Valorization applications of pineapple and papaya byproducts in food industry.

The recent increase in the harvesting and industrial processing of tropical fruits such as pineapple and papaya is leading to unavoidable amounts of byproducts rich in valuable compounds. Given the significance of the chemical composition of these byproducts, new research avenues are opening up to exploit them in the food industry. In this sense, the revalorization of pineapple and papaya byproducts is an emerging trend that is encouraging the full harnessing of these tropical fruits, offering the opportunity for developing innovative value-added products. Therefore, the main aim of this review is to provide an overview of the state of the art of the current valorization applications of pineapple and papaya byproducts in the field of food industry. For that proposal, comprehensive research of valorization applications developed in the last years has been conducted using scientific databases, databases, digital libraries, and scientific search engines. The latest valorization applications of pineapple and papaya byproducts in the food industry have been systematically revised and gathered with the objective of synthesizing and critically analyzing existing scientific literature in order to contribute to the advancement of knowledge in the field of tropical byproduct revalorization providing a solid foundation for further research and highlighting scientific gaps and new challenges that should be addressed in the future.

Phytochemistry and antifatigue activities of Carica papaya leaf from geothermal, coastal and urban areas, Indonesia.

Fatigue, a condition of lack of energy and motivation resulting in the feeling of extreme tiredness or exhaustion, is usually prevented and treated with ergogenic aids, such as in the form of nutritional supplements. Papaya (Carica papaya) may be a potential candidate for ergogenic aids, considering its healthy secondary metabolite properties and number of metabolite compounds that could be affected by the location where the plant growing. The aim of this study was to identify the phytochemicals of papaya leaves from three different locations: geothermal, coastal, and urban areas in Aceh province, Indonesia. Concentrations of papaya leaf with the highest number of secondary metabolite compounds were tested in rats to measure blood lactate acid concentrations after strenuous exercise. The number of chemical compounds identified from the three locations was 24 compounds; 23 compounds and 17 compounds, respectively. The highest concentration of chemical compounds that have antifatigue activity contained in all papaya leaf samples were neophytadiene, linolenic acid, gamma tocopherol, hexadecanoic acid, vitamin E, carpaine, octadecatrienoic acid, nor lean-12-ene, squalene, and phytol. Furthermore, most of the compounds' highest concentrations were found in papaya leaves from the coastal area and, therefore, tested on the animal model. Treatment was provided in 12 male rats with different doses of papaya powder supplements for 15 days. The results showed that lactic acid levels of rats received a dose of 400 mg/kg of papaya leaf extract reduced the lactic acid concentration (p=0.014) compared with the control group. This study highlights that papaya leaves from the coastal area have the most potential activities as ergogenic herbal aid and were able to reduce lactic acid levels in rats after strenuous exercise.

Effect of pre-cooling on the shelf-life and quality of formosa papaya.

Papaya is a climacteric fruit, rapidly ripening after harvesting due to ethylene production and increased respiratory rate. This swift ripening results in softening of fruit tissues, shortening the fruit shelf life. Pre-cooling serves as an alternative to minimize fruit ripening and post-harvest losses by reducing metabolism. This study aimed to evaluate the effect of pre-cooling on the quality and conservation of Formosa 'Tainung I' papaya. Papayas at maturation stage II were obtained from a commercial orchard with conventional production. The experimental design was a completely randomized 4×6 split-plot scheme, with pre-cooling treatments (Control, without pre-cooling treatment; pre-cooling at 15 °C in a cold chamber; pre-cooling at 7 °C in a cold chamber; and forced-air cooling at 7 °C) in the plot, and days of storage (0, 7, 14, 21, 28, and 35 days) in the subplot. Pre-cooling effectively delayed the ripening and senescence of Formosa papaya, reducing the loss of green color and firmness. Regardless of the treatment used, chilling injury and incidence of fungi from the genus Fusarium and Alternaria limited the shelf life of Formosa 'Tainung I' papaya up to 21 days of storage. Additionally, the appearance of hardened regions in the pulp compromised the sensory quality of the fruits, necessitating further investigation into the causes of this disorder.

Comparative proteomic analysis of papaya bud flowers reveals metabolic signatures and pathways driving hermaphrodite development.

Papaya (Carica papaya) is a trioecious species with female, male, and hermaphrodite plants. Given the sex segregation, selecting hermaphroditic plants is vital for orchard establishment due to their greater commercial value. However, selecting hermaphrodite plants through sexing is laborious and costly. Moreover, environmental stressors can exacerbate the issue by potentially inducing abnormal flower development, thus affecting fruit quality. Despite these challenges, the molecular mechanisms governing sex development in papaya remain poorly understood. Thus, this study aimed to identify proteins associated with sex development in female and hermaphrodite flowers of papaya through comparative proteomic analysis. Proteins from flower buds at the early and late developmental stages of three papaya genotypes (UENF-CALIMAN 01, JS12, and Sunrise Solo 72/12) were studied via proteomic analysis via the combination of the shotgun method and nanoESI-HDMSE technology. In buds at an early stage of development, 496 (35.9%) proteins exhibited significantly different abundances between sexes for the SS72/12 genotype, 139 (10%) for the JS12 genotype, and 165 (11.9%) for the UC-01 genotype. At the final stage of development, there were 181 (13.5%) for SS72/12, 113 (8.4%) for JS12, and 125 (9.1%) for UC-01. The large group of differentially accumulated proteins (DAPs) between the sexes was related to metabolism, as shown by the observation of only the proteins that exhibited the same pattern of accumulation in the three genotypes. Specifically, carbohydrate metabolism proteins were up-regulated in hermaphrodite flower buds early in development, while those linked to monosaccharide and amino acid metabolism increased during late development. Enrichment of sporopollenin and phenylpropanoid biosynthesis pathways characterizes hermaphrodite samples across developmental stages, with predicted protein interactions highlighting the crucial role of phenylpropanoids in sporopollenin biosynthesis for pollen wall formation. Most of the DAPs played key roles in pectin, cellulose, and lignin synthesis and were essential for cell wall formation and male flower structure development, notably in the pollen coat. These findings suggest that hermaphrodite flowers require more energy for development, likely due to complex pollen wall formation. Overall, these insights illuminate the molecular mechanisms of papaya floral development, revealing complex regulatory networks and energetic demands in the formation of male reproductive structures.

Evaluation of the effect of Carica papaya seed on the growth performance of fattening rabbits.

Successful breeding depends on feeding. The present study aims to evaluate the Carica papaya seed effect on the growth performance of rabbits. The zootechnical parameters studied are weight growth, average daily gain, Feed Conversion Ratio, and carcass characteristics of kits. The experiment was conducted on 48 rabbits, divided into 4 groups, for 6 weeks. Forty-eight rabbits were divided into four (04) groups of 3 repetitions of 4 rabbits. The animals were fed diets containing various levels of papaya seed powder at variable contents: 0% (group T0), 4% (group T1), 6% (group T2), and 8% (group T3). At the end of the experiment, three animals were slaughtered in each animal group to assess the quality of the carcasses and organs. 6% of the seeds of Carica papaya significantly improved (p < 0.05) the average daily gain of the kits: T2 (22.40 g / d) compared to the T0 group (11.32 g / d), T1 (12.20 g / d) and T3 (17.53 g / d). The best Feed Conversion Ratio (0.80) was recorded in the animals of group T2. In contrast, the highest carcass yield was recorded in the rabbits of group T3 (62.70%). In conclusion, 6% was optimal in the feed rations of fattened rabbits to improve production performance. Breeders can consider the benefits of introducing Carica papaya seeds into the rabbits' diet.

Transcriptome, Plant Hormone, and Metabolome Analysis Reveals the Mechanism of Purple Pericarp Formation in 'Zihui' Papaya (Carica papaya L.).

The color of the pericarp is a crucial characteristic that influences the marketability of papaya fruit. Prior to ripening, normal papaya exhibits a green pericarp, whereas the cultivar 'Zihui' displays purple ring spots on the fruit tip, which significantly affects the fruit's visual appeal. To understand the mechanism behind the formation of purple pericarp, this study performed a thorough examination of the transcriptome, plant hormone, and metabolome. Based on the UPLC-ESI-MS/MS system, a total of 35 anthocyanins and 11 plant hormones were identified, with 27 anthocyanins and two plant hormones exhibiting higher levels of abundance in the purple pericarp. In the purple pericarp, 14 anthocyanin synthesis genes were up-regulated, including CHS, CHI, F3H, F3'5'H, F3'H, ANS, OMT, and CYP73A. Additionally, through co-expression network analysis, three MYBs were identified as potential key regulators of anthocyanin synthesis by controlling genes encoding anthocyanin biosynthesis. As a result, we have identified numerous key genes involved in anthocyanin synthesis and developed new insights into how the purple pericarp of papaya is formed.

Identification and Validation of Key Genes Related to Preferred Flavour Profiles in Australian Commercial Papaya (Carica papaya L.).

Commercial papaya varieties grown in Australia vary greatly in taste and aroma. Previous profiling has identified undesirable 'off tastes' in existing varieties, discouraging a portion of the population from consuming papayas. Our focus on enhancing preferred flavours led to an exploration of the genetic mechanisms and biosynthesis pathways that underlie these desired taste profiles. To identify genes associated with consumer-preferred flavours, we conducted whole RNA sequencing and de novo genome assembly on papaya varieties RB1 (known for its sweet flavour and floral aroma) and 1B (less favoured due to its bitter taste and musty aroma) at both ripe and unripe stages. In total, 180,368 transcripts were generated, and 118 transcripts related to flavours were differentially expressed between the two varieties at the ripe stage. Five genes (cpBGH3B, cpPFP, cpSUS, cpGES and cpLIS) were validated through qPCR and significantly differentially expressed. These genes are suggested to play key roles in sucrose metabolism and aromatic compound production pathways, holding promise for future selective breeding strategies. Further exploration will involve assessing their potential across broader germplasm and various growth environments.

Ripe papaya pectins inhibit the proliferation of colon cancer spheroids and the formation of chemically induced aberrant crypts in rats colons.

Pectins are a class of soluble polysaccharides that can have anticancer properties through several mechanisms. This study aimed to characterize the molecular structure of water-soluble fractions (WSF) derived from ripe and unripe papayas and assess their biological effects in two models: the 3D colon cancer spheroids to measure cell viability and cytotoxicity, and the in vivo model to investigate the inhibition of preneoplastic lesions in rats. WSF yield was slightly higher in ripe papaya, and both samples mainly consisted of pectin. Both pectins inhibited the growth of colon cancer HT29 and HCT116 spheroids. Unripe pectin disturbed HT29/NIH3T3 spheroid formation, decreased HCT116 spheroid viability, and increased spheroid cytotoxicity. Ripe pectin had a more substantial effect on the reduction of spheroid viability for HT29 spheroids. Furthermore, in vivo experiments on a rat model revealed a decrease in aberrant crypt foci (ACF) formation for both pectins and increased apoptosis in colonocytes for ripe papaya pectins. The results suggest potential anticancer properties of papaya pectin, with ripe pectin showing a higher potency.

G-site residue S67 is involved in the fungicide-degrading activity of a tau class glutathione S-transferase from Carica papaya.

Thiram is a toxic fungicide extensively used for the management of pathogens in fruits. Although it is known that thiram degrades in plant tissues, the key enzymes involved in this process remain unexplored. In this study, we report that a tau class glutathione S-transferase (GST) from Carica papaya can degrade thiram. This enzyme was easily obtained by heterologous expression in Escherichia coli, showed low promiscuity toward other thiuram disulfides, and catalyzed thiram degradation under physiological reaction conditions. Site-directed mutagenesis indicated that G-site residue S67 shows a key influence for the enzymatic activity toward thiram, while mutation of residue S13, which reduced the GSH oxidase activity, did not significantly affect the thiram-degrading activity. The formation of dimethyl dithiocarbamate, which was subsequently converted into carbon disulfide, and dimethyl dithiocarbamoylsulfenic acid as the thiram degradation products suggested that thiram undergoes an alkaline hydrolysis that involves the rupture of the disulfide bond. Application of the GST selective inhibitor 4-chloro-7-nitro-2,1,3-benzoxadiazole reduced papaya peel thiram-degrading activity by 95%, indicating that this is the main degradation route of thiram in papaya. GST from Carica papaya also catalyzed the degradation of the fungicides chlorothalonil and thiabendazole, with residue S67 showing again a key influence for the enzymatic activity. These results fill an important knowledge gap in understanding the catalytic promiscuity of plant GSTs and reveal new insights into the fate and degradation products of thiram in fruits.

Calmodulin-like protein CML15 interacts with PP2C46/65 to regulate papaya fruit ripening via integrating calcium, ABA and ethylene signals.

It is well known that calcium, ethylene and abscisic acid (ABA) can regulate fruit ripening, however, their interaction in the regulation of fruit ripening has not yet been fully clarified. The present study found that the expression of the papaya calcium sensor CpCML15 was strongly linked to fruit ripening. CpCML15 could bind Ca2+ and served as a true calcium sensor. CpCML15 interacted with CpPP2C46 and CpPP2C65, the candidate components of the ABA signalling pathways. CpPP2C46/65 expression was also related to fruit ripening and regulated by ethylene. CpCML15 was located in the nucleus and CpPP2C46/65 were located in both the nucleus and membrane. The interaction between CpCML15 and CpPP2C46/65 was calcium dependent and further repressed the activity of CpPP2C46/65 in vitro. The transient overexpression of CpCML15 and CpPP2C46/65 in papaya promoted fruit ripening and gene expression related to ripening. The reduced expression of CpCML15 and CpPP2C46/65 by virus-induced gene silencing delayed fruit colouring and softening and repressed the expression of genes related to ethylene signalling and softening. Moreover, ectopic overexpression of CpCML15 in tomato fruit also promoted fruit softening and ripening by increasing ethylene production and enhancing gene expression related to ripening. Additionally, CpPP2C46 interacted with CpABI5, and CpPP2C65 interacted with CpERF003-like, two transcriptional factors in ABA and ethylene signalling pathways that are closely related to fruit ripening. Taken together, our results showed that CpCML15 and CpPP2Cs positively regulated fruit ripening, and their interaction integrated the cross-talk of calcium, ABA and ethylene signals in fruit ripening through the CpCML15-CpPP2Cs-CpABI5/CpERF003-like pathway.

Effects of Carica papaya peel meal-based diets on rabbit bucks' spermiogram and reaction time.

The study aimed to evaluate the effects of Carica papaya peel meal-based diet on spermiogram and reaction time in rabbit bucks. Ripe pawpaw fruits were harvested during the dry season. The peels were carefully removed from the pulp and sun-dried for a week. Afterward, they were ground and included in the test diets as pawpaw peel meal (PPM) at inclusion rates of 0%, 15%, and 30%. Rabbit bucks (n = 15) were randomly separated into three groups of five bucks and labeled as groups A, B, and C. Group A, the control group (0%), was fed the basal protein diet (BD), group B (PPM 15) was given a PPM-based diet (15%), while C (PPM 30) was given diet composed of PPM (30%). Semen samples were collected and evaluated fortnightly for 14 weeks. The reaction time and mean ejaculate volume were lower (P < 0.05) in the treatment groups than in the control. Sperm motility and concentration decreased significantly (P < 0.05) across the groups from week 4 to the end of the experiment. Bucks fed PPM 15%, and PPM 30% had significantly (P < 0.05) higher percentages of dead sperm cells and total spermatozoa abnormalities. The control had (86%) normal spermatozoa morphology while those of PPM 15% and PPM 30% were (61%) and (52%), respectively. PPM 30% had the highest abnormal spermatozoa (47%) compared to PPM 15% (38%) and control (13%). The findings indicate that pawpaw peels up to 15% and 30% in the diet have a negative effect on spermiogram.

Supplementation of papaya leaf juice has beneficial effects on glucose homeostasis in high fat/high sugar-induced obese and prediabetic adult mice.

Prediabetes is characterized by a cluster of glycemic parameters higher than normal but below the threshold of type 2 diabetes mellitus (T2DM). In recent years, phytochemical-rich plant extracts have gained popularity as therapeutic agents for metabolic disorders. This study investigated the effects of papaya leaf (PL) juice supplementation on blood glucose levels in diet-induced obese and prediabetic adult mice. B65JL F1 mice (n = 20) at 12-14 months old were fed a high fat/sugar diet (HFHS) for 120 days. Mice were switched to restricted rodent chow of 3 g feed/30 g body weight/day, supplemented with 3 g/100 mL PL juice for 30 days. HFHS diet remarkably increased fasting plasma glucose levels from 114 ± 6.54 mg/dL to 192.7 ± 10.1 mg/dL and body weight from 32.5 ± 1.6 to 50.3 ± 4.1 g. HFHS diet results in hyperglycemia, insulin resistance, hyperlipidemia, and liver steatosis. The combination of PL juice and restricted diet significantly reduced body weight and fasting blood glucose levels to 43.75 ± 1.4 g and 126.25 ± 3.2 mg/dl, respectively. Moreover, PL juice with a restricted diet significantly improved lipid profile: cholesterol from 204 to 150 mg/dL, LDL-c from 110.4 to 50 mg/dL, and triglyceride from 93.7 to 60 mg/dL. Additionally, PL juice combined with a restricted diet significantly reduced adiposity, reversed fatty liver, and restored skeletal muscle Glut4 and phosphorylated (p-AKT (ser473). This study demonstrated that supplementation of PL juice with a restricted diet was more effective than a restricted diet alone in reversing major symptoms related to prediabetic and obesity conditions.

First report of Ageratum yellow vein virus infecting papaya in Lampung, Indonesia.

BACKGROUND: Papaya (Carica papaya) is a tropical fruit of great economic and nutritional importance, loved for its sweet and delicious flesh. However, papaya cultivation faces serious challenges in the form of Begomovirus attacks. Begomoviruses are a group of viruses that pose a serious threat to plants worldwide. Including papaya, Begomovirus has become a significant threat to papaya production in various parts of the world and has been identified in several regions in Indonesia. METHODS: DNA was extracted from seven samples representing different papaya growing areas using a Plant Genomic DNA Mini Kit. Genomic DNA from the samples was subjected to PCR using universal primers of AC2, AC1, SPG1 and SPG2. The PCR products then sequenced using the dideoxy (Sanger) approach. The obtained sequence then compared to the gene bank using BLAST software available at NCBI. Multiple sequence alignment and phylogenetic tree construction were analyzed using the MEGA11 program. RESULTS: Detection based on viral nucleic acid in papaya plants in Pesawaran, Lampung Province with seven sampling points using universal primers SPG1/SPG2 showed positive results for Begomovirus infection with visible DNA bands measuring ± 900 bp. Direct nucleotide sequencing using SPG1/SPG2 primers for the AC2 and AC1 genes of the Begomovirus and confirmed by the BLAST program showed that papaya samples were infected with Ageratum yellow vein virus (AYVV). The phylogenetic results show that AYVV from papaya samples has a close relationship with the AYVV group from several other countries, with 98% homology. CONCLUSION: In the papaya cultivation area in Pesawaran, Lampung province, it was identified as Begomovirus, Ageratum yellow vein virus (AYVV) species and is closely related to the AYVV group from several other countries. Overall, our study further suggests that Ageratum acts as an alternative host and reservoir for Begomovirus.

Evaluation of microbiome and physico-chemical profiles of fresh fruits of Musa paradisiaca, Citrus sinensis and Carica papaya at different ripening stages: Implication to quality and safety management.

INTRODUCTION: The ripening of fleshy fruits is a developmental process that involves changes in color, texture, aroma, nutrients, and diversity of microbiomes. Some microorganisms, specially, bacteria and molds are responsible for postharvest spoilage of fruits. Thus, this study is aimed at evaluating the alterations in microbiome and physico-chemical properties of selected fruits at different ripening stages. METHODS: Totally, 108 fresh fruit samples of Musa paradisiaca, Citrus sinensis and Carica papaya at three ripening stages were collected and processed in this study. The biochemical methods and MALD-TOF MS were used in identification. The physico-chemical properties of all samples were analyzed using standard methods. RESULTS: The minimum counts (6.74± 0.48-6.76± 0.42 log CFU/mL) and the maximum count (7.51± 0.43-7.96± 0.34 log CFU/mL) of AMB in all fruit samples was observed at mature green and overripe stages of the fruits, respectively. The ripening stage has significantly affected the microbial counts (P < 0.05) in all fruits, except counts of Enterobacteriaceae in banana and orange, and fungal counts in orange. The bacterial community of all fruits was predominated by B. cereus (33.7%), A. faecalis (17.3%), P. putida (15.2%), M. morganii (11.1%), S. sciuri (6.6%) and S. epidermidis (4.9%); while the fungal microbiome was constituted by Candida spp. (33.9%) followed by Saccharomyces spp. (18.1%) and Aspergillus spp. (16.3%). The ripening stages have also significantly affected the physico-chemical property in all samples. Accordingly, the lowest pH (3.53) and highest content of ascorbic acid (69.87 mg/100g) were observed in mature green oranges and overripe papaya, respectively, while the maximum concentration of total sugar (17.87%) and reducing sugar (14.20%) were recorded in overripe bananas. CONCLUSION: The presence of some potential human pathogens and spoilage microorganisms in fruit samples could contribute to post-harvest product losses besides the potential health risk associated with consumption of the tainted fruits. Hence, proper safety management practices and preservation mechanisms should be developed and put in place to ensure consumers safety against pathogens besides minimizing product losses through microbial spoilage.

Sustainable papaya plant waste and green tea residue composite films integrated with starch and gelatin for active food packaging applications.

This study explores the sustainable utilization of wastes from a papaya plant (papaya peels (PP), papaya seeds (PS), leaf-stem (PL)) and dried green tea residues (GTR) for the synthesis of bioplastics. The dried GTR were individually blended with each papaya waste extract and then boiled in water to get three composite papaya plant waste-green tea supernatants. Potato starch and gelatin-based functional films were prepared by integrating each with the composite papaya waste-green tea supernatant liquid. This work introduces a dissolved organic matter (DOM) study to the field of bioplastics, with the goal of identifying the organic components and macromolecules inherent in the PW supernatants. When compared with the films prepared solely from papaya waste (PW) supernatants, PW-GTR composite supernatant films prevent UV light transmission with superior antioxidant and mechanical properties. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction spectroscopy (XRD), and atomic force microscopy (AFM) were utilized to characterize the starch and gelatin PW-GTR films. Owing to the exceptional antioxidant, UV barrier, and remarkable biodegradable properties of the starch/PW/GTR and gelatin/PW/GTR composite films, make them ideal for use in food packaging applications.

Eco-safe composite edible coating of hydrocolloids with papaya leaf extract improves postharvest quality and shelf life of papaya fruit under ambient storage.

Papaya postharvest management using low-temperature storage is discouraged as it is a tropical fruit. Extensive research is going on to preserve papaya quality at ambient storage using edible coatings and its composites. The present investigation examined the effects of an eco-safe composite edible coating consisting of hydrocolloid carboxymethyl cellulose (CMC) (1%), guar gum (1.5%), xanthan gum (0.3%), and Gum Arabic (10%) combined with papaya leaf extract (PLE) (1:1 ratio by volume) applied as dip treatment on "Red Lady" papaya fruit at ambient storage condition. Among all the attempted treatments, "PLE incorporated with CMC (1%)" was found to be the best, as the treated fruit exhibited the highest levels of biochemicals, whereas the lowest levels of physiological and enzymatic activity, which positively affected the shelf life. The "CMC + PLE" treatment enhanced the fruit gloss score by 70.1%, phenolics by 6.1%, ascorbic acid by 22.3%, total carotenoid content by 7.4%, and fruit predilection score by 22.0% over the control fruit. However, it lowered (controlling) the physiological loss in weight by 51.0%, decay incidence by 66.6%, and polygalacturonase and pectin methylesterase activity by 24.92% and 35.29%, respectively, over control. Moreover, this treatment exhibited the highest fruit purchase predilection score and prolonged the storage life for >3 days on the physiological loss standard basis (≤10%). This study indicates that "CMC (1%) with PLE (1:1)" composite coating application on papaya under ambient conditions might be an effective, environmentally friendly, and health-friendly way to retain the quality and extend the storage life.

Genome-wide identification of MAPK family in papaya (Carica papaya) and their involvement in fruit postharvest ripening.

BACKGROUND: Papaya (Carica papaya) is an economically important fruit cultivated in the tropical and subtropical regions of China. However, the rapid softening rate after postharvest leads to a short shelf-life and considerable economic losses. Accordingly, understanding the mechanisms underlying fruit postharvest softening will be a reasonable way to maintain fruit quality and extend its shelf-life. RESULTS: Mitogen-activated protein kinases (MAPKs) are conserved and play essential roles in response to biotic and abiotic stresses. However, the MAPK family remain poorly studied in papaya. Here, a total of nine putative CpMAPK members were identified within papaya genome, and a comprehensive genome-wide characterization of the CpMAPKs was performed, including evolutionary relationships, conserved domains, gene structures, chromosomal locations, cis-regulatory elements and expression profiles in response to phytohormone and antioxidant organic compound treatments during fruit postharvest ripening. Our findings showed that nearly all CpMAPKs harbored the conserved P-loop, C-loop and activation loop domains. Phylogenetic analysis showed that CpMAPK members could be categorized into four groups (A-D), with the members within the same groups displaying high similarity in protein domains and intron-exon organizations. Moreover, a number of cis-acting elements related to hormone signaling, circadian rhythm, or low-temperature stresses were identified in the promoters of CpMAPKs. Notably, gene expression profiles demonstrated that CpMAPKs exhibited various responses to 2-chloroethylphosphonic acid (ethephon), 1-methylcyclopropene (1-MCP) and the combined ascorbic acid (AsA) and chitosan (CTS) treatments during papaya postharvest ripening. Among them, both CpMAPK9 and CpMAPK20 displayed significant induction in papaya flesh by ethephon treatment, and were pronounced inhibition after AsA and CTS treatments at 16 d compared to those of natural ripening control, suggesting that they potentially involve in fruit postharvest ripening through ethylene signaling pathway or modulating cell wall metabolism. CONCLUSION: This study will provide some valuable insights into future functional characterization of CpMAPKs, and hold great potential for further understanding the molecular mechanisms underlying papaya fruit postharvest ripening.

Papaya peel extract-mediated green synthesis of zinc oxide nanoparticles and determination of their antioxidant, antibacterial, and photocatalytic properties.

This study describes an effective and eco-friendly approach to the synthesis of zinc oxide nanoparticles (ZnONPs) utilizing papaya fruit peel extract (PPE). The structural evaluation and morphological features of synthesized ZnONPs were examined using various physicochemical analyses. The formulated ZnONPs were spherical to hexagonal in shape with ⁓ 170 nm in diameter. ZnONPs exhibited improved antioxidant potential in terms of DPPH radical scavenging activity (IC50 = 98.74 µg/ml) and ferric-reducing potential compared with PPE. The antibacterial activity of ZnONPs was measured against pathogenic strains of Salmonella typhi, Bacillus subtilis, Staphylococcus aureus, and Escherichia coli. The biosynthesized ZnONPs showed potential antibacterial efficacy against all microbes. In addition, ZnONPs exhibited potential photocatalytic activity in rhodamine B degradation in the presence of sunlight. The results indicated that papaya peels, which are these fruit wastes, could be helpful for the green synthesis of ZnONPs with good dose-responsive antioxidant, antibacterial, and photocatalytic activities.

Phytochemical Extract from Carica papaya Leaves and Punica granatum Seeds as Therapy Against Cognitive Impairment in a Murine Model.

Mild cognitive impairment (MCI) is defined as inter-stage between normal cognitive aging and major neurocognitive disorder (MND). This state of decay is a crucial factor in treatment to prevent the progression to MND. In this study, our group developed a virtual screening process to evaluate 2568 phytochemical compounds against 5 key proteins associated with MCI and MND. As a result, two potential candidates were identified: carpaine, found in Carica papaya leaves, and punicalagin, present in Punica granatum. A model of cognitive impairment (CI) was developed in 10-month-old male Sprague Dawley rats by administering aluminum chloride (AlCl3) at a dose of 100 mg/kg/day for 30 days. After AlCl3 administration period, one of the groups received carpaine and punicalagin in a phytochemical extract (PE) by oral gavage for 30 days. Novel object recognition test (NOR) was assessed at three different time points (T1 - before CI, T2 - after CI, and T3 - after PE treatment). Glial fibrillary acidic protein (GFAP) and neurofilament light chain (NfL) were identified in the hippocampus of rats at the end of the study period. After administration of AlCl3, a reduction in discrimination index vs control rats (CI = 0.012 ± 0.08 vs Control = 0.076 ± 0.03), was observed. After phytochemical extract treatment, a significant increase in discrimination index values was observed in the PE group 0.4643 ± 0.13 vs CI group 0.012 ± 0.08. Additionally, the evaluation of immunohistochemistry showed an increase in GFAP positivity in the hippocampus of the CI groups, while a slight decrease was observed in the PE group. This work addressed a comprehensive methodology that utilized in silico tools to identify phytochemical compounds (carpaine and punicalagin) as potential candidates for affecting key proteins in CI. The phytochemical extract containing carpaine and punicalagin resulted in a trend in the decrease of GFAP expression in the hippocampus and improved recognition memory in rats with CI induced by age and AlCl3 administration.