Judul: Penapisan Senyawa Bioaktif Daun Jambu Biji (Psidium guajava L.) dan Potensinya secara In Silico sebagai Inhibitor Lipase Pankreas
Abstrak: Obesitas merupakan keadaan abnormal akibat akumulasi lemak dalam jumlah berlebih dan menyebabkan penyakit degeneratif dengan prevalensi yang meningkat di seluruh dunia. Ekstrak etanol daun jambu biji menyebabkan peningkatan metabolisme glukosa dan lipid pada tikus obesitas secara in vivo, namun potensi senyawa bioaktif daun jambu biji yang mampu menginhibisi lipase pankreas secara in silico belum diteliti lebih lanjut. Penelitian bertujuan melakukan penapisan virtual senyawa bioaktif daun jambu biji terhadap reseptor 1LPB. Metode yang digunakan adalah identifikasi senyawa melalui LCMS/MS QToF dilanjutkan penapisan virtual dengan software YASARA Structure. Hasil identifikasi dengan LCMS/MS QToF menunjukkan 21 senyawa dari golongan terpenoid, flavonoid, alkaloid, dan fenolik. Penapisan dilakukan terhadap ligan uji hasil LCMS/MS dan 168 ligan uji hasil studi literatur. Parameter penapisan yaitu nilai ∆Gbind dan Kd yang dibandingkan dengan MUP. Sebanyak 8 senyawa LCMS/MS dan 93 senyawa studi literatur memiliki potensi inhibisi terhadap reseptor 1LPB. Senyawa jacoumaric acid memiliki potensi inhibisi terbaik terhadap reseptor 1LPB Berdasarkan nilai ∆Gbind -9,234 kkal/mol dan Kd 0,1703 μM., Obesity is an abnormal condition due to the accumulation of excessive amounts of fat and it causes degenerative diseases with an increasing prevalence all over the world. The ethanol extract of guava leaves causes an increase in glucose and lipid metabolism of obese mice by in vivo study, but the potential of guava leaf bioactive compounds capable of inhibiting pancreatic lipase in silico has not been studied thoroughly. This study aimed to conduct a virtual screening of guava leaf bioactive compounds against 1LPB receptors. The method applied was compound identification through LCMS/MS QToF followed by virtual screening with YASARA Structure software. The identification results with LCMS/MS QToF showed 21 compounds from terpenoid, flavonoid, alkaloid, and phenolic groups. Virtual screening carried out on experimental ligands from LCMS/MS and 168 from literature studies. The screening parameter were ∆Gbind and Kd value which compared with MUP. A total of 8 LCMS/MS compounds and 93 literature study compounds have inhibitory potential against 1LPB receptors. Jacoumaric acid has the most potential inhibition against 1LPB receptors based on the ∆Gbind value -9.234 kcal/mol and Kd 0.1703 μM.
Keyword: Obesity, pancreatic lipase, guava leaf, in silico, virtual screening

Judul: Antioxidant Capacity and  Pancreatic Lipase Inhibition Assays Fractionation of Guava Leaves (Psidium  guajava) In Vitro
Abstrak: Obesity is an overweight condition that is still a problem around the world. Guava (Psidium guajava) is a plant that has potential as an antiobesity because contain phenolics, flavonoids, and antioxidant that are thought to prevent obesity through inhibition of pancreatic lipase. The purpose of this study was to determine the antioxidant capacity, total phenolic and flavonoid content, and inhibitory activity of crude extracts and fractions of guava leaves against pancreatic lipase. The method used was extraction by sonication and then fractionation using n-hexane, chlorophom, ethyl acetate, and water. The fractionation results were tested for total phenolic and flavonoid content, antioxidant capacity with DPPH (1,1-diphenyl-2-picryl-hydrazyl) and FRAP (Ferric Reducing Antioxidant Power) methods, and inhibition activity against pancreatic lipase. The results showed that the highest levels of total phenolics, total flavonoids, and antioxidant capacity by DPPH method were found in the water fraction. The highest percent inhibition value was in the crude extract and water fraction of 91,04% and 93,45%., Obesitas merupakan keadaan berat badan berlebih yang masih menjadi masalah yang terus berkembang di seluruh dunia. Jambu biji (Psidium guajava) merupakan tanaman yang berpotensi sebagai antiobesitas karena mengandung fenolik, flavonoid, dan antioksidan yang diduga dapat mencegah obesitas melalui penghambatan lipase pankreas. Tujuan penelitian ini adalah menentukan kapasitas antioksidan, kadar fenolik dan flavonoid total, serta aktivitas inhibisi ekstrak kasar dan fraksi daun jambu biji terhadap lipase pankreas. Metode yang digunakan yaitu ekstraksi dengan sonikasi kemudian difraksinasi bertingkat menggunakan n-heksana, klorofom, etil asetat, dan air. Hasil fraksinasi diuji kadar fenolik dan flavonoid total, kapasitas antioksidan dengan motode DPPH (1,1-diphenyl-2-picryl-hydrazyl) dan FRAP (Ferric Reducing Antioxidant Power), serta aktivitas inhibisi terhadap lipase pankreas. Hasil penelitian menunjukkan bahwa kadar fenolik total, flavonoid total, dan kapasitas antioksidan dengan metode DPPH tertinggi ditemukan pada fraksi air. Nilai persen inhibisi terhadap lipase pankreas tertinggi yaitu pada ekstrak kasar dan fraksi air sebesar 91,04% dan 93,45%.
Keyword: Antiobesitas, Lipase Pankreas, Psidium guajava, Anti-obesity, Pancreatic lipase, Daun jambu biji

Judul: Bifurkasi Hopf pada Model Siklus Bisnis Kaldor Kalecki tanpa dan dengan Waktu Tunda
Abstrak: Business cycle model is one of dynamical system models in economic. One of the business cycles model is Kaldor-Kalecki model. Kaldor-Kalecki business cycle model that is written in delayed defferential equations, is a business cycle model that involves gross product and capital stock of a company. In this paper Kaldor-Kalecki business cycle model is analyzed using both nondelay and delay in time of capital stock. By Taylor expansion for the time delayed model, an analysis of stability around the fixed points has been done. Furthermore, by using Hopf bifurcation theorem, it can be shown that there exists periodic orbits and limit cycle. In the nondelayed model, changing the parameter of goods market could lead to the occurrence of Hopf bifurcation and the existence of limit cycle. Similarly, for the delayed model, it has been shown that changing the time delay parameter may result in the occurrence of Hopf bifurcation and limit cycle.
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