Judul: Effect of UV Light and Different Color Bottle Packaging on Antioxidant Activity of Lindur Leaf Bruguiera gymnorrhiza
Abstrak: The quality of antioxidant materials such as those found in lindur leaves (Bruguiera gymnorrhiza) is greatly influenced by proper packaging and storage techniques, because they are very susceptible to damage due to external environmental influences. The study is aimed to determine the effect of UV exposure and packaging of dried lindur leaves in bottles of different colors (clear, brown, blue) on the quality of the antioxidant compound content of lindur leaves during storage. The content of antioxidant compounds during storage and UV exposure was observed through the DPPH method which would produce IC50 values so that the classification of the strength of the antioxidant activity of lindur leaves was obtained. The results showed that the color of the storage bottle and UV light caused the antioxidant activity of lindur leaves to decrease. The best storage bottle color treatment in the IC50 value was obtained in brown bottles 85.72 ± 1.35, blue 109.78 ± 1.31, and clear 131.42 ± 6.38. UV light exposure and storage bottle color could affect the antioxidant activity value during storage.
Keyword: antioxidant, lindur leaf, UV light, bottle color

Judul: Ekstraksi Komponen Bioaktif dan Aktivitas Antioksidan Daun Lindur (Bruguiera gymnorrhiza)
Abstrak: Lindur are mangrove plants that has been widely used as drug, yet informations on potential drug compounds and antioxidants contained in lindur were still limited. This study aimed to determine of bioactive compound and antioxidant activity of lindur leave. The result showed that lindur fresh leaves had a moisture content 54.91%, ash 4.49%, fat 1.87%, protein 4.45%, and crude fiber 8.67%. Lindur dried leaves had moisture content 9.78%, ash 8.19%, fat 3.90%, protein 9.78%, and crude fiber content 18.05%. The methanol extract had the highest yield (15.79%) compared to the ethyl acetate extract (2.85%), and n-hexane (1.53%). Bioactive compound found in lindur lindur leave extract was flavonoid, phenol hidroquinon, tannin, saponin, dan streoid. Methanol extract showed the highest antioxidant activity with IC50 values of 81.11 ppm, while the n-hexane extract showed the lowest activity with IC50 values of 815.67 ppm. Total phenolic extracts of n-hexane 12.41 mg GAE/g extract, ethyl acetate 97.57 mg GAE/g extract, and methanol 30.07 mg GAE/g extract.
Keyword: leave., Bruguierra gymnorrhiza, bioactive, antioxidant

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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