Implications of Fagopyrin Formation In Vitro by UV Spectroscopic Analysis.

The present work aims at studying the possible biosynthesis of fagopyrin in buckwheat plants with an attempt to address the existing gaps. The developed method of differential spectrophotometry can be used for identification of naphthodianthrones fagopyrins. It was found that in the vegetative mass of buckwheat plants, fagopyrin precursor-2-(piperidine-2-yl)-emodindianthron could be present. As fagopyrin can be produced by light effect, the temperature factor may influence the formation of protofagopyrin in vitro. An optimum temperature range was estimated for protofagopyrin formation. A possible fagopyrin biosynthesis under in vitro conditions was suggested.

Antifungal properties of hypericin, hypericin tetrasulphonic acid and fagopyrin on pathogenic fungi and spoilage yeasts.

CONTEXT: The role of hypericin-mediated photodynamic antimicrobial properties on pathogenic fungi and photodynamic therapy for human cancer cells is known. Antifungal properties of Hypericum perforatum L. (Hypericaceae) and Fagopyrum esculentum Moench. (Polygonaceae) extracts were also studied. The different polarities of solvents can cause complication in the identification of antifungal effects of separate biologically active compounds. In recent experimental work, we compared antifungal properties of purified hypericin, hypericin tetrasulphonic acid (hypericin + S) and fagopyrin, which is analogue of hypericin. OBJECTIVE: The antifungal properties of aromatic polyketide derivatives such as hypericin, hypericin + S and fagopyrin on the selected pathogenic fungi and spoilage yeasts have been studied. MATERIALS AND METHODS: The antifungal properties of hypericin, hypericin + S and fagopyrin were determined using the broth microdilution method against a set of pathogenic fungi and spoilage yeasts including: Microsporum canis, Trichophyton rubrum, Fusarium oxysporum, Exophiala dermatitidis, Candida albicans, Kluyveromyces marxianus, Pichia fermentans and Saccharomyces cerevisiae. The tested concentrations of hypericin, hypericin + S and fagopyrin ranged from 750 to 0.011 µg/mL and MIC values were evaluated after 48 h incubation at 30 °C. RESULTS: The results confirm different antifungal properties of hypericin, hypericin + S and fagopyrin on the selected pathogenic fungi and spoilage yeasts. For pathogenic fungi, the minimum inhibitory concentrations of hypericin ranged 0.18-46.9 µg/mL, hypericin + S 0.18-750 µg/mL and fagopyrin 11.7-46.9 µg/mL. For spoilage yeasts, the MICs of hypericin and hypericin + S ranged 0.18-46.9 and 0.011-0.73 µg/mL, respectively. DISCUSSION AND CONCLUSION: The results obtained herein indicate that various chemical structures of hypericin, hypericin + S and fagopyrin can develop different antifungal properties.