Judul: Sintesis Nanopartikel Ekstrak Sirih Merah (Piper Crocatum) dan Kajian Sistem Pengantarannya
Abstrak: Red betel plant is one of medicinal plants that can be used as an ingredient of functional drinks, because it contains phytochemical compounds such as alkaloids, flavonoids, and tannins having antihyperglycemic and antioxidant properties. Bitter flavors of red betel leaf extract and its low bioavailability are a problem. To improve the bioavailability can be done in the nanoparticles, because the surface of the nanoparticles will expand so the activity will increase. The main goals in designing nanoparticles as a delivery system for the active compound is (1) to control the particle size, surface properties and release of active compounds to achieve a target compounds at optimum levels, (2) increase the stability of the compound, and (3 ) to control the release of active compounds. This study provides diversification product of red betel-based functional food to increase its effectiveness and bioavailability. Development of nanoencapsulation of extracts of red betel is expected to improve its functional properties. The first stage of this study is extraction of active compounds of red betel using maceration and reflux method. The extract was analysed for its phytochemical compounds, yield, antioxidant capacity, total phenol, concentration providing 50% inhibition (IC50) and the profile of volatile components. The second stage is the synthesis of nanoparticles using ionic gelation method with four concentration of chitosan (0.1%, 0.2%, 1% and 2%) with 10% extract. At this stage, product characterization includes particle size, functional activities and stability are measured. The third stage is encapsulation using spray drying with two different encapsulants, i.e.maltodextrin (M) and a combination of maltodextrin and soy protein isolate (MISP). The fourth stage is examining delivery system by using dissolution technique and bioaccessibility assay. Red betel extracts contain polyphenols, tannins and flavonoids. Maceration method gave better results than the reflux method (yield of 7.2 ± 0.25%, ± 6.06 10892.86 antioxidant capacity AAE ppm with IC50 46.51 ± 0.05, and total phenolic content of 2388.37 ± 0.3 mg/100g). Volatile components of red betel extracts were dominated by the monoterpenes, which were sabinene and myrcene. Nanoparticles with a concentration of chitosan 0.2% still had a high antioxidant capacity values with smallest particle size (197.20 ± 11.68 nm), polydispersity index of 0.235 ± 0.03 and zeta potential of 32.75 mV ± 2.11 Spray drying using maltodextrin 80% and soy protein isolates 20% gave higher antioxidant activity but increased particle size value (8266.9 ± 1134.9 nm). Nanoparticle morphology showed spherical shapes with rough and wrinkle surface. The pH during storage showed more destabilization of phenolic compounds at high pH (6, 7 and 8) than in low pH (2, 3 and 4). Dissolution assay showed that the release of phenolic compounds in alkaline medium was faster than that in acidic medium. In the alkaline medium, the maximum release occurred at the 180th minute for both nanoparticles solution and MISP capsule powder, whereas in the acidic medium, the highest release was observed at free extract (96.51%) followed by maltodextrin capsule powder (49%), nanoparticle solution (42.78%). Bioacessibility analysis show that phenolic content was found in the stomach, with some part was wasted. All samples had alpha-glucosidase inhibitor properties
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Judul: Total Phenolics, Flavonoids, and ɑ-Glucosidase Inhibitory Activity of n-Hexane, Ethyl Acetate and Methanol Extracts of Red Betel (Piper crocatum)
Abstrak: Sirih merah (Piper crocatum) mempunyai berbagai senyawa dengan kemampuan penghambatan enzim ɑ-glukosidase. Penelitian ini bertujuan menentukan ekstrak yang memiliki tingkat kandungan fenolik dan flavonoid yang optimal, serta penghambatan tertinggi pada enzim α-glukosidase. Metode maserasi bertingkat digunakan untuk mengekstraksi senyawa bioaktif sirih merah menggunakan pelarut-pelarut dengan peningkatan kepolaran (n-heksana, etil asetat, metanol). Pengujian dilakukan terhadap kadar fenolik total, flavonoid, serta kemampuan inhibisi ɑ-glukosidase. Hasil pengukuran total kadar fenolik, flavonoid, dan aktivitas penghambatan α-glukosidase menunjukkan nilai yang secara signifikan berbeda (p<0,05) pada semua ekstrak dengan total kadar fenolik dan flavonoid tertinggi pada ekstrak n-heksana berturut-turut sebesar 25,68 ± 0,29 mg GAE/g dan 65,84 ± 0,96 mg QE/g. Sementara itu, ekstrak metanol daun sirih merah memiliki daya hambat diantara semua ekstrak dengan nilai persen inhibisi α-glukosidase sebesar 43,87 ± 1,83%., Red betel leaf (Piper crocatum) had various compounds with the ability to inhibit α-glucosidase enzymes. The research aimed to determine the extract with optimal levels of phenolic and flavonoid content, as well as the highest inhibition of α-glucosidase enzyme. A multistage maceration method was used to extract bioactive compounds from red betel leaf using solvents with increasing polarity (n-hexane, ethyl acetate, methanol). Tests were conducted on the total phenolic content, flavonoids, and α-glucosidase inhibition ability. The measurement results of the total phenolic content, flavonoids, and α-glucosidase inhibition activity showed significantly different values (p<0,05) in all extracts with the highest total phenolic and flavonoid content in n-hexane extract, respectively, at 25,68 ± 0,29 mg GAE/g and 65,84 ± 0,96 mg QE/g. Meanwhile, the methanol extract of red betel leaf had inhibitory power among all extracts with a percentage inhibition of α-glucosidase at 43,87 ± 1,83%.
Keyword: ɑ-glukosidase/ɑ-glucosidase, antidiabetes/antidiabetic, fenolik/phenolic, flavonoid/flavonoid, sirih merah/red betel

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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