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: Antioxidants and Antidiabetic Potency of Aqueous and Ethanolic Extracts of Bawang Dayak Bulbs (Eleutherine palmifolia) in vitro and in vivo.
Abstrak: Eleutherine palmifolia is an indigenous plant from Kalimantan and is widely used by the Dayak tribes to cure several diseases including diabetes mellitus. The purpose of this research is to scientifically prove antioxidant and antidiabetic properties of bawang dayak bulbs and to evaluate its safety that can be used as a source of functional food. Bawang dayak bulbs (BDB) were extracted with water and ethanol solvents. The solutions which contain the aqueous and the ethanolic extracts then freeze dryed. Phytochemical screening that was conducted upon aqueous and ethanolic extracts showed that both of extracts contained alkaloids, tannins, phenolics, flavonoids, triterpenoids, and steroids. Prominent types of phytochemical compounds in aqueous extracts are alkaloids phenolic and triterpenoids, whereas in the ethanolic extract are alkaloid, tannin, phenolic, flavonoids and triterpenoids. Both types of extracts showed antioxidant activity and alpha glucosidase inhibition activity. The antioxidant activity of the ethanolic extract is very significantly higher (P<0.01) than that of the aqueous extract, with IC50 112 ppm for ethanolic extract and 526 ppm for aqueous extract. Alpha glucosidase inhibition activity of ethanolic extract was also very significantly greater (P<0.01) than that of the aqueous extract, with IC50 241 for ethanolic extract and 505 ppm for aqueous extract. The result of NMR (Nuclear Magnetic Spectroscopy) analysis showed that there were eleutherinoside A, eleutherol, and eleuthoside B in ethanolic extract of BDB, but there was not enough sinyal in NMR spectra of aqueous extract to conduct NMR-J resolved data analysis. According to Ieyama et al. (2011) those compounds showed alpha glucosidase inhibitory activity, and eleutherinoside has the biggest activity with IC50 0.5 mM. So it is suggested that eleutherinoside A, eleutherol and eleuthoside B are the active compounds of alpha glucosidase inhibitory activity in BDB ethanolic extract. It is also suggested that alphaglucosidase inhibitory capacity in BDB aqueous extract was presented by the activities of phenolic, alkaloid and triterpenes compounds. Oral glucose tolerance test (OGTT) was done to decide the dose of bawang dayak extracts for in vivo analysis in diabetic experimental rats. The chosen dose was 100 mg/kg BW to diabetic rats, whereas a higher dose was chosen for nondiabetic rats (500 mg/kg BW). The reason of higher dose implementation to non diabetic rats is to evaluate the safety of aqueous and ethanolic extracts to the function and morphology of liver and kidney organs. Sprague-Dawley (SD) male rats age ± 8 weeks old and weighs ± 180 grams were used in this experiment. Conditions of diabetes mellitus (DM) is obtained by induction of 110 mg/kg BW of alloxan monohydrate to SD rats intraperitoneally. BDB aqueous and ethanolic extracts were administered orally by gavage to diabetic and non-diabetic rats for 28 days. Termination was done by using ketamine on day 29 and followed by blood, liver, kidneys and pancreas collections. Observations and analysis were conducted on the body weight, blood glucose levels, serum insulin levels, blood lipid profile (total cholesterol, HDL-cholesterol, LDL-cholesterol, and triglycerides), serum catalase and superoxide dismutase (SOD) enzymes activities, liver malonaldehyde levels, serum creatinine levels, serum albumin levels, Serum Glutamic-Piruvic Transaminase (SGPT) and Serum Glutamic-Oxaloacetic Transaminase (SGOT)
Keyword: diabetes, bawang dayak, Eleutherine palmifolia, antioxidant, functional food

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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