Analysis Of The Enantiomers Ratio Of Citronellal From Indonesian Citronella Oil Using Enantioselective Gas Chromatography

Citronellal 97,3% has been isolated from Java citronella oil (Cymbopogon winterianus) from Yogyakarta Indonesia by fractional distillation under reduced pressure (5 cmHg, 110-120 oC). Citronellal has two optical isomerics that can be separated by capillary column of chiral GC phase. Enantioselective capillary GC with heptakis(2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl)-β-cyclodextrin (β-DEX-225) as stationary phase has been used for analysis of the enantiomers ratio of citronellal. The analysis of enantiomer ratio showed that citronellal contain of 88.21% ee of (R)-(+)-citronellal. Physical properties of isolated citronellal showed that the compound was (+) enantiomer. Structure identification of citronellal was carried out by GC-MS, IR, and 1H NMR, resulted identical fragment and spectra with standard citronellal. Theoretical study with semiempirical-AM1 method showed that energy of (R)-(+)-citronellal on the β-DEX 225 was lower than its (S)-(-)-citronellal.

Reaction sites of N,N′-substituted p-phenylenediamine antioxidants

The geometries of N,N′-diphenylbenzene-1,4-diamine (DPPD), N-phenyl-N′-(1-phenylethyl)benzene-1,4-diamine (SPPD), N-(4-methylpentan-2-yl)-N′-phenylbenzene-1,4-diamine (6PPD), N-propan-2-yl-N′-phenylbenzene-1,4-diamine (IPPD), N-(2-methoxybenzyl)-N′-phenylbenzene-1,4-diamine (MBPPD), and N-phenyl-N′-(2-phenylpropan-2-yl)benzene-1,4-diamine (CPPD) as well as of their dehydrogenation products were optimized by the semiempirical AM1 method. The results support the idea of stable NB=CX structures formation during the consecutive dehydrogenation of SPPD, 6PPD, IPPD, and MBPPD antioxidants. The biradicals formed during the second step of dehydrogenation of substituted phenylenediamines might be important for their antioxidant effectiveness.

MODEL QSAR SENYAWA FLUOROKUINOLON BARU SEBAGAI ZAT ANTIBAKTERI Salmonella thypimurium Eva Vaulina, Ponco Iswanto

Modelling of novel Fluoroquinolone derivates as antibacterial compund of Salmonella thypimurium was conducted. The research was done as an initial step in discovering some new Fluoroquinolone compounds which have higher activity to Salmonella thypimurium. There are 16 compunds that use as the material of the research and they already have antibacterial activity data that expressed in Minimal Inhibitory Concentration (MIC, mg/mL). Calculation was performed by semiempirical AM1 method. The QSAR model was determined by multilinear regression analysis, with Log MIC as dependent variable and the independent variables are atomic net charges of C5 (qC5) and C7 (qC7), dipole moment (m), polarizability (a), n-octanol-water coefficien partition (Log P), molecular weight (Mw), and surface area of van der Waals (AvdW). The relationship between Log MIC and the descriptors which performed by statistical analysis is:(Log MIC) = -2.119 + 34.541(qC5) – 19.748(qC7) – 0.919polar + 1.170logP + 0.111(Mw) – 0.003(Avdw), with n =16, r = 0.907, r2 = 0.822, SD = 0.288, F calc = 6.938, F table = 3.374 , F calc/F table = 2.056 and PRESS = 0.749. The research can obtain the new coumpounds that modified from compound number 16 (etil fluoroquinolone, MIC prediction = 0.0354 mg/mL), (etil fluoroquinlone fosfate, 2.84. 10-19mg/mL), and (isopropyl fluoroquinlone, 0.1085 mg/mL), and compound number 2 (m-nitro fluoroquinolone sulfonat, 1.32. 10-11mg/mL). This results can be suggested to synthesis step.