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Optimized protocol for multigram preparation of emodin anthrone, a precursor in the hypericin synthesis

Gonçalves, Renato Sonchini, César, Gabriel Batista, Barbosa, Patrícia Magalhães, Hioka, Noboru, Nakamura, Celso Vataru, Bruschi, Marcos Luciano, Caetano, Wilker
Natural product research 2019 v.33 no.8 pp. 1196-1199
Hypericum, emodin, hypericin, photosensitizing agents, reducing agents, screening, spectroscopy
Emodin reduction to emodin anthrone comprise one of three process steps involved in the hypericin synthesis, a powerful natural photosensitiser found in plants of the genus Hypericum. In this communication, an optimized protocol was established for emodin reduction enabling an efficient multigram preparation of emodin anthrone. A screening of reducing agent (SnCl₂·2H₂O and HClcₒₙc) under different reaction times was employed in micro-scale and monitored by electronic absorption spectroscopy technique. Data showed lower yields of emodin anthrone when some experimental conditions previously described in the literature were reproduce. However, using the optimized protocol for the emodin reduction these yields were overcoming, and a gram-scale supply experiment was reproducible for the preparation of 10 grams of emodin anthrone with excellent yield.