Judul: Optimization of Temperature and pH Maceration of Cat Whisker Leaves (Orthosiphon aristatus) on Polyphenol Content and Antioxidant Capacity
Abstrak: Kumis kucing (Orthosipon aristatus) dilaporkan memiliki kandungan polifenol dan aktivitas antioksidan yang tinggi. Penelitian ini bertujuan mengukur, membandingkan, serta menentukan hasil optimal kandungan polifenol dan kapasitas antioksidan bagian daun kumis kucing (O. aristatus) dengan perbedaan suhu dan pH pada kondisi ekstraksi. Sampel diekstraksi menggunakan pelarut metanol 50% (v/v) dengan metode maserasi pada optimasi faktor tunggal suhu (30, 40, 50, 60, 70, dan 80 °C) pada pH netral dan faktor tunggal pH (2, 3, 4, 5, dan 6) pada suhu ruang. Hasil penelitian menunjukkan bahwa fenolik total, flavonoid total, serta kapasitas antioksidan (DPPH, ABTS, FRAP, CUPRAC) tertinggi pada suhu 70 °C (9,68 mg GAE/g DW), 80 °C (6,05 mg QE/g DW), 80 °C (8,95 µmol TE/g DW), 80 °C (102,71 µmol TE/g DW), 70 °C (101,9 µmol TE/g DW), 70 °C (56,12 µmol TE/g DW), serta pada pH 2 (5,62 mg GAE/g DW), pH 2 (1,31 mg QE/g DW), pH 3 (9,86 µmol TE/g DW), pH 6 (43,26 µmol TE/g DW), pH 2 (56,38 µmol TE/g DW), pH 3 (25,99 µmol TE/g DW). Penelitian ini menyimpulkan bahwa faktor ekstraksi suhu tinggi (70 dan 80 °C) dan pH rendah (2 dan 3) merupakan faktor yang paling optimal., Cat whisker (Orthosipon aristatus) is reported to have high polyphenol content and antioxidant activity. This study aimed to measure, compare, and determine the optimal results of polyphenol content and antioxidant capacity of cat whisker (O. aristatus) leaf parts with different temperatures and pH in extraction conditions. Samples were extracted using 50% (v/v) methanol solvent by maceration method at single factor optimization of temperature (30, 40, 50, 60, 70, and 80 °C) at neutral pH and single factor of pH (2, 3, 4, 5, and 6) at room temperature. The results showed that total phenolic, total flavonoids, and antioxidant capacity (DPPH, ABTS, FRAP, CUPRAC) were highest at 70 °C (9,68 mg GAE/g DW), 80 °C (6,05 mg QE/g DW), 80 °C (8,95 µmol TE/g DW), 80 °C (102,71 µmol TE/g DW), 70 °C (101,9 µmol TE/g DW), 70 °C (56,12 µmol TE/g DW), and at pH 2 (5,62 mg GAE/g DW), pH 2 (1,31 mg QE/g DW), pH 3 (9,86 µmol TE/g DW), pH 6 (43,26 µmol TE/g DW), pH 2 (56,38 µmol TE/g DW), pH 3 (25,99 µmol TE/g DW). This study concluded that the extraction factors of high temperature (70 and 80 °C) and low pH (2 and 3) are the most optimal factors.
Keyword: antioxidant, Orthosiphon aristatus, pH, polyphenols, temperature

Judul: Effect of shade on total terpenoid levels and antioxidant activity in cat's whisker (Orthosiphon stamineus) leaves
Abstrak: Kumis kucing (Ortosiphon stamineus) merupakan tanaman obat Indonesia yang digunakan untuk mengobati berbagai penyakit. Daun pada tanaman kumis kucing mengandung berbagai senyawa aktif, salah satunya adalah terpenoid. Penelitian ini bertujuan mengukur kadar total terpenoid pada daun kumis kucing serta pengaruhnya terhadap aktivitas antioksidan apabila dilakukan variasi naungan saat penanaman. Perlakuan naungan yang digunakan adalah sebesar 0%, 25%, 50%, dan 75%. Faktor fisiologis tanaman seperti kadar klorofil dan laju fotosintesis juga diukur terlebih dahulu sebelum dilakukan pemanenan. Kadar total terpenoid diukur menggunakan pereaksi Liebermann-Burchard dengan metode kolorimetri. Aktivitas antioksidan diukur berdasarkan kapasitas antioksidannya menggunakan metode DPPH dan FRAP. Hasil penelitian menunjukkan perlakuan naungan menyebabkan tingginya kadar total terpenoid pada naungan 75%, yaitu sebesar 1,409 ± 0,0016 mg UAE/gr, akan tetapi berbanding terbalik dengan kapasitas antioksidannya yang memiliki nilai tertinggi pada metode DPPH dan FRAP berturut-turut pada naungan 0% dan 25%, yaitu sebesar 0,7180 ± 0,022 mg TE/g dan 6,302 ± 0,113 µmol TE/g. Peningkatan kadar total terpenoid pada tiap perlakuan naungan menyebabkan aktivitas antioksidan menurun, karena senyawa terpenoid cenderung mengurangi reduksi senyawa radikal bebas., Cat's whiskers (Ortosiphon stamineus) is an Indonesian medicinal plant used to treat various diseases. The leaves of the cat's whisker plant contain various active compounds, one of which is terpenoids. This research aimed to measure the total levels of terpenoids in cat's whisker leaves and their effect on antioxidant activity if shade variations are applied during planting. The shading treatments used were 0%, 25%, 50%, and 75%. Plant physiological factors such as chlorophyll levels and photosynthesis rates are also measured before harvesting. Total terpenoid levels were measured using the Liebermann-Burchard reagent using the colorimetric method. Antioxidant activity was measured based on antioxidant capacity using the DPPH and FRAP methods. The results of the study showed that shade treatment caused high levels of total terpenoids at 75% shade, namely 1,409 ± 0,0016 mg UAE/gr, but this was inversely proportional to the antioxidant capacity which had the highest values in the DPPH and FRAP methods respectively at 0% shade and 25%, namely 0,7180 ± 0,022 mg TE/g and 6,302 ± 0,113 µmol TE/g. Increasing total terpenoid levels in each shade treatment causes antioxidant activity to decrease, because terpenoid compounds tend to reduce the reduction of free radical compounds.
Keyword: Antioxidant, Cat Whiskers, Terpenoid, Shading

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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