Judul: Isolation, Diversity, and Antioxidant Activity of Endophyte Actinobacteria from Dayak Onion (Eleutherine palmifolia L.Merr)
Abstrak: Bawang dayak merupakan tanaman khas Kalimantan yang berkhasiat sebagai antioksidan. Tanaman ini merupakan salah satu sumber potensial mikroorganisme endofit penghasil antioksidan. Penelitian ini bertujuan mengisolasi, mengkaji keragaman, dan menguji aktivitas antioksidan aktinobakteri bawang dayak. Tujuh isolat aktinobakteri telah berhasil diisolasi dari umbi bawang dayak menggunakan medium HVA. Berdasarkan karakter morfologi koloni, miselia aerial, dan penataan sporanya, isolat tersebut diduga termasuk kelompok Streptomyces sp. Uji aktivitas antioksidan menggunakan DPPH menunjukkan bahwa aktivitas antioksidan supernatan isolat-isolat tersebut memiliki aktivitas antioksidan dengan persen inhibisi berkisar antara 38,8% hingga 102,6%. Isolat EPB5 memiliki aktivitas antioksidan tertinggi sebesar 102,6%. Dengan demikian, tujuh isolat aktinobakteri tersebut berpotensi sebagai sumber antioksidan., Dayak onion (Eleutherine palmifolia L. Merr) is a typical Kalimantan herbaceous plant which is well known as a source of antioxidant. This plant could be a great source of endophytic microbes producing antioxidant compounds. The present study was aimed to isolate and analyze the morphological diversity of E. palmifolia endophytic actinobacteria as well as their antioxidant properties. Seven actinobacteria isolates have successfully been isolated from Dayak onion bulbs using HVA medium. Based on the morphological characteristics in different media and the type of their spore chains, it was assumed that these isolates belonged to the genus Streptomyces sp. As tested by DPPH analysis, supernatant derived from these isolates showed antioxidant activity with inhibition percentage ranging from 38,8% to 102,6%. The highest antioxidant activity exhibited by EPB5 isolate. In conclusion, all these isolates could be further studied and developed as the alternative source of antioxidant.
Keyword: morphology of colony, spore chains, supernatant, DPPH, inhibitory activity

Judul: Kapasitas Antioksidan Bawang Dayak (Eleutherine palmifolia) dalam Bentuk Segar,Simplisia dan Keripik, pada Pelarut Nonpolar, Semipolar dan Polar
Abstrak: Bawang dayak (Eleutherine palmifolia) is a red bulb plant from Central Kalimantan, which has bioactive compounds such as phenols, flavonoids, alkaloids, glycosides and tannins. The existence of bioactive compounds become parameter of antioxidant activity of this red bulb. The study showed antioxidant capacity of bawang dayak in fresh form, simplisia (dried) form and chips form, which were extracted by the solvent hexane, ethyl acetate, methanol, ethanol and water. Antioxidant capacity was measured by DPPH method and rancimat method. Phytochemical screening was conducted to determine the bioactive compounds of bawang dayak in each form for every solvent. Based on DPPH method, bawang dayak in fresh form was extracted with ethyl acetate had the highest antioxidant capacity value that is 227.0% equal to 1.02 mg AEAC/mg extract. Simplisia form which was extracted with ethanol had antioxidant capacity value 51.8% equal to 0.21 mg AEAC/mg extract. Chips form was extracted with ethylacetate and ethanol had the highest antioxidant capacity values 57.5% and 46.5% which were equal to 0.24 mg AEAC/ mg extract and 0.18 mg AEAC/ mg extract. The induction time of ethylacetate fresh extract, ethanol simplisia extract and ethylacetate chip extract based on measurement with rancimat method, were 3.7 hours, 2.8 hours and 2.6 hours. All of extract had higher induction time than tocoferol. Besides, the measurement of phenolic content resulted that methanol fresh extract, ethanol simplisia extract and methanol chip extract had 4.29 mg GAE/100 mg extract, 3.52 mg GAE/ 100 mg extract and 3.38 mg GAE/100 mg extract. Vitamin C (ascorbic acid) on fresh bawang dayak was quite high, reaching 61.5mg/100gram, whereas vitamin C on simplicia and chip were decreased, respectively 41.0 mg/100 gram and 22.0 mg/100gram due to the heating process. The Ethylacetate fresh extract contains of alkaloid , phenolic, flavonoids, triterpenoids, steroids and glycosides compounds, while the ethanol simplscia extract and ethylacetate chip extract contains of alkaloids, saponins, tannins, phenolics, flavonoids, triterpenoids, steroids and glycosides compounds.
Keyword: 

Judul: Cycle Hamilton pada Graf Lengkap, Graf Regular, dan Graf 2-Connected 4-Regular Berorder Kurang dari Sepuluh
Abstrak: Suatu graf disebut graf Hamilton apabila graf tersebut memuat cycle Hamilton, yaitu cycle yang melewati setiap vertex tepat satu kali. Menentukan keberadaan cycle Hamilton pada suatu graf dapat menggunakan syarat cukup yang berupa teorema-teorema yang telah diperkenalkan sejak tahun 1950-an. Beberapa syarat cukup yang dibahas dalam karya ilmiah ini adalah syarat cukup yang berhubungan dengan graf lengkap dan graf regular. Suatu graf lengkap berorder 𝑛������ ≥ 3 dan graf r-regular berorder 𝑛������ ≤ 2𝑟������ + 1 merupakan graf Hamilton, Karena kedua graf tersebut memuat cycle Hamilton. Selanjutnya, syarat cukup tersebut digunakan untuk menentukan keberadaan cycle Hamilton pada graf 2-connected 4- regular berorder kurang dari 10.
Keyword: graf Hamilton, graf regular, graf lengkap, graf 2-connected 4-regular