Judul: Prediction of Tyrosinase Inhibitors in Nyamplung Plant (Calophyllum inophyllum) and Local Tamanu Oil from Kebumen (Central Java)
Abstrak: Hiperpigmentasi kulit dapat diatasi dengan menginhibisi enzim tirosinase pada proses melanogenesis. Inhibitor tirosinase komersial, seperti asam kojat telah terbukti menimbulkan beberapa efek samping yang cukup serius bagi kulit. Tanaman nyamplung diketahui memiliki aktivitas inhibitor tirosinase yang masih belum banyak diteliti di Indonesia. Penelitian ini bertujuan memprediksi senyawa inhibitor tirosinase dari tanaman nyamplung yang dibandingkan dengan berbagai senyawa yang teridentifikasi pada sampel minyak tamanu lokal asal Kebumen, Jawa Tengah. Sebanyak 54 senyawa teridentifikasi pada analisis KNApSAcK sedangkan 52 senyawa teridentifikasi pada GC-MS. Kedua analisis tersebut menemukan 7 senyawa asam lemak yang sama. Simpulan dari penelitian ini adalah teridentifikasinya 3 senyawa inhibitor tirosinase yang lebih baik dari asam kojat dan senyawa targetnya (asam kalofilat dan kalofilolida), yaitu senyawa 2,4-diamino-6-[[4-fenil-2-tiazolil]tio]kuinazolin, 1,5-dihidroksixanton, dan asam sinamat. Namun, asam sinamat paling direkomendasikan karena nilai indeks kemiripannya >89% dan diprediksi paling aman dari yang lainnya., Skin hyperpigmentation can be overcome by inhibiting the tyrosinase enzyme in melanogenesis. Commercial tyrosinase inhibitor, such as kojic acid has been confirmed to cause some serious side effects for skin. Nyamplung plant has been confirmed to have tyrosinase inhibitory activity which still not widely studied in Indonesia. This study aims to predict tyrosinase inhibitors from the nyamplung plant compared with the compounds in local tamanu oil from Kebumen, Central Java. Fifty-four compounds were identified in KNApSAcK analysis whereas fifty-two compounds were identified in GC-MS. Both analyzes found 7 fatty acids that are similar. The conclusion of this research is the identification of 3 tyrosinase inhibitors which are better than kojic acid and their target compounds (calophyllic acid and calophyllolide), specifically 2,4-diamino-6-[[4-phenyl-2-thiazolyl]thio]quinazoline, 1,5-dihydroxyxanthone, and cinnamic acid. However, cinnamic acid is the most recommended compound because it has similarity index value >89% and predicted to be the safest compound from the others.
Keyword: Hyperpigmentation, Melanogenesis, Nyamplung, Tamanu Oil, Tyrosinase Inhibitor

Judul: Identification of Merbau Wood (Intsia palembanica) Active Compounds and Their Potential as In Silico Tyrosinase Enzyme Inhibitors
Abstrak: Tirosinase merupakan enzim pembatas laju yang terkait dengan sintesis melanin dalam melanosit. Peningkatan produksi melanin (melanogenesis) di melanosit menyebabkan terjadinya hiperpigmentasi atau penggelapan kulit. Senyawa aktif kayu merbau dapat digunakan sebagai inhibitor tirosinase. Penelitian ini bertujuan mengidentifikasi senyawa aktif kayu merbau dengan LC-MS serta menguji potensi senyawa aktif tersebut sebagai inhibitor tirosinase melalui parameter Energi Bebas Ikatan (∆G), Konstanta Disosiasi (Kd), dan jenis interaksi yang terbentuk antara ligan dan reseptor. Metode yang digunakan dalam penelitian ini adalah ekstraksi, LC-MS, dan penambatan molekuler menggunakan perangkat lunak YASARA Structure dengan reseptor 5M8M yang berasal dari homo sapiens. Hasil penelitian menunjukkan bahwa terdapat 25 senyawa aktif ekstrak etanol kayu merbau hasil LC-MS. Sebanyak 1 dari 25 senyawa yang berpotensi sebagai inhibitor tirosinase yaitu senyawa artemidiol. Senyawa artemidiol menunjukkan aktivitas inhibitor tirosinase terbaik dengan nilai ∆G sebesar -7.231 kkal/mol dan Kd 5.007 µM. Senyawa artemidiol memiliki 5 ikatan hidrogen. Simpulan dari penelitian adalah ligan uji artemidiol sangat berpotensi sebagai inhibitor tirosinase daripada ligan alami asam kojat., Tyrosinase is a rate limiting enzyme associated with melanin synthesis in melanocytes. Increased melanin production (melanogenesis) in melanocytes causes hyperpigmentation or darkening of the skin. The active compound of merbau wood can be used as a tyrosinase inhibitor. This study aimed to identify the active compound merbau wood with LC-MS and to test the potential of the active compound as a tyrosinase inhibitor through the parameters of bond free energy (∆G), dissociation constant (Kd), and the type of interaction formed between the ligand and the receptor. The methods used in this study were extraction, LC-MS, and molecular anchoring using YASARA Structure software with 5M8M receptors derived from homo sapiens. The results showed that there were 25 active compounds in the ethanol extract of merbau wood from LC-MS. As many as 1 of 25 compounds that had the potential as tyrosinase inhibitors were artemidiol compounds. Artemidiol compounds showed the best tyrosinase inhibitor activity with G values of -7.231 kcal/mol and Kd of 5.007 µM. Artemidiol compounds had 5 hydrogen bonds. The conclusion of the research was that the artemidiol test ligand had the potential as a tyrosinase inhibitor rather than the natural ligand of kojic acid.
Keyword: Hyperpigmentation, Melanogenesis, Merbau Wood, Molecular Docking, Tyrosinase

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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