Yellow Papaya Research Articles

Characterization of Green and Yellow Papaya (Carica papaya) for Anti-Diabetic Activity in Liver and Myoblast Cells and Wound-Healing Activity in Fibroblast Cells.

Obesity and diabetes, often characterized as "metabolic syndrome", have been recognized as two of the most important public health issues worldwide. The objective of the present research was to evaluate green and yellow papaya for anti-oxidation and anti-diabetic properties. Leaves, skin, pulp, and seed samples from papayas were freeze-dried and then extracted in water or 80% methanol. The extracts were used to determine total polyphenolic content and anti-oxidation activities, and to determine biological activities, including glucose uptake, Glut-2 expression, triglyceride reduction, and wound-healing activity. Our data demonstrated that methanol and water extracts of green and yellow papaya have similar concentrations of polyphenols in skin (10-20 mg/g dry powder), leaf (25-30 mg/g dry powder), and pulp (1-3 mg/g dry powder) fractions. However, both methanol and water extracts of seeds from yellow papaya have substantially higher concentrations of polyphenols compared to green papaya. Both water and methanol extracts of yellow papaya exhibited higher anti-oxidation activity compared to green papaya in skin (50-60%), pulp (200-300%), and seeds (10-800%). Old leaves also showed greater anti-oxidation activity (30-40%) compared to new leaves. Pulp extracts from both yellow and green papaya stimulated greater glucose uptake, but only pulp from green papaya stimulated glucose uptake in muscle cells. Similarly, pulp extract stimulated glucose transporter Glut-2 expression in liver cells. The skin, pulp, and seeds of green or yellow papaya showed triglyceride-lowering activity in liver cells by 60-80%, but samples taken from yellow papaya had a more potent effect. Seeds from both green and yellow papaya significantly stimulated the migration of fibroblasts in the wounded area by 2-2.5-fold compared to the untreated control. Consistent with these data, seeds from both green and yellow papaya also significantly stimulated collagen synthesis in fibroblast cells by almost 3-fold. In conclusion, our data indicate that different parts of papaya produce stimulatory effects on glucose uptake, Glut-2 expression, TG reduction, and wound-healing activities. This study concludes that different parts of the papaya can be beneficial for preventing diabetes and diabetes-related wound healing.

New sources of papain: SEM and SDS‐PAGE analysis to determine the natural tenderizer from papaya latex and senesced leaves

This study aims to determine the effectiveness of papaya‐fruit latex and yellow‐senesced leaves as a natural and organic tenderizer. The fruit and leaves of the plant were ground to powder, while 0 g, 10 g, 15 g and 20 g variations were used to cover 50 g of meat for 4 h. Subsequently, the Bradford and Kjeldahl methods were used to determine the protein content, while the protein profile was analyzed using SDS‐PAGE and confirmed using a Scanning Electron Microscope (SEM). The results showed that the protein concentration in mutton after fruit latex treatment was 41%, which was higher than the concentration of beef at 29.86%. Furthermore, the beef lost protein bands and its molecular weight fell from 225 kDa to 86 KDa, while the mutton experienced a reduction from 100 kDa to 65 kDa, which was significantly smaller than for raw meat. A single protein band was also observed at 21.6 kDa in the sample, indicating the presence of papain enzyme protein. Meanwhile, the SEM results showed that collagen and myofibril in the muscles were damaged in the treated meats. Based on these results, treatment with papaya fruit latex and yellow papaya leaves increases the tenderness of meat.

Characterization of Green and Yellow Papaya for Antioxidation and Glucose Uptake Stimulatory Activity in HepG2 Liver Cells

Abstract Objectives The long-term objective of present research is to evaluate papaya for anti-diabetic properties. The current objectives were (1) To determine polyphenolic contents and antioxidation activity of leaves, skin, pulp, and seeds of green and yellow papaya and (2) to evaluate their effects on glucose uptake in HepG2 liver cells. Methods The leaves, skin, pulp, and seeds samples were freeze dried and then extracted in water or 80% Methanol. The total phenolic contents of each extracted sample was determined using the Folin- Ciocalteu method. The antioxidation activity in each sample was determined using 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and Ferric ion reducing antioxidation power (FRAP) assays. Effect of each fraction on glucose uptake was determined using a fluorescent-tagged NBD-Glucose derivative. Results The concertation of polyphenols was highest in both water and methanol extracts of seeds from yellow papaya compared to that in seeds from green papaya. Leaves and skin fractions contained modest concentration of polyphenols whereas pulp contained the lowest concentration of polyphenols. FRAP assay indicates that both water and methanol extracts of leaves, skin, pulp, and seeds from yellow papaya exhibited higher antioxidation activity compared to that of green papaya. A similar antioxidation activity pattern was observed by DPPH assay. Leaves and skin from both green and yellow papaya showed modest to high antioxidation activity whereas pulp from both green and yellow papaya contained a low antioxidation activity. In contrast, green papaya extracts significantly stimulated glucose uptake in HepG2 liver cells compared to that of yellow papaya extracts. Both water and methanol extract of pulp from green papaya showed the greatest stimulation of glucose uptake followed by leaves and skin. Conclusions Although the seeds from yellow papaya contained highest concentration of polyphenols and exhibited highest antioxidation activity, pulp from green papaya showed significantly higher stimulation of glucose uptake in liver cells. Our data indicates that polyphenolic content and/or antioxidation activity in papaya may not be related to their glucose uptake stimulatory activity in liver cells. This study concludes that regular consumption of green papaya may be beneficial for preventing diabetes. Funding Sources Capacity Building Grant, USDA.

Characterization of chromoplasts and carotenoids of red- and yellow-fleshed papaya (Carica papaya L.)

Chromoplast morphology and ultrastructure of red- and yellow-fleshed papaya (Carica papaya L.) were investigated by light and transmission electron microscopy. Carotenoid analyses by LC-MS revealed striking similarity of nutritionally relevant carotenoid profiles in both the red and yellow varieties. However, while yellow fruits contained only trace amounts of lycopene, the latter was found to be predominant in red papaya (51% of total carotenoids). Comparison of the pigment-loaded chromoplast ultrastructures disclosed tubular plastids to be abundant in yellow papaya, whereas larger crystalloid substructures characterized most frequent red papaya chromoplasts. Exclusively existent in red papaya, such crystalloid structures were associated with lycopene accumulation. Non-globular carotenoid deposition was derived from simple solubility calculations based on carotenoid and lipid contents of the differently colored fruit pulps. Since the physical state of carotenoid deposition may be decisive regarding their bioavailability, chromoplasts from lycopene-rich tomato fruit (Lycopersicon esculentum L.) were also assessed and compared to red papaya. Besides interesting analogies, various distinctions were ascertained resulting in the prediction of enhanced lycopene bioavailability from red papaya. In addition, the developmental pathway of red papaya chromoplasts was investigated during fruit ripening and carotenogenesis. In the early maturation stage of white-fleshed papaya, undifferentiated proplastids and globular plastids were predominant, corresponding to incipient carotenoid biosynthesis. Since intermediate plastids, e.g., amyloplasts or chloroplasts, were absent, chromoplasts are likely to emerge directly from proplastids.

Effect of gamma-irradiation on ripening papaya pectin

Papaya (Carica papaya, L., var. Sunset) at three initial ripeness stages were irradiated with 0.25, 0.50, 0.75, 1.0, or 1.5 kGy gamma-irradiation and pectin changes during ripening determined. A significant linear relationship was found between irradiation dose and firmness immediately after irradiation. Irradiation had no effect on fruit skin or flesh color of papaya fruit irradiated at the 5 to 30% yellow stage and allowed to ripen. Papaya irradiated when 5 to 30% yellow showed no significant changes in pectin methylesterase activity when ripe. Immediately after irradiation, the pectin in 10 to 30% yellow papaya showed depolymerization and demethoxylation, though no effect on pectin methylesterase activity was detected. There was an increase in water soluble pectin (WSP), while chelator soluble (CSP) and alkali soluble pectin (ASP) decreased, with a significant decline in the methanol content of the ASP fraction. After the 25 to 30% yellow ripeness stage, fruit irradiated at 0.50 to 1.0 kGy had less pectic depolymerization, and had a firmer texture than nonirradiated when ripe. A lower level of WSP and higher levels of CSP and ASP were found in ripe fruit that had been irradiated at 0.5 to 1.0 kGy when 25 to 30% yellow skin with a significant quadratic relationship between irradiation dose and the three pectin fractions. The firmness of these irradiated fruit were retained for two days longer than the nonirradiated control.

MECHANICAL INJURY IN SOLO PAPAYA FRUIT

Ripe yellow papaya fruit in the markets frequently show green sunken areas called “green islands” (GI). This disorder seems to be caused by mechanical injury in a commercial postharvest handling system. Fruit at different stages of ripeness (5 to 50% yellow) were dropped from different heights (0 to 100 cm) onto a smooth steel plate to try to create GI. The injury sustained was not the same as GI seen in fruit from the handling system. Fruit (10 to 15% yellow) dropped on different grades of sandpaper (220 mesh to 36 mesh) from a height of 10 cm had injury symptoms similar to those seen on fruit from the handling system. These results suggest that abrasion damage was more important than impact damage in papaya fruit. Heating fruit at 48°C for -6 hours or until fruit core temperature (FCT) reached 47.5°C aggravated the severity of GI. Delaying the time of heating from the time of dropping did not significantly lower the severity of GI, except for fruit heated 24 hours after dropping. Waxing fruit alleviated the severity of GI. The results indicate that avoidance of abrasive surfaces such as the plywood walls of field bins is the best approach to avoiding the unsightly GI blemishes on papaya peel.