[Studies on antispetics for foodstuff. LXXI. Studies on orsellinic acid ester, beta-orcinolcarboxylic acid ester and olivetonide as a preservative for sake]

In vitro evaluation of the antimicrobial activity of lichen metabolites as potential preservatives

Antimicrobial screening of several lichen species and subsequent isolation and structure elucidation of active compounds revealed that the hydrolysis products of certain lichen metabolites, i.e., depsides, were active against gram-negative bacteria and fungi as well as gram-positive bacteria. The active constituents isolated from Stereocaulon alpinum and Peltigera aphthosa were identified, respectively, as methyl beta-orsellinate and a mixture of methyl and ethyl orsellinates. MIC determinations indicated that activity of these compounds was superior to that of the commonly used preservative agents methyl and propyl p-hydroxybenzoates and was of the same order as that of chlorocresol.

Inhibition of compound 48/80-mediated histamine release from isolated rat mast cells by oosponol-related compounds (4-acyl-isocoumarins)

Oosponol (4-hydroxymethylketone-8-hydroxyisocoumarin) is a metabolic product isolated from Oospora astringens which originated from house dust in a room of an asthmatic patient. The compound and the structurally related isocoumarins were studied to determine the inhibition of histamine release induced by compound 48/80 from isolated rat peritoneal mast cells. The released histamine was assayed by fluorometry. The compounds tested were not observed to release histamine. Some of 4-acyl-isocoumarins inhibited the histamine release at doses less than 10 micrometers, whereas the 3-acyl- and the 4-alkyl-compounds were not effective at doses over 100 microns. The pretreatment of mast cell with the compound for 15 min before the application of compound 48/80 was more effective than the simultaneous administration. The mode of inhibitory action of KIT-302, 4-(4'-carboxy-benzoyl)-isocoumarin, was non-competitive antagonism to compound 48/80 on the mast cells.