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This study aimed to determine the respiration rate, ethylene production, total reducing sugars, total phenolic compounds, chlorophylls, color and firmness of green and purple varieties of star apple fruit ( Chrysophyllum cainito ) during “on-plant” maturation and ripening in order to contribute determining a ripening index for appropriate harvesting time. Respiration rate (RRCO 2 ) and ethylene production decreased significantly during ripening, although an increase in ethylene was noted at mature stage of the purple variety. Total reducing sugars increased significantly during the three stages, while total phenolic compounds decreased, and skin showed higher level of total phenolics compared to pulp. Similarly, chlorophylls (a + b) and carotenoids in skin decreased during ripening, however, the decrease in carotenoids was less significant compared to the decrease of chlorophylls. Overall, color changed from darker to lighter and duller due to ripening. Firmness also decreased significantly during ripening causing softening of the fruit. Results also showed that color and firmness might be considered as a good ripening index for star apple. Conclusively, star apple does not seem to have a climacteric pattern, and its behavior during maturation and ripening was similar to most of non-climacteric fruits. [ABSTRACT FROM AUTHOR]

Diabetes is a kind of metabolic syndrome (MetS) that seriously threatens human health globally. The leaf of star apple (Chrysophyllum cainito L.) is an incompletely explored folk medicine on diabetes. And, the effects and mechanisms on diabetes complicated glycolipid metabolism disorders are unknown till now. This study aimed to investigate the constituents of star apple leaf polyphenol enriched-fraction (SAP), and elucidate their treatment effects and mechanism on diabetes and accompanied other MetS. The components of SAP were tentatively identified by HPLC-Q-TOF-MS/MS. The antioxidant activity was determined by the scavenging of free radicals and hypoglycemic activities by inhibition of α-glucosidase in vitro. HepG2 cells were used for evaluating the alleviation effects of SAP on lipid accumulation. Streptozotocin and high-fat diet induced diabetic mice were grouped to evaluate the effects of different dosages of SAP. 16S rRNA was conducted to analysis gut microbiome-mediated glucose and lipid metabolism mechanism. It showed that myricitrin was one of the main active constituents of SAP. SAP not only showed low IC50 on -glucosidase (24.427± 0.626 μg/mL), OH·(3.680± 0.054 μg/mL) and ABTS· (9.155±0.234 μg/mL), but significantly induced the lipid accumulation in HepG2 cells (p < 0.05). SAP at 200 mg/kg·day significantly decreased the blood glucose, insulin and oral glucose tolerance test value (p < 0.05). The insulin resistance indexes and oxidative stress were alleviated after administration. SAP not only attenuated hepatic lipid deposition, but also reversed the hepatic glycogen storage. 16S rRNA sequencing results revealed that the interaction between SAP and gut microbiota led to the positive regulation of beneficial bacteria including Akkermansia, Unspecified S24_7, Alistipes and Unspecified_Ruminococcaceae , which might be one of the mechanisms of SAP on MetS. For the first time, this study explored the regulation effect of star apple leaf polyphenols on the hepatic glycolipid metabolism and studied the underlying mechanism from the view of gut microbiota. These findings indicated that SAP possesses great potential to serve as a complementary medicine for diabetes and associated MetS. It provided scientific evidence for folk complementary medicine on the treatment of diabetes-complicated multiple metabolic disorders. [Display omitted] [ABSTRACT FROM AUTHOR]