Type of Solvent Methanol And N-Hexane Against Antioxidant Activity Seaweed Extract Gelidium sp.From Drini Beach Gunungkidul -Yogyakarta Gelidium sp. the one of red seaweed which has potential as natural antioxidant. The researh was to know the activity of methanol extract, n-hexane Gelidium sp., and determined total phenolic compound of pigments (chlorophyll a and carotenoid). Decriptive explorative method was used in this research and it was taken from Drini Beach, Gunungkidul, Yogyakarta. Maseration to this sample was done by methanol as solvent, evaporated by rotary evaporator and partitied by n-hexane solvent with separatory funnel. Antioxidant activity was determined by transfer electron method using DPPH (1,1-diphenyl-2-picrylhidrazyl) as free radicals. Total phenolic compound being tested using Folin-Ciocalteu solution with gallic acid as standard and measured at a wavelength of 725 nm, while the chlorophylls were spectrophotometry method and measured at a wavelength of 663 nm and 646 nm as well as carotenoids were measured at a wavelength of 470 nm. The results showed that IC50 value of methanol extract was 340,10 ppm and n-hexane was 66,25 ppm. IC50 value of methanol extract was categorized as very weak in antioxidant activity, while n-heksan extract was categorized as strong. Total phenolic content in each extract were 46,55 and 135,62 (mg GAE/g extract), chlorophyll a 8,47 and 10,88 (mg/g extract sample) and carotenoids 50,38 and 84,27 (μmol/g extract sample).
Keywords: Gelidium sp., Antioxidant, DPPH
AbstrakGelidium sp. merupakan salah satu rumput laut merah yang berpotensi sebagai sumber antioksidan alami. Penelitian ini bertujuan untuk mengetahui aktivitas antioksidan ekstrak metanol dan n-heksan Gelidium sp. (segar), menentukan kadar total fenolat dan pigmen (klorofil a dan karotenoid). Metode deskriptif eksploratif digunakan dalam penelitian ini dan diperoleh diambil dari Pantai Drini, Gunungkidul, Yogyakarta dibersihkan dengan air tawar, dimaserasi dengan pelarut metanol, diuapkan dengan rotary evaporator dan dipartisi dengan pelarut n-heksan menggunakan corong pemisah (separatory funnel). Aktivitas antioksidan ditentukan dengan metode transfer elektron menggunakan DPPH (1,1-diphenyl-2-picrylhidrazyl) sebagai radikal bebas. Kadar total fenolat diuji dengan metode Folin-Ciocalteu dengan asam galat sebagai larutan standar dan diukur pada panjang gelombang 725 nm. Kadar klorofil a diukur dengan metode spektrofotometri pada panjang gelombang 663 nm dan 646 nm sedangkan kadar karotenoid diukur pada panjang gelombang 470 nm. Hasil penelitian menunjukkan nilai IC50 ekstrak metanol sebesar 340,10 ppm dan ekstrak n-heksan 66,25 ppm. Nilai IC50 ekstrak metanol termasuk kategori aktivitas antioksidan sangat lemah sedangkan n-heksana termasuk kategori kuat. Kadar total fenolat pada masing-masing ekstrak 46,55 dan 135,62 (mg GAE/g ekstrak), kadar klorofil a sebesar 8,47 dan 10,88 (mg/g sampel) dan kadar karotenoid sebesar 50,38 dan 84,27 (µ mol/g sampel).
