Judul: Aktivitas antioksidan dan analisis komposisi senyawa fenolik dari pohon bidara laut (Strychnos ligustrina)
Abstrak: The bidara laut (Strychnos ligustrina) exhibits antioxidant activity. The objective of this study is to determine the highest antioxidant activity, total phenol, and bioactive compound analyzed using gas chromatography-mass spectrometer (GCMS) of the extract of bidara laut tree. Antioxidant activities was determined by radical scavenging assay using 1,1-diphenyl-2-pycryl-hydrazyl radical. The result showed that the highest of antioxidant activities is the wood methanol extract with IC50 value of 148.14 mg L-1. After partition using n-hexane the IC50 value was 103.14 mg L-1 and of butyl hydroxyl toluene which was used as control positive showed IC50 value of 10.86 mg L-1. The total phenol was determined using Folin-Ciocalteau method and resulted 1936.844 mg kg-1 dry sample. The result of compound analysis using GCMS showed that bidara laut contain phenolics with the major content is 1,2,3-benzenetriol, which is 2.66% (RT 10.77).
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Judul: Profil Fitokimia dan Aktivitas Antimalaria Ekstrak Kayu Bidara Laut Berdasarkan Perbedaan Bagian Batang dan Metode Ekstraksi
Abstrak: Penelitian ini bertujuan untuk menentukan rendemen dan menguji aktivitas antimalaria ekstrak air berbagai bagian kayu bidara laut, dan menganalisis profil fitokimia menggunakan LC-MS/MS untuk mengetahui senyawa bioaktif antimalaria melalui studi in silico, serta membandingkan ekstrak kayu teras bidara laut hasil ekstraksi menggunakan metode maserasi dan metode Ultrasound-assisted extraction (UAE). Perbedaan bagian batang dan metode ekstraksi kayu bidara laut mempengaruhi rendemen ekstrak, aktivitas antimalaria, dan profil fitokimia yang dihasilkan. Ekstrak aquades kayu teras bidara laut menghasilkan rendemen ekstrak tertinggi (6,62%) dan aktivitas antimalaria tertinggi, yang tergolong aktif (IC50 9,65 μg/mL). Analisis LC-MS/MS menunjukkan bahwa ekstrak kayu teras S. ligustrina mengandung strychnine, quinaprilat, 3,4-bis-cyclobut-3-ene-1,2-dione, dan choline. Alkaloid jenis quinine mendominasi dalam ekstrak kulit kayu. Ekstraksi kayu teras bidara laut dengan metode UAE selama 60 menit menghasilkan rendemen ekstrak tertinggi (7,95%) dan aktivitas antimalaria tertinggi yang tergolong sangat aktif (IC50 4,13 μg/mL). Berdasarkan hasil studi molecular docking, senyawa yang berperan sebagai antimalaria adalah senyawa quinaprilat, 3,4-bis-cyclobut-3-ene-1,2-dion, dan quinine. Ekstraksi dengan metode UAE lebih efektif dibandingkan dengan maserasi. UAE menghemat waktu ekstraksi, ramah lingkungan, dan meningkatkan kualitas ekstrak, sehingga metode ekstraksi UAE sangat efisien untuk pengembangan di industri produk alami., This study aims to determine the yield and the test of antimalarial activity of bidara laut wood extracts from various parts of the stem, and to analyze the phytochemical profiles using LC-MS/MS to determine the antimalarial bioactive compounds through in silico studies, as well as of this study was to compare the results of the bidara laut heartwood extracts extraction using the maceration and the Ultrasound-Assisted Extraction (UAE) method. Differences in stem parts and extraction methods of bidara laut wood affect the extract yield, antimalarial activity, and the resulting phytochemical profile. Bidara laut wood aquades extract produced the highest yield (6,62%) and the highest antimalarial activity (IC50 9,65 μg/mL), which was classified as active. LC-MS/MS analysis showed that bidara laut heartwood extract contained strychnine, quinaprilat, 3,4-bis-cyclobut-3-ene-1,2- dione, and choline. Quinine type alkaloids predominate in bark extracts. Extraction of bidara laut heartwood using the UAE method for 60 minutes resulted in the highest extract yield (7,95%), and the highest antimalarial activity which was classified as very active (IC50 4,13 μg/mL). Based on the results of molecular docking studies, compounds that act as an antimalarial activity are quinaprilat compounds, 3,4-bis-cyclobut-3-ene-1,2-dion, and quinine. Extraction using the UAE method is more effective than a maceration. UAE saves extraction time, environmentally friendly, and improves extract quality, so that the UAE extraction method is very efficient to develope in the natural product industry.
Keyword: Bark, Heartwood, Plasmodium falciparum, Sapwood, Strychnos lingustrina

Judul: Two Sector Economic Growth Model in Discrete Time
Abstrak: Economic growth is a condition in the economy that is reflected in the increase of goods and services produced within the community. The purpose of this thesis is to study two sectors economic growth model in discrete time proposed by Zhang (2007). The model involves an economic society with two commodities produced, i.e. capital goods and consumption goods. Both goods are produced with capital and labor as independent variables. The production function is the Cobb-Douglas function. This model shows that the dynamic system has a unique equilibrium solution. Based on some simulations, it has been shown that an increased propensity to save will increase per capita capital and output.
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