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Citrus fruits are subjected to a diversity of postharvest diseases caused by various pathogens during picking, packing, storage and transportation. Green and blue molds, caused by Penicillium digitatum and Penicillium italicum, respectively, are two major postharvest citrus diseases and cause significant economic losses during the commercialization phase. Currently, the control of postharvest citrus diseases relies mainly on the use of synthetic fungicides, which usually result in the resistance against fungal attack, environment pollution and health hazards. In recent years, much attention has been given to the preservation of citrus by naturally isolated edible plant extracts, medicinal plant extracts, Citrus extracts and volatiles, et al. Scientists worldwide devote their time and energy to discover the high effect, low toxicity, safety and inexpensive plant-derived fungicides. The current review will highlight plant-derived fungicides and chemical constituents that aim to inhibit P. digitatum and P. italicum in vitro and in vivo. Coatings enriched with plant extracts could be good alternative methods for Citrus fruits preservation. Problems and prospects of the research and development of plant-derived natural fungicides will also be discussed in this article.

Genistein, the predominant isoflavone found in soy products, has exerted its anticarcinogenic effect in many different tumor types in vitro and in vivo. Accumulating evidence in recent years has strongly indicated the existence of cancer stem cells in gastric cancer. Here, we showed that low doses of genistein (15 μM), extracted from Millettia nitida Benth var hirsutissima Z Wei, inhibit tumor cell self-renewal in two types of gastric cancer cells by colony formation assay and tumor sphere formation assay. Treatment of gastric cancer cells with genistein reduced its chemoresistance to 5-Fu (fluorouracil) and ciplatin. Further results indicated that the reduced chemoresistance may be associated with the inhibition of ABCG2 expression and ERK 1/2 activity. Furthermore, genistein reduced tumor mass in the xenograft model. Together, genistein inhibited gastric cancer stem cell-like properties and reduced its chemoresistance. Our results provide a further rationale and experimental basis for using the genistein to improve treatment of patients with gastric cancer.

7-demethoxytylophorine (DEM) is a phenanthroindolizidine alkaloid, which is reported to be effective in inhibiting leucocytes and regulation of human immunity. However, few studies reported the inhibitory effect of DEM against plant-pathogenic fungi, particularly postharvest pathogen Penicillium italicum (P. italicum). Current studies have investigated the antifungal activity of DEM through membrane damage and energy deficit in P. italicum. The results showed that the DEM potentially inhibits the growth of P. italicum in a dose-dependent manner. In vitro (mycelial growth and spore germination) tests showed great minimal inhibitory concentration (MIC) (1.56 µg mL−1) and minimum fugicide concentration (MFC) (6.25 µg mL−1). Microscopic analyses showed that mycelial morphology of P. italicum was severely damaged following DEM treatment. Moreover, relative electrical conductivity and lysis ability assays showed that DEM treatment aids in destroying the integrity of plasma membranes that deplete reducing sugars and soluble proteins. The activity of malate dehydrogenase (MDH) and succinate dehydrogenase (SDH) demonstrated that DEM led to the disruption of TCA cycle in P. italicum mycelia. The results of this study led us to conclude that, DEM could be used as a natural antifungal agent for controlling postharvest blue mold disease of citrus fruits caused by P. italicum.

An edible coating based on 1.5% sodium alginate (SA), 0.7% citric acid and 1.0% sucrose ester with and without Ficus hirta (FH) fruit extract was applied to Nanfeng mandarins to preserve their postharvest quality. Changes in decay rate, weight loss, quality parameters, respiration rate, and enzymatic activities of the coated and control samples were assessed at 10-day intervals for a 100-day storage period at 6 °C. The decay rate, weight loss, respiration rate and maleicdialdehyde (MDA) content were much lower in the FH-SA coated samples than in the control group. During the middle and later periods of storage, Nanfeng mandarin treated with FH-SA coating maintained good fruit quality. The FH-SA coating treatment enhanced the activities of antioxidant and defense-related enzymes such as superoxyde dismutase (SOD), catalase (CAT), peroxidase (POD), chitinase (CHI), β-1,3-glucanase (GLU), and phenylalanine ammonialyase (PAL), and stimulated the accumulation of phenolic compounds. Our study suggests that FH-SA coating has the potential to enhance the long term quality and storage of Nanfeng mandarin.

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