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Evaluation of the Biologically Active Properties of Seed Coat Phenolics from Pigeon Pea (Cajanus Cajan)

Viswa Janani, V. (2010) Evaluation of the Biologically Active Properties of Seed Coat Phenolics from Pigeon Pea (Cajanus Cajan). [Student Project Report]

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Abstract

This Dissertation / Report is the outcome of investigation carried out by the creator(s) / author(s) at the department/division of Central Food Technological Research Institute (CFTRI), Mysore mentioned below in this page.

Item Type: Student Project Report
Additional Information: Phenolic compounds are bioactive secondary plant metabolites that are widely present in commonly consumed foods of plant origin. The three main types of phenolic compounds are flavonoids, phenolic acids and tannins, which act as powerful antioxidants in vitro (Rice-Evans et al, 1996). Such antioxidants not only can defend lipids and other compounds contained in plants against undesirable oxidation, but can also be used to retard the oxidation in various food products (Shahidi et al 1995). Phenolic compounds work synergistically to promote human health through a variety of different mechanisms, such as enhancing antioxidant activity, impacting cellular processes associated with apoptosis, platelet aggregation, blood vessel dilation, and enzyme activities associated with starch, protein and lipid digestion, carcinogen activation and detoxification. The main dietary sources of polyphenols are fruits and beverages. In addition, cereals and dry legumes also contribute to the polyphenol intake. In legume seeds, these phenolics are concentrated in the seed coat fractions. The seed coat from two varieties of pigeon pea (toor dhal), C-11 (red) and ICP187119 (black) were evaluated for their phenolic content, phenolic composition, antioxidant and inhibitory properties against digestive enzymes. Analysis of phenolic compounds in pigeon pea seed coats revealed that that the phenolic compounds are mostly concentrated in the seed coat fractions and might be easily removed by dehulling. ICP187115 variety of pigeon pea contains higher content of total phenolics than C-11 variety. Reverse phase HPLC analysis of pigeon pea seed coat extracts indicated the presence of various types of phenolic acids such as vanillic, syringic, ferulic, p- coumaric, sinapic and chlorogenic acids. Seed coat fractions are most active 2,2-diphenyl-1-picryl hydrazyl (DPPH) radical scavengers and inhibited the hydroxyl radical mediated protein fragmentation. The multiple antioxidant activity of the two varieties of pigeon pea fractions was evident, as they also possessed reducing power and hydroxyl radical scavenging activity. The pigeon pea seed coat phenolics are potent inhibitors of α-amylase, α-glucosidase and trypsin with IC50 values 37.9, 110, 63.3μg (C-11) and 53.9, 126.2, 56.84μg (ICP187119) respectively. The enzyme kinetic studies, using Michaelis-Menton and Lineweaver-Burk derivations revealed that seed coat phenolics from both the varieties non-competitively inhibited α-amylase, α-glucosidase and trypsin. The binding of the seed coat phenolics affected the velocity of the reaction catalyzed by α-amylase proportionately to the concentration of the phenolic compound in the reaction mixture but without affecting the Km. The inhibitory constants (Ki) determined from Dixon plot for α-amylase, α-glucosidase and 56 trypsin were 2,13,19 μg for C-11 and 0.8, 42, 17 μg for ICP187119 varieties of pigeon pea, respectively. These results revealed the content and composition of phenolic compunds in seed coat fractions of fractions of C-11 and ICP187119 varieties of pigeon pea and their antioxidant and antiradical activities. Furthermore, these results contributed to the understanding of the relationships between major phenolic compounds and antioxidant activities of pigeon pea seed coats and provided useful information for effective utilization of legume-seed coat fractions as functional food ingredients for promoting health. However, physiological significance of dietary antioxidants depends on their mechanism of absorption and biotransformation, thus warranting further investigations on the bioavailability of the phenolic compounds. Furthermore, elucidating the mechanisms of action of these compounds in several physiological processes including cellular signal transduction, cell proliferation and differentiation, apoptosis, inflammation may yield important insights into their prophylactic uses.
Uncontrolled Keywords: Legumes; pigeon pea; legume seed coat; phenolic compounds; enzymes; food ingredients
Subjects: 600 Technology > 08 Food technology > 16 Nutritive value
600 Technology > 08 Food technology > 22 Legumes-Pulses
Divisions: Grain Science and Technology
Depositing User: Food Sci. & Technol. Information Services
Date Deposited: 02 Jul 2010 10:29
Last Modified: 28 Dec 2011 10:14
URI: http://ir.cftri.com/id/eprint/9454

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