Aktivitas Antioksidan Ekstrak Daun Mangrove Rhizopora mucronata
Authors: Ridlo Ali , Pramesti Rini , Koesoemadji Koesoemadji , Supriyantini Endang , Soenardjo Nirwani 
Published: July 2018

Rhizopora mucronata merupakan salah satu jenis mangrove yang berpotensi  sebagai sumber antioksidan alami. Daun tanaman ini mengandung senyawa metabolit sekunder seperti tanin, fenolat, klorofil, karotenoid dan alkaloid. Penelitian ini bertujuan menentukan aktivitas antioksidan ekstrak daun R. mucronata. Sampel diambil dari kawasan mangrove Tugurejo, Semarang dan diekstraksi  secara bertingkat berturut-turut dengan pelarut n-heksana, etil asetat dan metanol. Aktivitas antioksidan diukur dengan metode DPPH (1,1-diphenyl-2-picrylhidrazyl) dan nilainya ditentukan berdasarkan nilai Inhibitory Concentration (IC50)pada panjang gelombang 516,5 nm. Kadar senyawa fenolat total ditentukan secara spektrofotometri pada panjang gelombang 725 nm dengan metode Folin-Ciocalteu, kadar klorofil a dan b ditentukan dengan metode spektrofotometri pada panjang gelombang 663 nm dan 645 nm dan kadar karotenoid diukur pada 480 nm. Hasil penelitian menunjukkan ekstrak metanol memiliki nilai IC50terkecil (113,41  ppm), diikuti ekstrak n-heksana 151,13 ppm dan ekstrak etil asetat 184,78 ppm. Kandungan total fenolat tertinggi terdapat pada ekstrak metanol yaitu 21,06 mg GAE/g sampel, ekstrak n-heksana 13,27 mg GAE/g sampel dan ekstrak etil asetat 2,08 mg GAE/g sampel. Kandungan klorofil a tertinggi terdapat pada ekstrak metanol yaitu 2,304  mg/g, diikuti ekstrak n-heksana 0,705 mg/g dan ekstrak etil asetat 0,64 mg/g. Kandungan klorofil b tertinggi dicapai ekstrak metanol yaitu 0,97 mg/g, ekstrak n-heksana 0,50 mgg dan ekstrak etil asetat 0,13 mg/g. Kandungan karotenoid tertinggi dicapai pada ekstrak metanol yaitu 6,49 mg GAE/g, diikuti ekstrak etil asetat (0.54 mg GAE/g) dan ekstrak n-heksana (1,37 mg GAE/g). Ekstrak metanol memiliki aktivitas antioksidan tertinggi dan termasuk dalam antioksidan kategori sedang, sedangkan ekstrak etil asetat dan  n-heksana termasuk dalam  antioksidan kategori lemah.   Rhizopora mucronata is one type of mangrove that has the potential as a source of natural antioxidants. The leaves of this plant contain secondary metabolite compounds such as tannins, phenolics, chlorophyll, carotenoids and alkaloids. This study aims to determine the antioxidant activity of R. mucronata leaf extract. Samples were taken from Tugurejo mangrove area, Semarang and extracted successively with n-hexane, ethyl acetate and methanol solvent. Antioxidant activity was measured by DPPH (1,1-diphenyl-2-picrylhidrazyl) method and its value was determined based on Inhibitory Concentration (IC50) value at 516,5 nm wavelength. Total phenolic compound concentration was determined spectrophotometrically at 725 nm wavelength with Folin-Ciocalteu method. The levels of chlorophyll a and b was determined by spectrofotometry method at 663 nm and 645 nm wavelength and carotenoid levels were measured at 480 nm. The results showed that methanol extract had the smallest IC50 value (113,41 ppm), followed by n-hexane extract 151,13 ppm and ethyl acetate extract 184,78 ppm. The highest total phenolic content was found in methanol extract, 21.06 mg GAE / g sample, n-hexane extract 13,27 mg GAE / g sample and ethyl acetate extract 2.08 mg GAE / g sample. The highest content of chlorophyll a contained in methanol extract is 2,304 mg / g, followed by n-hexane extract 0,705 mg / g and ethyl acetate extract 0,64 mg / g. The highest content of chlorophyll b was methanol extract of 0.97 mg / g, n-hexane extract 0,50 mgg and ethyl acetate extract 0,13 mg / g. The highest carotenoid content was achieved in the methanol extract of 6.49 mg GAE / g, followed by ethyl acetate extract (0.54 mg GAE / g) and n-hexane extract (1.37 mg GAE / g). Methanol extract has the highest antioxidant activity and is included in medium category antioxidants, while ethyl acetate and n-hexane extracts are included in weak category antioxidants.