Judul: Aktivitas antidiabetes ekstrak air dan etanol daun sirsak secara in vitro melalui inhibisi enzim α-glukosidase
Abstrak: Soursop leaf is a part of the soursop plant used in traditional medicine and proven for antidiabetic agent through decrease in blood glucose level. However, the mechanism of decrease in blood glucose level has not been determined. The research was done to determine the activity of aqueous and ethanol extract of soursop leaf at 1, 1.50, 2% as α-glucosidase inhibitor, compared their activities with acarbose 1% as positive control and determine the mechanism of inhibition. Soursop leaf were extracted with ethanol 70% using maceration method and boiling water method. Aqueous and ethanol extract of soursop leaf were used for phytochemical assay and used for α-glucosidase inhibition method. The α- glucosidase activity was determined by measuring the p-nitrophenol release from the reaction of the enzyme and substrate p-nitrophenil- α-D-glucopiranoside (p- NPG) at 400 nm. The phytochemical analysis indicates that aqueous extract and ethanol extract contained alkaloid, flavonoid, saponin, tannin, and steroid. Both of them can inhibit α-glucosidase activity, but the mechanism of inhibition of the extract has not been able to determined. Aqueous extract can inhibit α-glucosidase activity up to 41.91%, and ethanol extract can inhibit α-glucosidase activity up to 89.33%. Acarbose as positive control can inhibit 93.84% of α-glucosidase activity.
Keyword: 

Judul: Aktivitas Ekstrak, Fraksi Pelarut, dan Senyawa Flavonoid Daun Sukun (Artocarpus altilis) terhadap Enzim α-Glukosidase sebagai Antidiabetes
Abstrak: Breadfruits plants is one of the herbal plants that its leaves has been reported to have biological properties, such as antioxidant, cytotoxic, antiinflammatory, antimicrobial, 5α-reductase enzyme inhibitors, tyrosinase enzyme inhibitors, and chatepsin K inhibitors. This study was conducted to investigate inhibitor activity of extracts and flavonoids compounds from breadfruit leaves against α-glucosidase enzyme using in vitro method. Extract and flavonoid compound are from Indonesian Science Intitute’s research. Inhibitor activity was determined by inhibition percentage and followed by determining the IC50 value. The results showed that extract ethanol, and three other solvent fraction (ethyl acetate, butanol, and hexane) has ability to inhibit α-glucosidase enzyme activity. Based on IC50 values and statistical tests, ethanol and ethyl acetate extracts which has a potential ability to inhibit α-glucosidase enzyme. Ethyl acetate fraction from breadfruit leaves (IC50=6,01 μg/mL) has a better to inhibit α-glucosidase activity than ethanol extracts (IC50=8,89 μg/mL). Based on fourth flavonoid derivative compounds results, which has the best active compound as an antidiabeticis (1-(2,4-dihydroxyphenyl)-3-[8-hydroxy-2-methil- 2-(4-methyl-3-pentenil)-2H-1-ben zopyran-5-yl]-1-propanon) with AC-31code (IC50=16,23 μM). This compound is a flavonoids derivatives compound in dihydrocalcon group.
Keyword: 

Judul: Transisi Fasa Materi Hadronik ke Materi Kuark pada Inti Bintang Neutron.
Abstrak: Bintang neutron terdiri dari beberapa lapisan yang disusun oleh materi nuklir yang berbeda dengan kerapatan yang semakin tinggi ketika mendekati pusat bintang. Inti luar bintang neutron disusun oleh materi hadronik (nukleon, lepton, dan hyperon), sedangkan inti dalam bintang neutron disusun oleh kuark-kuark bebas (up, down, strange) yang saling berinteraksi. Tujuan penelitian ini adalah mempelajari bagaimana transisi dari inti luar ke inti dalam bintang neutron dengan menggunakan pendekatan RMF (Relativistic Mean Field) untuk materi hadronik dan CIDDM (Confined Isospin Density Dependent Mass) untuk materi kuark. Tekanan transisi diperoleh ketika potensial kimia barion materi hadronik dan materi kuark bernilai sama. Nilai tekanan transisi dengan parameter SU6-TM1 sekitar 87 MeV/fm3 dan diperoleh massa maksimum bintang neutron yaitu 1.92M dengan jari-jari sekitar 8.62 km. Nilai tekanan transisi dengan parameter SU6-G2 sekitar 53 MeV/fm3 dan massa maksimum bintang neutron yaitu 1.88M dengan jari-jari sekitar 8.16 km. Jenis transisi fasa adalah orde satu ditandai dengan diskontinuitas dalam kerapatan energi (adanya mixed phase). Parameter-parameter pada model nuklir yang digunakan menyebabkan perbedaan kekakuan persamaan keadaan (EOS) dari materi hadronik dan materi kuark sehingga nilai tekanan transisi dari fasa hadronik ke fasa kuark juga berbeda.
Keyword: bintang neutron, persamaan keadaan, transisi fasa