Antimicrobial Activity of Catechol and Pyrogallol as Allelochemicals

Catechol and pyrogallol are allelochemicals which belong to phenolic compounds synthesized in plants. Their antimicrobial activities were investigated on three bacteria (Pseudomonas putida, Pseudomonas pyocyanea, Corynebacterium xerosis) and two fungi (Fusarium oxysporum, Penicillium italicum) phytopathogenic species as test organisms using the disc diffusion method. Both catechol and pyrogallol were found to have antibacterial effects on all the bacteria used in the study at 5 and 10 mм concentrations. Catechol has also been found to have an antifungal effect on the fungi used in the study, whereas no antifungal effects of pyrogallol were observed. The most sensitive species among the bacteria was P. putida which was inhibited by the allelochemicals even at 1 mм concentration.

Antimicrobial Activity of Compounds from Artemisia campestris

The antimicrobial activities of several compounds isolated from Artemisia campestris were studied using an agar diffusion technique. At a concentration of 125 μg/ml, six of the extracted compounds inhibited growth of Staphylococcus aureus, three of the compounds inhibited Escherichia coli and two inhibited growth of Proteus vulgaris. Pseudomonas pyocyanea was resistant to all extracted compounds.

“Maḥmūd” and “Laudable”

It is common knowledge that the term used to denote the fluid product of suppuration at the site of an infection of tissue is “pus”. Less well known, perhaps, is the use of the term qualified by the adjective “laudable”. This is hardly surprising since even in medical circles “laudable pus” is nowadays rather an expression familiar to historians of medicine than a terminological commonplace currently circulating among practitioners of the art. Prior to World War II, however, the expression seems to have been common enough in popular parlance; it was part of the vocabulary of folk-medicine. Moreover, it is worth noting that in 1939 it still merited inclusion (s.v. “pus”) in Gould's Pronouncing medical dictionary. In that work it is defined as “a whitish, inodorous pus, formerly thought to be essential to healing of wounds”. Before proceeding to our main focus of interest it is important to point out that such a definition reflects the position of Galenic thinking and not that of the more advanced practitioners of 19th-century medicine. In the age of Lister (1827–1912) laudable pus was bluish-green matter characterized by the presence of what we now know to be a natural antibiotic, namely pyocyanin, generated by the organism Pseudomonas pyocyanea. Nowadays no pus is considered “laudable”, and the expression, to all intents and purposes, went out with Listerian surgery. So much for the purely medical aspect of the question.

Characteristics of Aerobacter beta-lactamase

In this investigation, Aerobacter cloacae is shown to inactivate cephalosporin by hydrolysis of its beta-lactam ring. This was demonstrated by iodine absorption and infrared absorption spectra.The values of the Michaelis constant obtained with cephalosporin C and deacetyl cephalosporin C indicate a great affinity of the Aerobacter's beta-lactamase for its substrate. The enzyme was most active at pH 7.0 and 37 C. Aqueous washings of the Aerobacter cells were a potent source of enzyme.The beta-lactamase of A. cloacae was active on both cephalosporin and penicillin. A higher rate of hydrolysis was observed with cephalosporin C and deacetyl cephalosporin C than with cephalothin and cephaloridine. The ratio of reaction rates on cephalosporin C to that on penicillin G was consistently of the order of 100 to 1. The activity on V, N, and especially the semisynthetic penicillins was also low.The A. cloacae enzyme was easily demonstrable in large amount without added inducer. By contrast, the activity of the beta-lactamase from Pseudomonas pyocyanea cannot be detected unless high concentrations of inducer are used.