The Malaysian Journal of Analytical Sciences, Vol 16 No 3 (2012): 309 - 317 309 PHYTOCHEMICAL SCREENING AND ACTIVITIES OF HYDROPHILIC AND LIPOPHILIC ANTIOXIDANT OF SOME FRUIT PEELS (Kajian Fito-kimia dan Aktiviti Hidrofilik dan Lipofilik Antioksida untuk Beberapa Kulit Buah) Khairusy Syakirah Zulkifli 1 , Noriham Abdullah 1 , Aminah Abdullah 2 , Nurain Aziman 1 , Wan Saidatul Syida Wan Kamarudin 1 1 Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia 2 School of Chemicals Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia *Corresponding author: Abstract This study was conducted to screen the secondary metabolites compounds including alkaloids, tannins, saponins and flavonoids as well as to determine the antioxidant activities of four types of fruit peels namely Psidium guajava (guava), Mangifera indica (Chakonan mango), Citrus sinensis (Navel orange) and Malus sylvestris (Granny Smith apple). The hydrophilic and lipophilic antioxidant activities were investigated using three different assays such as Ferric Reducing Antioxidant Power (FRAP), 2, 2- diphenyl-1-picrylhydrazyl (DPPH) scavenging activity and Oxygen Radical Absorbance Capacity (ORAC). Total Phenolic Content (TPC) and Total Flavonoids Content (TFC) were also conducted and the correlations between the antioxidant assays with TPC and TFC were evaluated. The TPC in the peels extract ranged between 204.90 to 517.00 mg GAE/g extract weight while TFC ranged between 97.48 to 177.86 mg QE/g extract weight. The FRAP, EC 50 scavenging activity and ORAC values were 18.78 to 45.36 mM TE/100g extract weight, 0.146 to 0.717 mg/ml scavenging effect and 37.54 to 60.59 μM TE/g extract weight respectively. The extract of M. indica peels appeared to be as potent as ascorbic acid with maximum inhibition of 74% at 200 ppm. M. indica peels showed highest value in all antioxidant assays and in TPC while the highest in TFC was found in M. sylvestris peels. There were strong correlations between all antioxidant assays with TPC but very weak correlations with TFC. This study suggested that the extracts of fruit peels are convenient to be use as functional ingredients in food product development as they are rich in antioxidant activities. Keywords: Secondary metabolites, hydrophilic, lipophilic, antioxidant, fruit peels Abstrak Kajian ini dijalankan untuk mengkaji kompaun metabolit sekunder termasuklah alkaloid, tannin, saponin dan flavonoid dan mengkaji aktiviti antioksida keatas empat jenis kulit buah-buahan antaranya Psidium guajava (jambu batu), Mangifera indica (mangga madu), Citrus sinensis (oren Navel) and Malus sylvestris (epal Granny Smith). Aktiviti hidrofilik dan lipofilik antioksida dikaji menggunakan tiga ujian berbeza iaitu ujian penurunan ferrik (FRAP), pemerangkapan radikal bebas 2, 2- difenil-1-pikrilhidrazil (DPPH) dan kapasiti menyerap oksigen radikal (ORAC). Kandungan fenolik total (TPC) dan kandungan flavonoid total (TFC) turut dijalankan dan korelasi antara ujian antioksida dengan TPC dan TFC dinilai. TPC di dalam esktrak kulit buah berada dalam lingkungan 204.90 hingga 517.00 mgGAE/100g berat ekstrak manakala TFC berada di antara 97.48 hingga 177.86 mgQE/100g berat ekstrak. Nilai FRAP, aktiviti pemerangkapan EC 50 dan nilai ORAC masing-masing ialah 18.78 hingga 45.36 μM TE/g berat ekstrak, 0.146 hingga 0.717 mg/ml kesan pemerangkapan dan 37.54 hingga 60.59 μM TE/g berat ekstrak. Ekstrak kulit M. indica menunjukkan kekuatan setaraf asid askorbik dengan perencatan semaksima 74% pemerangkapan di kepekatan 200 ppm. Esktrak kulit M. indica menunjukkan nilai tertinggi di dalam semua ujian antioksida dan TPC manakala nilai TFC tertinggi dijumpai di dalam ekstrak kulit M. sylvestris. Korelasi yang kukuh ditunjukkan antara semua ujian antioksida dengan TPC tetapi korelasi yang lemah dengan TFC. Kajian ini menunjukkan bahawa esktrak kulit buah-buahan tersebut sesuai digunakan sebagai bahan berfungsi di dalam penghasilan produk makanan berikutan kekayaan aktiviti antioksida. Kata kunci: metabolit sekunder, hidrofilik, lipofilik, antioksida, kulit buah-buahan