Judul: Analysis of Antioxidant Activity of Flavonoid Compounds from Moringa Oleifera Leaves Using Density Functional Theory
Abstrak: Perubahan gaya hidup dan pola makan manusia telah meningkatkan risiko penyakit degeneratif akibat oksidasi berlebihan dan pembentukan radikal bebas. Radikal bebas ini berhubungan dengan penyakit serius seperti aterosklerosis, diabetes, dan kanker. Antioksidan dari tanaman, seperti flavonoid dalam daun kelor (Moringa Oleifera) yaitu quercetin, myricetin dan kaempferol, dapat menghambat kerusakan oksidatif ini. Analisis sifat aktivitas antioksidan diperlukan untuk mengetahui senyawa flavonoid mana yang paling efektif dalam pembersihan radikal bebas. Metode perhitungan komputasi DFT dapat menjadi solusi dalam studi teoritis untuk menganalisis sifat tersebut, dengan fungsi exchange-correlation B3LYP dan basis set def2/SVP. Perhitungan yang dilakukan pada penelitian ini adalah optimasi molekul, frekuensi vibrasi, dan single point energy yang dilakukan pada fase gas dan fase pelarut air dengan nilai parameter pelarut air diambil dari model CPCM (Conductor-like Polarizable Continuum Model) pada Software ORCA 5.2.0 sebagai pelarut implisit (Implicit Solvent). Efektifitas antioksidan dianalisis berdasarkan tiga mekanisme interaksi senyawa flavonoid, yaitu HAT, SET-PT, dan SPLET dengan memperoleh nilai terendah dari parameter-parameter termodinamika berupa BDE, IP+PDE, dan PA+ETE pada ketiga mekanisme tersebut. Selanjutnya, dianalisis nilai perhitungan parameter reaktivitas global dengan nilai HOMO dan LUMO yang diperoleh dari perhitungan single point energy dari ketiga senyawa flavonoid tersebut pada fase gas dan fase pelarut air. Sifat antioksidan yang baik ditandai dengan nilai energi gap (?E) yang kecil, electronegativity(?) yang tinggi, potensial kimia (µ) yang lebih positif, hardness (?) yang rendah, softness (s) yang tinggi, electrophilicity (?) yang besar, nucleophilicity (e) yang kecil, energi ionisasi (IE) yang rendah, dan afinitas elektron (EA) yang tinggi. Kata kunci: antioksidan, DFT, CPCM, Quercetin, Myricetin dan Kaempferol, Human lifestyle and dietary habits have increased the risk of degenerative diseases due to excessive oxidation and the formation of free radicals. These free radicals are associated with serious diseases such as atherosclerosis, diabetes, and cancer. Plant-based antioxidants, such as the flavonoids quercetin, myricetin, and kaempferol found in Moringa Oleifera leaves, can inhibit this oxidative damage. Analyzing the antioxidant activity properties is necessary to determine which flavonoid compounds are most effective in free radicals scavenging. Computational DFT calculations can be a solution in theoretical studies to analyze these properties, using the B3LYP exchange-correlation function and def2/SVP basis set. The calculations performed in this study include molecular optimization, vibrational frequencies, and single point energy, conducted in both gas phase and aqueous solvent phase, with the aqueous solvent parameters taken from the CPCM (Conductor-like Polarizable Continuum Model) model in ORCA 5.2.0 software as the implicit solvent. Antioxidant effectiveness is analyzed based on three interaction mechanisms of flavonoid compounds, namely HAT, SET-PT, and SPLET, by obtaining the lowest values of thermodynamic parameters such as BDE, IP+PDE, and PA+ETE in these three mechanisms. Furthermore, the global reactivity parameters are analyzed with HOMO and LUMO values obtained from single point energy calculations of the three flavonoid compounds in both gas phase and aqueous solvent phase. Good antioxidant properties are indicated by a small energy gap (?E), high electronegativity (?), more positive chemical potential (µ), low hardness (?), high softness (s), large electrophilicity (?), small nucleophilicity (e), low ionization energy (IE), and high electron affinity (EA). Keywords: Antioxidant, DFT, CPCM, Quercetin, Myricetin dan Kaempferol
Keyword: Antioksidan, antioxidant, DFT, CPCM, Quercetin, Myricetin, Kaempferol, Teori Fungsi Kerapatan

Judul: Analysis of Antioxidant Activity of Three Flavonoid Compounds from Lime Fruit Using Density Functional Theory
Abstrak: Radikal bebas tubuh dapat diklasifikasikan dari 2 jenis berdasarkan sumbernya, yaitu radikal bebas endogen dan eksogen. Radikal bebas endogen adalah radikal bebas yang berasal dari dalam tubuh sendiri seperti autoksidasi, oksidasi enzimatik dan respiratory burst, sedangkan radikal bebas eksogen adalah radikal bebas yang berasal dari luar tubuh seperti polusi udara, radiasi UV, sinarX, pestisida dan asap rokok. Menghadapi hal ini dibutuhkan antioksidan alami yang meningkatkan imunitas tubuh dengan mengikat radikal bebas. Ketersediaan andtioksidan alami sangat banyak ditemukan pada tanaman lokal seperti jeruk nipis dengan kandungan flavonoid seperti hesperetin, kuersetin, dan naringenin. Diperlukan analisis sifat antioksidan senyawa – senyawa tersebut untuk mengetahui kereaktifan molekul dalam menangkal radikal bebas. Melalui DFT dengan exchange-correlation B3LYP dan basis sets def2/SVP, penulis menganalisis sifat antioksidan hesperetin, kuersetin, dan naringenin. Perhitungan yang dilakukan dengan DFT adalah optimasi molekul, frekuensi vibrasi, dan single point energy. Analisis sifat antioksidan yang diinginkan dengan memperoleh nilai dari parameter BDE rendah, IP rendah, PDE rendah, PA rendah, dan ETE rendah melalui tiga mekanisme HAT, SPLET, dan SET-PT. Selanjutnya dianalisis dengan parameter nilai reaktivitas global yang dipengaruhi oleh nilai energi HOMO dan energi LUMO. Antioksidan yang baik diperoleh dengan nilai parameter reaktivitas global yaitu energi gap kecil, elektronegativitas besar, potensial kimia lebih positif, hardness kecil, softness besar, electrophilicity besar, nucleophilicity kecil, energi ionisasi kecil, dan afinitas elektron besar., Free radicals can be classified into 2 types based on their source, namely endogenous and exogenous free radicals. Endogenous free radicals are free radicals originating from within the body itself such as autoxidation, enzymatic oxidation and respiratory burst, while exogenous free radicals are free radicals originating from outside the body such as air pollution, UV radiation, X-rays, pesticides and cigarette smoke. In dealing with this condition, natural antioxidants are needed to enhance human body’s immune system by scavenging free radicals. Natural antoxidant are abundantly found in local plants such as lime fruits, which contain flavonoids like hesperetin, quercetin, and naringenin. The analysis of the antioxidant properties of these compounds is necessary to understand their molecular reactivity in neutralizing free radicals. Using DFT with the B3LYP exchange-correlation functional and def2/SVP basis sets, the author analyzed the antioxidant properties of hesperetin, quercetin, and naringenin. The DFT calculations involved molecular optimization, vibrational frequency analysis, and single-point energy calculation. The analysis aimed to identify desirable antioxidant properties, characterized by low BDE, low IP, low PDE, low PA, and low ETE, through three mechanisms: HAT, SPLET, and SET-PT. Additionally, the global reactivity values were analyzed, influenced by the HOMO energy and LUMO energy. Excellent antioxidants were identified by having small gap energy, high electronegativity, most positive value of chemical potential, low hardness, high softness, high electrophilicity, low nucleophilicity, low ionization energy, and high electron affinity
Keyword: DFT, Antioxidant, Hesperetin, Quercetin, Naringenin

Judul: Posisi Filogenetik Kura-Kura Carettochelys Insculpta  (Reptillia: Testudinata)
Abstrak: Carettochelys insculpta is an endemic freshwater turtle of southern Papua and northern Australia. Phylogenetic position of this turtle is remain unresolved until now. Most of the research conducted show close relationships of C. insculpta and members of Trionychidae family. However, some of the research show distance between C. insculpta and members of Trionychidae family. This research is conducted to analyze phylogenetic relationship between C. insculpta and other members of Testudinata using 12S rRNA, 16S rRNA, and both gene as markers. DNA samples were obtained from three different organisms of C. insculpta. Two species used as outgroups were Alligator mississippiensis and Iguana iguana. Phylogenetic analysis was carried out using Neighbor-Joining method with Felsenstein 1981 (F81) modeltest. A polytomy tree of Testudinata was produced by using 12S rRNA gene. However, analysis using 16S rRNA and both genes as markers confirmed that C. insculpta was located between the Chelonidae and the Trionychidae family.
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