Electronic Theses and Dissertation

Aktinobakteri merupakan bakteri Gram positif yang berpotensi menghasilkan metabolit sekunder bioaktif, termasuk senyawa antioksidan. Penelitian ini bertujuan untuk menganalisis aktivitas antioksidan ekstrak aktinobakteri tanah ATS11 asal Stasiun Penelitian Soraya menggunakan pelarut etanol, etil asetat, dan n-heksan serta mengidentifikasi metabolit sekundernya menggunakan Gas Chromatography-Mass Spectrometry (GC-MS). Aktivitas antioksidan diuji menggunakan metode 2,2-diphenyl-1-picrylhydrazyl (DPPH) pada konsentrasi 10, 50, 100, dan 150 ppm. Persentase inhibisi dihitung berdasarkan nilai absorbansi, kemudian ditentukan nilai IC₅₀ menggunakan analisis regresi probit. Hasil penelitian menunjukkan bahwa ekstrak etanol memiliki aktivitas antioksidan tertinggi dengan nilai IC₅₀ sebesar 14,87 ppm, diikuti ekstrak etil asetat sebesar 21,87 ppm, dan n-heksan sebesar 111,93 ppm. Analisis GC-MS terhadap ekstrak etanol mengidentifikasi 55 senyawa, dengan senyawa dominan berupa Maltol (13,58%), 2-Furanmethanol (11,09%), dan 4H-Pyran-4-one, 2,3-dihydro-3,5-dihydroxy-6-methyl- (4,18%). Berdasarkan hasil penelitian dapat disimpulkan bahwa ekstrak etanol aktinobakteri ATS11 memiliki aktivitas antioksidan paling tinggi dan berpotensi sebagai sumber antioksidan alami karena mengandung berbagai metabolit sekunder bioaktif.

Kata kunci: aktinobakteri ATS11, antioksidan, DPPH, GC-MS, metabolit sekunder.

Actinobacteria are Gram-positive bacteria capable of producing various bioactive secondary metabolites, including antioxidant compounds. This study aimed to evaluate the antioxidant activity of soil actinobacteria isolate ATS11 from the Soraya Research Station using ethanol, ethyl acetate, and n-hexane extracts and to identify its secondary metabolites using Gas Chromatography-Mass Spectrometry (GC-MS). Antioxidant activity was determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay at concentrations of 10, 50, 100, and 150 ppm. The percentage of inhibition was calculated from absorbance values, and the IC₅₀ values were determined using probit regression analysis. The results showed that the ethanol extract exhibited the highest antioxidant activity with an IC₅₀ value of 14.87 ppm, followed by the ethyl acetate extract (21.87 ppm) and the n-hexane extract (111.93 ppm). GC-MS analysis of the ethanol extract identified 55 compounds, with the major compounds being Maltol (13.58%), 2-Furanmethanol (11.09%), and 4H-Pyran-4-one, 2,3-dihydro-3,5-dihydroxy-6-methyl- (4.18%). The results indicate that the ethanol extract of actinobacteria isolate ATS11 exhibited the highest antioxidant activity and has potential as a natural antioxidant source due to the presence of various bioactive secondary metabolites. Keywords: Actinobacteria ATS11, antioxidant, DPPH, GC-MS, secondary metabolites.