Inhibition of azole-resistant Candida albicans ATPase and oxidoreductase activity by a flavonoid from Dalea elegans.

BACKGROUND: The flavonoid 2', 4'-dihydroxy-5'-(1''', 1'''-dimethylallyl)-8-prenylpinocembrin (8PP) obtained from Dalea elegans roots inhibits cell growth and cdr pumps, in addition to reversing fluconazole (FCZ) resistance in Candida albicans. AIMS: To study the effects of 8PP and FCZ on cdr-associated ATPase and cell energy generation in azole-resistant C. albicans planktonic cultures. MATERIALS AND METHODS: ATPase activity was measured as oligomycin-sensitive release of inorganic phosphate in fractions containing plasmatic membranes. Cell oxidoreductase activity was evaluated by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) reduction in C. albicans cells. RESULTS: FCZ, 8PP and their combination at a concentration of 125 µM of each compound inhibit ATPase activity by 61; 58 and 70, respectively. Inhibitory concentration 50 % (IC50) of 8PP was 78.59 ± 1.45 and 104.70 ± 1.25 µM for FCZ. In combination with 125 µM 8PP, FCZ IC50 was reduced by 3 times. Km was 0.96 ± 0.35 mM and Vmax 43.58 ± 5.49 picomoles/mg protein.min. At 125 µM, 8PP shifts the ATP saturation plot to right. A Dixon study using 2 and 5 mM ATP suggests a competitive interaction of 8PP and ATP for the hydrolysis enzymatic site. FCZ, 8PP or their combination at 125 µM does not produce cytotoxicity dependent on oxidoreductase activity. At higher concentrations, toxic effects are observed with both drugs at the MTT assay. IC50 (µM) was 355 ± 6 and 789 ± 11, for 8PP and FCZ, respectively. CONCLUSIONS: The flavonoid 8PP inhibits competitively oligomycin-sensitive ATPase activity associated to cdr transporters and decreases oxidoreductase-dependent cell viability in azole-resistant Candida albicans.

[Inhibitory effect of diethylstilbestrol on clinical strains of Candida albicans susceptible and resistant to azoles]. / Efecto inhibitorio del dietilestilbestrol sobre aislamientos clínicos de Candida albicans sensibles y resistentes a los azoles.

BACKGROUND: Candida albicans is a microorganism frequently involved in several infections; the patient's oral cavity, caries niches or periodontal disease can sometimes be the reservoir.. The fungal resistance to the available treatments, among other reasons, has led to the search for new antifungal alternatives. AIMS: To carry out a comparative study of the in vitro effects of diethylstilboestrol (DES) and fluconazole (FLZ) on the growth of clinical strains of C. albicans. METHODS: Seven strains of C. albicans were used: a) one FLZ-sensitive culture collection strain, ATCC 90028 (ATCC); b) four oral isolates from four oncological patients with periodontal disease (period 8, 9, 10, and 11); and c) two oral isolates from an AIDS patient with oropharyngeal candidiasis: one FLZ- sensitive (2-76), and another FLZ- resistant (12-99). The MIC was evaluated by standard spectrophotometric techniques using the CLSI (M27-A3) guidelines. The inhibitory concentration 50% (IC50) was calculated using functional analysis with the Graph Pad software. RESULTS: DES inhibited the growth of all C. albicans strains, whether sensitive or resistant to FLZ. Experimental data fitted non-linear functions of inhibitor concentration versus response. Minimum inhibitory concentrations (MIC) for DES and FLZ were as follows: 28.18µg/ml and 4.90µg/ml (ATCC); 17.16µg/ml and 3.14µg/ml (period); 27.64µg/ml and 4.22µg/ml (2-76); 6.16µg/ml and 438.19µg/ml (12-99), respectively. CONCLUSIONS: DES showed antifungal activity on all clinical C. albicans strains isolated from patients with dental and medical diseases. It showed the highest potency on the FLZ-resistant isolate.

Effects of tamoxifen on periodontal disease and Candida albicans of patients with breast cancer and other pathologies.

Candida albicans is involved in periodontal disease, which is influenced by sex hormones. AIM: To study the effects of the estrogen antagonist tamoxifen (TAM) on periodontal disease of oncological patients; clinical oral strains of C. albicans. PATIENTS: With periodontitis and breast cancer and other with AIDS were used. MATERIALS & METHODS: Periodontal disease was evaluated by the academy of periodontology procedures and the growth of clinical C. albicans isolates were evaluated by the Clinical and Laboratory Standards Institute techniques. RESULTS: Women who consumed TAM for more than 2 years decreased periodontitis severity. In vitro, TAM inhibited the growth of both fluconazole-sensitive and resistant C. albicans. CONCLUSION: Administered TAM chronically improves periodontal health and has antifungal activity on oral strains isolated from patients with odontologic and medical pathologies.