Farnesol is well known as a quorum-sensing molecule of Candida albicans. To assess the pathological function of farnesol, its effects on macrophage viability and functions including growth inhibitory activities against C. albicans were examined in vitro. Murine macrophages, when cultured in the presence of 56-112 μM of farnesol for 1-2 hr, decreased their activity inhibiting the mycelial growth of C. albicans and lost their viability. This suppression of macrophage function by farnesol was neutralized by the coexistence of the anti-oxidants probucol and trolox. Macrophages cultured in the presence of farnesol for 2 hr displayed morphological change of nuclei and DNA fragmentation, which suggested apoptosis of the cells. Intracellular production of ROS in the farnesol-treated macrophages was shown by fluorescence of DCFH-DA and increase of peroxidized materials. These effects of farnesol were blocked by probucol or trolox. These results indicate that farnesol lowered viability of the murine macrophages and suppressed their anti-Candida activity, perhaps through induction of ROS.

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Glucosyltransferase (GTF)‐I from cariogenic Streptococcus sobrinus elongates the α‐(1→3)‐linked glucose polymer branches on the primer dextran bound to the C‐terminal glucan‐binding domain. We investigated the GTF‐I‐catalyzed glucan synthesis reaction in the absence of the primer dextran. The time course of saccharide production during dextran‐independent glucan synthesis from sucrose was analyzed. Fructose and glucose were first produced by the sucrose hydrolysis. Leucrose was subsequently produced, followed by insoluble glucan [α‐(1→3)‐linked glucose polymers] after a lag phase. High levels of intermediate nigerooligosaccharide series accumulation were characteristically not observed during the lag phase. The results from the enzymatic activity of the acceptor reaction for the nigerooligosaccharide with a degree of polymerization of 2–6 and methyl α‐d‐glucopyranoside as a glucose analog indicate that the activity increased with an increase in the degree of polymerization. The production of insoluble glucan was numerically simulated using the fourth‐order Runge–Kutta method with the kinetic parameters estimated from the enzyme assay. The simulated time course provided a profile similar to that of experimental data. These results define the relationship between the kinetic properties of GTF‐I and the time course of saccharide production. These results are discussed with respect to a mechanism that underlies efficient glucan synthesis.