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COMPARATIVE PHYCOCHEMICAL INVESTIGATION ON A VARIETY OF MARINE ALGAE FROM KARACHI COAST

Shehnaz, Laila (2003) COMPARATIVE PHYCOCHEMICAL INVESTIGATION ON A VARIETY OF MARINE ALGAE FROM KARACHI COAST. PhD thesis, University of Karachi, Karachi.

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Abstract

Fourteen commonly occurring species of marine benthic algae i.e., Acanthophora spicifera (Vahl) Borgessen, Caulerpa scalpelliformis (R Brown ex Turner) C Agardh, Chaetomorpha antennina (Bory de Saint-Vincent) Kutizing Champia compressa Harvey, Cladophora albida (Nees) Kutzing Dictyopteris australis, (Sonder) Askenasy, Enteromorpha intestinolis (Linnaeus) Nees, Halimeda tuna (Ellis et Solander) Lamouroux, Melanothamnus afaqhusainii Shameel, Oscillatoria sancta (Kutzing) Gomont, Sargassum swartzii C agardh, Udotea indica A Gepp et e Gepp, Ulva fasciata Delile and U lactuca Linnaeus have been collected from the coastal areas near Karachi, Pakistan. These seaweeds which belong to 2 kingdoms, 4 phyla, 6 classes, 8 orders and 9 families have been investigated taxonomically as well as phycochemically. All the investigated seaweeds are taxonomically known species. During this study Oscillatoria sancta has reported for the first time from this region and Sargassum swartzii taxonomically described for the first time from the coast of Pakistan A variety of saturated and unsaturated fatty acids were detected from the extracts of these algal species and analyzed as methyl esters qualitatively as well as quantitatively through GLC and GC-MS techniques. Apart from that certain sterols have also been detected, isolated and purified, their structures have been elucidated chemically through standard spectroscopic methods, e g IR & UN, EI-, FAB-, FD-GC- & HR – MS and H-^NMR. Altogether 57 different fatty acids (21 saturated & 36 unsaturated) and 2 sterols have been extracted. All natural products described, have been reported for the first time from the corresponding algal species The saturated fatty acids (SFAs) were present in overwhelming quantity (53-84%) and this tendency was exhibited by 12 seaweeds of all the 4 kingdoms, except Chaetomorpha antennina and Acanthophora spicifera. The fatty acid composition of the investigated seaweeds varied not only from order to order or family to family but also from genus to genus species to species, and no generalization may be made. The investigated species also behaved differently in the diversity of their fatty acid compositions Udotea indica appeared to be the least diverse species with three fatty acids (FAs) only, while Halimeda tuna exhibited the greatest diversity with 39 FAs. Caldophora albida was with the next divers seaweed with 33 FAs followed by Champia compressa with 23 FAs. Palmitic acid (C16:0) appeared to be the most predominanty FA. It was not only detected in most of the investigated species but was found to be present as a major FA in 12 species, except Chaetomorpha antennina and Caulerpa scalpelliformis. The next common SFAs were pentadecylic (C15:0), margaric (C17:0), stearic (C18:0) and nonadecylic (C19:0) acids The SFAs showed a range between C-7 and C-32 chain lengths, but only acids of the range C-13 to C-22 and C-24 to C-28 were found in the several investigated species. While heptylic (C7:0), nonylic (C9:0), lauric (C12:0), tricosanoic (C23:0), nonacosanoic (C29:0), melissic (C30:0) and diteriacontanoic (C32:0) acids were the least common acids, as they were detected in only one species each The unsaturated fatty acids (UFAs) and 3 polyunsaturated (PUFA) fatty acids. The MUFAs exhibited a large range between C-7 and C-29 chain length. Olic acid (C18:1) appeared to be the most occurring MUFA, as it was found in 8 species. Myristoleic (C14:1) and palmitoleic (C16:1) aicds were the nextg common acids as they could be detected in 5-7 species. Heptenoic (C7:1), tetracosenoic (C24:1) and nonacosenoic (C29:1) were the least common acids as they were present in only one of the investigated species. Pentadecatrienoic acid (C15:3) was detected as the most common TUFA, being present in 6 species. The PUFAs were only detected in Champia compressa Only two sterols ie cholesterol (Cholest-5-en-3β-ol) from three green and one brown and β-sitosterol (24R-ethyl-cholest-5-en-3β-0l) from three green and two red seaweeds could be isolated. These algae were also investigated for a variety of bioactivity tests. Acanthopora spicifera appeared to be the most active seaweed against most of the tested gram positive as well as Gram negative bacteria. Staphylococcus aureus was found to be affected most against it and only two did not Among Gram negative species the most sensitive bacterium was Shigella flexneriae Chaetomorpha antennina exhibited antifungal activity against nine out of 13 tested fungal species and appeared to be the most active seaweed in this aspect. Microporum canis was the most sensitive fungal species, its growth was affected by eleven out of 13 tested seaweeds. Next to it other sensitive species were Pseudallescheria boydii, Trichophyton mentagrophytes and T schoenleinii. Oscillatoria sancta, Caulerpa scalpelliformis and Dityopteris australis displayed a significant phytotoxicity and Acanthophora spicifera showed a significant cytotoxicity Blur-green marine algae revealed the presence of very limited number of FAs. No oleic acid, DUFA, TUFA and PUFA could be detected in them. Some green algae possessed pentadecylic (C15:0), margaric (C17:0) and nonadecylenic (C19:1) acids in largest quantity and not plamitic acid, while in some of them UFAs were present in larger amount than SFAs. In brown algae no DUFA and PUFA could be detected and the observed numbers of SFA and MUFAs were not very high. The red algae exhibited a diversity in all the categories of FAs, even PUFAs could be detected in them The blue-green and red algae were found to display much more antibacterial activity than the green and brown algae. In the case of antifungal activity the blue-green and green algae exhibited much more activity than brown and red algae. No comparative conclusion about different phyla of algae may be drawn in the cases of sterol composition, phytotoxic activities, as the data obtained are too small and inadequate

Item Type:Thesis (PhD)
Uncontrolled Keywords:marine algae, benthic algae, acanthophora spicifera borgessen, caulerpa scalpelliformis c agardh, chaetomorpha antennina, kutizing champia compressa harvey, cladophora albida kutzing dictyopteris australis, askenasy, enteromorpha intestinolis nees, halimeda tuna lamouroux, melanothamnus afaqhusainii shameel, oscillatoria sancta gomont, sargassum swartzii c agardh, udotea indica a gepp et e gepp, ulva fasciata delile, u lactuca linnaeu
Subjects:Biological & Medical Sciences (c) > Biological Sciences(c1) > Paleo-botany(c1.9)
ID Code:1296
Deposited By:Mr. Muhammad Asif
Deposited On:27 Jan 2007
Last Modified:04 Oct 2007 21:05

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