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The negative effects of free radicals can be reduced by antioxidants. Antioxidants inhibit the oxidation reaction due to free radicals. Antioxidants can be found in a variety of plants, such as Bilimbi (Averrhoa Bilimbi L.). The objectives of this research were to study antioxidant activity of leaves, fruit and twigs of Bilimbi by DPPH (2,2diphenyl-1-picrylhydrazyl) and ABTS [2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid)] and determine its phytochemical content. Antioxidant activities, total phenolic content (TPC) and total flavonoid content (TFC) were performed by the UV-Visible spectrophotometric method. Correlation of TPC and TFC with their IC50 of DPPH and IC50 of ABTS and also a correlation of two methods were conducted by Pearson's method. All parts extracts of Bilimbi were generally classified as a very strong antioxidant by DPPH and ABTS methods. Waste products of Bilimbi (leaves and twigs) were a potential antioxidant. The major contributors in antioxidant activities of leaves, fruit and twigs extracts of Bilimbi by DPPH and ABTS methods were phenolic compounds. DPPH and ABTS methods gave linear results in antioxidant activities of leaves and twig extracts of Bilimbi.

Rahmawati AN, Astirin OP, Pangastuti A. 2018. Intracellular antioxidant activity of Muntingia calabura leaves methanolicextract. Nusantara Bioscience 19: 210-214. Excessive reactive oxygen species (ROS) results in oxidative damage that destroys proteins,lipids, and DNA, resulting in various diseases and accelerating the aging process. Antioxidants are compounds that have the ability tosuppress oxidative stress. Muntingia calabura has a high phytochemical content, especially the phenolic group that can act asantioxidant. This study aimed to determine the intracellular antioxidant activity of M. calabura leaves methanolic extract (MLME)through intracellular ROS levels in 3T3 fibroblast cells under normal condition and oxidative stress due to UVB exposure. Tests wereperformed using the DPPH (Diphenyl-1-picrylhydrazyl) method and modified NBT (Nitroblue Tetrazolium). Testing of antioxidantactivity with DPPH method obtained result that MLME had high antioxidant activity with IC50 value of 3.030 μg mL-1, whileintracellular antioxidant activity with modified NBT method showed that MLME statistically had significant effect on intracellular ROSlevel under normal condition (p < 0.05) based on dose-dependent manner, but not significant (p > 0.05) under oxidative stress condition.Significant effects were only shown at a concentration of 20 μg mL-1 against the control of oxidative stress due to UVB exposure.

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Penelitian ini bertujuan untuk mendapatkan jarak tanam yang optimal dan frekuensi pembumbunan yang tepat untuk mendapatkan hasil panen terbaik. Penelitian ini menggunakan rancangan kelompok lengkap teracak (RKLT) faktorial dengan dua faktor dan tiga ulangan. Faktor pertama adalah jarak tanam yang terdiri atas enam taraf, yaitu 40 cm x 25 cm, 50 cm x 25 cm, 60 cm x 25 cm, 40 cm x 40 cm, 50 cm x 50 cm, dan 60 cm x 60 cm. Faktor kedua adalah frekuensi pembumbunan yang terdiri dari dua taraf yaitu dua kali pembumbunan dan tiga kali pembumbunan. Hasil penelitian menunjukkan jarak tanam berpengaruh nyata terhadap peubah jumlah daun, lebar kanopi, indeks luas daun (ILD), bobot brangkasan kering per tanaman, bobot polong basah per tanaman, bobot polong kering per tanaman, bobot biji per tanaman, jumlah polong bernas per tanaman, jumlah tanaman yang dipanen, bobot polong basah petak, bobot polong kering petak, dan bobot biji petak, sedangkan frekuensi pembumbunan hanya berpengaruh pada bobot brangkasan kering per tanaman. Jarak tanam 60 cm x 25 cm dan 40 cm x 40 cm memberikan hasil panen terbaik dan sesuai digunakan dalam budidaya kacang bogor.