Judul: Pengaruh Pelarut Ekstraksi Rimpang Temu Ireng Metode Microwave Assisted Extraction Terhadap Kandungan Polifenol dan Kapasitas Antioksidan
Abstrak: Temu ireng (Curcuma aeruginosa) merupakan salah satu tanaman yang mengandung senyawa fenolik berupa flavonoid yang berpotensi sebagai antioksidan alami. Pemilihan pelarut ekstraksi yang tepat merupakan hal yang penting untuk mendapatkan metabolit sekunder berkualitas. Penelitian ini bertujuan menentukan pelarut terbaik untuk mengekstrak rimpang temu ireng berdasarkan kadar fenolik total, kadar flavonoid total, dan kapsitas antioksidan dengan metode 2,2-diphenyl-1-pycrilhidrazil (DPPH) dan Ferric Reducing Antioxidant Power (FRAP). Kadar fenolik total diukur menggunakan metode Folin-Ciocalteu dan kadar flavonoid total diukur menggunakan metode Alumunium Klorida. Sampel diekstraksi dengan metode microwave assisted extraction (MAE) dengan pelarut akuades, etanol 50%, metanol 50%, dan aseton 50%. Hasil penelitian menunjukkan pelarut aseton 50% memiliki kadar fenolik total tertinggi (3,10 mg GAE/g BK), sedangkan pelarut metanol 50% menunjukkan kadar flavonoid total tertinggi (4,10 mg QE/g BK), serta kapasitas antioksidan DPPH (1,28 µmol TE/g BK), dan FRAP (12,21 µmol TE/g BK). Pelarut terbaik dalam mengekstrak senyawa aktif pada rimpang temu ireng adalah metanol 50% karena menghasilkan kadar flavonoid total serta kapasitas antioksidan metode DPPH dan FRAP tertinggi., Curcuma aeruginosa is one of the plants that contain phenolic compounds in the form of flavonoids that have the potential to be natural antioxidants. Choosing the right extraction solvent is essential to obtaining quality secondary metabolites. This study aimed to determine the best solvent to extract black rhizomes based on total phenolic content, total flavonoid content, and antioxidant capacity by DPPH and FRAP methods. The total phenolic content was measured using the Folin-Ciocalteu method and the total flavonoid content was measured using the Aluminum Chloride method. The samples were extracted by microwave assisted extraction (MAE) method with aqueous solvents, 50% ethanol, 50% methanol, and 50% acetone. The results showed that 50% acetone solvent had the highest total phenolic content (3,10 mg GAE/g BK), while 50% methanol solvent showed the highest total flavonoid content (4,10 mg QE/g BK), as well as the antioxidant capacity of DPPH (1,28 µmol TE/g BK), and FRAP (12,21 µmol TE/g BK). The best solvent for extracting the active compounds in the rhizomes of black temu is 50% methanol because it produces the total flavonoid levels and the highest antioxidant capacity of the DPPH and FRAP methods.
Keyword: flavonoid, Antioksidan, Pelarut, Fenolik, Temu ireng

Judul: Effect of Solvent in Continuous Shaking Extraction (CSE) Using Temu Ireng (Curcuma aeruginosa Roxb) on Total Terpenoids and Antioxidants Capacity.
Abstrak: Temu ireng (Curcuma aeruginosa Roxb) adalah salah satu ta man obat na di Indonesia yang memiliki manfaat sebagai antioksidan. Manfaat ini dikarenakan adanya kandungan berbagai jenis metabolit sekunder salah satunya senyawa terpenoid. Pemilihan metode dan jenis pelarut dalam proses ekstraksi penting agar senyawa metabolit sekunder dapat diteliti. Penelitian ini bertujuan menentukan jenis pelarut terbaik berdasarkan kadar total terpenoid dan kapasitas antioksidan rimpang temu ireng. Rimpang temu ireng diekstraksi dengan metode continuous shaking extraction (CSE) dengan pelarut n-heksana, aseton, heksan:aseton (1:1), dan heksan:etil asetat (1:1). Hasil ekstraksi diukur kadar total terpenoid dan kapasitas antioksidan menggunakan 2,2-diphenyl-1-picrylhydrazyl (DPPH) dan Ferric-reducing Antioxidant Power (FRAP). Hasil penelitian menujukkan kadar total terpenoid tertinggi diperoleh oleh pelarut heksan:aseton senilai 1471,58, Temu ireng (Curcuma aeruginosa Roxb) is one of the medicinal plants in Indonesia which has benefits as an antioxidant. This research aimed to determine the best type of solvent based on total terpenoid content and antioxidant capacity of temu ireng rhizomes. Temu ireng rhizomes were extracted using continuous shaking extraction (CSE) method with the solvents n-hexane, acetone, hexane:acetone (1:1), and hexane:ethyl acetate (1:1). The extraction were measured for total terpenoid content and antioxidant capacity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and Ferric-reducing Antioxidant Power (FRAP). The research showed that the highest total terpenoid content was obtained by hexane:acetone solvent worth 1471.58
Keyword: antioksidan, pelarut, temu ireng, terpenoid, antioxidant, solvent, temu ireng, terpenoid

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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