Gamma irradiation delays softening and extends postharvest shelf life of ‘Golden’ papaya by modulating cell wall enzymes Bruna Figueredo Lopes, Enilton Nascimento de Santana, Raquel Gouvea Santos, Juliana Barbosa Coitinho, Suely Gomes de Figueiredo Revista Brasileirade Ciencias Agrarias, 2025 Papaya (Carica papaya L.) is a widely consumed tropical fruit but is highly perishable, which limits its storage and export potential. This study evaluated the effects of gamma irradiation (0.8 kGy) applied on the first day postharvest on the postharvest quality of ‘Golden’ papaya, focusing on pulp firmness, mass loss, enzymatic activity of ?-galactosidase, cellulase, and pectin methylesterase, titratable acidity, and soluble sugar content. Irradiated fruit maintained firmness up to four days longer than non-irradiated controls, showing a significant delay in softening. This effect can be attributed to a transient reduction of approximately 30% in the activity of cell wall-degrading enzymes between days 2 and 4 postharvest, with enzyme levels approaching those of the control group only from day 6 onward. Irradiation preserved key physicochemical attributes atthe edible stage without compromising flavor or visual qualities. These data demonstrate that low-dose gamma irradiation is an effective, non-chemical strategy to delay ripening and extend papaya shelf life while maintaining its nutritional and sensoryquality. This approach holds great potential for reducing postharvest losses and improving the fruit’s marketability and export competitiveness.
Fish cytolysins in all their complexity Fabiana V. Campos, Helena B. Fiorotti, Juliana B. Coitinho, Suely G. Figueiredo Toxins, 2021 The majority of the effects observed upon envenomation by scorpaenoid fish species can be reproduced by the cytolysins present in their venoms. Fish cytolysins are multifunctional proteins that elicit lethal, cytolytic, cardiovascular, inflammatory, nociceptive, and neuromuscular activities, representing a novel class of protein toxins. These large proteins (MW 150–320 kDa) are composed by two different subunits, termed α and β, with about 700 amino acid residues each, being usually active in oligomeric form. There is a high degree of similarity between the primary sequences of cytolysins from different fish species. This suggests these molecules share similar mechanisms of action, which, at least regarding the cytolytic activity, has been proved to involve pore formation. Although the remaining components of fish venoms have interesting biological activities, fish cytolysins stand out because of their multifunctional nature and their ability to reproduce the main events of envenomation on their own. Considerable knowledge about fish cytolysins has been accumulated over the years, although there remains much to be unveiled. In this review, we compiled and compared the current information on the biochemical aspects and pharmacological activities of fish cytolysins, going over their structures, activities, mechanisms of action, and perspectives for the future.
