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 and Metabolite Profile of Brown Marine Algae Sargassum sp. from a Different Location
Abstrak: Sargassum sp. memiliki potensi untuk dikembangkan karena mengandung beragam senyawa bioaktif. Lokasi dan kondisi pertumbuhan yang berbeda dapat berdampak pada komposisi senyawa bioaktif sehingga perlu dilakukan penelitian untuk mendapatkan informasi kelimpahan metabolit yang terkandung. Penelitian ini bertujuan mengevaluasi dan menentukan aktivitas antioksidan, senyawa fitokimia, dan profil metabolit Sargassum sp. yang berasal dari perairan Kepulauan Seribu, Ujung Genteng, dan Buton. Sampel Sargassum sp. diekstrak menggunakan metode maserasi dengan pelarut metanol untuk mendapatkan ekstrak kasar. Ekstrak kasar difraksinasi dengan kromatografi lapis tipis (KLT) lalu dilakukan evaluasi aktivitas antioksidan dan penentuan senyawa fitokimia secara kualitatif. Evaluasi aktivitas antioksidan secara kuantitatif dilakukan menggunakan reagen 1,1-difenil2-pikrilhidrazil (DPPH) dengan instrumen spektrofotometer UV-Vis. Penentuan profil metabolit menggunakan instrumen UPLC-MS. Hasil penelitian menunjukkan aktivitas antioksidan Sargassum sp. dari ketiga lokasi tergolong kuat. Nilai IC50 Sargassum sp. dari Kepulauan Seribu, Ujung Genteng, dan Buton secara berturutturut 65,277 ppm, 67,044 ppm, dan 62,412 ppm. Senyawa fitokimia yang teridentifikasi yaitu steroid, saponin, dan polifenol. Hasil analisis PCA menunjukkan tingkat kemiripan antar sampel tidak signifikan. Ditemukan delapan senyawa penciri, empat senyawa penciri yang teridentifikasi tergolong kedalam senyawa amida, amina ester (surfaktan), lipida betain, dan naphthyridine. Empat senyawa penciri lain tidak teridentifikasi., Sargassum sp. has the potential to be developed because it contains a variety of bioactive compounds. Different locations and growth conditions can have an impact on the composition of bioactive compounds, so it is necessary to carry out research to obtain information on the abundance of metabolites contained. This study aims to evaluate and determine the antioxidant activity, phytochemical compounds, and metabolite profile of Sargassum sp. originating from the waters of the Seribu Islands, Ujung Genteng, and Buton. Samples of Sargassum sp. were extracted using the maceration method with methanol as the solvent to obtain crude extracts. The crude extracts were fractionated using thin-layer chromatography (TLC), followed by evaluating antioxidant activity and determining phytochemical compounds qualitatively. Quantitative evaluation of antioxidant activity was performed using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) reagent with a UV-Vis spectrophotometer instrument. The metabolite profile was determined using UPLC-MS instrumentation. The results showed the antioxidant activity of Sargassum sp. quite strong. IC50 value of Sargassum sp. from the Seribu Islands, Ujung Genteng, and Buton respectively 65.277 ppm, 67.044 ppm and 62.412 ppm. The identified phytochemical compounds are steroids, saponins, and polyphenols. PCA analysis results show that the level of similarity between samples is not significant. There are eight marker compounds, four identified marker compounds are classified as amides, amine esters (surfactants), betaine lipids, and naphthyridine. The other four marker compounds were not identified.
Keyword: antioxidants, metabolomics, phytochemicals, Sargassum sp., UPLC-MS

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