Electronic Theses and Dissertation

Meningkatnya resistensi Escherichia coli (E. coli) terhadap antibiotik mendorong pencarian senyawa antibakteri baru dari bahan alam yang lebih aman dan mudah didapat. Biji alpukat (Persea americana Mill.), telah dimanfaatkan sebagai obat herbal tradisional oleh masyarakat lokal. Penelitian ini menguji aktivitas antibakteri ekstrak etanol, fraksi n-heksana, etil asetat serta metanol dari ekstrak kasar metanol biji alpukat terhadap E. coli. Analisis fitokimia dilakukan untuk mengidentifikasi golongan senyawa pada setiap fraksi, sementara komposisi ekstrak etanol dianalisis menggunakan GC-MS. Aktivitas antibakteri dievaluasi dengan metode difusi cakram pada konsentrasi 20%, 40%, 60%, dan 80%. Gentamisin 10 µg dan metanol sebagai kontrol positif dan kontrol negatif. Analisis GC-MS mengidentifikasi gliserin (28,76%), asam palmitat (n-hexadecanoic acid) (2,83%), asam erukat (1,31%), dan kampesterol (0,96%) sebagai komponen utama ekstrak etanol. Uji fitokimia menunjukkan selektivitas ekstraksi: fraksi n-heksana positif triterpenoid/steroid; fraksi etil asetat positif fenolik, flavonoid, tanin, triterpenoid/steroid; fraksi metanol positif fenolik, alkaloid, dan saponin. Namun, pada uji antibakteri, semua konsentrasi ekstrak dan fraksi tidak menghasilkan zona hambat, sedangkan kontrol positif gentamisin menghasilkan zona hambat rata-rata 21,75 mm. Hasil penelitian mengindikasikan bahwa ekstrak etanol dan fraksi biji alpukat tidak memiliki aktivitas antibakteri terhadap pertumbuhan E. coli pada konsentrasi yang diuji, sehingga diperlukan penelitian lainnya dengan metode ekstraksi, konsentrasi, atau strategi formulasi yang berbeda untuk meningkatkan potensi bioaktivitasnya.

Kata kunci: Persea americana Mill., GC-MS, antibakteri, Escherichia coli, zona hambat.

The increasing resistance of Escherichia coli (E. coli) to antibiotics has driven the search for new antibacterial agents derived from natural sources that are safer and readily available. Avocado seeds (Persea americana Mill.) have traditionally been used as herbal medicine by local communities. This study evaluated the antibacterial activity of ethanolic extract and the n-hexane, ethyl acetate, and methanol fractions of crude methanolic avocado seed extract against E. coli. Phytochemical analysis was conducted to identify the classes of compounds present in each fraction, while the composition of the ethanolic extract was analyzed using GC–MS. Antibacterial activity was assessed using the disc diffusion method at concentrations of 20%, 40%, 60%, and 80%, with gentamicin (10 µg) as the positive control and methanol as the negative control. GC–MS analysis identified glycerin (28.76%), palmitic acid (n-hexadecanoic acid) (2.83%), erucic acid (1.31%), and campesterol (0.96%) as the major components of the ethanolic extract. Phytochemical screening showed extraction selectivity: the n-hexane fraction was positive for triterpenoids/steroids; the ethyl acetate fraction was positive for phenolics, flavonoids, tannins, and triterpenoids/steroids; and the methanol fraction was positive for phenolics, alkaloids, and saponins. However, in the antibacterial assay, none of the extract or fraction concentrations produced inhibition zones, whereas the positive control gentamicin produced a mean inhibition zone of 21.75 mm. These findings indicate that the ethanolic extract and fractions of avocado seed did not exhibit antibacterial activity against E. coli at the tested concentrations, suggesting that further studies using different extraction methods, concentrations, or formulation strategies are required to enhance their bioactivity. Keywords: Persea americana Mill., GC–MS, antibacterial, Escherichia coli, inhibition zone