Evaluation of the Effectiveness of Crotoxin as an Antiseptic against Candida spp. Biofilms.

The growing number of oral infections caused by the Candida species are becoming harder to treat as the commonly used antibiotics become less effective. This drawback has led to the search for alternative strategies of treatment, which include the use of antifungal molecules derived from natural products. Herein, crotoxin (CTX), the main toxin of Crotalus durissus terrificus venom, was challenged against Candida tropicalis (CBS94) and Candida dubliniensis (CBS7987) strains by in vitro antimicrobial susceptibility tests. Minimum inhibitory concentration (MIC), minimum fungicidal concentration (MFC), and inhibition of biofilm formation were evaluated after CTX treatment. In addition, CTX-induced cytotoxicity in HaCaT cells was assessed by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) colorimetric assay. Native CTX showed a higher antimicrobial activity (MIC = 47 µg/mL) when compared to CTX-containing mouthwash (MIC = 750 µg/mL) and nystatin (MIC = 375 µg/mL). Candida spp biofilm formation was more sensitive to both CTX and CTX-containing mouthwash (IC100 = 12 µg/mL) when compared to nystatin (IC100 > 47 µg/mL). Moreover, significant membrane permeabilization at concentrations of 1.5 and 47 µg/mL was observed. Native CTX was less cytotoxic to HaCaT cells than CTX-containing mouthwash or nystatin between 24 and 48 h. These preliminary findings highlight the potential use of CTX in the treatment of oral candidiasis caused by resistant strains.

Karl Heinrich Slotta (1895-1987) biochemist: snakes, pregnancy and coffee.

In 1923 Karl H. Slotta obtained his PhD in chemistry from the University of Breslau, Germany, where he continued to work. At the instigation of the gynaecologist Ludwig Fraenkel, Slotta made the first isolation of progesterone in 1933. In 1934 he proposed the correct structural formula. Slotta was appointed professor of chemistry in 1935, but with the oppression of the Nazi regime mounting, he soon left Germany with his family to take a post at the Instituto Butantan, Brazil. Initially he worked on the chemistry of coffee. In 1938 Slotta and his brother-in-law Heinz Fraenkel-Conrat isolated crotoxin from Crotalus durissus terrificus venom, the first snake toxin to be obtained in crystalline form. They had evidence to suggest that the toxicity of crotoxin was due to a phospholipolytic action on nerve lipids. In 1938 Slotta's department was closed; he subsequently cofounded a biopharmaceutical company. In 1956 Slotta was appointed research professor of biochemistry at the University of Miami, USA. Slotta purified the most basic polypeptide from Naja naja venom, known as direct lytic factor, and with James Vick identified this as cardiotoxin. Karl H. Slotta will be remembered not only for his skill as a biochemist but also for his indomitable and cheerful spirit.