Anti-Inflammatory & Antioxidant Effects of Dragon Fruit with Its Bioactive Compounds
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Dragon fruit (Selenicereus genus) has the potential for the prevention of diseases associated with inflammatory and oxidative processes. We aimed to comprehensively review dragon fruit health effects, economic importance, and possible use in delivery systems. Pubmed, Embase, and Google Scholar were searched, and PRISMA (Preferred Reporting Items for a Systematic Review and Meta-Analysis) guidelines were followed. Studies have shown that pitaya can exert several benefits in conditions such as diabetes, dyslipidemia, metabolic syndrome, cardiovascular diseases, and cancer due to the presence of bioactive compounds that may include vitamins, potassium, betacyanin, p-coumaric acid, vanillic acid, and gallic acid.
Moreover, pitaya has the potential to be used in food and nutraceutical products as functional ingredients, natural colorants, ecologically correct and active packaging, edible films, preparation of photoprotective products, and additives. Besides the importance of dragon fruit as a source of bioactive compounds, the bioavailability is low. The development of delivery systems such as gold nanoparticles with these compounds can be an alternative to reach target tissues.
The health-promoting potential of pitaya fruit is due to the presence of bioactive compounds related to numerous benefits such as anti-diabetic, anti-inflammatory, antioxidant, anti-cancer, and antimicrobial. As a result of these beneficial actions, the consumption of this fruit has increased in different regions worldwide
Dragon fruit is becoming popular in many countries and is consumed raw or can be added to drinks, jelly, and candies. In addition, the pigments can be used as a coloring agent in the pharmaceutical and food industries. Three varieties that are distinguished by the color of the skin and flesh are mainly cultivated
In addition, there are some studies showing dragon fruit’s effects, but there is still a need for detailed scientific investigations to show the benefits this plant can bring to consumers. Moreover, dragon fruit can open a new window for developing multi-targeting drugs to prevent and treat several diseases and can be used for several technological applications in the food and pharmaceutical industries. For these reasons, we aimed to comprehensively review dragon fruit’s health effects, its economic importance, and its possible use in delivery systems. To the best of our knowledge, this is the first review considering the species S. Undatus, S. Polyrhizus, and S. Megalanthus and their role in health and technological applications.
Results
Many studies have shown that dragon fruit can benefit numerous health problems and work as an analgesic, antioxidant, anti-diabetic, anti-cancer, cardio-protective, liver protective, and neuroprotective. However, only five clinical trials were found and included. All of them were performed with S. Polyrhizus. Three of them were performed in Malaysia, one was performed in Indonesia, and one in the United Kingdom.
The primary outcomes were improved glycemia, lipid profile, and antioxidant status , flow-mediated dilation, and arterial stiffness .
In vitro studies showed anti-glycation, anti-diabetes, anti-viral, anti-plasmodium, hepatoprotective, immunomodulatory, and osteogenic effects.
In vivo studies have also shown the effects of the genus Selenicereus on animal models . Lira et al.demonstrated the anxiolytic effects of pitaya in zebrafish. Anand Swarup demonstrated that pitaya’s pulp extracts have potent actions against arterial stiffness, reducing blood pressure and controlling pulse wave velocities. Holanda investigated the effects of Hylocereus on the lipid and glycemic profile of rats. Silva investigated the use of red pitaya in glycemia.
Yeh and Ramli showed that pitaya affects the liver’s health, reducing liver lipids content and enhancing the enzymatic potential of the hepatocytes against liver injuries. Ramli and Song demonstrated more profoundly the metabolic effects of pitaya, principally in enhancing lipid metabolism, diminishing obesity, and augmenting the gut microbiota content of Akkermansia. Macias-Ceja demonstrated that pitaya could exert anti-inflammatory actions in rats’ gastrointestinal systems, principally regulating pro-inflammatory pathways and diminishing the chance of the rats developing colitis.
Lastly, Perez demonstrated that many extracts of pitaya could exert wound-healing effects against diabetic-induced wounds principally by enhancing tensile strength, hydroxyproline, DNA, total proteins, collagen content, and epithelization. The evaluation of the bias of the animal studies is shown in Table 2.
Bioactive Compounds of Selenicereus Species
The phytochemical compounds found in dragon fruit mainly belong to phenols, flavonoids, sterols, fatty acids, and tocopherol. Among the numerous bioactive compounds found in the pulp and peel, it is possible to highlight the presence of ascorbic acid, tocopherol, thiamin, niacin, and riboflavin, minerals like calcium, magnesium, potassium, phosphorous, betacyanin, β-carotene, lycopene, p-coumaric acid, protocatechuic acid, vanillic acid, gallic acid, syringic acid, and p-hydroxybenzoic acid. The properties of these phytochemicals are shown in Table 3 .
The analysis performed on S. undatus pulp with different solvents indicated the presence of carbohydrates, tannins, saponins, anthocyanins, quinones, glycosides, terpenoids, triterpenoids, phenols, acids, and steroids in aqueous extract. In the methanolic extract, carbohydrates, tannins, saponins, flavonoids, alkaloids, anthocyanins, cardiac glycosides, terpenoids, triterpenoids, phenols, acids, and steroids were identified.
Extraction with hexane showed carbohydrates, saponins, anthocyanin, quinones, phenols, and acids. Carbohydrates, saponins, alkaloids, cardiac glycosides, triterpenoids, phenols, and coumarins were extracted in chloroform, as well as carbohydrates, tannins, saponins, flavonoids, alkaloids, anthocyanin, cardiac glycosides, terpenoid acids, triterpenoids and steroids in ethyl acetate.
Antioxidant Effects by Species
S. Polyrhizus is rich in betalains and other bioactive compounds such as vitamins and phenolic compounds that exert relevant antioxidant properties and, for these reasons, are related to the prevention of several human diseases. The oil results from the seeds, and the peel is also an essential source of antioxidant compounds. The peel of S. undatus possesses more flavonoids than the flesh (Table 3).
Anti-Inflammatory Effects
Besides the antioxidant actions, dragon fruit can also exert anti-inflammatory actions. Saenjum found anthocyanins (cyanidin 3-glucoside, delphinidin 3-glucoside, and pelargonidin 3-glucoside) in the pulp and peel of pitaya red.
The authors found that the pulp enriched with the first anthocyanin (cyanidin 3-glucoside) inhibited the synthesis of reactive oxygen and nitrogen species, cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS), in in vitro models and without resulting in cytotoxicity.
Another study showed that the dragon flesh and peel extract and the isolated squalene led to the inhibition of pro-inflammatory enzymes such as cyclooxygenase-2 lipoxygenase and acetylcholinesterase and concluded that this fruit could produce a significant potential for the control and management of inflammatory processes through different pathways that may include, prostaglandin, leukotriene, and cholinergic pathways
Prebiotic Effects
The main carbohydrates in white and red flesh dragon fruit are glucose, fructose, and oligosaccharides. The mixed oligosaccharides are resistant to hydrolysis by human α-amylase and artificial human gastric juice (about 34.88% and 4.04%, respectively). Moreover, the mixed oligosaccharides can also stimulate the growth of lactobacilli and bifidobacterial, thus showing prebiotic properties [76].
Dasaesamoh et al. [77] showed that the fecal fermentation of pitaya oligosaccharides increased the populations of Bifidobacteria and Lactobacillus and reduced the populations of Bacteroides and Clostridium. Moreover, this fecal fermentation resulted in a positive prebiotic effect. Lactic acid, acetic acid, propionic, and butyric acids were produced at substantial concentrations.
4.2.4. Antimicrobial Effects
In a study to investigate the antimicrobial effect of red pitaya peels, Temak et al. [78] found that the extract has efficient in vivo and in vitro effects against several microorganisms, such as Escherichi coli and P. aeruginosa.
Sushmitha et al. [79] investigated the effects of H. undatus seeds in Gram-negative and Gram-positive bacterial species and found that the minimum inhibitory concentration is 50 µL for Staphylococcus aureus and Escherichia coli. Tenore also found antimicrobial activity for hexane, chloroform, and ethanol extract of the skin of H. undatus and showed inhibition of the growth of Gram-negative and Gram-positive bacteria.
Extract of the peel and fruit of the red dragon fruit can also exert anti-fungal actions against Rhizoctonia solani, Candida albicans, Aspergillus flavus, Botrytis cinerea, Fusarium oxysporum, and Cladosporium herbarum .
Anti-Cancer Effects
Some studies have shown the anti-cancer potential of dragon fruit. Divakaran aimed to evaluate the ability of this fruit to produce nanoparticles and found they can significantly inhibit the growth of MCF-7 breast cancer cells.
Another study showed that the fecal fermentation of pitaya oligosaccharides augmented the populations of Lactobacillus and decreased the populations of Bacteroides and Clostridium, and resulted in the production of lactic acid, acetic acid, propionic and butyric acids that can inhibit Caco-2 cells and has a potential for risk reduction in colon cancer.
In a very interesting study, Padmavathy demonstrated that methanol extracts of H. undatus have promising anti-cancer effects against human liver cancer (HepG-2) cells.
Wu investigated the anti-proliferative effect of red pitaya on B16F10 melanoma cells. They showed that the peel has stronger inhibition of the growth of these cancer cells than the flesh. The authors concluded that both peel and flesh are rich in polyphenols and good sources of antioxidants, and for these reasons, the peel can inhibit the growth of melanoma cells.
The anti-cancer activities promoted by pitaya are related to several bioactive compounds such as phenolic acids, flavonoids, and betacyanin.
Figure 6 shows the most pronounced anti-cancer effects associated with the Selenicereus species.
