Search Repository Universitas Fort De Kock

Radikal bebas dapat menimbulkan stres oksidatif yang berperan dalam proses
penuaan dan berbagai penyakit degeneratif. Antioksidan dari bahan alam
dianggap lebih aman dibandingkan antioksidan sintetik. Kulit putih semangka
(Citrullus lanatus) dan daun salam (Syzygium polyanthum) diketahui
mengandung metabolit sekunder seperti flavonoid, alkaloid, saponin, tanin, dan
fenol yang berpotensi sebagai antioksidan. Penelitian ini bertujuan untuk
mengetahui aktivitas antioksidan ekstrak etanol kulit putih semangka dan daun

salam baik secara tunggal maupun kombinasi dengan metode DPPH (2,2-difenil-
1-pikrilhidrazil), serta mengevaluasi efek interaksi kombinasi menggunakan nilai

FICI (Fractional Inhibitory Concentration Index). Ekstraksi dilakukan dengan
maserasi menggunakan etanol 96%. Aktivitas antioksidan diukur pada panjang
gelombang 517 nm menggunakan spektrofotometer UV-Vis, kemudian nilai IC50
ditentukan melalui analisis regresi linear. Hasil penelitian menunjukkan bahwa
ekstrak daun salam memiliki IC50 sebesar 55,73 ppm (kategori kuat), ekstrak kulit
putih semangka 72,94 ppm (kategori kuat), dan vitamin C sebagai kontrol positif
12,11 ppm (sangat kuat). Kombinasi ekstrak kulit putih semangka dan daun salam
rasio 1:1 menghasilkan IC50 71,75 ppm dengan nilai FICI 1,134 yang tergolong
indiferen. Kombinasi rasio 1:3 menghasilkan IC50 86,90 ppm dengan nilai FICI
1,466 (indiferen), sedangkan kombinasi rasio 3:1 menghasilkan IC50 lebih tinggi
dari ekstrak tunggal dengan nilai FICI 0,478(sinergis).

Free radicals can cause oxidative stress, which plays a role in the aging process
and various degenerative diseases. Antioxidants derived from natural sources are
considered safer than synthetic antioxidants. White watermelon rind (Citrullus
lanatus) and salam leaves (Syzygium polyanthum) are known to contain
secondary metabolites such as flavonoids, alkaloids, saponins, tannins, and
phenols, which have potential antioxidant properties. This study aimed to
determine the antioxidant activity of ethanol extracts of white watermelon rind
and salam leaves, both individually and in combination, using the DPPH (2,2-
diphenyl-1-picrylhydrazyl) method. It also aimed to evaluate the interaction effect
of the combinations using the FICI (Fractional Inhibitory Concentration Index)
value. Extraction was performed by maceration using 96% ethanol. Antioxidant
activity was measured at a wavelength of 517 nm using a UV-Vis
spectrophotometer, and IC50 values were determined through linear regression
analysis. The results showed that the salam leaf extract had an IC50 of 55.73 ppm
(strong category), white watermelon rind extract had an IC50 of 72.94 ppm (strong
category), and vitamin C (used as a positive control) had an IC50 of 12.09 ppm
(very strong). The 1:1 combination produced an IC50 of 71.75 ppm with a FICI
value of 1.134, categorized as indifferent. The 1:3 combination had an IC50 of
86.90 ppm with a FICI value of 1.466 (indifferent), While the 3:1 combination
showed a higher IC50 than the individual extracts but with a FICI value of 0.478,
indicating a synergistic effect.