Aktivitas Antioksidan dan Inhibitor Enzim Pengubah Angiotensin (ACE) Hidrolisat Kolagen Kulit Ikan Nila (Oreochromis niloticus)

Abstract

Ikan nila (Oreochromis niloticus) merupakan salah satu jenis ikan budidaya yang produksinya terus meningkat. Pengolahan ikan nila menjadi produk siap konsumsi menyisakan hasil samping, diantaranya adalah bagian kulit. Kulit ikan diketahui dapat dimanfaatkan sebagai sumber alternatif kolagen halal dan hidrolisatnya memiliki aktivitas biologis yang berguna bagi kesehatan tubuh sehingga mampu meningkatkan nilai fungsinya. Penelitian ini bertujuan untuk mengembangkan potensi kulit ikan nila sebagai sediaan bioaktif hidrolisat kolagen yang mempunyai aktivitas antioksidan dan inhibitor enzim pengubah angiotensin (ACE). Penelitian ini terbagi menjadi tiga tahapan utama, yakni optimasi fase pretreatment kolagen, ekstraksi kolagen dan hidrolisis kolagen. Optimasi proses pretreatment menggunakan larutan NaOH dengan lama waktu yang berbeda berdasarkan kandungan protein terlarut dan asam amino pada larutan sampel. Ekstraksi kolagen dilakukan dengan metode asam dan sifat kolagen yang diperoleh dideterminasi meliputi berat molekul, gugus fungsi, suhu transisi, nilai zeta potensial serta nilai rendemen. Optimasi proses hidrolisis kolagen menggunakan enzim papain komersil untuk menghasilkan hidrolisat kolagen terbaik berdasarkan beberapa parameter uji meliputi derajat hidrolisis, aktivitas penghambatan angiotensin converting enzyme (ACE), dan aktivitas antioksidan secara in vitro. Hasil penelitian menunjukkan bahwa kondisi pretreatment terbaik pada proses ekstraksi kolagen kulit ikan nila yakni selama 12 jam pada konsentrasi NaOH 0,1 N, karakteristik kolagen merupakan kolagen tipe I diindikasikan adanya rantai α1 dan α2. Rerata nilai rendemen kolagen kulit ikan nila dan hidrolisatnya berturut-turut 17,05% dan 15,17%. Waktu hidrolisis, konsentrasi enzim serta interaksi antar kedua faktor tersebut berpengaruh secara signifikan (p < 0,05) terhadap nilai derajat hidrolisis, aktivitas penghambatan ACE dan aktivitas antioksidan hidrolisat kolagen kulit ikan nila. Hidrolisat kolagen kulit ikan nila yang dihidrolisis selama 120 menit dengan pemberian konsentrasi enzim sebesar 8000 U memiliki rerata persentase derajat hidrolisis 33,94%, serta rerata persentase penghambatan ACE tertinggi yakni 74,78%. Pada kombinasi perlakuan yang sama hidrolisat kolagen kulit ikan nila memiliki rerata nilai IC50 terbaik yakni 93,32 µg/mL, termasuk pada kategori senyawa antioksidan kuat. Persentase derajat hidrolisis memiliki korelasi terhadap aktivitas penghambatan ACE dan aktivitas antioksidan, dengan nilai koefisien korelasi Pearson berturut-turut 0,8592 dan - 0,4069.

Tilapia (Oreochromis niloticus) is a type of farmed fish whose production continues to increase. Processing of tilapia into ready-to-consume products leaves some side products, including the skin. Fish skin is known to be used as an alternative source of halal collagen and its hydrolyzate has biological activity that is useful for body health so that it can increase its function value. This study aimed to develop the potential of tilapia skin as a collagen hydrolyzate which had antioxidant and angiotensin converting enzyme (ACE) inhibitor activity. This research was divided into three main stages, including optimization of the collagen pretreatment, collagen extraction and collagen hydrolysis. Optimization of the pretreatment process using NaOH solution with different lengths of time based on the dissolved protein and amino acid content in the sample solution. Collagen extraction was carried out by the acid method and the properties of collagen obtained were determined including molecular weight, functional group, transition temperature, zeta potential value and yield value. Optimization of the collagen hydrolysis process using commercial papain enzymes to produce the best collagen hydrolyzates based on several test parameters including the degree of hydrolysis, inhibitory activity of angiotensin converting enzyme (ACE), and antioxidant activity in vitro. The results showed that the best pretreatment conditions in the collagen extraction process was for 12 hours at a concentration of 0.1 N NaOH. The characteristics of collagen were type I collagen which indicated α1 and α2 chains. The average yield of tilapia skin collagen and its hydrolyzate were 17.05% and 15.17%, respectively. Hydrolysis time, enzyme concentration and the interaction between the two factors had a significant effect (p<0.05) on the degree of hydrolysis, ACE inhibitory activity and antioxidant activity of collagen hydrolysate. Collagen hydrolyzed for 120 minutes with an enzyme concentration of 8000 U had a percentage of degree of hydrolysis 33.94%, and the highest mean percentage of ACE inhibition was 74.78%. In the same treatment combination, tilapia skin collagen hydrolyzate had the best IC50 value of 93.32 µg/mL, categorized as strong antioxidant compounds. The percentage of the degree of hydrolysis had a correlation with ACE inhibitory activity and antioxidant activity, with the Pearson correlation coefficient values 0.8592 and -0.4069, respectively.