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Title of Thesis

Shahina Naz
Institute/University/Department Details
University of Karachi/ Department of Food Science & Technology
Food Science & Technology
Number of Pages
Keywords (Extracted from title, table of contents and abstract of thesis)
onosma hispidum, ratanjot, terminalia catappa, jangli badam, tropical plant, punica granatum, pomegranate, natural pigments, o. hispidum

The colors of foods are the result of natural pigments or of added colorants. The natural pigments are a group of substances present in animal and plant products. The added colorants may be synthetic or natural (isolated from natural sources.) Since ever the use of synthetic colors has been discouraged due to carcinoma and other toxicological effects, the consumers’ demand for natural colorants has been enforcing the examination of natural coloring substances

The importance of the use of natural colorants in food products provided an impetus for examining many natural coloring substances from plant sources. Focused research on natural colorants by many workers disclosed that besides being colorants, some natural colorants also exhibit antibacterial, antienzymic, antioxidant and protein-staining properties. The present work has been designed to study structure and functional properties of the pigments isolated from Onosma hispidum (Ratanjot), Punica granatum (pomegranate) and Terminalia catappa (Jangli Badam). Being very good sources of natural pigments and colorants

O. hispidum has a history of being used for dying wool, oil and oil based products. Extracts of some species of Onosma, other than hispidum, have also been used as antioxidant, antibacterial, antiviral and anti-inflammatory agents. The extracts have been used successfully for the treatment of wounds, skin carcinogenesis, tumour and oxidative stress. In view of the available literature and knowledge though many species of Onosma have already been screened for its important biological functions yet the species O. hispidum has still not been fully investigated for its bioactivities. Similarly extracts from T. catappa and P. granatum have been investigated by many scientists for their potential biological applications in food and medicines. Since both of these plants are rich in natural dyes and active biological components, still there is a need for systematic studies to exploit even more of its potential uses

The present study was therefore undertaken to isolate various colored fractions/compounds from the root bark of O. hispidum, P. granatum fruit and T. catappa leaves and fruit following bioassays using standard chromatographic and spectroscopic procedures. Initially the crude extracts were screened for their antibacterial, antioxidant, antienzymic, protein-binding, pesticidal and antitussive activities, fractions were then obtained following these assays. Agar well diffusion method for antibacterial activity, DPPH, ABTS and PV tests were used for assessing antioxidant activity. Protein binding ability was assessed by staining resolved protein in PAGE while SO2 induced method was selected to evaluate antitussive activity. Pesticidal activities were tested against Sitophilus oryzae, Tribolium castaneum and Culex fatigans

In view of the results obtained, root bark of O. hispidum exhibit antibacterial, antioxidant, antienzymic, antitussive, pesticidal and protein binding activities which have been reported for the first time in this species. However when the isolation procedures, based on these activities were followed and the fractions obtained were analyzed, all of the fractions (except hexane and methanolic fractions of ehtanolic extract which stained oil and protein respectively) though colored were not found to be pigments as they did not stain either oil or protein. Bioassays directed isolation led to the isolation of 4-hydroxy-3-methoxy cinnamic acid and 4-hydroxy-3-methoxy benzoic acid which have been reported for the first time in O. hispidum. Antioxidant and antiproteolytic activities of 4-hydroxy-3-methoxy benzoic acid were found to be higher than that of 4-hydroxy-3-methoxy cinnamic acid while the antibacterial activity of cinnamic acid was found to be higher. Antitussive activities of both the compounds were almost some P. granatium fruit not only showed antibacterial and antioxidant activities, previously reported, but also pesticidal activity against Culex fatigans which has not been reported earlier. Activities directed isolation led to the isolation of pelargonidine-3-galactose, cyaniding-3-glucose, gallic acid, myricetin and quercetin, first two fo which are well known anthocyanin pigments and last two often occur as co-pitments to anthoeyanins in plants. The order of antioxidant activity was-gallic acid>quercetin>myricetin>cyaniding>pelargonidin. Gallic acid also showed highest antibacterial activity while the activities of the remaining four compounds were almost same. Anthocyanin bound protain was also isolated from the fruit juice using dialysis, DEAE and Sephadex columns and its essential amino acid composition was evaluated using automatic analyzer. The essential amino acid composition was found to be comparable to egg protein, which is the best food protein known with respect to nutritive quality

Extracts from both the leaves and fruit of T. catappa showed antibacterial and antioxidant activities. Ethyl acetate fraction of choloroform layer of the aqueous portion of crude ethanolic extract showed higher antibacterial potential while petroleum ether fraction showed higher antioxidant activity

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2676.26 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents 0
247.86 KB
2 1 General Introduction 1-52
446.59 KB
  1.1 Introduction To Pigments 1-38
  1.2 Literature Cited 39-52
3 2 Onosma Hispidum 53-175
1180.32 KB
  2.1 Abstract 53
  2.2 Introduction 54-60
  2.3 Liturature Review 61-65
  2.4 Experimental 66-90
  2.5 Results And Discussion 91-166
  2.6 References 167-174
4 3 Punica Granatum 175-275
824.04 KB
  3.1 Abstract 175-176
  3.2 Introduction 177-184
  3.3 Literatue Review 185-207
  3.4 Experimental 208-226
  3.5 Results And Discussion 227-263
  3.6 References 264-275
5 4 Terminclia Catappa 276-312
360.62 KB
  4.1 Abstract 276
  4.2 Introduction 277-280
  4.3 Literature Review 281-289
  4.4 Experimental 290-292
  4.5 Results And Discussion 293-306
  4.6 References 307-312