavenging activity and FRAP values. Many of the literature suggest that, various extracts of turmeric are having antioxidant activities calculated referring to the DPPH radical-scavenging potential.

In this method, 1 mL of the extract was added to around 1.2 mL of 0.003% DPPH in methanol using at varying concentrations (2.5–80.0 μg/mL). The percentage of DPPH inhibition was then calculated using the equation: % of DPPH inhibition = [(*A*DPPH − *AS* ADPPH)] × 100, in this *A*DPPH is the absorbance measured for DPPH in the absence of a sample and *AS* is the absorbance value of DPPH in the presence of either a sample or the standard. DPPH scavenging activity can be given as concentration of a sample required to reduce absorbance of DPPH by 50% (IC50). This value then graphically determined once after plotting the absorbance that is percentage inhibition of DPPH radicals against the log concentration of DPPH, further determining the slope of the nonlinear regression.

Ferric Reducing Antioxidant Power (FRAP) assay was carried out for confirmation of antioxidant potential of the turmeric. Complex of ferric tripyridyltriazine is reduced into ferrous form which then resulted in an intense blue color observed at low pH range. This colour intensity further confirmed by measuring its absorbance value at 593 nm. 200 L of the extract solution prepared in varying concentrations from 62.5–1000.0 μg/mL was then added to 1.5 mL of the previously prepared FRAP reagent, then reaction mixture was incubated at 370 C for 4 min. FRAP reagent was prepared by adding 10 volumes of 300 mM acetate buffer having pH 3.6 with 1 volume of 10 mM TPTZ solution in 1 volume of 20 mM ferric chloride (FeCl3.6H2O) and 40 mM hydrochloric acid. The FRAP reagent was then prewarmed to 37°C and was used when freshly prepared. Plotting of the standard curve was then done A using an aqueous solution of ferrous sulfate (FeSO4.7H2O) (100–1000 μmol), with FRAP values expressed as micromoles of ferrous equivalent (μM Fe [II] per 100 g of sample).

The obtained results from antioxidant studies indicated that the free radical scavenging activity may be due to to the high contents of phenolics and flavonoids having a higher reducing capacity. FRAP assay treats the antioxidants in the sample as reductants in a redox reaction and measures the reducing potential of the test sample. These antioxidants exert their activities by donating electron or hydrogen atoms to the ferric complex which converts to ferrous complex (Fe3+ to Fe2+ -TPTZ complex), thus breaking the radical chain reaction.

Many major diseases such as liver problem, myocardial infarction, diabetes, cancer are believed to be associated with lipid peroxidation and thus causing major cell damage. Curcuminoids and other polyphenols in turmeric can ameliorate and prevent lipid peroxidation, can stabilize the cell membrane, hence proving its significant role in prevention of atherosclerosis. Inhibitory action of turmeric polyphenols such as curcuminoids on lipid accumulation, oxidation, nitric oxide as well as the formation of inflammatory molecules, nuclear factor-kappa B- (NF-kB-) dependent gene expression, and its activation can thus influence therapeutic potential of turmeric in the treatment of pancreatic, hepatic, cancer and intestinal diseases. The ethanolic extract of turmeric can produce promisable symptomatic relief on external cancerous lesions in human. Along with this, curcumin has resulted to be effective in preventing and treatment of many of the neurodegenerative disorders as a free radical scavenger including Alzheimer's disease. Also after giving short-term supplementation it has proved to reduce hematuria, proteinuria, including systolic blood pressure in patients with relapsed or refractory lupus nephritis. By referring all the literature, Curcumin can be considered as a safe adjuvant therapy. The previous studies had indicated that

*Antioxidant Potential of Phytoconstituents with Special Emphasis on Curcumin DOI: http://dx.doi.org/10.5772/intechopen.103982*

the high antioxidant properties of turmeric was found to inhibit cellular lipid peroxidation and can also ameliorate other oxidative damage caused by free radicals [72–76].

Thus Turmeric is proven to be an important source of high contents of flavonoids, polyphenols, tannins and ascorbic acid. Curcumin as important phytoconstituent of turmeric varieties is and effective and important antioxidant compound and which can be effective in management of various diseased conditions.
