Changes in Antioxidant Activity ofCyphomandra betacea(Cav.) Sendtn. Fruits During Maturation and Senescence

Averrhoa carambola L., Cyphomandra betacea, Myrciaria dubia as a Source of Bioactive Compounds of Antioxidant Properties

Natural bioactive compounds play an important role in the prevention of various diseases. The exotic fruits Averrhoa carambola L. (star fruit), Cyphomandra betacea (tamarillo) and Myrciaria dubia (camu-camu) can be valuable sources of phytochemicals with antioxidant properties. The aim of this study has been to compare the antioxidant properties of these exotic fruits, the structure of polyphenolic compounds and the content of vitamin C and β-carotene. All the juices were analyzed for their antioxidant capacity (DPPH and ABTS assays) and the composition of phenolic compounds (TP and FBBB assays, total flavonoid content, total anthocyanins). In addition, HPLC assays were performed to analyse the content of phenolic acids, flavonoids, vitamin C and β-carotene. The results demonstrated that juice from the Myrciaria dubia fruit had the highest antioxidant capacity, which was 4.5-fold higher than that of juice from Averrhola carambola L., and nearly 7-fold higher than the antioxidant capacity of Cyphomandra betacea fruit juice. Additionally, juice from the camu-camu fruit had a 3- to 4-fold higher total polyphenol content (8290 ± 254 mg GAE L^-1) and a high level of vitamin C (8410.8 ± 16.9 mg AA kg^-1). In turn, tamarillo juice had a high content of total anthocyanins (5796 mg CGE L^-1) and phenolic acids (mostly chlorogenic acid and caffeic acid). Juice produced from carambola had a high content of total flavonoids (1345 mg CAE L^-1), and the composition of these compounds was dominated by flavanols (epicatechin). The research results justify the conclusion that fruits of Myrciaria dubia, Averrhoa carambola L., Cyphomandra betacea are rich sources of bioactive compounds with antioxidant properties, and in the near future may serve as healthful food ingredients.

Syzygium aromaticum bud (clove) essential oil is a novel and safe aldose reductase inhibitor: in silico, in vitro, and in vivo evidence

PURPOSE

This study aimed to evaluate the antioxidant and antidiabetic properties of clove essential oil (CEO) and to elucidate its mode of action, using selected biochemical targets, relevant to diabetes, and, specifically, its inhibitory effect on the polyol pathway.

METHODS

In the current study, CEO was examined for its inhibitory effects on aldose reductase in silico, in vitro, and in vivo, as well as its antioxidative activity.

RESULTS

In silico docking studies showed that all the selected major compounds of CEO have an energy change ranging between - 5.5 and - 8.8 kcal/mol and an inhibition constant ranging between 357.08 nM and 93.12 µM. CEO significantly inhibits aldose reductase with an IC₅₀ value of 58.55 ± 5.84 µg/mL in a noncompetitive manner. The supplementation of CEO at 20 mg/kg BW decreases retinal sorbitol dehydrogenase activity via decreased aldose reductase activity in streptozotocin (STZ)-induced diabetic Sprague Dawley rats. Moreover, diabetic rats injected with CEO have exhibited improved levels of glycemia. The IC₅₀ values for ABTS, hydroxyl, and hydrogen peroxide scavenging activities of CEO were found to be 34.42, 277.4, and 39.99 µg/mL, respectively. Reducing power assay and phosphomolybdate assay exhibited a reduction force with the A_0.5 values of 50.25 and 140.16 µg/mL, respectively.

CONCLUSION

CEO potentially exerts a beneficial effect on diabetes-related complications due to its antioxidant and inhibitory effect on aldose reductase activity.

Blanching and antimicrobial mixture (potassium sorbate-sodium benzoate) impact on the stability of a tamarillo (Cyphomandra betacea) sweet product preserved by hurdle technology

In a previous study, a stable tamarillo sweet product (TSP) was obtained by applying hurdle technology (low pH, reduction of water activity, sodium benzoate addition and stored at 4 °C, with oxygen and light protection). In order to improve the TSP shelf life, it was decided to employ a mixture of antimicrobial agents (sodium benzoate and potassium sorbate 50-50%) and fruit blanching. The phenolic compounds content, total monomeric anthocyanins of TSP, antioxidant capacity, microbial growth (aerobic mesophilic bacteria, molds and yeasts) and net color change were evaluated, during 63 days. The results showed that the use of blanched tamarillo and the addition of the antimicrobial mixture increased the TSP stability, in which the microbial counts were maintained below the limits established by the official food safety norms, without effects the antioxidant compounds and color.

Developmental changes in carbon and nitrogen metabolism affect tea quality in different leaf position

Leaf position represents a specific developmental stage that influences both photosynthesis and respiration. However, the precise relationships between photosynthesis and respiration in different leaf position that affect tea quality are largely unknown. Here, we show that the effective quantum yield of photosystem II [ΦPSⅡ] as well as total chlorophyll concentration (TChl) of tea leaves increased gradually with leaf maturity. Moreover, respiration rate (RR) together with total nitrogen concentration (TN) decreased persistently, but total carbon remained unchanged during leaf maturation. Analyses of major N-based organic compounds revealed that decrease in TN was attributed to a significant decrease in the concentration of caffeine and amino acids (AA) in mature leaves. Furthermore, soluble sugar (SS) decreased, but starch concentration increased with leaf maturity, indicating that source-sink relationship was altered during tea leaf development. Detailed correlation analysis showed that ΦPSⅡ was negatively correlated with RR, SS, starch, tea polyphenol (TP), total catechins and TN, but positively correlated with TChl; while RR was positively correlated with TN, SS, TP and caffeine, but negatively correlated with TChl and starch concentrations. Our results suggest that biosynthesis of chlorophyll, catechins and polyphenols is closely associated with photosynthesis and respiration in different leaf position that greatly influences the relationship between primary and secondary metabolism in tea plants.