|Exotic fruits such as mangosteen are attracting consumer attention for their potential health benefits as well as their taste. Photo Courtesy of Istockphoto.|
Recently there has been growing consumer interest in “exotic” (terminology currently used to refer to “mysteriously different” or “unusual”) fruits due to anecdotal claims of their medicinal values and purported health benefits. This has been fueled, in part, by a shift in ethnic demographics as immigrants bring native foods common to their cultures to the Western marketplace. Popular examples of such fruits include the pomegranate ( Punica granatum ), açaí, goji berries, mangosteen, and noni.
Although exotic fruits are found in all parts of the world, India, which is blessed by a rich diversity of climatic zones—from tropical to tundra—is home to several exotic fruits that have attracted recent consumer attention. A perennial leader in the production of amla ( Emblica officinalis syn. Phylanthus emblica , also known as Indian gooseberry), mango, papaya, and tamarind, India also produces what many regard as the sweetest pomegranates available.
Because of India's strong agricultural foundation and its thousands of years of traditional medicinal use of fruits, as well as the recent focus of modern research into the bioactive properties of the fruits, we are now graced with a growing wealth of knowledge on the potential uses for what we may call the Indian superfruits: pomegranate, mango, papaya, amla, and tamarind.
These fruits include the pomegranate, amla, and jamun berries ( Eugenia jambolana syn. Syzygium cumini ). In terms of their phytochemistry, these fruits share a commonality in that they all contain ellagitannins (ETs), a family of polyphenols that have been linked with a diverse range of biological activities.
ETs are obtained in the Western diet primarily through the consumption of berries and tree nuts such as strawberries, red and black raspberries, walnuts, and almonds. Emerging science has demonstrated that ET-rich foods may impart human health benefits, including antineurodegenerative, antidiabetic, and anticancer properties.
Although many drug-discovery research groups seek to identify single active ingredients in medicinal foods, there has been a shift in this paradigm in the functional foods and dietary supplement arenas. This is because multiple phytochemicals present in a complex food matrix may provide better protection through complementary, additive, or synergistic effects. Therefore the consumption of bioactive food components in whole foods and their derived extracts offers an attractive dietary strategy for the prevention or delay of onset of several chronic human diseases. Due to the paucity of clinical data, however, there is great need for well-designed human clinical studies to substantiate the health claims of many of these fruits.
Pomegranate juice, peels, and seeds are an ancient mainstay of Ayurveda, the traditional Indian system of medicine. Pomegranate deserves special mention among the aforementioned fruits, because it has the most published clinical data to support its health benefits, specifically against cardiovascular disease and prostate cancer.1–4 The fruit peel is a rich source of hydrolyzable ETs, including punicalagins, punicalins, gallagic acid, several ellagic acid-glucose esters, and oligomeric ETs. Pomegranate juice obtained from squeezing the whole fruit provides more potent antioxidants than other common fruit juices.5,6
Since 2006, the antioxidants in pomegranate fruit extracts and juices have been studied in vivo or clinically for applications in cardiovascular, glycemic, cellular/DNA, and cognitive health, in addition to gender-related health issues. The triple-whammy of antioxidant, antiinflammatory, and antimicrobial effects also has led to research in skin- and oral-care applications.
Bioavailability, metabolism, and ex vivo bioactivities of pomegranate ETs have been established for both juice and extract preparations.7–10 On consumption, pomegranate ETs release ellagic acid (EA). Following metabolism by gut flora, the ETs form urolithins that are conjugated in the liver prior to excretion up to 56 hours in urine. These urolithins circulate in the blood as well and can reach many of the target organs, such as the prostate gland, where the effects of pomegranate ETs have been noted.11
Pomegranate juice also contains other polyphenols included among its minor constituents, such as anthocyanins, the pigments that impart the red color to the fruit aril and therefore to fruit juice. Pomegranate extracts have been shown to inhibit prostate cancer xenografts in animal studies11,12 and to date there is a phase-II human clinical that suggests effects against prostate cancer.4 It is noteworthy that ETs previously were shown to exhibit in vitro and in vivo anticarcinogenic properties, such as induction of cell-cycle arrest and apoptosis in vitro.13 A recent review on the effects of pomegranate ETs on cancer is available.2
The absorption of a pomegranate extract standardized to punicalagins, Pomella Extract (supplied by Verdure Sciences Inc.; Noblesville, IN), was analyzed by measuring a time-curve of EA in human plasma. In this study, a 32% increase in antioxidant capacity was observed as a result of consumption of the extract.23
The amla fruit, touted as one of nature's richest sources of vitamin C, is also known to contain ETs and other polyphenols, including emblicanins A and B.4 Amla fruits constitute one of three ingredients in a well-known antioxidant-rich Ayurvedic herbal formulation, Triphala (the other two Indian fruits are Terminalia chebula and T. belerica ).
Amla is used for the treatment of liver diseases, stomach ulcers, inflammatory diseases, and also to inhibit tumor growth, in diabetes and in geriatric complaints.14 Recently, a preparation of amla fruit was shown to prevent liver toxicity15 and age-related renal dysfunction.16
|Noni, also known as Indian mulberry, has been used for centuries as a tonic for a variety of ailments. Photo Courtesy of Istockphoto.|
Obtained from a large evergreen tree that reaches up to 30 meters in height, Jamun fruits have been valued in both Ayurvedic and Unani systems of medicine for possessing a wide variety of therapeutic properties.17,18 Jamun is most often recognized as an adjuvant therapy in type-2 diabetes. This has been traced not only to its anthocyanin-rich, dark-purple fleshy pulp, but also to its seeds, which have been most studied for their antidiabetic principles.18 Jamun seeds are reported to be a rich source of ETs, including corilagin, 3,6-hexahydroxydiphenoylglucose and its isomer 4,6- hexahydroxydiphenoylglucose, 1-galloylglucose, 3-galloylglucose, gallic acid, and EA.17
Jamun fruit seeds and pulp have been reported to serve various purposes in diabetic patients, such as lowering blood glucose levels and delaying diabetic complications including neuropathy and cataracts. However, most of the studies have been conducted using a crude preparation of E. jambolana fruit parts without mention of their chemical profile. Therefore, detailed research that identifies the antidiabetic bioactive components, using well-characterized and standardized fruit pulp and/or seed extracts, is urgently needed.
Although mango fruit ( Mangifera indica ) is widely consumed as a whole ripe fruit in diets of tropical populations worldwide, it also is widely consumed in Indian cuisine in mango chutneys, which include preparations of the bitter and unripe mango flesh, seeds, and peel. Mango is a good source of carotenoids, ascorbic acid, quercetin, xanthone, mangiferin, and other polyphenols. Recently, a mango peel extract prevented degradation of rat erythrocytes,19 a mango extract prevented mitochondrial oxidative stress in an atherosclerotic mouse model20, and the mango triterpene lupeol also has been shown to inhibit certain cancers in in vivo models.21
Garcinia cambogia is a small fruit indigenous to India, where it is often used in Indian cuisine for the purposes of adding a “sour-tasting ingredient” to curries. An extract from G. camobgia fruit and its rind is popularly used with claims of “weight-loss” effects.
G. cambogia fruit and its extract contain large quantities of hydroxycitric acid (HCA), which is believed to be the putative active component and is claimed to suppress appetite and enhance fat-burning.22 Recent reports have shown that apart from HCA, the fruit also contains polyisoprenylated benzophenones and xanthones.23 Given the paucity of data available on the weight-loss potential of this fruit, more detailed clinical studies are needed.
India ranks second only to China in production of fruit, with 46 million tons produced per year.1 With this abundant wealth of supply and forthcoming research, India's superfruits are sure to continue to endow the world with an ever-impressive array of fruit-derived ingredients.
Navindra P. Seeram, PhD, is currently an assistant professor of pharmacognosy at the University of Rhode Island's College of Pharmacy (Kingston, RI). His research interests include the evaluation of medicinal plants and bioactive food components for the prevention and therapy of chronic human illnesses including cancer, diabetes, and neurodegenerative diseases.
1. NP Seeram, RN Schulman, D Heber (Eds), Pomegranates: Ancient Roots Modern Medicine , CRC Press & Taylor and Francis Group (Boca Raton, FL), Medicinal & Aromatic Plant Series, 2006.
2. D. Heber, “Multitargeted Therapy of Cancer by Ellagitannins,” Cancer Letters , 2008, in press.
3. M Aviram M, et al, “Pomegranate Juice Consumption for 3 Years by Patients with Carotid Artery Stenosis Reduces Common Carotid Intima-Media Thickness, Blood Pressure and LDL Oxidation,” Clinical Nutrition , vol 23, no. 3 (2004): 423–433.
4. AJ Pantuck, et al, “Phase II Study of Pomegranate Juice for Men with Rising Prostate-Specific Antigen Following Surgery or Radiation for Prostate Cancer,” Clinical Cancer Research , vol. 12, (2006): 4018–4026.
5. MI Gil et al., “Antioxidant Activity of Pomegranate Juice and Its Relationship with Phenolic Composition and Processing,” J Agric Food Chem , vol 48, no. 10 (2000): 4581–4589.
6. NP Seeram et al, “Comparison of Antioxidant Potency of Commonly Consumed Polyphenol-Rich Beverages in the United States ,” J Agric Food Chem , vol 56, no. 4 (2008): 1415–1422.
7. NP Seeram et al., “Pomegranate Juice Ellagitannin Metabolites are Present in Human Plasma and Some Persist in Urine for up to 48 Hours,” Journal of Nutrition , vol 136, (2006): 2481–2485.
8. B Cerdá et al., “The Potent In Vitro Antioxidant Ellagitannins from Pomegranate Juice are Metabolized into Bioavailable but Poor Antioxidant Hydroxy-6H-dibenzopyran-6-one Derivatives by the Colonic Microflora of Healthy Humans,” European Journal of Nutition , vol. 43 (2004): 205-220.
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10. NP Seeram et al., “Ellagitannin Metabolites Are Present in Human Plasma and Urine in Similar Levels after Consumption of Pomegranate Fruit Juice and Its Liquid and Solid Extracts,” J Med Food , 2008, in press.
11. NP Seeram et al., “Pomegranate Ellagitannin Derived Metabolites Inhibit Prostate Cancer Growth and Localize to the Mouse Prostate Gland,” J Agric Food Chem , vol 55, no. 19 (2007): 7777–7785.
12. A Malik et al., “Pomegranate Fruit Juice for Chemoprevention and Chemotherapy of Prostate Cancer,” Proc Natl Acad Sci , vol 102 (2005): 14813–14818.
13. A Castongua et al., “Antitumorigenic and Antipromoting Activities of Ellagic Acid, Ellagitannins and Oligomeric Anthocyanin and Procyanidin,” Int J Oncol , vol 10 (1997): 367– 373.
14. S Ghosal et al., “Antioxidant Effects of Emblica officinalis and Their Biological Consequences,” in Recent Progress in Medicinal Plants , Volume 8, ed. DK Majumdar, JN Govil, and VK Singh (Houston, TX: Studium Press, 2003), 149–162.
15. KR Anilakumar et al., “Reduction of Hexachlorocyclohexane-Induced Oxidative Stress and Cytotoxicity in Rat Liver by Emblica officinalis ,” Indian Journal of Experimental Biology , vol 45, no. 5 (2007): 450-454
16. T Yokozawa et al., “Amla ( Emblica officinalis Gaertn.) Attenuates Age-Related Renal Dysfunction by Oxidative Stress,” J Agric Food Chem , vol 55, no. 19 (September 19, 2007): 7744–7752.
17. A. Helmstadter, “ Syzygium cumini (L.) SKEELS (Myrtaceae) Against Diabetes: 125 Years of Research,” Pharmazie , vol 63 (2008): 91–101.
18. H Sagrawat et al., “Pharmacological Potential of Eugenia jambolana : A Review,” Pharmacognosy Magazine , vol 2, no. 6 (April/June 2006): 96–105.
19. CM Ajila et al., “Protection Against Hydrogen Peroxide Induced Oxidative Damage in Rat Erythrocytes by Mangifera indica L. Peel Extract,” Food Chem Toxicol , vol 46, no. 1 (2008): 303-9.
20. GL Pardo-Andreu GL et al., “ Mangifera indica L. Extract (Vimang) and Its Main Polyphenol Mangiferin Prevent Mitochondrial Oxidative Stress in Atherosclerosis-Prone Hypercholesterolemic Mouse,” Pharmacol Res , vol 57, no. 5 (2008): 332–338.
21. HG Preuss et al., “An Overview of the Safety and Efficacy of a Novel, Natural(-)-Hydroxycitric Acid Extract (HCA-SX) for Weight Management,” J Med , vol 35 (2004): 33–48.
22. M Masullo et al., “Polyisoprenylated Benzophenones and an Unusual Polyisoprenylated Tetracyclic Xanthone from the Fruits of Garcinia cambogia ,” J Agric Food Chem , 2008, in press.
23. SU Mertens-Talcott et al., “Absorption, Metabolism, and Antioxidant Effects of Pomegranate ( Punica granatum L.) Polyphenols after Ingestion of a Standardized Extract in Healthy Human Volunteers,” J Agric Food Chem , vol 54 (2006): 8956–61.