From by-products to new application opportunities: the enhancement of the leaves deriving from the fruit plants for new potential healthy products

In the last decades, the world population and demand for any kind of product have grown exponentially. The rhythm of production to satisfy the request of the population has become unsustainable and the concept of the linear economy, introduced after the Industrial Revolution, has been replaced by a new economic approach, the circular economy. In this new economic model, the concept of "the end of life" is substituted by the concept of restoration, providing a new life to many industrial wastes. Leaves are a by-product of several agricultural cultivations. In recent years, the scientific interest regarding leaf biochemical composition grew, recording that plant leaves may be considered an alternative source of bioactive substances. Plant leaves' main bioactive compounds are similar to those in fruits, i.e., phenolic acids and esters, flavonols, anthocyanins, and procyanidins. Bioactive compounds can positively influence human health; in fact, it is no coincidence that the leaves were used by our ancestors as a natural remedy for various pathological conditions. Therefore, leaves can be exploited to manufacture many products in food (e.g., being incorporated in food formulations as natural antioxidants, or used to create edible coatings or films for food packaging), cosmetic and pharmaceutical industries (e.g., promising ingredients in anti-aging cosmetics such as oils, serums, dermatological creams, bath gels, and other products). This review focuses on the leaves' main bioactive compounds and their beneficial health effects, indicating their applications until today to enhance them as a harvesting by-product and highlight their possible reuse for new potential healthy products.

Biochemical dynamics during postharvest: Highlighting the interplay of stress during storage and maturation of fresh produce

The lifecycle of fresh produce involves a sequence of biochemical events during their ontology, and these events are particularly significant for climacteric fruits. A high demand during ripening is observed in these plant products, which is reflected in a high rate of respiration and ethylene production. Increased respiratory demand triggers the activation of secondary pathways such as alternate oxidase, which do not experience critical increases in energy consumption in non-climacteric fruit. In addition, biochemical events produced by external factors lead to compensatory responses in fresh produce to counteract the oxidative stress caused by the former. The dynamics of these responses are accompanied by signaling, where reactive oxygen species play a pivotal role in fresh product cell perception. This review aims to describe the protection mechanisms of fresh produce against environmental challenges and how controlled doses of abiotic stressors can be used to improve quality and prolong their shelf-life through the interaction of stress and defense mechanisms.

Exploring genetic diversity in inbred papaya lines for fruit quality in advanced stage of improvement

Despite the relevance of the global scenario regarding the papaya (Carica papaya L.) trade, there is still a limited number of papaya cultivars with different fruit patterns. Therefore, it is essential to explore the genetic variability at all levels of the germplasm used in the development of new papaya cultivars to meet its marketing goal. Thus, this study measured and explored the potential of genetic variability based on related to fruit quality traits, of a population of papaya lines in the F5 generation through several statistical analyzes. For this, 97 inbred lines obtained using the Single Seed Descent method, resulting from a cross between the JS-12 and Sekati genotypes, both with Formosa fruit pattern, were evaluated. Results indicated there was genetic variability in the fruit quality. The traits that most contributed to the variability were related to the fruit shape. The diverse population of 97 inbred papaya lines in the F5 generation showed promise for producing commercial-sized fruits in Formosa, Intermediate, and Solo patterns. Additionally, the selection of inbred papaya lines based on fruit shape using morpho-anatomical traits does not compromise physical and chemical parameters related to fruit quality.

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.

Carica papaya L. Leaves: Deciphering Its Antioxidant Bioactives, Biological Activities, Innovative Products, and Safety Aspects

The prevalence of viral infections, cancer, and diabetes is increasing at an alarming rate around the world, and these diseases are now considered to be the most serious risks to human well-being in the modern period. There is a widespread practice in Asian countries of using papaya leaves (C. papaya L.) as herbal medicine, either alone or in combination with prescribed medications, to treat a variety of ailments. The importance of conducting the necessary descriptive studies in order to determine the safety of papaya leaf consumption is also emphasized in the context of their application in the healthcare sector. Electronic databases such as Google Scholar, Scopus, and PubMed were used to gather information on papaya leaves, their therapeutic potential, and clinical evidence-based studies. The literature was gathered from publications on papaya leaves, their therapeutic potential, and clinical evidence-based studies. The antidengue, anticancer, antidiabetic, neuroprotective, and anti-inflammatory effects of papaya leaves discussed in this article are supported by evidence from preclinical, in vivo, in vitro, and clinical trial studies, as well as from other sources. Leaves have been investigated for their mechanism of action as well as their potential to be used in the development of novel herbal products for the health business. According to the reports gathered, only a small number of research demonstrated that leaf extract at high concentrations was hazardous to certain organs. The collective literature reviewed in this review provides insights into the use of papaya leaves as a cure for epidemic diseases, highlighting the phytochemical composition and pharmacological attributes of papaya leaves, as well as the results of various preclinical and clinical studies that have been conducted so far on the subject. The review clearly demonstrates the successful medical evidence for the use of papaya leaf extracts in the healthcare system as a supplemental herbal medication in a variety of clinical settings.

Papaya (Carica papaya L.) for cancer prevention: Progress and promise

Cancer is a leading cause of morbidity and mortality across the globe. Emerging evidence suggests that consumption of a well-balanced diet containing a wide variety of vegetables, fruits, and whole grains can prevent the development of, halt, or reverse cancer progression. Carica papaya L. (papaya) has a wide distribution throughout many countries. Although the fruits of C. papaya are primarily consumed as food, various parts of this tree, including the bark, fruits, latex, seeds, and roots, have been used in traditional medicine for health promotion and disease mitigation. While numerous individual studies have investigated anticancer efficacies of various products and constituents of C. papaya, an up-to-date, comprehensive, and critical evaluation of available research data covering its role in the prevention and intervention of various human malignancies has not been conducted according to our knowledge. The purpose of this review is to present a systematic, comprehensive, and critical analysis of the cancer-preventive potential of C. papaya extracts, fractions, and isolated phytochemicals with a special emphasis on the cellular and molecular mechanisms of action. Moreover, the bioavailability, pharmacokinetics, and safety profiles of individual phytochemicals of C. papaya, as well as current limitations, challenges, and future directions of research, have also been discussed.

Benefits of Fermented Papaya in Human Health

Fermented foods have been used for several years all over the world, due to their unique nutritional characteristics and because fermentation promotes conservation and food security. Moreover, fermented foods and beverages have a strong impact on human gut microbiota. Papaya is the fruit of the Carica papaya plant, traditionally used as a medicinal fruit, but there are also references to the use of the fermented form of this fruit. The main purpose of this review is to provide an improved understanding of fermented papaya nutritional and health applications. A literature search was conducted in the PubMed and Google Scholar databases. Both in vitro and in vivo studies were included. According to the retrieved studies, fermented papaya has proven to be an excellent antioxidant and an excellent nutraceutical adjuvant in combined therapies against several diseases, such as Alzheimer’s disease, allergic reactions, anticancer activity, and anemias. Therefore, it is concluded that fermented papaya has many benefits for human health and can be used as prevention or aid in the treatment of various diseases.

Tentative qualitative and quantitative analysis of phenolic compounds in leaf extract from Carica papaya Linn. plant growing in Uganda

Introduction

Carica papaya L. belongs to Caricaceae family. It is an evergreen tree or shrub with usually unbranched trunk. Previous studies on the methanolic leaf extract of this plant proved the antibacterial, cytotoxic, anticancer and antioxidant effects indicative of promising therapeutic potentials.

Methods

Chromatographic and spectroscopic techniques along with high performance liquid chromatography quantitative analysis were performed to isolate, tentatively identify and quantify polyphenolic compounds in MeOH extract of C. papaya leaves. UHPLC-DAD-ESI-MS/MS and UHPLC-DAD methods were adopted for qualitative and quantitative analysis respectively. In the case of polyphenol separation, some reference substances were isolated by preparative HPLC.

Results

Six polyphenols were isolated and quantified from C. papaya leaf extract, including three phenolic acids: derivatives of caffeic acid, p-coumaric acid, ferulic acid and three flavonoids: quercetin dirhamnosylhexoside, kaempferol dirhamnosyl-hexoside, quercetin 3-O-rutinoside. Among them quercetin dirhamnosyl-hexoside was significantly higher (1.9 mg/g extract) than other identified compounds.

Conclusion

The results of present study provide a new data on polyphenols composition of C. papaya plant derived from Uganda and promote research on its possible standardization and use as a dietary supplement and/or herbal medicine.

Cosmeceutical Potential of Major Tropical and Subtropical Fruit By-Products for a Sustainable Revalorization

The increasing production of tropical fruits followed by their processing results in tons of waste, such as skins or seeds. However, these by-products have been reported to be rich in bioactive compounds (BACs) with excellent properties of interest in the cosmeceutical industry: antioxidant, anti-aging, anti-inflammatory, antimicrobial and photoprotective properties. This review summarizes the tropical fruits most produced worldwide, their bioactive composition and the most important and studied therapeutic properties that their by-products can contribute to skin health, as well as the different approaches for obtaining these compounds using techniques by conventional (Soxhlet, liquid-liquid extraction or maceration) and non-conventional extractions (supercritical fluid extraction (SFE), ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), pressurized liquid extraction (PLE) and two-phase aqueous system), followed by their identification by HPLC-MS or GC-MS analysis. Moreover, this work encompasses several studies that may prove the effects of seeds and skins from tropical fruits against oxidative stress, hyperpigmentation, acne, aging or UV radiation. Therefore, the investigation of functional components present in tropical fruit by-products under a circular bioeconomy model could be of great interest for the cosmeceutical industry and a very promising option for obtaining new cosmeceutical formulations.

Development and Greenness Assessment of HPLC Method for Studying the Pharmacokinetics of Co-Administered Metformin and Papaya Extract

Foods with medical value have been proven to be beneficial, and they are extensively employed since they integrate two essential elements: food and medication. Accordingly, diabetic patients can benefit from papaya because the fruit is low in sugar and high in antioxidants. An RP-HPLC method was designed for studying the pharmacokinetics of metformin (MET) when concurrently administered with papaya extract. A mobile phase of 0.5 mM of KH2PO4 solution and methanol (65:35, v/v), pH = 5 ± 0.2 using aqueous phosphoric acid and NaOH, and guaifenesin (GUF) were used as an internal standard. To perform non-compartmental pharmacokinetic analysis, the Pharmacokinetic program (PK Solver) was used. The method's greenness was analyzed using two tools: the Analytical GREEnness calculator and the RGB additive color model. Taking papaya with MET improved the rate of absorption substantially (time for reaching maximum concentration (Tmax) significantly decreased by 75% while maximum plasma concentration (Cmax) increased by 7.33%). The extent of absorption reduced by 22.90%. Furthermore, the amount of medication distributed increased (30.83 L for MET concurrently used with papaya extract versus 24.25 L for MET used alone) and the clearance rate rose by roughly 13.50%. The results of the greenness assessment indicated that the method is environmentally friendly. Taking papaya with MET changed the pharmacokinetics of the drug dramatically. Hence, this combination will be particularly effective in maintaining quick blood glucose control.

Herbal products as skincare therapeutic agents against ultraviolet radiation-induced skin disorders

This paper aims to highlight the pharmacological aspects of listed herbal skincare products used for the treatment of various disorders caused due to ultraviolet radiation. The pharmacological aspects include safety and efficacy validation as per regulatory guidelines following internationally accepted scientific principles for their development of skincare products. Herbal products have always been used traditionally for the treatment of various skin ailments and have become more prevalent because of their safety and high efficacy benefits. The incorporation of synthetic molecules and chemical substances in the different medicinal and pharmaceutical formulations is the leading cause of the dermal toxicity. Therefore, the developments of herbal skincare products containing scientifically validated herbal ingredients have better acceptance, respect, and belief in the society. The listed herbal products in this review can help take forward the commercial development of skincare products for therapeutic as well as beauty care purposes from such plants.

Molecular identification and biological control of Ralstonia solanacearum from wilt of papaya by natural compounds and Bacillus subtilis: An integrated experimental and computational study

Ralstonia solanacearum is a harmful pathogen that causes severe wilt disease in several vegetables. In the present study, we identified R. solanacearum from wilt of papaya by 16S rRNA PCR amplification. Virulence ability of R. solanacearum was determined by amplification of approximately 1500 bp clear band of hrpB gene. Further, in-vitro seed germination assay showed that R. solanacearum reduced the germination rate up to 26.21%, 34% and 33.63% of cucumber, bottle guard and pumpkin seeds, respectively whereas shoot and root growth were also significantly decreased. Moreover, growth inhibition of R. solanacearum was recorded using antibacterial compound from medicinal plant and antagonistic B. subtilis. Petroleum ether root extract of Rauvolfia serpentina showed highest 22 ± 0.04 mm diameter of zone of inhibition where methanolic extract of Cymbopogon citratus and ethanolic extract of Lantana camara exhibited 20 ± 0.06 mm and 20 ± 0.01 mm zone of inhibition against R. solanacearum, respectively. In addition, bioactive compounds of B. subtilis inhibited R. solanacearum growth by generating 17 ± 0.09 mm zone of inhibition. To unveil the inhibition mechanism, we adopted chemical-protein interaction network and molecular docking approaches where we found that, rutin from C. citratus interacts with citrate (Si)-synthase and dihydrolipoyl dehydrogenase of R. solanacearum with binding affinity of -9.7 kcal/mol and -9.5 kcal/mol while quercetin from B. subtillis interacts with the essential protein F0F1 ATP synthase subunit alpha of the R. solancearum with binding affinity of -6.9 kcal/mol and inhibit the growth of R. solanacearum. Our study will give shed light on the development of eco-friendly biological control of wilt disease of papaya.

Pharmacological potentials and Nutritional values of Tropical and Sub-tropical Fruits of India: Emphasis on their anticancer bioactive components

BACKGROUND

Fruits are an important dietary component, which supply vitamins, minerals, as well as dietary fiber. In addition, they are rich sources of various biological and pharmacologically active compounds. Among these, temperate fruits are well studied for their pharmacological potentials, whereas tropical/subtropical fruits are less explored for their health impacts. In India, most of the consumed fruits are either tropical or subtropical.

OBJECTIVES

The present review aims to provide a health impact of major tropical and sub-tropical fruits of India, emphasizing their anticancer efficacy. In addition, the identified bioactive components from these fruits exhibiting anticancer efficacy are also discussed along with the patent literature published.

METHODS

The literature was collected from various repositories, including NCBI, ScienceDirect, Eurekaselect, and Web of Science; literature from predatory journals was omitted during the process. Patent literature was collected from google patents and similar patent databases.

RESULTS

Tropical fruits are rich sources of various nutrients and bioactive components including polyphenols, flavonoids, anthocyanin, etc. By virtue of these biomolecules, tropical fruits have been shown to interfere with various steps in carcinogenesis, metastasis, and drug resistance. Their mode of action is either by activation of apoptosis, regulation of cell cycle, inhibition of cell survival and proliferation pathways, increased lipid trafficking or inhibiting inflammatory pathways. Several molecules and combinations have been patented for their anticancer and chemoprotective properties.

CONCLUSION

Overall, the present concludes that Indian tropical/ subtropical fruits are nutritionally and pharmacologically active and may serve as a source of novel anticancer agents in the future.

An efficient papaya leaf distortion mosaic potyvirus vector for virus-induced gene silencing in papaya

Papaya (Carica papaya L.) is regarded as an excellent model for genomic studies of tropical trees because of its short generation time and its small genome that has been sequenced. However, functional genomic studies in papaya depend on laborious genetic transformations because no rapid tools exist for this species. Here, we developed a highly efficient virus-induced gene silencing (VIGS) vector for use in papaya by modifying an artificially attenuated infectious clone of papaya leaf distortion mosaic virus (PLDMV; genus: Potyvirus), PLDMV-E, into a stable Nimble Cloning (NC)-based PLDMV vector, pPLDMV-NC, in Escherichia coli. The target fragments for gene silencing can easily be cloned into pPLDMV-NC without multiple digestion and ligation steps. Using this PLDMV VIGS system, we silenced and characterized five endogenous genes in papaya, including two common VIGS marker genes, namely, phytoene desaturase, Mg-chelatase H subunit, putative GIBBERELLIN (GA)-INSENSITIVE DWARF1A and 1B encoding GA receptors; and the cytochrome P450 gene CYP83B1, which encodes a key enzyme involved in benzylglucosinolate biosynthesis. The results demonstrate that our newly developed PLDMV VIGS vector is a rapid and convenient tool for functional genomic studies in papaya.

Antibacterial activity and main action pathway of benzyl isothiocyanate extracted from papaya seeds

The development of natural antimicrobial agents has attracted long-term attention due to the increasing demand for food preservation. Papaya, a widely cultivated nutritious tropical fruit, has benzyl isothiocyanate (BITC) as one of the most important secondary metabolites in its seeds. And the antibacterial activity of BITC toward different strains and the main antibacterial pathway remain unclear. The current study focused on characterizing the antibacterial effect and exploring the major bacteriostatic pathway of BITC. BITC was shown to have a broad-spectrum antibacterial effect, with a minimum inhibitory concentration of 1 µL/mL for Escherichia coli, Bacillus subtilis, and Aspergillus niger, and 0.5 µL/mL for Salmonella enterica, Staphylococcus aureus, and Penicillium citrinum. Additionally, BITC was identified to affect the integrity of the biological oxidation system rather than the permeability or morphology of cell membranes. Furthermore, BITC was found not only to affect ATP production but also to hinder a series of important chemical reactions of the coenzymes involved in the transfer of hydrogen ions in the respiratory chain. The bacteriostatic pathway of BITC was shown to be implicated in an incomplete respiratory chain and the deregulation of the metabolism system. These results indicate the potential of BITC as a natural preservative in the food industry. PRACTICAL APPLICATION: BITC is present in papaya seeds and can be extracted and purified. Exploring its antibacterial activity and main action pathway may facilitate its application as a new bacteriostatic agent in food industry.

Therapeutic application of Carica papaya leaf extract in the management of human diseases

INTRODUCTION

Papaya (Carica papaya Linn.) belongs to the family Caricaceae and is well known for its therapeutic and nutritional properties all over the world. The different parts of the papaya plant have been used since ancient times for its therapeutic applications. Herein, we aimed to review the anticancer, anti-inflammatory, antidiabetic and antiviral activities of papaya leaf.

METHODS

All information presented in this review article regarding the therapeutic application of Carica papaya leaf extract has been acquired by approaching various electronic databases, including Scopus, Google scholar, Web of science, and PubMed. The keywords Carica papaya, anticancer, anti-inflammatory, immunomodulatory, and phytochemicals were explored until December 2019.

RESULTS

The papaya plant, including fruit, leaf, seed, bark, latex, and their ingredients play a major role in the management of disease progression. Carica papaya leaf contains active components such as alkaloids, glycosides, tannins, saponins, and flavonoids, which are responsible for its medicinal activity. Additionally, the leaf juice of papaya increases the platelet counts in people suffering from dengue fever.

CONCLUSION

The major findings revealed that papaya leaf extract has strong medicinal properties such as antibacterial, antiviral, antitumor, hypoglycaemic and anti-inflammatory activity. Furthermore, clinical trials are needed to explore the medicative potential of papaya leaf. Graphical abstract Graphical abstract showing the medicinal properties of Carica papaya leaf.

Compound Identification and In Vitro Cytotoxicity of the Supercritical Carbon Dioxide Extract of Papaya Freeze-Dried Leaf Juice

Carica papaya leaves are used as a remedy for the management of cancer. Freeze-dried C. papaya leaf juice was extracted using a supercritical fluid extraction system. Compound identification was carried out using analytical techniques including liquid chromatography coupled to high-resolution quadrupole time-of-flight mass spectrometry (LC–QToF-MS) and gas chromatography–mass spectrometry (GC–MS). The cytotoxic activities of the scCO2 extract and its chemical constituents were determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on squamous cell carcinoma (SCC25) and human keratinocyte (HaCaT) cell lines. The chemical constituents were quantified by QToF-MS. The supercritical carbon dioxide (scCO2) extract of papaya freeze-dried leaf juice showed cytotoxic activity against SCC25. Three phytosterols, namely, β-sitosterol, campesterol, and stigmasterol, together with α-tocopherol, were confirmed to be present in the scCO2 extract. Quantitative analysis showed that β-sitosterol was the major phytosterol present followed by α-tocopherol, campesterol, and stigmasterol. β-Sitosterol and campesterol were active against SCC25 (half maximal inhibitory concentration (IC50) ≈ 1 µM), while stigmasterol was less active (~33 µM) but was biologically more selective against SCC25. Interestingly, an equimolar mixture of phytosterols was not more effective (no synergistic effect was observed) but was more selective than the individual compounds. The compounds identified are likely accountable for at least part of the cytotoxicity and selectivity effects of C. papaya.

Synthesis of caffeic acid sulfonamide derivatives and their protective effect against H2O2 induced oxidative damage in A549 cells

Exogenous antioxidants are considered as important therapeutic tools for oxidative stress associated disorders as they can regulate the redox state, which is associated with cell and organ function. Inspired by natural polyphenols, six new caffeic acid sulfonamide derivatives were synthesized by coupling sulfonamides to the backbone of caffeic acid with good yields. Their structure and lipophilicity were characterized by 1H nuclear magnetic resonance (NMR), 13C{1H} NMR, infrared spectroscopy (IR) and oil-water partition coefficient assay. Their free radical scavenging activity and antioxidant activity were assessed by DPPH assay and hydrogen peroxide (H2O2) induced oxidative stress in human lung carcinoma A549 cells. The oil-water partition coefficient results indicate that the conjugation of sulfonamides increases the lipophilicity of caffeic acid. The CASMD, CASDZ and CASN results show higher free radical scavenging effects compared with vitamin C. The derivatives do not show any inhibitory effect on the proliferation of A549 cells up to a concentration of 200 μM, except CASDZ which significantly inhibits the growth of A549 cells at a concentration of 200 μM. In addition, the obtained derivatives markedly attenuate H2O2 induced decrease of cell viability, inhibit the production of ROS and MDA, and promote the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px). Besides, treatment of H2O2 stimulated A549 cells with caffeic acid sulfonamide derivatives further increases mRNA expression of NF-E2-related factor 2 (Nrf2) and its target genes, including heme oxygenase-1 (HO-1), NAD(P)H quinone dehydrogenase 1 (NQO1) and thioredoxin reductase 1 (TXNRD1). These results suggest that these new caffeic acid sulfonamide derivatives have higher lipophilicity and better antioxidant activities than the parent caffeic acid, and they might be able to control the antioxidant response in cells via the Nrf2 pathway.

Carica papaya: Potential Implications in Human Health

Background:

Carica papaya, a tree-like herb, is cultivated in more than 50 tropical and subtropical countries worldwide. The parts [leaves, fruit (ripe and unripe), seeds and latex] are used as food as well as traditional medicine in several ways for a number of diseases. Papaya, with a variety of phytochemicals like carotenoids, polyphenols, benzyl isothiocynates, benzyl glucosinates, prunasin (cyanogenic substrate), papain and chymopapain, alkaloids, phenolic compounds, flavonoids, vitamins (A, C, E), carotenoids, cyanogenicglucosides, cystatin, and glucosinolates exhibits significant health benefits ranging from digestive to immune modulation. These compounds have antioxidant, chemoprotective, anti-diabetic, anti-bacterial, anti-plasmodial and anti-fungal activities. Papaya aqueous leaf extract was evaluated for immunomodulatory and anti-tumor activities through cytokine modulation with Th1 type shift in human immune system through molecular studies. The platelet augmenting potential of aqueous leaf extract has been reported in numerous clinical studies and deserves special mention.

Objective:

The scientific knowledge of carica papaya in the post-genomic era including molecular studies and clinical trials is discussed in the review.

Methods:

The published literature on botany, chemical composition, ethnopharmacology, and uses of papaya in food and medical industry was searched through databases like Pub- Med, Scopus, and Google scholar to comprehend the benefits of Carica papaya for human use with around more than 600 published peer- reviewed papers.

Results:

Many traditional and novel uses of Carica papaya for the human benefit are detailed in the review that significantly adds to the scientific knowledge of curious readers.

Conclusion:

Each component of the papaya plant is rich in phytochemicals and is economically important. Most of the phytochemicals are linked to biological functions and influence a variety of cellular processes; hence they have implications in refining human health.

Immunomodulatory effect of papaya (Carica papaya) pulp and seed extracts as a potential natural treatment for bacterial stress

The current study evaluated the immunomodulatory effects of Carica papaya pulp and seeds methanol (MeOH) extracts on mice infected with Listeria monocytogenes. Gas chromatography-mass spectrometry analysis identified 10 active constituents in C. papaya seed MeOH extract and 10 compounds in C. papaya pulp MeOH extract. The experimental animals were divided into negative control (G1) group, positive control (G2) group, pulp extract treated (G3) group, and seed extract treated (G4) group. After infection of animals (G2, G3, and G4), treatments were started for 3 weeks. Estimation of the immunological parameters showed a marked decrease in IgM levels and an increase in IgG levels in the treated groups (G3 and G4) compared with those in G2. The proinflammatory cytokines (IL-10, IL-12, IL-1β, IL-6, and TGF-β1) were decreased in the treated groups (G3 and G4) compared with those in G2. Nitric oxide levels were also decreased, and the percentages of phagocytosis increased compared with those of G2. The results demonstrated the immunomodulatory and anti-inflammatory effects of C. papaya pulp and seeds MeOH extracts. PRACTICAL APPLICATIONS: Based on the antioxidant and antibacterial activities exhibited by the pulp and seed MeOH extracts investigated in this study, Carica papaya might be considered as a natural source of phytochemicals that could be utilized in novel foods and pharmaceuticals. Further investigation are needed to identify and purify compounds that might be responsible for the observed effects.

A New Phenolic Constituent From Carica papaya Flowers and Its Tyrosinase Inhibitory Activity

A new phenolic (caricapapayol, 1) and 8 known compounds (2-9) were isolated from the flowers of Carica papaya. Their structures were determined by analysis of HR-ESI-MS, NMR spectral data, and comparison with the literature. Among known compounds, compound 2 has not been reported from natural source. Compounds 1, 2, and 4 exhibited tyrosinase inhibitory activity with IC50 values of 14.3 ± 2.7, 25.5 ± 1.9, and 19.8 ± 3.0 µM, respectively, in comparison with positive control kojic acid IC50 11.3 ± 1.6 µM.

Factorial design-assisted supercritical carbon-dioxide extraction of cytotoxic active principles from Carica papaya leaf juice

The aims of this study are to investigate the selective cytotoxic activity of supercritical carbon dioxide (scCO₂)-extracted freeze-dried leaf juice (FDLJ) of Carica papaya on squamous cell carcinoma (SCC25) cells, and to delineate the best small scale extraction parameters allowing maximal extract activity. Using scCO₂ as a solvent, six operating parameters were studied and the supercritical fluid extraction (SFE) process investigated using a factorial design 2^6-2. The processing values promoting cytotoxic activity towards SCC-25 are: high pressure (250 bar), low temperature (35 °C), extended processing time (180 minutes), as well as a large amount of starting material (5 g). The factorial experimental design successfully identified the key parameters controlling the SFE of molecules cytotoxic to SCC cells from C. papaya juice. This study also validated the extraction method and showed that the SFE yield was reproducible. The chromatographic and mass spectrometric profiles of the scCO₂ extract acquired with high-resolution quadrupole time-of-flight mass spectrometry (LC-QToF-MS) were used to tentatively identify the bioactive compounds using comparative analysis. The principal compounds were likely to be mainly vitamins and phytosterols, some of which are documented to be cytotoxic to cancer cells.

Oral Administration of Fermented Papaya (FPP®) Controls the Growth of a Murine Melanoma through the In Vivo Induction of a Natural Antioxidant Response

Prolonged oxidative stress may play a key role in tumor development. Antioxidant molecules are contained in many foods and seem to have a potential role in future anti-tumor strategies. Among the natural antioxidants the beneficial effect of Fermented Papaya (FPP^®) is well known. The aim of this study was to investigate the effects of orally administered FPP^® in either the prevention or treatment of a murine model of melanoma. The tumor growth was analyzed together with the blood levels of both oxidants (ROS) and anti-oxidants (SOD-1 and GSH). The results showed that FPP^® controlled tumor growth, reducing the tumor mass of about three to seven times vs. untreated mice. The most significant effect was obtained with sublingual administration of FPP^® close to the inoculation of melanoma. At the time of the sacrifice none of mice treated with FPP^® had metastases and the subcutaneous tumors were significantly smaller and amelanotic, compared to untreated mice. Moreover, the FPP^® anti-tumor effect was consistent with the decrease of total ROS levels and the increase in the blood levels of GSH and SOD-1. This study shows that a potent anti-oxidant treatment through FPP^® may contribute to both preventing and inhibiting tumors growth.

The Use of Natural Health Products Especially Papaya Leaf Extract and Dandelion Root Extract in Previously Untreated Chronic Myelomonocytic Leukemia

Chronic myelomonocytic leukemia (CMML) is a clonal hematopoietic disorder which shares clinical and morphological features of myelodysplastic syndrome and myeloproliferative neoplasms. Conventional therapeutic options include hydroxyurea, hypomethylating agents, and systemic chemotherapy, which are all palliative measures and are associated with potential side effects. Allogeneic hematopoietic cell transplantation is the only curative option. Natural health products such as papaya leaf extract and dandelion root extract have been shown to demonstrate anticancer activity in preclinical and clinical studies, respectively. We present a case study of a 76-year-old male with previously untreated CMML, whose hematological parameters remained stable and whose bone marrow blast counts vastly improved while taking papaya leaf extract and dandelion root extract.

Effect of a Toothpaste/Mouthwash Containing Carica papaya Leaf Extract on Interdental Gingival Bleeding: A Randomized Controlled Trial

Clinical research on herbal-based dentifrice +/− mouth rinse products is very limited compared with the plethora of research on conventional oral care products under normal oral hygiene conditions. The aim of this study was to determine the anti-inflammatory effects of a novel plant Carica papaya leaf extract (CPLE) on interdental bleeding in healthy subjects. In this randomized, single-blind parallel-design study, the eligible subjects were generally healthy non-smokers, aged 18–26, who exhibited healthy periodontal conditions upon study entry. The participants were equally randomized into the following four groups: CPLE dentifrice, CPLE dentifrice and mouthwash, sodium lauryl sulfate (SLS)-free enzyme-containing dentifrice and SLS-free enzyme-containing dentifrice with essential oil (EO) mouthwash. Subjects were instructed to brush their teeth twice a day without changing their other brushing habits. Interdental bleeding (BOIP) was measured from inclusion (T₀) until the fourth week (T₄) of the study. Clinical efficacy was assessed after one, two, three and four weeks of home use. The analyses compared BOIP between groups and were then restricted to participants with ≥70% and then ≥80% bleeding sites at T₀. Pairwise comparisons between groups were performed at T₀ and T₄, and a logistic regression identified correlates of gingival bleeding (T₄). Among 100 subjects (2273 interdental sites), the median percentage of bleeding sites per participant at T₀ was 65%. The bleeding sites dramatically decreased in all groups between T₀ and T₄ (relative variations from −54% to −75%, p < 0.01 for all). Gingival bleeding did not significantly differ between the CPLE dentifrice and the SLS-free dentifrice +/− EO mouthwash groups (from p = 0.05 to p = 0.86), regardless of the baseline risk level. Among the CPLE dentifrice users, fewer bleeding sites were observed when toothpaste and mouthwash were combined compared to bleeding sites in those who used toothpaste alone (21% vs. 32%, p = 0.04). CPLE dentifrice/mouthwash provides an efficacious and natural alternative to SLS-free dentifrice +/−EO-containing mouthwash when used as an adjunct to mechanical oral care to reduce interdental gingival inflammation.

Bio-Guided Fractionation of Papaya Leaf Juice for Delineating the Components Responsible for the Selective Anti-proliferative Effects on Prostate Cancer Cells

Alternative therapies against cancer cells with minimal or no effect on healthy tissues are highly sought after. Prostate cancer (PCa) is the second most frequently diagnosed malignancy in males. The Carica papaya L. leaf extract has been traditionally used by Australian aboriginal people for anticancer properties. In this study, medium polar fraction of papaya leaf extract that had shown anti-proliferative activity in PCa cell lines in vitro, in earlier studies, was further fractionated to 28 fractions by semi-preparative HPLC. Nine of these fractions were identified to possess selective anti-proliferative responses on PCa cells in comparison to non-cancerous cells of prostate gland origin. When these nine sub-fractions were mixed in various combinations, a combination containing six of the specific fractions (FC-3) showed the best potency. FC3 inhibited the growth of BPH-1, PC-3, and LNCaP cells in a concentration-dependent manner with an IC₅₀ value <20 μg/mL, while (unlike paclitaxel, the positive control) minimal effect was observed on the proliferation of non-cancerous, WPMY-1 and RWPE-1cells. Furthermore, synergistic interaction of FC-3 with paclitaxel was observed with combination index values in the range of 0.89–0.98 and 0.85–1.10 on PC-3 and LNCaP cells, respectively. Untargeted qualitative analysis using UHPLC (Ultra High-Performance Liquid Chromatography)-QToF (Quadrupole Time of-Flight) mass spectrometry and screening against the METLIN database indicated presence of multiple known anticancer compounds in the FC-3 extract. These outcomes show that the potent and selective anti-proliferative effects are due to a range of bio-active compounds within the medium polar fraction of papaya leaf juice.

Discovering the Health Promoting Potential of Fermented Papaya Preparation—Its Future Perspectives for the Dietary Management of Oxidative Stress During Diabetes

The simplistic morphological characteristics of Carica papaya fruit or “pawpaw” should not be the cause for underestimating its potential as a nutraceutical. The market for papaya has been expanding at a staggering rate, partly due to its applicability as a biofortified product, but also due to its phytochemical properties and traditional health benefits. Papaya or formulations of fermented papaya promotion (FPP) display effective free radical scavenging abilities thought to be influenced by its phenolic, carotenoid, flavonoid, or amino acid profile. The antioxidant properties of FPP have been extensively reported in literature to potently target a broad spectrum of free radical-induced diseases ranging from neurological impairments, such as senile dementia, to systemic diseases, to its interference at the cellular level and the support of normal biological ageing processes. FPP has thus been extensively investigated for its ability to exert cellular protective effects and reduce oxidative stress via the mitigation of genetic damage, reduction of lipid peroxidation, and enzymatic inactivation in specific diseases. The focus of this review is to appraise the potential of oxidative stress reduction strategies of FPP and discuss its holistic approach in disease prevention and management, with a particular focus on diabetes and cancer. However, with the current lack of information surrounding its mechanism of action, this review wishes to set the stage and aspire researchers to more profoundly investigate molecular pathways related to how FPP can unequivocally contribute to wellness in an aging population.

Novel and classical renal biomarkers as evidence for the nephroprotective effect of Carica papaya leaf extract

The present study is aimed at utilization of novel and classical kidney function biomarkers to evaluate the nephroprotective potential of Carica papaya leaf extract (CPLE) in gentamicin nephrotoxicity model in albino rats. The used classical biomarkers were urea and creatinine; while the new biomarkers were Kidney injury molecule-1 (KIM-1) and Clusterin. Forty-five male albino rats were assigned into five groups and subjected to different treatments for nine consecutive days (vehicles; gentamicin, 100 mg/kg, subcutaneously; ascorbic acid, 200 mg/kg, orally; CPLE, 150 and 300 mg/kg b wt., orally). Three rats/group were killed on days 3, 6, and 9 for blood and tissue samples for renal and oxidation markers. Gentamicin resulted in significant increase in urea and creatinine only by the end of the experimental course; while the novel biomarkers were evident as early as 3 days upon gentamicin injection. When concurrently administered with gentamicin, CPLE significantly protected kidney tissues against gentamicin nephrotoxic effects indicated by decrement of both the novel and the classical standard biomarkers, in a dose-dependent manner. CPLE-mediated protection was attributed to its antioxidant potential indicated by significant inhibition of malondialdehyde (MDA) levels in both serum and kidney homogenates. The results were further supported by histopathological examination that revealed considerable amelioration of the pathological microscopic alterations induced by repeated gentamicin injection. Phytochemical analysis of CPLE indicated presence of tannins and flavonoids. These data may suggest CPLE, based on improvement of both classical and novel renal markers, as a highly potent nephroprotective and antioxidant from natural source that could be a good remedy in conditions associated with renal disorders.

A Purported Detoxification Supplement Does Not Improve Body Composition, Waist Circumference, Blood Markers, or Gastrointestinal Symptoms in Healthy Adult Females

Numerous popular "detoxification" supplements claim to promote the removal of harmful compounds from the body, thereby alleviating gastrointestinal symptoms, improving body composition, and enhancing overall health. The present double-blind, randomized, placebo-controlled trial was conducted to examine the effects of a purported detoxification supplement in healthy young adult females. Participants were randomly assigned to consume a multi-ingredient supplement or placebo daily for four weeks. The supplement contained 1,350 mg/serving of a proprietary blend of papaya leaf, cascara sagrada bark, slippery elm bark, peppermint leaf, red raspberry leaf, fenugreek seed, ginger root, and senna leaf. Body composition, waist circumferences, symptoms of gastrointestinal distress, and blood safety markers were evaluated before and after supplementation. Twenty-two participants completed the study, and data were analyzed via two-way mixed ANOVA and t tests. No beneficial or harmful effects of supplementation were found for body composition, waist circumference, gastrointestinal symptoms, or blood markers. These results indicate that consuming a commercially available dietary supplement that purportedly provides detoxification and body composition benefits is apparently safe in healthy young adult females but does not provide any beneficial effects for body composition or gastrointestinal symptoms.

An ethnopharmacological survey of medicinal plants traditionally used for cancer treatment in the Ashanti region, Ghana

AIMS

Cancer represents a major health burden and drain on healthcare resources in the world. The majority of the people of Africa still patronize traditional medicine for their health needs, including various forms of cancer. The aim of the following study is the identification of medicinal plants used for cancer treatment by the traditional healers in the Ashanti area of Ghana and to cross-reference the identified plant species with published scientific literature.

METHODOLOGY

Validated questionnaires were administered to 85 traditional healers in 10 communities within Ashanti region. For cross-validation, also 7 healers located outside Ashanti region were investigated to evaluate regional differences. Interviews and structured conversations were used to administer the questionnaires. Selected herbal material dominantly used by the healers was collected and identified.

RESULTS

The ethnopharmacological survey revealed 151 plant species used for cancer treatment. Identified species were classified into different groups according to their frequency of use, resulting in the "top-22" plants. Interestingly group I (very frequent use) contained 5 plant species (Khaya senegalensis, Triplochiton scleroxylon, Azadirachta indica, Entandrophragma angolense, Terminalia superba), three of which belong to the plant family Meliaceae, phytochemically mainly characterized by the presence of limonoids. Cross-referencing of all plants identified by current scientific literature revealed species which have not been documented for cancer therapy until now. Special interest was laid on use of plants for cancer treatment of children.

CONCLUSION

A variety of traditionally used anti-cancer plants from Ghana have been identified and the widespread use within ethnotraditional medicine is obvious. Further in vitro and clinical studies will be performed in the near future to rationalize the phytochemical and functional scientific background of the respective extracts for cancer treatment.

Lactic Fermentation as an Efficient Tool to Enhance the Antioxidant Activity of Tropical Fruit Juices and Teas

Tropical fruits like pineapple, papaya, mango, and beverages such as green or black teas, represent an underestimated source of antioxidants that could exert health-promoting properties. Most food processing technologies applied to fruit beverages or teas result in an impairment of inherent nutritional properties. Conversely, we hypothesise that lactic acid fermentation may constitute a promising route to maintain and even improve the nutritional qualities of processed fruits. Using specific growth media, lactic acid bacteria were selected from the fruit phyllosphere diversity and fruit juice, with the latter undergoing acidification kinetics analyses and characterised for exopolysaccharide production. Strains able to ferment tropical fruit juices or teas into pleasant beverages, within a short time, were of particular interest. Strains Weissella cibaria 64 and Leuconostoc mesenteroides 12b, able to increase antioxidant activity, were specifically studied as potential starters for lactic fermented pineapple juice.

Extracts of Mauritian Carica papaya (var. solo) protect SW872 and HepG2 cells against hydrogen peroxide induced oxidative stress

In line with literature documenting the pluripotent activities of tropical fruits, this study evaluated the antioxidant effects of Carica papaya fruit extracts at cellular level. Investigations using cellular models of oxidative stress provided complementary evidence of the antioxidant activities of papaya fruit. At 2 mg dry weight ml^-1, extracts of seed from ripe and unripe fruit significantly reduced oxidative stress levels within human pre-adipocytes (SW872) and hepatocellular carcinoma cells (HepG2) exposed to hydrogen peroxide (H₂O₂). Maintenance of mitochondrial viability, reduction of intracellular reactive oxygen species levels and mediation of pro-inflammatory cytokine secretory levels (tumour necrosis factor-α, interleukin-6, monocyte chemoattractant protein-1) were all indicative of its cytoprotective effects against oxidative-inflammation. This work demonstrates that the Mauritian Solo papaya is an important source of natural antioxidants that could be used for the dietary modulation of oxidative stress and inflammation.

Selective anti-proliferative activities of Carica papaya leaf juice extracts against prostate cancer

BACKGROUND

Prostate cancer (PCa) is the leading cause of cancer related deaths in men. Carica papaya is a popular tropical plant that has been traditionally used for its nutritional and medicinal properties.

METHODS

We investigated the anti-proliferative responses of papaya leaf juice (LJP) and its various extracts ("biological"- in vitro digested, "physical"- size exclusion, and "chemical"-solvent extraction) on a range of cell lines representing benign hyperplasia, tumorigenic and normal cells of prostate origin.

RESULTS

Time course analysis (by 24h, 48h and 72h) of LJP (1-0.1mg/mL) before and after in vitro digestion, and of molecular weight based fractions of LJP showed anti-proliferative responses. The medium polarity fraction of LJP (0.03-0.003mg/mL) after 72h exposure showed potent growth inhibitory (IC₅₀=0.02-0.07mg/mL) and cytotoxic activities on all prostate cells, with the exception of the normal (RWPE-1 and WPMY-1) cells. Flow cytometry analysis showed S phase cell cycle arrest and apoptosis as a possible mechanism for these activities. Medium polar fraction of LJP also inhibited migration and adhesion of metastatic PC-3 cells.

CONCLUSION

This is the first report suggesting selective anti-proliferative and anti-metastatic attributes of LJP extract against prostatic diseases, including PCa.

In Vitro Effects of Some Botanicals with Anti-Inflammatory and Antitoxic Activity

Several extrinsic factors, like drugs and chemicals, can foster autoimmunity. Tetracyclines, in particular oxytetracycline (OTC), appear to correlate with the emergence of immune-mediated diseases. Accumulation of OTC, the elective drug for gastrointestinal and respiratory infectious disease treatment in broiler chickens, was reported in chicken edible tissues and could represent a potential risk for pets and humans that could assume this antibiotic as residue in meat or in meat-derived byproducts. We investigated the in vitro anti-inflammatory properties of a pool of thirteen botanicals as a part of a nutraceutical diet, with proven immunomodulatory activity. In addition, we evaluated the effect of such botanicals in contrasting the in vitro proinflammatory toxicity of OTC. Our results showed a significant reduction in interferon- (INF-) γ production by human and canine lymphocytes in presence of botanicals ((⁎) p < 0.05). Increased INF-γ production, dependent on 24-hour OTC-incubation of T lymphocytes, was significantly reduced by the coincubation with Haematococcus pluvialis, with Glycine max, and with the mix of all botanicals ((⁎) p < 0.05). In conclusion, the use of these botanicals was shown to be able to contrast OTC-toxicity and could represent a new approach for the development of functional foods useful to enhance the standard pharmacological treatment in infections as well as in preventing or reducing the emergence of inflammatory diseases.

Anti-inflammatory and immunomodulatory properties of Carica papaya

Chronic inflammation is linked with the generation and progression of various diseases such as cancer, diabetes and atherosclerosis, and anti-inflammatory drugs therefore have the potential to assist in the treatment of these conditions. Carica papaya is a tropical plant that is traditionally used in the treatment of various ailments including inflammatory conditions. A literature search was conducted by using the keywords "papaya", "anti-inflammatory and inflammation" and "immunomodulation and immune" along with cross-referencing. Both in vitro and in vivo investigation studies were included. This is a review of all studies published since 2000 on the anti-inflammatory activity of papaya extracts and their effects on various immune-inflammatory mediators. Studies on the anti-inflammatory activities of recognized phytochemicals present in papaya are also included. Although in vitro and in vivo studies have shown that papaya extracts and papaya-associated phytochemicals possess anti-inflammatory and immunomodulatory properties, clinical studies are lacking.

The Papaya Transcription Factor CpNAC1 Modulates Carotenoid Biosynthesis through Activating Phytoene Desaturase Genes CpPDS2/4 during Fruit Ripening

Papaya fruits accumulate carotenoids during fruit ripening. Although many papaya carotenoid biosynthesis pathway genes have been identified, the transcriptional regulators of these genes have not been characterized. In this study, a NAC transcription factor, designated as CpNAC1, was characterized from papaya fruit. CpNAC1 was localized exclusively in nucleus and possessed transcriptional activation activity. Expression of carotenoid biosynthesis genes phytoene desaturases (CpPDSs) and CpNAC1 was increased during fruit ripening and by propylene treatment, which correlates well with the elevated carotenoid content in papaya. The gel mobility shift assays and transient expression analyses demonstrated that CpNAC1 directly binds to the NAC binding site (NACBS) motifs in CpPDS2/4 promoters and activates them. Collectively, these data suggest that CpNAC1 may act as a positive regulator of carotenoid biosynthesis during papaya fruit ripening possibly via transcriptional activation of CpPDSs such as CpPDS2/4.

Fermented papaya preparation modulates the progression of N-methyl-N-nitrosourea induced hepatocellular carcinoma in Balb/c mice

AIM AND MAIN METHOD

The medicinal properties of fermented papaya preparation (FPP) derived from Carica papaya fruit was investigated in order to determine its ability to modulate the progression of N-methyl-N-nitrosourea induced hepatocellular carcinoma in Balb/c mice.

KEY FINDINGS

As well as reducing the physical symptoms associated with N-methyl-N-nitrosourea (MNU)-induced hepatocellular carcinoma, supplementation of Balb/c mice with 500mg FPP/kg BW for 92days normalized the blood cell count, led to an increased activity of several key antioxidant enzymes (SOD: +20%, CAT: +81%, GPx: +66.1%, GR: +54.4%; P<0.001 vs. MNU control), increased the ferrous reducing antioxidant potential (+36.7%, P<0.001 vs. MNU control) and reduced the extent of lipid peroxidation in the liver by 44.3% (P<0.001 vs. MNU control).

SIGNIFICANCE

Results demonstrated the ability of FPP to preserve the integrity of liver against oxidative damage and protect hepatocytes against irreversible DNA structural modifications induced by MNU, highlighting its potential role as an immune-defense modulator during hepatocarcinoma.

Traditional Aboriginal Preparation Alters the Chemical Profile of Carica papaya Leaves and Impacts on Cytotoxicity towards Human Squamous Cell Carcinoma

Carica papaya leaf decoction, an Australian Aboriginal remedy, has been used widely for its healing capabilities against cancer, with numerous anecdotal reports. In this study we investigated its in vitro cytotoxicity on human squamous cell carcinoma cells followed by metabolomic profiling of Carica papaya leaf decoction and leaf juice/brewed leaf juice to determine the effects imparted by the long heating process typical of the Aboriginal remedy preparation. MTT assay results showed that in comparison with the decoction, the leaf juice not only exhibited a stronger cytotoxic effect on SCC25 cancer cells, but also produced a significant cancer-selective effect as shown by tests on non-cancerous human keratinocyte HaCaT cells. Furthermore, evidence from testing brewed leaf juice on these two cell lines suggested that the brewing process markedly reduced the selective effect of Carica papaya leaf on SCC25 cancer cells. To tentatively identify the compounds that contribute to the distinct selective anticancer activity of leaf juice, an untargeted metabolomic approach employing Ultra High Performance Liquid Chromatography-Quadrupole Time of Flight-Mass Spectrometry followed by multivariate data analysis was applied. Some 90 and 104 peaks in positive and negative mode respectively were selected as discriminatory features from the chemical profile of leaf juice and >1500 putative compound IDs were obtained via database searching. Direct comparison of chromatographic and tandem mass spectral data to available reference compounds confirmed one feature as a match with its proposed authentic standard, namely pheophorbide A. However, despite pheophorbide A exhibiting cytotoxic activity on SCC25 cancer cells, it did not prove to be the compound contributing principally to the selective activity of leaf juice. With promising results suggesting stronger and more selective anticancer effects when compared to the Aboriginal remedy, Carica papaya leaf juice warrants further study to explore its activity on other cancer cell lines, as well as investigation to confirm the identity of compounds contributing to its selective effect, particularly those compounds altered by the long heating process applied during the traditional Aboriginal remedy preparation.

In vitro antimicrobial and anti-proliferative activities of plant extracts from Spathodea campanulata, Ficus bubu, and Carica papaya

CONTEXT

African medicinal plants represent a prominent source of new active substances. In this context, three plants were selected for biological investigations based on their traditional uses.

OBJECTIVE

The antimicrobial and anti-proliferative features of three plants used for medicinal purpose were evaluated.

MATERIALS AND METHODS

The antimicrobial activities of methanol extracts of Ficus bubu Warb. (Moraceae) stem bark and leaves, of Spathodea campanulata P. Beauv. (Bignoniaceae) flowers, as well as those of Carica papaya Linn. (Caricaceae) latex, were determined using the microbroth dilution method against a set of bacteria and fungi pathogens including: Enterococcus faecalis, Staphylococcus aureus, S. saprophyticus, S. epidermididis, Escherichia coli, Klebsiella pneumonia, Salmonella typhimurium, Candida albicans, and Trichophyton rubrum. The tested concentrations of extracts ranged from 2500.0 to 2.4 μg/mL and MIC values were evaluated after 24 h incubation at 37 °C. Subsequently, MTT assay was used to estimate anti-proliferative activity of these methanol extracts and of F. bubu latex on three human cancer cell lines (U373 glioblastoma, A549 NSCLC, and SKMEL-28 melanoma).

RESULTS

The methanol extract of F. bubu stem bark exhibited the highest antimicrobial activity against C. albicans with a MIC value of 9.8 μg/mL, while the F. bubu latex and the methanol extract of F. bubu leaves induced significant anti-proliferative activity against lung (IC50 values of 10 and 14 μg/mL, respectively) and glioma (IC50 values of 13 and 16 μg/mL, respectively) cancer cells.

CONCLUSION

These results indicate that effective drugs could be derived from the three studied plants.

Chemical Characterization and in Vitro Cytotoxicity on Squamous Cell Carcinoma Cells of Carica papaya Leaf Extracts

In traditional medicine, Carica papaya leaf has been used for a wide range of therapeutic applications including skin diseases and cancer. In this study, we investigated the in vitro cytotoxicity of aqueous and ethanolic extracts of Carica papaya leaves on the human oral squamous cell carcinoma SCC25 cell line in parallel with non-cancerous human keratinocyte HaCaT cells. Two out of four extracts showed a significantly selective effect towards the cancer cells and were found to contain high levels of phenolic and flavonoid compounds. The chromatographic and mass spectrometric profiles of the extracts obtained with Ultra High Performance Liquid Chromatography-Quadrupole Time of Flight-Mass Spectrometry were used to tentatively identify the bioactive compounds using comparative analysis. The principal compounds identified were flavonoids or flavonoid glycosides, particularly compounds from the kaempferol and quercetin families, of which several have previously been reported to possess anticancer activities. These results confirm that papaya leaf is a potential source of anticancer compounds and warrant further scientific investigation to validate the traditional use of papaya leaf to treat cancer.