Judul: Penapisan Ekstrak Daun Famili Zingiberaceae Sebagai Inhibitor Tirosinase Dan Antioksidan
Abstrak: Penapisan atas daun Zingiberaceae telah dilakukan sebagai inhibitor tirosinase dan antioksidan. Kadar total antosianin, klorofil, karotenoid, tanin, dan flavonoid ditentukan menggunakan metode spektroskopi. Metode penapisan antioksidan menggunakan 1,1-difenil-2-pikril hidrazil (DPPH) dan penapisan inhibitor tirosinase menggunakan substrat L-tirosina (monofenolase) dan L-DOPA (difenolase). Ekstrak metanol daun temulawak (Curcuma xanthorrhiza) lebih aktif sebagai antioksidan daripada ekstrak lainnya dengan nilai IC50 281.85 mg/L dan hubungannya dengan kadar tanin ialah 22.76%. Ekstrak etil asetat dari daun bangle hantu (Zingiber purpureum) memiliki aktivitas inhibisi monofenolase 82.86% dan hubungannya dengan kadar karotenoid ialah 52.02%. Ekstrak etil asetat daun temu putih (Curcuma zedoaria) memiliki aktivitas inhibisi difenolase 90.20% dan hubungannya dengan kadar flavonoid ialah 39%. Jadi, dari 10 daun spesies Zingiberaceae, temulawak lebih berpotensi sebagai antioksidan, sementara bangle hantu dan temu putih lebih berpotensi sebagai inhibitor tirosinase.
Keyword: antioksidan, inhibitor tirosinase, penapisan, Zingiberaceae

Judul: Pengaruh Jenis Pelarut terhadap Total Terpenoid dan Kapasitas Antioksidan Ekstrak Rimpang Temulawak  (Curcuma zanthorrhiza)
Abstrak: Temulawak (Curcuma zanthorrhiza) merupakan tanaman asli Indonesia mengandung antioksidan dan terpenoid yang mampu menangkal radikal bebas. Sampel rimpang temulawak diekstraksi dengan berbagai jenis pelarut diperlukan untuk mendapatkan senyawa bioaktif temulawak terbaik secara kuantitatif. Penelitian ini bertujuan menentukan pengaruh berbagai jenis pelarut ekstraksi terhadap total terpenoid dan kapasitas antioksidan rimpang temulawak. Sampel diekstraksi dengan gabungan metode sonikasi dan maserasi. Tahapan penelitian meliputi pengujian kadar total terpenoid rimpang temulawak, kemudian dilanjutkan pengujian kapasitas antioksidan dengan metode DPPH, CUPRAC, FRAP, dan ABTS. Hasil penelitian menunjukkan kadar total terpenoid terbesar dihasilkan oleh pelarut H (heksan p.a) sebesar 243.74 ± 8.13a mg UA/g DW dan kapasitas antioksidan terbesar dihasilkan oleh metode FRAP dengan pelarut aseton sebesar 131.25 ± 4.33a. Berdasarkan data dapat disimpulkan terpenoid bukan merupakan komponen utama senyawa antioksidan pada rimpang temulawak karena perbedaan pelarut yang dihasilkan antara data kapasitas antioksidan dan kadar total terpenoid., Temulawak (Curcuma xanthorrhiza) is a plant native to Indonesia that contains antioxidants and terpenoids which are able to ward off free radicals. Temulawak rhizome samples were extracted with various types of solvents to obtain the best bioactive compounds in curcuma quantitatively. This research aimed to determine the effect of various types of extraction solvents on the total terpenoids and antioxidant capacity of curcuma rhizomes. Samples were extracted by a combination of sonication and maceration methods. The research stages included testing the total terpenoid content of curcuma rhizomes, then continued with testing the antioxidant capacity using the DPPH, CUPRAC, FRAP, and ABTS methods. The results showed that the highest total terpenoid content was produced by the H solvent (hexane p.a) of 243.74 ± 8.13a mg UA/g DW and the largest antioxidant capacity was produced by the FRAP method with acetone solvent of 131.25 ± 4.33a. Based on the data, it can be concluded that terpenoids are not the main component of antioxidant compounds in curcuma rhizomes due to differences in the solvent produced between antioxidant capacity data and total terpenoid levels.
Keyword: curcuma, types of solvent, antioxidant, terpenoids

Judul: Dynamics Model for Rural and Urban Economic Growth
Abstrak: Lewis theory of structural change has focused on mechanisms that allow countries to transform their domestic economic structure to a more modern economy. The proposed model deals with the mechanism of interaction between rural and urban Economic. This model is concerned with the process of labor transfer from rural to urban areas. This study aims to model the dynamics of economic growth in rural and urban areas, including determining the equilibrium solution and to carry out simulation of the model. The simulation results show that the transfer of labor from rural to urban areas will increase the rate of change of capital so that structural changes can be realized. In addition, increased propensity to save in rural areas will also accelerate structural change
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