Judul: Profil Bioaktif Ekstrak dan Fraksi Larut Lemak Sargassum cristaefolium dari Indonesia dan Evaluasi Aktivitas Anti-Inflamasi dan Antioksidan secara In-vitro
Abstrak: Sargassum is a popular brown seaweed genus which has been traditionally utilized by East Asian community as food and medicine. This brown seaweed is reported to exhibit several biological activities which promote human health, including anti-inflammatory and antioxidant activity. This research aimed to evaluate the potency of Indonesian S. cristaefolium as a source of antiinflammatory and antioxidant agents. To achieve the aforementioned general objective, this research was carried out through three main stages, i.e. 1) preliminary chemical characterization of brown seaweed obtained from four different water areas in Java - Indonesia, 2) preliminary screening of anti-inflammatory and antioxidant activity of brown seaweed crude lipid extracts, and 3) antiinflammatory and antioxidant evaluation of lipid-soluble fractions derived from selected brown seaweed sample and putative identification of bioactive compounds using ultra-high-performance liquid chromatography electrospray ionization orbitrap tandem mass spectrometry (UHPLC-ESI-ORBITRAP-MS/MS) instrument. Research was conducted at Chemistry Laboratory of Southeast Asian Food and Agricultural Science and Technology (SEAFAST) Center, Primate Research Center, and Tropical Biopharmaca Research Center of IPB University, Fat and Oil Laboratory, Food Science and Technology Faculty – University Putra Malaysia (UPM), and Institute of Bioscience of UPM. Results of preliminary chemical characterization of brown seaweeds obtained from different coastal areas showed that samples from southern waters of Java (Sayang Heulang Beach/SHB and Ujung Genteng Beach/UGB) were characterized by high contents of ash, alginate and fucose-containing sulfated polysaccharides (FCSPs) yield, and FCSPs’ fucose content, while samples from northern waters (Awur Bay/AB and Pari Island/PI) had a high amount of total sugar and crude fiber. Principle component analysis (PCA) result on lipid-soluble components showed different tendency that SHB and AB samples were located at close proximity and characterized by larger blade size, higher content of chlorophyll, fucoxanthin, carotenoid, PUFA, total n-3 fatty acids, total n-6 fatty acids, and also lower ratio of n-6 to n-3. Results of second research stage showed that treatment of RAW 264.7 macrophage cells with UGB and AB crude lipid extracts (12.5-50 μg/ml) significantly suppressed the nitric oxide production after lipopolysaccharide stimulation, both in pre-incubated and co-incubated cell culture model. Both crude lipid extracts showed strong 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and high ferric reducing antioxidant power (FRAP), which were amounted to 36.93-37.87 μmol trolox equivalent/g lipid extract and 681.58-969.81 μmol FeSO4/g lipid extract, respectively. AB samples was chosen for further research stage because this sample yielded the highest total lipid content with a selective anti-inflammatory effect and strong antioxidant activity. In the third stage, selected crude lipid extract was fractionated by normal-phase column chromatography, yielding three different lipid-soluble fractions, namely DCM (dichloromethane), ACT (acetone), and MeOH (methanol). The ACT fraction exerted strongest anti-inflammatory activity in both pre-incubated and co-incubated cell culture models. This was in accordance with its DPPH radical scavenging activity and its FRAP value. The anti-inflammatory effect of brown seaweed lipid-soluble fractions was most marked in the pre-incubated cell culture model. Metabolite profiling of lipid fractions was run by UHPLC-ESI-ORBITRAPMS/ MS. Orthogonal Projection to Latent Structures (OPLS) analysis was conducted to determine some features which were significantly correlated with the bioactivity of active fraction. There were 14 feature
Keyword: anti-inflammatory, antioxidant, coastal area, lipid-soluble component, Sargassum cristaefolium, UHPLC-ESI-ORBITRAP-MS/MS, water soluble component

Judul: Antioxidant Activity of Sargassum sp. Extracts with Different Drying Methods
Abstrak: Rumput laut Sargassum sp. merupakan salah satu jenis rumput laut yang kaya akan senyawa bioaktif dengan aktivitas antioksidan. Penggunaan metode pengeringan yang tepat sangat penting untuk mempertahankan aktivitas senyawa antioksidan. Penelitian ini bertujuan untuk mengevaluasi aktivitas antioksidan dan bioautografi ekstrak Sargassum sp. dengan metode pengeringan yang berbeda. Pengeringan dilakukan menggunakan oven, sinar matahari langsung dan pengeringan kering angin. Tahapan penelitian meliputi ekstraksi, pengujian aktivitas antioksidan dengan metode DPPH 2,2- diphenyl-1-picrylhydrazyl, dan analisis bioautografi. Hasil penelitian menunjukkan bahwa metode pengeringan memengaruhi kadar antioksidan dalam ekstrak Sargassum sp. Ketiga pengeringan penjemuran langsung, pengeringan angin-angin serta oven menunjukkan adanya aktivitas antioksidan dengan nilai Rf masing-masing 0,19; 0,54 dan 0,77. Senyawa saponin, steroid dan polifenol terdeteksi pada ketiga metode pengeringan. Hasil aktivitas antioksidan yang didapat secara berurutan dengan nilai IC50 diatas 1000 ppm, 467 ppm dan 951 ppm. Penelitian ini menunjukkan bahwa metode pengeringan dengan oven lebih efektif dalam mempertahankan aktivitas antioksidan pada ekstrak Sargassum sp., Sargassum sp. is a type of seaweed rich in bioactive compounds with antioxidant activity. The appropriate drying method is crucial to retain the activity of these compounds. This study aimed to evaluate the antioxidant activity and bioautography of Sargassum sp. extracts with different drying methods. Drying was performed using an oven, direct sunlight, and ambient drying. The methods used included extraction, antioxidant activity testing using the DPPH method, and bioautography analysis. The results showed that the drying method affected the antioxidant content in Sargassum sp. extracts. The three drying methods—direct sunlight, air drying, and oven drying—showed antioxidant activity with Rf values of 0.19, 0.54, and 0.77, respectively. Saponins, steroids, and polyphenols were detected in all three drying methods. The antioxidant activity results, measured by IC50 values, were above 1000 ppm, 467 ppm, and 951 ppm, respectively. This study concludes that oven drying is more effective in maintaining antioxidant activity in Sargassum sp. extracts.
Keyword: Bioautography, brown alga, extraction, IC50, thin layer chromatography

Judul: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf