Influence of species, geographic location, seasonal variation and extraction method on the fucoidan yield of the brown seaweeds of Gulf of Mannar, India

Abstract

Brown seaweeds such as Sargassum wightii, S. oligocystum, Padina tetrastromatica and Turbinaria ornata were collected from two locations, Valinokkam and Hare Island in Gulf of Mannar, South East coast of India, to extract fucoidan and to analyse its variation in the yield for a period from July 2012 to January 2013. Water and acid extraction methods were followed to extract fucoidan. Water extraction yielded much higher fucoidan (9.46±0.18) than acid method (1.63±0.05). The yield of fucoidan also varied between the species, season and also geographic location. The highest yield was obtained from P. tetrastromatica (9.46±0.18%) followed by T. ornata (5.83±0.07%) and S. wightii (3.90±0.05%). The yield was higher during maturation stage of the algae, which was September for T. ornata and S. wightii and January for P. tetrastromatica. Seaweeds found in shallow region gave higher yield (Hare Island) than those collected from more than 1 m depth in Valinokkam region. Compositional analysis of fucoidan revealed that sulphate content was higher in T. ornata (24.27±0.85%) than P. tetrastromatica (22.70±0.53%) and S. wightii (18.73±0.82%). The fucose content was higher in P. tetrastromatica (54.51±1.08) and lower in S. oligocystum (43.16±3.21). Fourier transform infrared spectroscopy carried out for the two dominant species viz. P. tetrastromatica and S. oligocystum, showed a major broad band centered around 3448 cm-1 assigned to be due to hydrogen bonded O-H stretching vibration. Another two bands appeared at 723 cm-1 and 601 cm-1 seem to be the characteristic of C-O-S stretching of sulphate group and C=C-H stretching vibration, respectively in both the species. However, the major differences among the species were the presence of a minor band at 2103.73 cm-1 in P. tetrastromatica and slight shifts noticed in sulphate group band.