Mangrove leaves or also known as “bakau” by the people of Mempawah Regency, which has (Rhizopora stylose) species containing alkaloids, flavonoids, steroids, terpenoids, phenolics, and saponins that can be used as antioxidant compounds. This study was aimed to determine the antioxidant activity of extracts and secondary metabolite fractions, and also to determine the characteristics of isolate compounds from mangrove leaves (Rhizopora stylose). Maceration of 1.57 kg of dry powder of mangrove leaves (Rhizopora stylose) with methanol as a solvent obtained a crude extract of 141.13 g of methanol with a percent yield of 8.98%. Partitioning the crude methanol extract obtained the n-hexane, dichloromethane, ethylacetate, and residue fractions by weight and percent yield, respectively, namely 6.95 g (0.44%), 26.74 g (1.70%), 26 .66 (1.69%), and 25.75 g (1.64%). The results of the antioxidant activity test showed that the dichloromethane fraction had a better antioxidant activity with an IC50 value of 121.314 g/mL. Separation and purification of the dichloromethane fraction to obtain isolates were carried out by column chromatography in order to obtain pure isolates which were characterized by the appearance of a single spot on the tested plate with various eluents, namely, isolate F7. The 1H-NMR data for isolate F7 showed chemical shifts for aromatic protons of 8.52 ppm, 7.70 ppm, 7.67 ppm, protons for tertiary C of 5.41 ppm, and protons for methyl and methylene of 3.50 ppm, 3.47 ppm, 1.59 ppm, 1.23 ppm, 1.05 ppm, and 0.84 ppm. H-NMR data showed that isolate F7 had similarities with the chemical shift of p-Oxy-2-Ethylhexyl benzaldehyde, namely 7.71 ppm, 7.54 ppm, 4.22 ppm, 1.68 ppm, 1.35 ppm, 1.32 ppm, 1.30 ppm, 0.90 ppm but different in the alkoxy substituent position from isolate F7 which was in the meta position
The aim of this study was to develop the psychomotor assessment instruments on experiment of factors that influence the rate of reaction which is feasible to be used. The development model used in this research was the modification model of 4P development into 3P which is recommended by Thiagarajan that is defining, designing and developing. Data collection techniques used were structured observation and questionnaire. The research instruments used were observation sheet and questionnaire. Initial field trials conducted on six students of class XII IPA 1, involving four observers while the main field trial conducted on 36 students of class XI IPA 1. The researcher involved four observers and one chemistry teacher. The feasibility of the developed psychomotor aspects assessment instrument is based on validity and practical aspects. The results obtained in this study were: (1) the average value of the validity of the psychomotor aspects assessment instrument was 1.00 with very high criteria and (2) the practicality of the psychomotor aspects assessment instrument based on the observers' response of 94.44 with very high criteria and teachers' response 90.27 with very high criteria. Based on the validity and practicality of the psychomotor aspect appraisal instrument the factors affecting the reaction rate are feasible to use
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