Judul: Antioxidant activity of brown algae (Sargassum echinocarpum) as preventive on dysfunction of endothelium cell in aorta of diabetes mellitus rats
Abstrak: 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.
Keyword: brown algae

Judul: Profil Bioaktif Ekstrak dan Fraksi Larut Lemak Sargassum cristaefolium dari Indonesia dan Evaluasi Aktivitas Anti-Inflamasi dan Antioksidan secara In-vitro
Abstrak: Sargassum is a popular brown seaweed genus which has been traditionally utilized by East Asian community as food and medicine. This brown seaweed is reported to exhibit several biological activities which promote human health, including anti-inflammatory and antioxidant activity. This research aimed to evaluate the potency of Indonesian S. cristaefolium as a source of antiinflammatory and antioxidant agents. To achieve the aforementioned general objective, this research was carried out through three main stages, i.e. 1) preliminary chemical characterization of brown seaweed obtained from four different water areas in Java - Indonesia, 2) preliminary screening of anti-inflammatory and antioxidant activity of brown seaweed crude lipid extracts, and 3) antiinflammatory and antioxidant evaluation of lipid-soluble fractions derived from selected brown seaweed sample and putative identification of bioactive compounds using ultra-high-performance liquid chromatography electrospray ionization orbitrap tandem mass spectrometry (UHPLC-ESI-ORBITRAP-MS/MS) instrument. Research was conducted at Chemistry Laboratory of Southeast Asian Food and Agricultural Science and Technology (SEAFAST) Center, Primate Research Center, and Tropical Biopharmaca Research Center of IPB University, Fat and Oil Laboratory, Food Science and Technology Faculty – University Putra Malaysia (UPM), and Institute of Bioscience of UPM. Results of preliminary chemical characterization of brown seaweeds obtained from different coastal areas showed that samples from southern waters of Java (Sayang Heulang Beach/SHB and Ujung Genteng Beach/UGB) were characterized by high contents of ash, alginate and fucose-containing sulfated polysaccharides (FCSPs) yield, and FCSPs’ fucose content, while samples from northern waters (Awur Bay/AB and Pari Island/PI) had a high amount of total sugar and crude fiber. Principle component analysis (PCA) result on lipid-soluble components showed different tendency that SHB and AB samples were located at close proximity and characterized by larger blade size, higher content of chlorophyll, fucoxanthin, carotenoid, PUFA, total n-3 fatty acids, total n-6 fatty acids, and also lower ratio of n-6 to n-3. Results of second research stage showed that treatment of RAW 264.7 macrophage cells with UGB and AB crude lipid extracts (12.5-50 μg/ml) significantly suppressed the nitric oxide production after lipopolysaccharide stimulation, both in pre-incubated and co-incubated cell culture model. Both crude lipid extracts showed strong 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and high ferric reducing antioxidant power (FRAP), which were amounted to 36.93-37.87 μmol trolox equivalent/g lipid extract and 681.58-969.81 μmol FeSO4/g lipid extract, respectively. AB samples was chosen for further research stage because this sample yielded the highest total lipid content with a selective anti-inflammatory effect and strong antioxidant activity. In the third stage, selected crude lipid extract was fractionated by normal-phase column chromatography, yielding three different lipid-soluble fractions, namely DCM (dichloromethane), ACT (acetone), and MeOH (methanol). The ACT fraction exerted strongest anti-inflammatory activity in both pre-incubated and co-incubated cell culture models. This was in accordance with its DPPH radical scavenging activity and its FRAP value. The anti-inflammatory effect of brown seaweed lipid-soluble fractions was most marked in the pre-incubated cell culture model. Metabolite profiling of lipid fractions was run by UHPLC-ESI-ORBITRAPMS/ MS. Orthogonal Projection to Latent Structures (OPLS) analysis was conducted to determine some features which were significantly correlated with the bioactivity of active fraction. There were 14 feature
Keyword: anti-inflammatory, antioxidant, coastal area, lipid-soluble component, Sargassum cristaefolium, UHPLC-ESI-ORBITRAP-MS/MS, water soluble component

Judul: Penentuan dan Penjadwalan Pekerja Full-time dan Pekerja Part-time dengan Kendala Libur Hari Kerja dan Libur Akhir Pekan
Abstrak: Suatu perusahaan beroperasi tujuh hari dalam seminggu, yaitu lima hari kerja dan dua hari akhir pekan. Banyaknya pekerja yang dibutuhkan pada setiap hari kerja diasumsikan sama setiap harinya. Demikian juga, banyaknya pekerja yang dibutuhkan pada hari akhir pekan, adalah sama setiap harinya, tetapi boleh berbeda dengan banyaknya pekerja yang dibutuhkan di hari kerja. Pada awalnya, pekerja yang dibutuhkan perusahaan hanyalah pekerja full-time. Setiap pekerja full-time diberikan dua hari libur setiap pekannya yang di antaranya adalah sejumlah libur akhir pekan. Akibatnya terkadang perusahaan membutuhkan pekerja tambahan untuk memenuhi kebutuhan pekerja pada hari-hari yang kekurangan pekerja. Untuk itu perusahaan juga mempekerjakan pekerja part-time. Dalam tulisan ini dibahas tentang formula dalam menentukan banyaknya pekerja full-time dan pekerja part-time yang dibutuhkan perusahaan beserta penjadwalan kerjanya.
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