Profile and Antioxidant Capacity of Phenolic Compounds from Rice Straw

Abstract

ABSTRACT

A study was conducted with the purpose of comparing the antioxidant properties of the aquadest extracts of three varieties of red rice straw: Memberamo, Ciherang, and Barak Cenana. The extraction was done using ultrasound-assisted extraction (UAE) technique. The compound profiling of the phenolic compounds in the extracts were done by thin-layer chromatography (TLC) and gas chromatography (GC). The antioxidant activity measurements were done using the DPPH and FRAP assays, using garlic acid as the standard. The total phenolic content assay showed no significant difference in the total phenolic content among the three rice straw varieties. TLC results showed two presumable flavonoids in Memberamo and Ciherang rice straw extracts, and three presumable flavonoids in Barak Cenana rice straw extract. GC analysis results detected three components in Memberamo rice straw extract, five components in Ciherang rice straw extract, and six components in Barak Cenana rice straw extract. The DPPH assay results showed that Barak Cenana rice straw extract indicated the highest antioxidant activity among the three varieties, while the FRAP assay results showed no significant difference in the antioxidant activity among the three rice straw varieties.

Keywords: Antioxidant, phenolic compounds, rice straw, ultrasound-assisted extraction

ABSTRAK

Penelitian dilakukan untuk membandingkan sifat antioksidan dari ekstrak akuades jerami tiga varietas padi, yaitu padi Memberamo, padi Ciherang, dan padi Barak Cenana. Ekstraksi dilakukan dengan metode ultrasound-assisted extraction (UAE). Penelitian profil senyawa fenolik dalam ekstrak dilakukan dengan metode kromatografi lapis tipis (KLT) dan kromatografi gas (GC). Pengukuran aktivitas antioksidan dilakukan dengan uji DPPH dan uji FRAP menggunakan asam galat sebagai standar. Pengukuran kadar fenolik total menunjukkan bahwa tidak ada perbedaan signifikan antara kadar senyawa fenolik ekstrak jerami ketiga varietas padi. Hasil KLT menunjukkan dua senyawa yang diduga golongan flavonoid pada ekstrak jerami varietas Memberamo dan Ciherang, serta tiga senyawa yang diduga golongan flavonoid pada ekstrak jerami varietas Barak Cenana. Analisis GC mendeteksi tiga komponen dalam ekstrak jerami padi Memberamo, lima komponen dalam ekstrak jerami padi Ciherang, serta enam komponen dalam ekstrak jerami padi Barak Cenana. Uji DPPH menunjukkan bahwa aktivitas antioksidan tertinggi dimiliki oleh jerami padi Barak Cenana, sedangkan uji FRAP menunjukkan bahwa tidak ada perbedaan siginifikan antara aktivitas antioksidan ekstrak jerami ketiga varietas padi.

Keywords: Antioksidan, senyawa fenolik, jerami padi, ultrasound-assisted extraction