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: Tegangan permukaan dan aktivitas inhibitor tirosinase in vitro pada minyak nyamplung (Calophyllum inophyllum L.).
Abstrak: Minyak nyamplung (Calophyllum inophyllum L.) merupakan tanaman obat tradisional yang multifungsi, kaya akan asam lemak dan metabolit sekunder yang baik untuk kulit, serta minyak nyamplung diprediksi secara in silico memiliki aktivitas penghambatan tirosinase. Penelitian ini bertujuan mengevaluasi aktivitas inhibitor tirosinase sebagai pencerah kulit melalui uji in vitro dan mengukur nilai tegangan permukaan pada minyak nyamplung. Pengukuran tegangan permukaan minyak nyamplung diukur dengan metode cincin du-Nouy menggunakan alat tensiometer. Pengukuran aktivitas inhibisi tirosinase pada minyak nyamplung diukur dengan metode spektrofotometri menggunakan microplate reader pada panjang gelombang 479 nm selama inkubasi 40 menit pada suhu 37 °C dan dievaluasi melalui nilai persen inhibisi yang diperoleh. Berdasarkan hasil penelitian, diperoleh nilai tegangan permukaan minyak nyamplung sebesar 41,83 ± 0,76 mN/m. Aktivitas penghambatan tirosinase pada minyak nyamplung diproleh persen inhibisi tertinggi sebesar 83,75% ± 0,41, sementara itu asam kojat sebagai kontrol positif memiliki persen inhibisi tertinggi sebesar 84,59% ± 2,04. Simpulan penelitian ini minyak nyamplung dapat digunakan sebagai bahan baku dalam pembuatan surfaktan alami dan juga berpotensi sebagai inhibitor tirosinase., Nyamplung oil (Calophyllum inophyllum L.) is a multifunctional traditional medicinal plant, rich in fatty acids and secondary metabolites that are good for skin, and nyamplung oil is predicted in silico to have tyrosinase inhibitory activity. This study aimed to evaluate the activity of tyrosinase inhibitors as skin lightening agents through in vitro tests and to measure the surface tension value of nyamplung oil. The surface tension of nyamplung oil was measured by the du-Nouy ring method using a tensiometer. The measurement of tyrosinase inhibition activity in nyamplung oil was measured by the spectrophotometric method using a microplate reader at a wavelength of 479 nm during a 40 minute incubation at 37 °C and evaluated by the percentage inhibition value obtained. Based on the results, the surface tension value of nyamplung oil was 41.83 ± 0.76 mN/m. Tyrosinase inhibitory activity in nyamplung oil obtained the highest percentage inhibition of 83.75% ± 0.41, while kojic acid as a positive control had the highest percentage inhibition of 84.59% ± 2.04. This research concludes that nyamplung oil can be used as a raw material in the production of natural surfactants and also has the potential as a tyrosinase inhibitor.
Keyword: Nyamplung oil, Surface tension, 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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