Electronic Theses and Dissertation

Kulit batang cempaka kuning (Magnolia champaca L.) diketahui mengandung
senyawa metabolit sekunder yang berpotensi sebagai antioksidan, namun aktivitas
antioksidannya berdasarkan perbedaan tingkat kepolaran pelarut masih belum banyak
dilaporkan. Penelitian ini bertujuan untuk menentukan aktivitas antioksidan ekstrak n
heksan, etil asetat, dan metanol kulit batang cempaka kuning. Ekstraksi dilakukan
menggunakan metode maserasi bertingkat dengan pelarut n-heksan, etil asetat, dan
metanol. Uji kualitatif dilakukan menggunakan pereaksi FeCl₃ 1%, sedangkan
aktivitas antioksidan dianalisis menggunakan metode 2,2-difenil-1-pikrilhidrazil
(DPPH) dengan asam askorbat sebagai kontrol positif. Aktivitas antioksidan
dinyatakan berdasarkan nilai IC₅₀ yang diperoleh melalui analisis regresi. Hasil
penelitian menunjukkan bahwa ekstrak metanol memiliki rendemen tertinggi sebesar
5,39% diikuti etil asetat sebesar 0,84% dan n-heksan sebesar 0,23%. Uji fenolik
menunjukkan bahwa ekstrak metanol memberikan perubahan warna hijau kehitaman,
yang mengindikasikan kandungan senyawa fenolik lebih tinggi dibandingkan ekstrak
lainnya. Nilai IC₅₀ ekstrak n-heksan, etil asetat, metanol, dan asam askorbat berturut
turut sebesar 4956,1; 162,8; 5,1; dan 2,7. Berdasarkan klasifikasi aktivitas antioksidan,
ekstrak n-heksan tergolong sangat lemah, etil asetat tergolong lemah, sedangkan
ekstrak metanol dan asam askorbat tergolong sangat kuat. Hasil penelitian
menunjukkan bahwa metanol merupakan pelarut yang paling efektif dalam
mengekstraksi senyawa antioksidan dari kulit batang cempaka kuning (Magnolia
champaca L.) dan berpotensi sebagai sumber antioksidan alami.
Kata kunci: antioksidan, DPPH, IC₅₀, Magnolia champaca L., fenolik

The stem bark of yellow champaca (Magnolia champaca L.) is known to contain secondary metabolites with potential antioxidant properties, however, its antioxidant activity based on differences in solvent polarity has not been widely reported. This study aimed to the determine the antioxidant activity of the n-hexane, ethyl acetate, and methanol extracts of yellow champaca (Magnolia champaca L.) stem bark. Extraction was carried out using a successive maceration method with n-hexane, ethyl acetate, and methanol as solvents. Qualitative analysis was performed using 1% FeCl₃ reagent, while antioxidant activity was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, with ascorbic acid as the positive control. Antioxidant activity was expressed as the IC₅₀ value obtained through regression analysis. The results showed as the methanol extract produced the highest extraction yield (5.39%), followed by the ethyl acetate extract (0.84%) and the n-hexane extract (0.23%). The phenolic test showed that the methanol extract exhibited a dark green coloration, indicating a higher phenolic compound content than the other extracts. The IC₅₀ values of the n-hexane, ethyl acetate, methanol extracts, and ascorbic acid were 4956.1, 162.8, 5.1, and 2.6, respectively. Based on the classification of antioxidant activity, the n-hexane extract exhibited very weak antioxidant activity, the ethyl acetate extract showed weak activity, whereas the methanol extract and ascorbic acid demonstrated very strong antioxidant activity. These findings indicate that methanol is the most effective solvent for extracting antioxidant compounds from the stem bark of yellow champaca (Magnolia champaca L.) and that the stem bark has potential as a natural source of antioxidants. Keywords: antioxidant, DPPH, IC₅₀, Magnolia champaca L., phenolic