COMOSITION OF FATTY ACIDS IN MARINE AND FRESHWATER ALGAE OF SINDH

Ninety-seven species of marine and freshwater algae belonging to six different phyla were collected from various coastal areas of Karachi such as Clifton, Manora, Sandspit, Hawkes Bay, Somar Goth, Buleji, Paradise Point, Pacha, Naugaza and Cape Monze during September 1997 to May 1998 as well as from pools, ditches, lakes, irrigation canals, riverin ponds and other water reservoirs in different districts of the province of Sindh (Pakistan) such as Karachi, Dadu, Thatta, Badin and Hyderabad during September 1997 to August 1998. When taxonomically determined and systematically arranged, 10 species were found to belong to the phylum Cyanophyta, 4 to the phylum Volvocophyta, 35 to Chlorophyta, 5 to Charophyta, 16 to Phaeophyta and 27 species to the phylum Rhodophyta. They were thoroughly washed, dried in shade, extracted in chloroform: methanol, saponified, subjected to column chromatography (CC, TLC), esterified and analysed for fatty acid composition initially by gas-liquid-chromatography (GLC) and finally by gas chromatography-mass spectrometry (GC-MS). This study has revealed an interesting array of fatty acid composition In marine and freshwater species of algae. One hundred and four different fatty acids (F As) were identified including 31 saturated (SF As) and 73 unsaturated fatty acids (UFAs) from the investigated algal species. The SF As contained 27 monocarboxylic, one dicarboxylic (DCF A) and three substituted F AL The UF As included 25 monounsaturated (MUFAs), 11 diunsaturated (DUFAs), 11 triunsaturated (TUFAs), 19 polyunsaturated (PUF As), 5 substituted and 2 cyclic (CF As) fatty acids. The MUF As contained 21 monoenoic and four monoynoic F As.Members of the phylum Cyanophyta showed medium number of short chain fatty acids (SCFAs) and very long chain fatty acids (VLCFAs), large number of PUF As and substituted F As, small number of monoynoic FAs with a triple bond (TB), CI8 UFAs up to 6 double bonds (DBs), C20 and C22 UFAs up to 4 DBs, very large rang~ of C chain length (RCCL) and FA-diversity, low quantity of palmitic acid (CI6:0), medium amount of oleic acid (C18:1) and no CFA and DCFA. They were characterized by highest degree of unsaturation of C 18 F As, the largest RCCL and the largest FA-diversity as compared to other phyla Algae of the phylum Volvocophyta exhibited a few SCFAs, VLCFAs, PUFAs, CFAs ad substituted FAs, very small quantities ofC16:0 and C18:0 acids, CI8 UFAs up to 2 DBs only, C20 UF As up to 6 DBs, C22 UF As with a single DB, medium RCCL and FA-diversity, and lack of monoynoic FA and DCF A. They were characterized by the lowest amounts of C16:0 and CI8:1, high degree of unsaturation of C20 acids and low unsaturation of C22 acids. Members of the phylum Chlorophyta have shown large number of SCF As, VLCFAs, PUFAs and substituted FAs, a few CFAs, DCFAs and monoynoic FA, large amount of CI6:0, low quantity of C18:0 acids, C18 and C22 UFAs up to 5 DBs, C20 UFAs up to 6 DEs, long RCCL and very large FA-diversity. They were characterized by the largest number Of SCFAs, VLCFAs and substituted FAs, highly unsaturated C18, C20 and C22 acids, the largest F A-diversity and presence of all categories of FAs as compared to the other phyla of algae. The investigated algae of the phylum Charophyta possessed small number of SCF As, VLCF As, PUF As, monoynoic and substituted F As, no CF A and DCF A, small quantity of :16:0, medium amount ofC18:1 acids, CI8 UFAs up to 5 DBs, C20 UFAs up to 6 DEs, C22 UFAs up to 4 DBs, medium RCCL and FA-diversity. They were characterized by the largest unsaturation of C20 UF As, the small number of occurrence and the medium size of most of the variables of FA-diversity. Algae of the phylum Phaeopnyta displayed only a few SCFAs, PUFAS and substituted F's, no VLCFA, C22, UFA, CFA, DCFA and monoynoic FA, large amount of C16:0, very large quantity of C18:1, very small RCCL and FA-diversity, CIS UFAs up to four DBs, C20 UFAs up to three DBs only. They were characterized by the largest amount of C18:1, lowest degree of unsaturation of C20 UFAs, lack of C22 UFAs, the shortest RCCL and the smallest FA-diversity as compared to other phyla. Members of the phylum Rhodophyta contained no CF A, DCF A and monoynoic FA, a few SCFAs, VLCFAs, PUFAs and substituted FAs, very large quantity of C16:0, medium amount of C18:1 acids, C18 UFAs up to four DBs, C20 UFAs up to five DBs, C22 UFAs with a single DB, large RCCL and small FA-diversity. They were characterized by the largest quantity O! CI6:0, the smallest degree of unsaturation of C22 UFAs, absence or poor representation of all the categories of FAs in comparison with the other phyla of algae. Different types of green algae were also found to differ from one another in their FA-composition. The planktonic, microalgae possessed only a few SCFAs, VLCF As, PUF As, CF As and substituted FAs, no DCFA and monoynoic FA, very small amount of C16:0 and C18:1 acids, C22 UF As with a single DB, CI8 UF As with two DBs, C20 UF As with DBs up to six, large RCCL and medium F A-diversity. They were characterized by the smallest amount of C16:0 and C 18:1 acids, the greatest degree of unsaturation of C IS and C22 UFAs as compared to other groups of green algae. The investigated normal green macroalgae i.e. those having uninucleated cells, uncalcified thallus and sexual reproduction by iso-, aniso- or oogamy, contained a few SCF As, VLCFAs, DCFAs and substituted FAs, medium number of PUFAs, no CFA and monoynoic FA, very large amounts ofC16:0 and C18:1 acids, C18 UFAs with four DBs, C20 and C22 UF As up to live DBs, large RCCL and small FA-diversity. They were characterized by the higi1est amounts of C16:0 and C18:1 acids, the higi1est degree of unsaturation of C22 UFAs and the presence of DCF As in them, as compared to the other green algal groups.The conjugating, green macroalgae displayed in their FA-profile a few SCF As, VLCFAs, PUFAs and substituted FAs, small amount of C16:O, medium quantity of C18:I, absence of C22 UFA, monoynoic FA, CFA and DCFA categories, C18 UFAs up to four and C20 UFAs with a single DB, very small RCCL and FA-diversity. They were characterized by the smallest degree of unsaturation of C20 UF As, smallest RCCL and FA-diversity in comparison with other groups of green algae. The coenocytic green algae possessed a few SCF As, PUF As and monoynoic F As, no CF A and DCF A, medium number of substituted F As, large number of VLCF As, small amounts ofC16:0 and C18:1 acids, CI8 and C22 UFAs up to five and C2() UFAs up to six DBs. large RCCL and high FA-diversity. They were characterized by the largest .number of VLCFAs and RCCL, the highest degree of un saturation ofCl8, C20 and C22 UF As and high FA-diversity as compared to the other groups.The siphonaceous green algae showed a few PUF As, DCF As and monoynoic FAs, a large number of SCFAs, VLCFAs and substituted FAs, large amounts of C16:0 and C18:1 acids, no CFA, unsaturation of CI8 UFAs up to three, C20 UFAs up to five and C22 UFAs up to four DBs, large RCCL and high FA-diversity. They were characterized by the presence of all the categories of F As except CF A, largest number of SCF As, VLCF As and substituted F As and the largest RCCL than other groups. The calcified green algae indicated the presence of a few SCF As, PUF As, CF As and monoynoic F As, medium number of VLCF As and substituted F As, medium quantities of C16:0 and C18:1 acids, unsaturation of CI8 UFAs with five, C20 UFAs with six and C22 UFAs with four DBs, no DCFA, large RCCL and very high FA diversity. They were characterized by the large RCCL and the highest FA-diversity as compared to the other groups. Most of their FA-characteristics were of medium type. Algae having different thallus structures differed from one another in their FA-composition. Large amount of SCF As were found in siphonaceous algae, while its medium quantity occurred in filamentous and coenocytic algae, and only a few of them were detected in unicellular, colonial and calcified algae. The VLCF As were found in large number in filamentous, coenocytic and siphonaceous thalli and other types contained medium number. The PUF As occurred frequently in filamentous, multicellular and thalloid structures, while others contained only a few. Substituted F As were found in large number in filamentous and siphonaceous thalli, while in other types they occurred in medium amount.Palmitic acid was found in high amounts in siphonaceous, multicellular, thalloid and calcified structures, while in others it occurred in small quantities. Oleic acid was present in the highest amount in unicellular and thalloid structures and in the smallest quantity in. coenocytic thalli, while in others it was in medium amount. Monoynoic FAs were detected in all thallus types except multicellular and thalloid structures. The CF As were only found in unicellular, colonial and calcified thalli, while DCF As occurred only in filamentous and siphonaceous types.The Cl8 UFAs up to three DBs were found in unicellular, colonial and siphonaceous thalli, while other types exhibited much greater unsaturation. The unsaturation of C20 acids lied between four to six DBs in all the structures and that of C22 acids between. four and five DBs except unicellular and colonial structures where only one DB was found. The largest RCCL was displayed by filamentous thalli and the smallest by multicellular and thalloid structures, the others showed RCCl. within this range. High F A- diversities were exhibited by filamentous, siphonaceous and calcified thalli and small F A-diversities by unicellular, colonial, multicellular and thalloid structures. Algae growing in different environments also differed in their FA-composition. Marine algae were found to have the smallest amounts of SCPAs, PUFAs, CFAs, DCF As, monoynoic and substituted F As, medium quantity of VLCF As, long RCCL, the highest amounts of C16:0 and C18:1 acids and the highest FA-diversity as compared to the other two environments. Freshwater algae differed from them in having more SCFAs, VLCFAs, PUFAs, CFAs, DCFAs, monoynoic and substituted FAs, lesser quantities of C16:0 and C18:1 acids, more unsaturation of C18 and C22 UFAs and slightly larger RCCL than them. They resembled marine algae in the degree of unsaturation of C20 UFAs in the RCCL and FA-diversity, which were almost equal. The brackish water algae differed from both of them in having the highest amounts of SCFAs and monoynoic FAs, medium quantity of PUFAs and substituted FAs, in lacking CFA and DCFA, small proportion of VLCFAs, less amounts of C16:0 and C 18:1 acids, and in small RCCL and FA-diversity. They resembled the other two types in the degree of unsaturation ofCl8, C20 and C22 UFAs. When all the ninety-seven species were considered together, it was observed that the SCFAs, VLCFAs, PUFAs and substituted FAs were of the same proportion (2.44 - 3.77 %). The VLCF As were slightly mOle than SCF As and PUF As occupied the intermediate position and substituted F As occupied in the highest proportion. The CFAs, DCFAs and monoynoic FAs were found in very small proportion (0.13 - 0.50 %). The UFAs were quite abundant and found in greater amount than SFAs. Among them CI8 UFAs were found in the largest quantity and C22 UFAs in the smallest, their proportion of occurrence was: CI8>C16>C20>C22 UFAs. Palmitic acid (CI6:0) occurred in the largest proportion (22.06 %) and was followed by oleic acid (CI8:1), which was not so high in amount (6.48 %). Stearic (C18:0) was the next acid to occur in appreciable quantity (4.12 %). Lauric (CI2:0), linoleic (CI8:2), a-linolenic (CI8:3) and arachidonic (C20:4) acids were present in very small proportions (0.46 - 1.94 %). They exhibited an RCCL 00-33 carbons and FA-diversity of 3-39 acids.