ABSTRACT
MUHAMAD FIRDAUS. Antioxidant activity of brown algae (Sargassum
echinocarpum) as preventive on dysfunction of endothelium cell in aorta of
diabetes mellitus rats. Under supervision of MADE ASTAWAN as chairman,
DEDDY MUCHTADI, TUTIK WRESDIYATI, SARWONO WASPADJI, and
SETYAWATI S. KARYONO, as member committee.
Diabetes mellitus may cause oxidative stress. Chronic oxidative stress initiates
the dysfunction of endothelium cell. Polyphenols are believed to have ability to
prevent the dysfunction of endothelium cell. Marine brown algae contain
polyphenol which is probably has good antioxidant activity. The aims of this
study were to obtain the antioxidant activity and structure of phlorotannin, the
lethal dose, the anti oxidative stress, and the anti endothelium cell dysfunction of
Sargassum echinocarpum extract. The Sargassum echinocarpum was collected in
April 2008 from the coastline of Talango island in Sumenep District of East Java,
Indonesia and authenticated by the botanist, Research Centre of Oceanography,
Indonesian Institute of Sciences. The antioxidant activity was assayed with DPPH
radicals, the structure elucidation was assessed with spectroscopic methods, the
lethal dose was investigated on mice, and the anti oxidative stress and the anti
endothelium cell dysfunction were evaluated in diabetic rats. The experimental
animals were divided into 5 groups, i.e.: (1) normal, (2) diabetic treated with 0, (3)
150, (4) 300, and (5) 450 mg/kg body weight of Sargassum echinocarpum extract,
respectively. Extracts were administered by oral gavages for 12 weeks. Diabetes
was induced by single administration of streptozotocin (45 mg/kg, i.p.). Diabetes
was confirmed ten days later in streptozotocin induced animals with blood glucose
levels > 200 mg/dL. After the treatment period, the blood serum acquired was
used for antioxidant enzymes assays while the thoracic aorta was used for
vasodilatation assay. The result showed that the phlorotannin content of
Sargassum echinocarpum extract was 4.25 - 12.16 equivalent of mg
phloroglucinol/g extract. The strongest antioxidant activity obtained from the
methanol extract of Sargassum echinocarpum, i.e. 67.77 %. The methanol extract
of Sargassum echinocarpum contained phloroglucinol and bifuhalol. The
methanol extract of Sargassum echinocarpum was relatively non-toxic. The mice
treated with 1250 mg/kg or more methanol extract of Sargassum echinocarpum
showed inhibition of body weight and necrosis on hepatocyte and tubules of
kidney. It was affected by inhibition activity of gastrointestinal enzymes and
initiation lipid peroxidation. The diabetic rats revealed the oxidative stress;
meanwhile, the diabetic rats treated with 450 mg/kg extract showed the mild
oxidative stress. It was caused by free radical scavenging and induction of
antioxidant defense activity by extract. The diabetic rats exhibited the endothelial
dysfunction; meanwhile, the diabetic rats treated with 450 mg/kg extract showed
the mild endothelial dysfunction. It appeared that Sargassum echinocarpum
extract has the capability to preserve bioavailability of nitric oxide and protect the
muscarinic receptor and endothelium cell against free radical damage.
Keywords: Antioxidant, diabetes mellitus, endothelium cell dysfunction, rat,
Sargassum echinocarpum