Preliminary Screening Experiments Research Articles

Microbial transformations of the sesquiterpene lactone costunolide

The microbial transformation of the sesquiterpene lactone costunolide has been studied. Preliminary screening experiments indicated a large number of fungi were capable of biotransforming costunolide. In preparative-scale fermentptions, Aspergillus niger converted costunolide into dihydrocostunolide (5) and into four eudesmanolide derivatives, colartin (2), 11,13-dihydrosantamarine (6), 11,13-dihydroreynosin (7), and tetra hydrovulgarin (8) formed by a sequence in which costunolide was reduced, epoxidized, and then cyclized. Cunninghamella echinulata produced 1β-hydroxyarbusculin A (10) and Fusarium oxysporum produced dihydrocostunolide (5). A proposal of the sequence of events in the conversion of costunolide to the eudesmanolide metabolites is discussed.

A. low‐cost, communal grazing design for preliminary evaluation of grazing systems

AbstractA field design using a decagonal geometric shape is described which enables twenty small plots, each 0.08 ha in size, to be evaluated under communal grazing condilions. The decagonal design was compared with a conventional design using botanical composition and plant density as discriminating parameters. The results showed that communal grazing in the decagonal design gave similar botanical composition and plant density as the conventional design. Since less materials per treatment were used in the decagonal design, it offers a means of minimizing costs in preliminary screening experiments. However, since animal production cannot be monitored under communal grazing the most successful treatments would have to be further evaluated using the conventional approach.

Antithyroid Activity of Thiouracil Derivatives

A RECENT report by Anderson et al.1 on the antithyroid activity of a series of alkyl derivatives of thiouracil shows that peak activity is reached at the n-propyl compound. A similar series of compounds is under investigation in this Laboratory, and some preliminary results may be of interest as confirming those of Anderson et al. in regard to the high activity of the n-propyl derivative. The substances under examination comprise methyl, ethyl, n-propyl, isopropyl and n-amyl thiouracil, and preliminary screening experiments indicated that the n-propyl compound was probably the most active of the series. Our experiments are not yet sufficiently complete to allot comparative values to the whole series, but they confirm the preliminary findings of the high activity of the n-propyl compound.