Judul: Antioxidant, HMG-CoA Reductase Ihibition activity, and Chemical Compound Identification of Surian (Toona sinensis) Leaves Extract.
Abstrak: Surian (Toona sinensis) is forest plant that are widespread in Asia. This plant only used and known as a comodity for carpentry in Indonesia but in other nation surian is known as spices and traditional medicine because of its natural antioxidant potential. The objective of this study was assayed total phenolic content, total flavonoids content, antioxidant activity, HMG-CoA reductase inhibition activity and to analyze chemical compound from Surian leaves extract. Surian leaves were extracted by water and ethanol solvent. Water extraction was conducted by reflux in 90 oC then ethanol extraction was conducted by maceration, which is through various concentration 70%, 80%, 90%, and 96% of ethanol. Total Phenolic content was determined according to the Folin–Ciocalteu method using miligram of gallic acid equivalent and total flavonoid content was evaluated using aluminium chloride by compared with quercetin standard. Antioxidant activity of the water and ethanol extracts was evaluated using DPPH radical scavenging method. Inhibition of HMG-CoA reductase was assayed in vitro using single concentration inhibition with atorvastatin as comparison. Total phenolic and flavonoid content of ethanol 90% extract and ethanol 96% extract had higher amount than the other. The ethanol 96% extract had the strongest DPPH inhibition conccentration 50% (IC50), which is 3.38 μg /mL while ascorbic acid is 3.90 μg /mL as a comparison. The ethanol 96% extract also had highest inhibition HMG-CoA reductase activity which is 79.13% and this activity strongest in water fraction from this extract with inhibition 91.49% while atorvastatin as a comparsion is 92.45%. Antioxidant and inhibition ezyme activity had strong corelaltion with total flavonoid content. Chemical compound by LC-MS assay mostly are counted in the flavonoids group.
Keyword: Antioxidant, Flavonoids, HMG-CoA reductase, Toona sinensis

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: 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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