Homalomena occulta is a plant that grows in Madiun, especially Caruban. Patients can overcome kidney stone disease by boiling the H. occulta (nampu) rhizome with water. The present study aimed to evaluate the antilithiatic effect of the ethanol extract of the H. occulta rhizome in preventing nephrolithiasis in rats. Ethylene glycol was used to induce the urolithiasis in the Wistar rats. The rats were divided into six groups, namely I (normal), II (ethylene glycol induced), III (commercial drug treated, Cystone® 750 mg/kg BW), IV (H. occulta rhizome extract treated, dose 250 mg/kg BW), V (H. occulta rhizome extract treated, dose 500 mg/kg BW), and VI (H. occulta rhizome extract treated, dose 1000 mg/kg BW). Keywords: kidney stone, ethylene glycol, calcium level, Homalomena occulta

Chemical compounds that can donor one or more electrons to free radicals to inhibit free radical reactions are called antioxidants. Manalagi apple is a fruit with high antioxidant activity. Manalagi apple is a typical fruit of Batu City. Processed apple products are apple cider, vinegar, dodol, and chips. These products are sold in Batu city and produced the same home industry. The aim of this study was to determine the antioxidant activity comparison between Manalagi apple and four processed apple products based on IC50 values. This study used the ABTS method (2,2-azino bis (3-ethyl benzothiazoline-6-sulfonic acid) and analysis used spectrophotometric visible. IC50 value as  apples and their processed products were analyzed using a one-way ANOVA. The study results indicated that IC50 value of Manalagi apple was insignificantly different from the processed apple product of dodol and chips. However, the IC50 value of manalagi apple was significantly different from apple cider and vinegar.

Vitamin C is a water-soluble vitamin that is important for human health as it helps to maintain the body’s resistance to various diseases. It functions as an antioxidant, which is a substance that gives electrons to free radicals and helps to stabilize free radicals, which protects cells from damage. Because vitamin C is easily oxidized, an analytical method is needed which measures vitamin C levels accurately and quickly. Analytical methods must be validated before being implemented to ensure the validity of the data generated. In this study, the validation of two vitamin C measurement methods were be compared: high-performance liquid chromatography (HPLC) and potentiometric titration. The results of the HPLC method showed that the linearity, accuracy, and precision met the validation requirements of the official methods of analysis (AOAC). The potentiometric titration method validation results showed that the accuracy met the AOAC requirements while the precision did not meet the AOAC requirements. Keywords: validation, HPLC, potentiometric titration, vitamin C