Hypnea musciformis (Wulf.) Lamour., H. pannosa J. Ag. and H. valentiae (Turn.) Mont., collected from the northern Arabian Sea coast of Pakistan, have been investigated for their fatty acid compositions through GC-MS. Palmitic acid was present in largest quantity (55-57%) and oleic was the major (7.6-8.4%) unsaturated fatty acid. Pentacosanoic and hexacosenoic acids are being reported for the first time from any species of Hypnea. The three species differed remarkably due to their habitat ecology

Ahmad, V.U.

Hayee-Memon, A.

Shameel, M.

Usmanghani, K.

Aquatic Commons

Pakistan Journal of Marine Sciences, Vol.1(1), 7-10, 1992 
FATTY ACID COMPOSITION OF THREE SPECIES OF HYPNEA 
(GIGARTINALES, RHODOPHYTA) FROM KARACHI COAST 
A. Hayee-Memon, Mustafa Shameel, K. Usmanghani and Viquar Uddin Ahmad 
Department of Botany, University of Karachi (AHM,MS); 
Department of Pharmacognosy, University of Karachi (KU) and HEJ Research 
Institute of Chemistry, University of Karachi, Karachi-75270, Pakistan (VUA) 
ABSTRACT: Hypnea muscifonnis (Wulf.) Lamour., H. pannosa J. Ag. and H. valentiae (Turn.) Mont., 
collected from the northern Arabian Sea coast of Pakistan, have been investigated for their fatty acid 
compositions through GC-MS. Palmitic acid was present in largest quantity (55-57%) and oleic was the 
major (7.6-8.4%) unsaturated fatty acid. Pentacosanoic and hexacosenoic acids are being reported for the 
first time from any species of Hypnea. The three species differed remarkably due to their habitat ecology. 
KEY WORDS: Fatty acid - Hypnea spp.- Rhodophyta- Karachi. 
INTRODUCTION 
Phycochemistry is a term recently used by Shameel (1990). Various species of 
Hypnea Lamour, have often been subjected to a broad phycochemical investigation, 
regarding e.g. sterols (Combaut et at., 1984), carbohydrates (Mahran et al., 1985) and 
nucleosides (Kazlauskas, 1983). This genus is represented by three species at north-
ern Arabian Sea coast of Pakistan. They grow abundantly on lower and sub-littoral 
rocks during October to March at Karachi and the adjacent coastal areas of Lasbela 
(Shameel, 1987). The present investigation reports a phycochemical study of fatty 
acids isolated and identified from Hypnea muscifonnis (Wulf.) Lamour., H. pannosa J. 
Ag. and H. valentiae (Turn.) Mont., collected from the coast of Karachi. 
MATERIALS AND METHODS 
Fresh thalli of H. musciformis, H. pannosa and H. valentiae were collected from 
lower littoral rocks as well as drift material from the rocky ledges at Buleji and Para-
dise Point, during the months of October to March in 1986 and 1987. The healthy 
specimens, free from epiphytes and animal castings were selected, thoroughly washed 
and dried in the shade. 
EXTRACTION: 
Dried thalli (ca. 500g) of each species were extracted with hexane:chloroform (1:1, 
v /v) to give a total soluble extract, which on evaporation under reduced pressure 
afforded a reddish black residue weighing about 1 g. 
SAPONIFICATION: 
Saponification of the extract was carried out by refluxing at 100°C for 6 hours with 
15% KOH in 50% ethanol (25ml). The resulting mixture was concentrated under 
vacuum and distilled· water was added to make up the volume and finally ethylacetate 
was added. The partitioning procedure between distilled water and ethylacetate was 
8 Pakistan Journal of Marine Sciences, Vol.1(1), 1992 
repeated three times. The total combined ethylacetate fraction was acidified with 1N 
HCl (pH 4-5) and then extracted again with ethylacetate. The procedure was repeat-
ed several times to furnish a total of 1.5 litre ethylacetate extract, which on evapora-
tion under reduced pressure yielded 0.5 g of the material. 
ESTERIFICATION: 
The extract so obtained was subjected to methylation with diazomethane. About 2 
ml of diazomethane was added to 0.25 g fatty acid fraction and the reaction mixture 
was left at room temperature for 24 hours until dissolved, and the aliquotes were 
directly injected into a gas chromatograph-mass spectrometer (GC-MS). 
GAS CHROMATOGRAPH MASS SPECTROMETERY: 
The GC-MS of the methylated fatty acid fractions was performed on a GC-Hewlett 
Packard with 11/73 DEC computer data system and a 1.2m x 4mm packed glass capil-
lary column coated with gas chrome Q (100-120 mesh, OV 101, 1%). The column 
temperature was programmed between 70-250°C with a rate of increse of 80 °C per 
minute. The carrier gas (helium) flow rate was 32 ml/min. and the injector tempera-
ture was 250 °C. 
RESULTS AND DISCUSSION 
Altogether 11 saturated and 4 unsaturated fatty acid methyl esters have been identi-
fied from lipid fractions of H. muscifonnis, H. pannosa and H. vatentiae (Table I). 
Both the quantity and variety of saturated fatty acids (86-92%) were appreciably 
greater than those of unsaturated fatty acids (8-14%). Similar observations have also 
been made in other red seaweeds of Karachi (Shameel, 1990). However, Kato and 
Ariga (1982) observed the other way round in the red algae of Japan, which indicates 
geographical differences in the phycochemistry of seaweeds. 
Palmitic acid was present in largest quantity (55-57%) in all the three species. This 
is quite usual as it was also found in greatest amount in several red seaweeds (Qasim, 
1986; Shameel, 1990). Myristic and margaric acids were the next abundant acids (14-
15%) in H. pannosa. Myristic acid was also found in great amount (38%) in Scinaia 
fascicutaris (BQ)rg.) Huisman (Hayee-Memon et at., 1991b), while margaric acid has 
been detected in large quantity (28-29%) in Dennonema abbottiae Afaq., Nizam. et 
Shameel (Afaq-Husain et at., 1991) and Gracilaria foliifera (Forssk.) BQ)rg. (Hayee 
-Memon et al., 1991a). All the other acids were present in small quantity (less than 
9%) in the three species of Hypnea. 
H. valentiae exhibited the greatest variation of fatty acids by possessing nine saturat-
ed and three unsaturated acids, while in H. pannosa five saturated and one unsaturat-
ed fatty acids could be detected. Myristic, palmitic, margaric, stearic and oleic were 
the most common fatty acids found in all the three species of Hypnea; pentadecylic, 
nonadecylic and behenic were present in two species only; while the remaining acids 
were least common and could be detected in only one species. Oleic acid was present 
in largest quantity (7.6-8.4%) among unsaturated acids. It is the major unsaturated 
fatty acid of several red algae (Shameel, 1990). 
Hayee-Memon, et al.: Fatty acid composition of Hypnea 9 
Table 1: Relative percentages of fatty acids analysed as methyl esters from Hypnea. 
Common !Iaine Systematic name Mol. form.j(M+) H H. H 
musci- pan- valen-
formis nos a tiae 
A. SATURATED FATTY ACID METHYL ESTERS: 89.54 91.58 86.06 
Methyl undecylate Methyl-11-undecanoate c 12H 240 2/(200) 3.36 
Methyl tridecylate Methyl-n-tridecanoate c 14H 280J(228) 5.80 
Methyl myristate Methyl-n-tetradecanoate c 15H 30o 2; (242) 4.32 14.83 '3.58 
Methyl pentadecylate Methyl-n-pentadecanoate c16H3P2/ (256) 3.95 4.87 
Methyl palimitate Methyl-n-hexadecanoate C17H 340 2/(270) 56.71 50.41 54.98 
Methylmargarate Methyl-n-heptadecanoate clsH36o2; (284) 3.16 13.58 5.57 
Methyl stearate Methyl-n-octadecanoate c 19H 38o 2; (298) 5.92 6.84 3.25 
Methyl nonadecylate Methyl-n-nonadecanoate c 20H 40o 2; (312) 5.92 4.96 
Methyl antchidate Methyl-n-eicosanoate C 21H 420 2j(326) 2.17 
Methyl behenate Methyl-n-docosanoate c 23H 46o 2; (354) 6.32 3.92 
Methyl pentacosanoate Methyl-n-pentacosanoate C26H 520 2/ (396) 2.76 
B. UNSATURATED FATTY ACID METHYL ESTERS: 10.40 8.38 13.91 
Methyl tetradecatrienoate Methyl-tetradecatrienoate C1sH240 2/(236) 3.21 
Methyl palmitoleate Methyl-9,10-hexadecenoate C17H3P2/ (268) 2.85 
Methyl oleate Methyl-9,10-octadecenoate c 19H 36o 2; (296) 7.55 8.38 8.13 
Methyl hexacosenoate Methyl-17,18-hexacosenoate c27Hs2oi ( 408) 2.57 
10 Pakistan Journal of Marine Sciences, Vol.1(1), 1992 
The saturated and unsaturated fatty acids detected from red seaweeds of Karachi 
were only upto C19 (Qasim, 1986). Behenic acid, which was recently detected from 
Dennonema abbottiae (Afaq-Husain et a!., 1991), was also found in H. muscifonnis 
and H. valentiae in appreciable amount ( 4-6% ). The presence of pentacosanoic and 
hexacosenoic acids in H. valentiae is a unique feature. Such long chain fatty acids 
have not so far been detected from any marine alga of Karachi. Furthermore, they 
have been detected for the first time from any species of Hypnea. The fatty acid 
compositions of H. muscifonnis and H. valenti~e were more or less similar, while H. 
pannosa differed remarkably from the other two species. 
It appears that different species of Hypnea exhibit prominent differences in the fatty 
acid composition and this may be due to their habitat ecology. H. musciformis is 
purely a sub-littoral alga and grows in more or less uniform conditions (Shameel, 
1987), while the other two species grow on lower littoral rocks and are subjected to 
diurnal exposure, which has a direct influence on their general metabolism. H. 
pannosa is epilithic as cushions of interwoven filaments on lower littoral rocks faced 
to rough conditions of the open sea and thus is often exposed to very severe condi-
tions. Therefore, the three species of Hypnea differ in their phycochemistry. 
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Fatty acid composition of three species of Hypnea (Gigartinales, Rhodophyta) from Karachi coast

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Fatty acid composition of three species of Hypnea (Gigartinales, Rhodophyta) from Karachi coast

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