Judul: Studi In Silico Pengaruh Senyawa Afrodisiak Cabai Jawa  (Piper retrofractum Vahl) Terhadap Peningkatan Libido  Sapi Jantan
Abstrak: Cabai jawa telah lama dikenal sebagai afrodisiak, namun mekanisme kerjanya belum diketahui. Penelitian ini bertujuan mengetahui interaksi senyawa aktif cabai jawa dengan fosfodiesterase tipe 5 (PDE5) (ID: 1UDT) dan menentukan senyawa yang memiliki potensi afrodisiak sebagai inhibitor PDE5 melalui pendekatan in silico. PDE5 sebagai reseptor dan ligan-ligan uji dipreparasi menggunakan software Discovery Studio dan AutoDock Vina. Lima ligan uji guineensine, piperin, piperlongumin, β-sitosterol, dan filfilin dibandingkan dengan sildenafil sitrat setelah diuji stabilitas dan toksisitas ligan. Pemilihan kelima ligan didasari kemiripan struktur ligan dengan hormon steroid. Hasil analisis penambatan molekuler menunjukkan ligan uji yaitu β-sitosterol memiliki nilai ΔG lebih kecil dibandingkan sildenafil sitrat sebesar -10 kkal/mol serta β-sitosterol dan piperin memiliki aktivitas penambatan terbaik dengan %BSS sebesar 63,6% berdasaran analisis visualisasi 2D dan 3D. β-sitosterol dan piperin berpotensi sebagai afrodisiak dengan bekerja sebagai inhibitor PDE5., Java long pepper (Piper retrofractum Vahl) has known for many years as aphrodisiac in traditional medicine, however the molecular mechanism of this action is not very clear. This study is focused to figure out the interactions between active compounds of long pepper and phosphodiesterase type 5 (PDE5) (ID: 1UDT) and which compounds have aphrodisiac potential as PDE5 inhibitor in silico. PDE5 as receptor and tested ligands were prepared using Discovery Studio and AutoDock Vina. Five tested ligands including guineensine piperine, piperlongumine, β-sitosterol, and filfiline was compared to sildenafil citrate after stability and toxicity test. The five ligand was elected by the structure similarity to steroid hormones. The result of molecular docking showed tested ligands β sitosterol with smaller value of ΔG (-10 kcal/mol) than sildenafil citrate. Piperine and β-sitosterol had best docking activity with %BSS value of 63,6%. β-sitosterol and piperine has potential as aphrodisiac by acting as PDE5 inhibitor.
Keyword: afrodisiak, cabai jawa, in silico, PDE5, sapi jantan

Judul: Molecular Docking of Javanese Long Pepper (Piper retrofractum) Active Compound as Acetyl-CoA Carboxylase Inhibitor
Abstrak: Peningkatan lipogenesis de novo secara kronis perlu dihambat karena dikaitkan dengan berbagai penyakit dan gangguan. Asetil-KoA karboksilase (ACC) merupakan enzim penentu laju dalam lintasan tersebut. Senyawa aktif dalam cabai jawa terbukti mampu menurunkan aktivitas enzim ACC. Penelitian ini bertujuan mengidentifikasi senyawa aktif cabai jawa yang dapat menghambat asetil-KoA karboksilase melalui studi penambatan molekuler serta menganalisis interaksi molekuler yang terbentuk. Senyawa aktif cabai jawa diseleksi melalui penapisan virtual menggunakan perangkat lunak YASARA Structure, prediksi kemiripan dengan obat, serta prediksi farmakokinetik dan toksisitas. Sejumlah empat senyawa aktif dalam cabai jawa lolos pada semua tahap penyaringan sehingga berpotensi menghambat ACC. Potensi terbaik ditunjukkan oleh ligan uji N-sinamoilpiperidin. N-sinamoilpiperidin memiliki nilai ΔG yang paling negatif (-7,930 kkal mol-1) dan nilai Kd yang paling kecil (1,538979 μM) di antara empat ligan yang lolos. Interaksi N-sinamoilpiperidin dengan reseptor juga paling serupa dengan ligan alami dengan 11 residu memiliki tipe interaksi sama dan 2 di antaranya merupakan residu penting., Chronic increases in de novo lipogenesis should be inhibited because they have been associated with a wide variety of diseases and disorders. Acetyl-CoA carboxylase (ACC) is the rate-limiting enzyme in this pathway. The active compounds in javanese long pepper have been shown to reduce the activity of ACC. This research aims to identify the active compounds of javanese long pepper that can inhibit acetyl-CoA carboxylase through a molecular docking study and analyze the molecular interactions formed. The active compounds of javanese long pepper were selected through virtual screening using YASARA Structure software, prediction of drug-likeness, pharmacokinetics, and toxicity. Four active chemicals of javanese long pepper passed all levels of screening, showing that they have the potential to inhibit ACC. The best potency was shown by N-cinamoylpiperidine. N-cinnamoylpiperidine had the most negative ΔG value (-7,930 kcal mol-1) and the lowest Kd value (1,538979 M) among the four screened ligands. N-cinnamoylpiperidine interaction with the receptor was also most similar to the native ligand with 11 residues exhibiting the same type of interaction and two of them are important residues.
Keyword: acetyl-CoA carboxylase, javanese long pepper, molecular docking

Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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