No abstract

The plant pentacyclic triterpenoids, oleanolic and ursolic acids, inhibit the growth and survival of many bacteria, particularly Gram-positive species, including pathogenic ones. The effect of these compounds on the facultative human pathogen Listeria monocytogenes was examined. Both acids affected cell morphology and enhanced autolysis of the bacterial cells. Autolysis of isolated cell walls was inhibited by oleanolic acid, but the inhibitory activity of ursolic acid was less pronounced. Both compounds inhibited peptidoglycan turnover and quantitatively affected the profile of muropeptides obtained after digestion of peptidoglycan with mutanolysin. These results suggest that peptidoglycan metabolism is a cellular target of oleanolic and ursolic acids.

Trends in research on Calendula officinalis L. saponins performed in Department of Plant Biochemistry at Warsaw University are reviewed. Calendula officinalis, a well known medicinal plant, contains significant amounts of oleanane saponins, which form two distinct series of related compounds, called ''glucosides'' and ''glucuronides'' according to the structure of the respective precursor. Both series differ in the pathway of their biosynthesis and further metabolism, i.e. the rate of formation and stages of possible degradation; distribution in the single cell and in the whole plant, including accumulation sites; and the possible physiological role played in the plant according to appropriate biological activities.

The antibacterial and antiparasitic activities of free oleanolic acid and its glucosides and glucuronides isolated from marigold (Calendula officinalis) were investigated. The MIC of oleanolic acid and the effect on bacterial growth were estimated by A600 measurements. Oleanolic acid's influence on bacterial survival and the ability to induce autolysis were measured by counting the number of cfu. Cell morphology and the presence of endospores were observed under electron and light microscopy, respectively. Oleanolic acid inhibited bacterial growth and survival, influenced cell morphology and enhanced the autolysis of Gram-positive bacteria suggesting that bacterial envelopes are the target of its activity. On the other hand, glycosides of oleanolic acid inhibited the development of L3 Heligmosomoides polygyrus larvae, the infective stage of this intestinal parasitic nematode. In addition, both oleanolic acid and its glycosides reduced the rate of L3 survival during prolonged storage, but only oleanolic acid glucuronides affected nematode infectivity. The presented results suggest that oleanolic acid and its glycosides can be considered as potential therapeutic agents.

Triterpene saponins in the roots of Beta vulgaris cultivars Red Sphere, Rocket, and Wodan were profiled and quantitated using reverse-phase liquid chromatography coupled with electrospray ionization mass spectrometry (HPLC-ESI/MS/MS). Results obtained indicated that the roots of all three cultivars contained 11 saponins consisting of oleanolic acid or hederagenin aglycone and varying numbers of sugars, with the dominant triglycoside derivative of oleanolic acid. The relative proportions of derivatives of these two aglycones were similar in the three subspecies: cv. Red Sphere contained 99.1 and 0.9%; cv. Rocket, 98.2 and 1.8%; and Wodan 98.8 and 1.2% of oleanolic acid and hederagenin glycosides, respectively. To the best of our knowledge this is the first report on the occurrence, structure, and content of triterpenoid saponins in red beet.