Total flavonoid and phenolic contents in some natural products was suspected of having a positive correlation to its activity in inhibiting the growth of bacteria. The aim of this study was to determine the total flavonoid and phenolic contents of n-butanol extract of Samanea saman leaf, and to evaluate the antibacterial activity towards Escherechia coli and Staphylococcus aureus. Extraction of compounds was done by ethanol 96%, followed by fractionation into n-hexane, ethyl acetate, and n-butanol. Determination of total flavonoid and phenolic contents was done by UV-Vis Spectrophotometer using standard of quersetin and galic acid respectively. In addition, antibacterial activity was evaluated by agar disc diffusion method. Extraction of 1000 g of Samanea saman leaf was obtained 80 g of ethanol extracts, fractionation of the extract was obtained 8.02 g of n-hexane extracts, 7.11 g of ethyl acetate extracts, 13.5 g of n-butanol extracts, and 14.16 g of aqueous extracts. Phytochemical screening of the n-butanol extracts revealed the presence of flavonoid and phenolic compounds. Total flavonoid and phenolic contents were successively 43.5798 mg QE/100g and 34.0180 mg GAE/100g. The butanol extracts inhibited the growth of S.aureus higher than the growth of E.coli. At the concentration of 2, 4, 6, 8 % (b/v), and positive control (meropenem 10 g/disc), inhibition zone towards S.

Coffee is one of the agriculture commodities that are cultivated by farmers. One of the compounds in the coffee is caffeine. Caffeine is one of alkaloids which contains in coffee bean. The purpose of this study was to determine the contents of caffeine in unripe coffee, pure coffee powder, and mix coffee powder by using UV-Vis spectrophotometer. Standard solutions of caffeine used were 1 ppm; 3 ppm; 6 ppm; 9 ppm; 12 ppm; and 15 ppm. Caffeine calibration curve equation was y = 0.0494x ??+ 0.01862 with a correlation coefficient (r) of 0.99714. Caffeine content in unripe coffee was 1,28±0,82 % with water content 3%, pure coffee powder 1,63±0,13 % with water content 1%, and mix coffee powder 0,87±0,01 % with water content 1%. According to SNI 01-7152-2006 maximum limit of caffeine in food and drink was 150 mg/day and 50 mg/dish.

Graphene is a thin material, has a hexagonal two-dimentional lattice and is considered as an interesting material for adsorption process. Nowadays, graphene has been known as a potential material for diverse application, such as adsorbent. In this study graphene was synthesized from graphite. Furthermore, graphene was applied for adsorption of dichloro diphenyl trichloroethane (DDT). Graphene was synthesized by Hummer’s method using hydrothermal and reduced by Zn. The samples were characterized by Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD) methods. The results of the XRD showed graphene structure in the 2θ, appeared at 23.9369 with interlayer spacing was about 3.71763 Å, compared with graphite oxide structure in the 2θ appeared at 11.2055 with interlayer spacing was about 7.89649 Å. The results of SEM analysis showed graphene has one layer with planar hexagonal structure and seems transparent whose single layer and multi layers. The graphene adsorption was analyzed by using the UV-Visible spectrophotometer. The results indicated the surface area of graphene was shown as 46.8563 m2/g. The amount of DDT adsorbed by graphene during 15 minutes was 7.5859 mg/g. This adsorption mechanism of DDT and graphene might be due to π-π and hydrogen interactions.   Keywords: Adsorption, dichloro diphenyl trichloroethane (DDT), graphena. DOI: http://dx.doi.org/10.15408/jkv.v2i1.2233

Antibacterial activity of Samanea saman usually shows a positif correlation to the flavonoid and phenolic contents.  The aim of this study was to evaluate the antibacterial activity of the ethanol extract of Samanea saman against Escherechia coli and Staphylococcus aureus and determine the total flavonoid and phenolic contents of the extract. The extraction was done by ethanol 96% at room temperature. The antibacterial assay was conducted by agar disc diffusion method. The total flavonoid and phenolic contents were determined by UV-Vis Spectrofotometer with the standard of quersetin and galic acid, respectively. The extraction of 250 g of Samanea saman leaves resulted in 24.5 g of ethanol extracts. The ethanol extract showed a moderate inhibition of 8.33 mm towards E. coli and a strong inhibition of 13.6 mm towards S. aureus at the concentration of 4%. The Minimum Inhibitory Concentration (MIC) of the extract against E. coli and S.aureus were of 3% and 0.3%”, respectively. The total flavonoid and phenolic contents were successively 1233.2991 mg QE/100g and 2544.6154 mg GAE/100g. Keywords: Escherechia coli, flavonoid and phenolic content,  Samanea saman, Staphylococcus aureus

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