Judul: Pengaruh Lama Perebusan terhadap Kandungan Gizi dan Komponen Bioaktif Keong Matah merah (Cerithidea obtusa)
Abstrak: Indonesia has a great potential with marine life, matah merah snail is one from many marine life is used to consume. People generally serve matah merah snail using boiling manner. This study aims to determine the effect boiling time on nutrition and bioactive components of matah merah snail. The design of the research is completely randomized design (CRD) with 1 factor and 4 levels, there was fresh (M0), boiling (M1), boil + 10 minutes (M2), boil + 20 minutes (M3) with 2 replications. The test that conducted was proximate test, phytochemical test and BSLT test . Data were analyzed by analysis of variance, if the analysis of variance significant effect on the level of 5%, then the test is continued by real difference test. Based on the results of the statistical analysis of variance factor treatment were not significant effect on moisture, ash and fat. The significant results of statistical analysis on the protein content gained followed by Duncan test, the results are treatment M0 is significantly different to the treatment M1, M2, and M3. Phytochemical test results, the M0 metanol extract compounds contains ninhydrin, flavonoids, alkaloids, tanins and terpenes. Compounds that Contained on M1 and M2 are ninhydrin, flavonoids, alkaloids, tanins and terpenes, while the M3 contains flavonoids, ninhydrin, alkaloids and terpenes. The M0 ethyl acetate extract containing flavonoids and ninhydrin, alkaloids and terpenes weak. M1 contains ninhydrin, polyphenols and terpenes, whereas in M2 and M3 contains ninhydrin, alkaloids and terpenes. Hexan extract M0 contains flavonoids, terpenes, saponins, while the M1, M2 and M3 contains terpenes and saponins. LC50 values in the M0, M1, M2, and M3 metanol extract are 15.58; 22.54; 25.68; 39.8 ppm. Ethyl acetate extract M0, M1, M2, and M3 LC50 values at 40.08; 364.58; 146.12; 130.27 ppm. N-hexane extract M0, M1, M2, and M3 have LC50 values of 1100.43; 352.5; 90.49; 14.95 ppm.
Keyword: bioactive compounds, gastropods, matah merah snails, nutrition

Judul: Kajian Aktivitas Komponen Bioaktif dari Keong Matah Merah (Cerithidea obtusa)
Abstrak: Cerithidea obtusa is one of species that can be found in the mangrove ecosystem in the Asia-Pacific region. It has been widely used for food and reliable as medicine. This study was aimed to explore the potential of bioactive components activity through characterization of C. obtusa; characterization of C. obtusa extract; antioxidant, antidiabetic, antiinflammatory and antibacterial activity assay of C. obtusa extract in vitro. The characterization of C. obtiusa were included identification, morphometric observations, proportions and proximate analysis. Whereas, the characterization of C. obtusa extract were included yield, extract descriptions, toxicity with BSLT method, and screening of active component qualitatively. Bioactive activity was measured in vitro included antioxidant by DPPH method, antidiabetic by α-glucosidase inhibition method, antiinflammatory by red blood cell membrane stabilizing method, and antibacterial by disc diffusion method. The identification results indicated that the C. obtusa had a blunt at the tip of the shell characterization. The average of shell length, shell width, columella width, and weight were 40.5 mm, 19.9 mm, 16.9 mm, and 5.1 g, respectively. The proportion of shells, meat, and offal were 66.7%, 18.1%, and 15.2%, respectively. Moisture content, protein, fat, ash, and carbohydrate were 82.8%, 11.9%, 0.3%, 2.0%, and 3.1%, respectively. The highest yield was methanol extract (4.7%), followed by ethyl acetate extract (0.5%) and n-hexane extract (0.2%). All of extracts had characteristics of paste form and fishy smell. The colour of methanol extract, ethyl acetate extract, and n-hexane extract were faded green, dark green, and tawny, recpectively. Toxicity test showed that all of extracts were toxic with the lowest of LC50 value was n-hexan extract (176.3 μg/ml), followed by ethyl acetate extract (476.3 μg/ml) and methanol extract (715.4 μg/ml). Screening of active component adduced that methanol extract contained alkaloids, flavonoids, triterpenoids, and saponins; ethyl acetate extract contained flavonoids, phenolic hydroquinone, triterpenoids, and saponins; n-hexane extract contained triterpenoids. Ethyl acetate extract had antioxidant activity (IC50 = 645,6 μg/ml) while methanol extract had antidiabetic activity (IC50 = 36.4 mg/ml). antiinflammatory activity was not found at all of extracts while antibacteria activity was discovered at n-hexane extract but the activity was very low (MIC = 46 mg/ml).
Keyword: Antibacteria, antidiabetes, antiinflammatory, antioxidant, Cerithidea obtusa

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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