Judul: Total Tannin Content and Tyrosinase Enzyme Inhibitory Activity of Surian (Toona sinensis) Leaf Extract in Varying Solvents and Tree Age
Abstrak: Penelitian mengenai tanaman surian telah banyak dikembangkan baik dalam bidang kesehatan maupun industri. Daun surian (Toona sinensis) diketahui memiliki aktivitas penghambatan tirosinase untuk mencegah hiperpigmentasi. Penelitian ini bertujuan mengetahui kandungan total tanin dan aktivitas inhibisi tirosinase dari ekstrak daun surian variasi pelarut dan umur pohon. Penentuan kadar total tanin menggunakan metode follin ciocalteu dan menggunakan substrat LTyrosin untuk inhibisi tirosinase. Hasil penelitian menunjukkan bahwa ekstrak etanol 96% daun surian menghasilkan kandungan total tanin tertinggi pada umur pohon 34 tahun sebesar 24,299 %, terendah pada ekstrak etanol 30% pada umur 16 tahun sebesar 3,723%. Aktivitas inhibisi terbesar ditunjukkan pada ekstrak etanol 96% pada umur 16 tahun sebesar 86,658% dan terendah pada ekstrak etanol 30% pada umur 34 tahun sebesar 35,949 %.. Nilai IC50 terbaik adalah 53, 712 ppm pada ekstrak etanol 96 persen umur tanaman 16 tahun. Simpulan penelitian ini adalah aktivitas penghambatan tirosinase dan persentase kandungan tanin pada daun surian (Toona sinensis) dipengaruhi oleh umur tanaman dan pelarut yang digunakan dalam ekstraksi dan berpotensi sebagai bahan kosmetika., Research on surian plants has been widely developed both in the health and industrial fields. Surian leaves (Toona sinensis) are known to have tyrosinase inhibitory activity to prevent hyperpigmentation. This research aimed to determine the total tannin content and tyrosinase inhibitory activity of surian leaf extract with various solvents and tree age. Determination of total tannin content using the Follin Ciocalteu method and using L-Tyrosine as a substrate for tyrosinase inhibition. The results of the research showed that the 96% ethanol extract of surian leaves produced the highest total tannin content at 34 years of age at 24.299%, the lowest was 30% ethanol extract at 16 years of age at 3.723%. The greatest inhibitory activity was shown in the 96% ethanol extract at the age of 16 years, amounting to 86.658% and the lowest in the 30% ethanol extract at the age of 34 years, amounting to 35.949%. The best IC50 value was 53.712 ppm in the 96 percent ethanol extract at the age of 16 years. The research concluded that the tyrosinase inhibitory activity and the percentage of tannin content in surian (Toona sinensis) leaves are influenced by the age of the plant and the solvent used in extraction and has the potential as a cosmetic ingredient
Keyword: tanin, L-Tyrosin, surian, tirosinase

Judul: Antioxidant Activity and Total Flavonoids Content of Water and Ethanol Extract of Surian Leaves (Toona sinensis) on Various Tree Ages
Abstrak: Ekstrak daun tanaman surian diketahui memiliki kandungan senyawa flavonoid yang berfungsi sebagai antioksidan. Penelitian ini bertujuan menguji aktivitas antioksidan dan menghitung kadar total flavonod dari ekstrak air dan etanol daun surian pada berbagai umur pohon surian. Penelitian ini menggunakan pelarut air, etanol 30%, 70% dan 96% pada umur tanaman 16, 27 dan 34 tahun. Kadar total flavonoid diukur menggunakan metode Alumunium Klorida (AlCl3) dan aktivitas antioksidan menggunakan metode FRAP. Hasil penelitian menunjukan ekstrak etanol 96% daun surian menghasilkan kadar total flavonoid dan aktivitas antioksidan FRAP tertinggi pada umur tanaman 34 tahun dan ekstrak air daun surian menghasilkan kadar total flavonoid dan aktivitas antioksidan FRAP terendah pada umur tanaman 16 tahun. Kadar total flavonoid tertinggi sebesar 84.4559 mg QE/g DW dan kadar total flavonoid terendah sebesar 5.1069 mg QE/g DW. Aktivitas antioksidan FRAP tertinggi sebesar 330.061 μmol TE/g DW dan aktivitas antioksidan FRAP terendah sebesar 837.939 μmol TE/g DW. Simpulan dari penelitian adalah semakin tinggi kadar total flavonoid pada ekstrak daun surian maka semakin berpotensi sebagai sumber antioksidan alami., Surian leaves extract is known to contain flavonoid compounds that function as antioxidants. This study aimed to examine the antioxidant activity and calculate the levels of flavonoid from the aqueous and ethanol extracts of surian leaves from various ages of surian trees. This study used water, 30%, 70%, and 96% ethanol as a solvent for the surian plants ages 16, 27, and 34 years. Total flavonoid levels are measured using the Aluminum Chloride (AlCl3) method and antioxidant activity using the FRAP method. The results showed that the 96% ethanol extract of surian leaves produced the highest levels of total flavonoids and FRAP antioxidant activity at the age of 34 years and the aqueous extract of surian leaves produced the lowest levels of total flavonoids and antioxidant activity of FRAP at the age of 16 years. The highest total flavonoid content is 84.4559 mg QE/g DW and the lowest total flavonoid content is 5.1069 mg QE/g DW. The highest FRAP antioxidant activity is 330.061 μmol TE/g DW and the lowest FRAP antioxidant activity is 837.939 μmol TE/g DW. The conclusion from the research is that the higher the total flavonoid content in surian leaves extract, the more potential it is as a source of natural antioxidants.
Keyword: antioxidant, FRAP, surian leaves, flavonoids

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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