Lipoxygenase inhibitory tetraketones: potential remedial source for inflammation and asthma

OBJECTIVE

A series of tetraketones has been synthesized by way of a one pot synthesis and screened for inhibitory activity against the enzyme lipoxygenase.

METHOD

An efficient and high yielding one pot synthesis to tetraketones [2-22] has been developed by way of tetraethyl ammonium bromide (Et4N+Br-) mediated condensation of cyclohexane-1, 3-dione [1] with a variety of aldehydes. Lipoxygenase enzyme solution was prepared so that enzyme concentration in reaction mixture was adjusted to give rates of 0.05 absorbance/minute. The test compounds were prepared in methanol of concentrations 50, 25, 12.5, 6.25 and 3.125 microM. The reaction mixture contained 160 microL (100 mM) sodium phosphate buffer (pH 8.0), 10 microL of test-compound solution and 20 microL of lipoxygenase solution. The contents were mixed and incubated for 10 minutes at 25 degrees C. The reaction was then initiated by the addition of 10 microL substrate solution (linoleic acid, 0.5 mM, 0.12% w/v tween 20 in the ratio of 1:2), with the formation of (9Z, 11E)-(13S)-13-hydroperoxyoctadeca-9,11-dienoate, the change of absorbance at 234 nm was followed for 6 minutes. The concentrations of the test compounds that inhibited the lipoxygenase activity by 50% (IC50) were determined by monitoring the effect of increasing concentrations of these compounds in the assays on the degree of inhibition. The IC50 values were calculated by means of the EZ-Fit Enzyme-Kinetics Program (Perrella Scientific Inc., Amherst, U.S.A.).

RESULT

The tetraketones [2-22] were synthesized in high yields (91-98%) using mild reaction conditions. Most of these compounds showed significant inhibitory activity against the enzyme lipoxygenase. It was found that the presence of substituents which increase delocalization of electrons enhances the inhibitory activity.

CONCLUSION

It is concluded that the study is likely to lead to the discovery of therapeutically efficient agents against important disorders such as inflammation and asthma.

Production of dextran from sucrose by a newly isolated strain of Leuconostoc mesenteroides (PCSIR-3) with reference to L. mesenteroides NRRL B-512F

A newly isolated strain of Leuconostoc mesenteroides (PCSIR-3) produced a different dextran compared with that of L. mesenteroides NRRL B-512F. Different media compositions used for dextran production showed that media containing CaCl(2) produced dextran in higher quantities compared with other media. The viscosity of the dextran produced in different media varied in nature. Dextran from media 1 and 2 was of higher molecular mass compared with that from media 3, 4 and 5. Dextran production is also effected by the sucrose concentration in the media. The higher the initial concentration of sucrose, the higher is the yield of dextran produced per unit volume; however, the percentage conversion of sucrose into dextran decreases. A continuous drop in pH was associated with growth and dextran production. The yield of dextran increases during the growth phase and maximum yield was obtained at the end of the exponential phase. Dextran produced by L. mesenteroides PCSIR-3 is quite different from the dextran produced by NRRL B-512F. Maximum dextran production from L. mesenteroides PCSIR-3 occurs in 18 h compared with 12 h for NRRL B-512F.