Flavonoid diosmetin increases ATP levels in kidney cells and relieves ATP depleting effect of ochratoxin A

Diosmetin (DIOS) is a flavone aglycone commonly occurring in citrus species and olive leaves, in addition it is one of the active ingredients of some medications. Based on both in vitro and in vivo studies several beneficial effects are attributed to DIOS but the biochemical background of its action seems to be complex and it has not been completely explored yet. Previous investigations suggest that most of the flavonoid aglycones have negative effect on ATP synthesis in a dose dependent manner. In our study 17 flavonoids were tested and interestingly DIOS caused a significant elevation of intracellular ATP levels after 6- and 12-h incubation in MDCK kidney cells. In order to understand the mechanism of action, intracellular ATP and protein levels, ATP/ADP ratio, cell viability and ROS levels were determined after DIOS treatment. In addition, impacts of different enzyme inhibitors and effect of DIOS on isolated rat liver mitochondria were also tested. Finally, the influence of DIOS on the ATP depleting effect of the mycotoxin, ochratoxin A was also investigated. Our major conclusions are the followings: DIOS increases intracellular ATP levels both in kidney and in liver cells. Inhibition of glycolysis or citric acid cycle does not decrease the observed effect. DIOS-induced elevation of ATP levels is completely abolished by the inhibition of ATP synthase. DIOS is able to completely reverse the ATP-depleting effect of the mycotoxin, ochratoxin A. Most probably the DIOS-induced impact on ATP system does not originate from the antioxidant property of DIOS. Based on our findings DIOS may be promising agent to positively influence ATP depletion caused by some metabolic poisons

Antifungal Activity of Fused Mannich Ketones Triggers an Oxidative Stress Response and Is Cap1-Dependent in Candida albicans

International audienceWe investigated the antifungal activity of fused Mannich ketone (FMK) congeners and two of their aminoalcohol derivatives. In particular, FMKs with five-membered saturated rings were shown to have minimum inhibitory concentration (MIC90s) ranging from 0.8 to 6 µg/mL toward C. albicans and the closely related C. parapsilosis and C. krusei while having reduced efficacy toward C. glabrata and almost no efficacy against Aspergillus sp. Transcript profiling of C. albicans cells exposed for 30 or 60 min to 2-(morpholinomethyl)-1-indanone, a representative FMK with a five-membered saturated ring, revealed a transcriptional response typical of oxidative stress and similar to that of a C. albicans Cap1 transcriptional activator. Consistently, C. albicans lacking the CAP1 gene was hypersensitive to this FMK, while C. albicans strains overexpressing CAP1 had decreased sensitivity to 2-(morpholinomethyl)-1-indanone. Quantitative structure-activity relationship studies revealed a correlation of antifungal potency and the energy of the lowest unoccupied molecular orbital of FMKs and unsaturated Mannich ketones thereby implicating redox cycling-mediated oxidative stress as a mechanism of action. This conclusion was further supported by the loss of antifungal activity upon conversion of representative FMKs to aminoalcohols that were unable to participate in redox cycles

QSAR models for antifungal potency of Mannich ketones.^a

a<p>Includes unsaturated cyclic Mannich ketones and aminoalcohols reported in Kocsis <i>et al.</i><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0062142#pone.0062142-Kocsis1" target="_blank">[13]</a>.</p

Fungal strains used in this study.

<p>Fungal strains used in this study.</p

QSAR analysis of Mannich ketones for antifungal activity towards <i>Candida albicans</i>.

<p>Comparison of the experimental and calculated negative logarithms of the minimum inhibitory concentration from QSAR (pMIC_Exp and pMIC_Calc) of Mannich ketones in <i>C. albicans</i> was based on the equation considering three descriptors: energy of the lowest unoccupied molecular orbital (LUMO, eV) solvent-accessible surface area (SASE, Ų), and ionization potential (IP, eV) (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0062142#pone-0062142-t002" target="_blank">Table 2</a>). Green triangles: Fused Mannich ketones reported here; Magenta squares: unsaturated cyclic Mannich ketones and aminoalcohols reported earlier <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0062142#pone.0062142-Kocsis1" target="_blank">[13]</a>.</p

Chemical structures of the fused Mannich ketones investigated.

<p>Chemical structures of the fused Mannich ketones investigated.</p

Growth kinetics in 96-well microtiter plates of <i>C. albicans</i> strains exposed to various concentrations of compound 2.

<p><b>A.</b> Representative growth kinetics of BWP17 and <i>cap1Δ/Δ</i> strains exposed to decreasing concentrations of compound 2 in SD minimal medium. <b>B.</b> Representative growth kinetics of BWP17, <i>cap1Δ/Δ</i> and <i>CAP1</i> overexpression strains in inducible medium (YNB-casa) exposed to 12.5 µg/mL compound 2. <b>C.</b> Representative growth kinetics of several transcription factor mutants and parent strains in SD minimal medium exposed to 6.25 µg/mL compound 2.</p