Structure, conformation in aqueous solution and antimicrobial activity of ulvan extracted from green seaweed <i>Ulva reticulata</i>

<p>The aim of this study is to elucidate the structure and investigate the antimicrobial activity of an ulvan obtained by water extraction from green seaweed <i>Ulva reticulata</i> collected at Nha Trang sea of Vietnam by using IR, NMR, SEC-MALLS and SAXS methods. The ulvan is composed of rhamnose, galactose, xylose, manose and glucose (mole ratio Rha: Gal: Xyl: Man: Glu = 1:0.12:0.1:0.06:0.03), uronic acid (22.5%) and sulphate groups (17.6%). Chemically structural determination showed that the ulvan mainly composed of disaccharide [→4)β-D-GlcA(1→4)α-L-Rha3S-(1→]. The results from SAXS indicated that ulvan under study has a rod-like bulky chain conformation. Ulvan from <i>U.</i> <i>reticulata</i> showed high antimicrobial activity, with inhibition zone diameter of 20 mm against <i>Enterobacter cloace</i> and 18 mm against <i>Escherichia</i> <i>coli</i>.</p>