Abstrak: Penelitian ini bertujuan untuk melakukan biosintesis nanopartikel perak menggunakan ekstrak rimpang jahe merah sebagai pereduksi pada suhu ruang. Sintesis dilakukan dengan pengadukan pada shaker (150 rpm) dan tanpa pengadukan dengan rasio ekstrak dan larutan AgNO 3 1:1; 1:3; 1:4; 1:5; 1:10 dan 1:20 pada berbagai rentang waktu pengamatan. Hasil memperlihatkan bahwa metabolit sekunder pada ekstrak jahe merah mampu mereduksi Ag + menjadi Ag 0 dan membentuk nanopartikel perak yang diindikasikan dengan adanya perubahan warna larutan. Nanopartikel perak dikarakterisasi menggunakan spektrofotometer UV-Vis dan absorbansi maksimum terukur di sekitar 450 nm. Secara keseluruhan, sintesis dengan pengadukan menghasilkan produk dengan waktu yang lebih singkat dibanding tanpa pengadukan.

Tanaman mangrove Rhizophora apiculatamemiliki potensi yang sangat besar digunakan dalam bidang fitofarmakasebagai bahanantibakteri. Penelitian ini bertujuan untuk melihat sensitivitas daun R. apiculata yang diekstraksi menggunakan 4 jenis bahan pelarut berbeda, yaitu etanol, air panas, etil asetat, dan n-heksana terhadap Aeromonas hydrophila. Metode yang digunakan pertama pembuatan ekstrakdaun R. apiculata dengan pelarut etanol 96%, yang selanjutnya dipartisi menggunakan pelarut air panas, etil asetat, dan n-heksana. Kemudian dilakukan uji sensitivitas (zona hambat)  ekstrak daunR. apiculata terhadap  A. hydrophila. Konsentrasi ekstrakdaun R. apiculata dari setiap jenis pelarut yang digunakan adalah 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000ppm, sebagai kontrol digunakan antibiotik oxytetracyclin, disc  blank yang digunakan berukuran 6mm. Setiap perlakuan dilakukan tiga kali ulangan. Hasil penelitian menunjukkan bahwa ekstrak daun R. apiculata yang diekstraksi menggunakan pelarut berbeda pada dosis 1000 sampai 10000 ppm mampu menghambat pertumbuhan bakteri A. hydrophila, yakni berkisar antara 6,15-9,08 mm dengan pelarut etanol, air panas berkisar antara 6,20-8,50 mm, etil asetat berkisar antara 7,55-12,03 mm, dan n-heksana berkisar antara 6,15-8,45. Simpulan yang diperoleh bahwa ekstrak etil asetat lebih sensitif dibandingkan pelarut lainnya terhadap pertumbuhan A. hydrophila. Kata kunci :Rhizophora apiculata, Aeromonas hydrophila, Bahan Pelarut, dan                   Sensitivitas

Abstract. Saryono, Octarina N, Yuharmen, Pratiwi NW, Ardhi A. 2017. Antifungal activity of the extracts and fractions of dahlia tuber (Dahlia variabilis) against pathogenic skin fungi. Nusantara Bioscience 9: 146-151. Dahlia plant (Dahlia variabilis) can be easily found in the highlands in Indonesia and its tuber has been reported to have some bioactive compounds which are potential to be utilized as an antimicrobial agent. This study aimed to determine antifungal activity and minimum inhibitory concentration (MIC) of n-hexane and methanol extracts and fractions of red-flowered dahlia tubers against pathogenic skin fungi Candida albicans and Microsporum gypseum using disc diffusion method. The n-hexane and methanol extracts and fractions of dahlia tuber showed their antifungal activity against C. albicans and M. gypseum, with the larger activity, was found in both extracts and fractions of methanol. The best fractions of n-hexane and methanol were chosen and determined their minimum inhibitory concentration; which the F5 n-hexane fraction and the F2 methanol fraction gave the MIC of 1.50% and 0.50% against C. albicans respectively, whereas both F1 n-hexane and F2 methanol fraction gave the MIC of 0.50% against M. gypseum. The high antifungal activity of F2 of methanol extract against C. albicans and M. gypseum allowed this fraction to be utilized as a medicinal drug for candidiasis and other fungal skin infections.

Over the past decade, the use of biological agents such as plants, cyanobacteria, bacteria, and fungi for synthesis of metal nanoparticles has been developed. The aim of this study was to investigate antibacterial activity of Cucumis melo L. peel extract and its nanoparticles formulation against Eschericia coli. The nanoparticles were made using silver nitrate with the ratio between C. melo L. extract and silver nitrate aqueous solution (1 mM) were 1:10 and 1:15. The formation of silver nanoparticles was observed after microwaved for 30, 60, 90, 120, 150, and 180 seconds by visible spectrophotometry analysis. Phytochemical screening revealed the presence of flavonoid and terpenoid within the extract. However, the characteristic of surface plasmon resonance band, which occurs in the range of 410-500 nm were not found in the nanoparticle extract, even though the reaction time was extended to 330s. Antibacterial activity against E. coli of the extract and its nanoparticle formulations was determined using Resazurin microtiter assay and compared to Amoxsan ® as positive control. The highest E. coli inhibition was exhibited by the nanoparticles (79.8739±0.3859), followed by the extract (65.2821±0.9949). The nanoparticles and the extract have potent antibacterial activity compared to positive control (84.5519 ± 0.2544). In conclusion, the antibacterial activity of the C. melo L. nanoparticles formulation was better than its extract.

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