Sonochemical degradation of dilute aqueous solutions of 2-, 3- and 4-chlorophenol and pentachlorophenol has been investigated under air or argon atmosphere. The degradation follows first-order kinetics in the initial state with rates in the range 4.5-6.6 microM min-1 under air and 6.0-7.2 microM min-1 under argon at a concentration of 100 microM of chlorophenols. The rate of OH radical formation from water is 19.8 microM min-1 under argon and 14.7 microM min-1 under air in the same sonolysis conditions. The sonolysis of chlorophenols is effectively inhibited, but not completely, by the addition of t-BuOH, which is known to be an efficient OH radical scavenger in aqueous sonolysis. This suggests that the main degradation of chlorophenols proceeds via reaction with OH radicals; a thermal reaction also occurs, although its contribution is small. The addition of appropriate amounts of Fe(II) ions accelerates the degradation. This is probably due to the regeneration of OH radicals from hydrogen peroxide, which would be formed from recombination of OH radicals and which may contribute a little to the degradation. The ability to inhibit bacterial multiplication of pentachlorophenol decreases with ultrasonic irradiation.
A novel antitumor antibiotic, methylenolactocin, was isolated from the culture nitrate of a new isolate of fungus identified as Penicillium sp. The fermentation yield reached about 100 mg per liter of the broth. Methylenolactocin has the molecular formula of CnHi6O4 and possess an exomethylene lactone structure. Its structure was determined to be 3-carboxy-2-methylene-4-nonanolide by spectroscopic data. It is active against some Gram-positive bacteria and it prolongs the life span of mice inoculated with Ehrlich carcinoma.
A new antibiotic, terrecyclic acid A was isolated from the culture filtrate of a new isolate of fungus, identified as Aspergillus terreus. The fermentation yields reached about one gram per liter of the broth. Chemical and biological characterization of the antibiotic revealed that it was a new sesquiterpene having a wide antimicrobial spectrum and antitumor activity.
In the previous paper,1>2) we reported the isolation and structural determination of a new pimarane diterpene, myrocin C (2), the metabolite of Myrothecium verrucaria strain No. 55 (FERM P-8880).
Recently, the development of natural antioxidative substances has been expected to replace the synthetic compounds which are widely used at the present time. Some natural antioxidants of microbial origin have already been isolated, but the screening procedures used were indirect and complicated.1>2) Wehave also tried to isolate these active substances from fungi. In this paper, a simple and direct method for screening, identification and evaluation of the isolates will be described. Filamentous fungi, just isolated from soil samples, were cultured on a reciprocating shaker at 30°C for 3~4 days. The culture medium consisted of 3% sucrose, 0.3%
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.