Structure-activity Study of Bacteriostatic Kojic Acid Analogs

The bacteriostatic activity of kojic acid derivatives, where various substituents are introduced into the 2- and/or 7-positions was analyzed in terms of the physicochemical characteristics of the substituents using the method developed by Hansch and his co-workers. Analyses show that 1) activity is attributable to the neutral form of the molecule in the medium, 2) the site of action seems to be in a region close to the bacterial cell surface, and 3) the higher the hydrophobicity of the substituents at the 7-position and the greater the electron withdrawal from the 3-hydroxyl group, the stronger the activity.     

Comparison of two kinds of cell packets of Micrococcus luteus by scanning electron microscopy: outermost layer maintaining the packet structure

Two kinds of cell packets of Micrococcus luteus, one having teichuronic acids (TUA) in the cell wall and the other lacking TUA, have been independently reported by two groups of workers. A comparison by scanning electron microscopy of these packets provided a possibly consistent interpretation for the seemingly conflicting opinions whether TUA were involved in packet induction. It was strongly suggested that the packets having TUA in the wall were rigidly maintained by a bridging structure of the outermost layer of the peripheral wall, while the packets lacking TUA showed low contribution of the outermost layer to the bridging structure probably due to the absence of TUA.