Exotic Antioxidant Superfruits - Pomegranate Punicalagins: Ancient Aril Antioxidants

Paul M. Gross, PhD

A deciduous fruit-bearing tree native to the Mediterranean Middle East, now cultivated in many subtropical regions of the world, the pomegranate (Punica granatum L.) (Fig. 1) has been favored for centuries as a health-giving plant mainly for its brilliant red seed pulp (botanically, the seed coat is called an “aril”, Fig. 2). Juice pressed from the many arils of each fruit has become popular for its delicious taste and rich content of antioxidant phenolics shown in an increasing number of medical studies to have potent anti-disease potential and clinical efficacy in specific diseases.

Pomegranate is mainly an inedible fruit, as only the purple aril with flesh-like texture and seeds inside can be consumed. The seed aril, however, is sweet and delicious if ripe, yields a high amount of juice and contains rich levels of red pigment antioxidant phenolics, the majority of which are called punicalagins.

Figure 1. Pomegranate, Punica granatum L. Figure 2. Pomegranate arils and seeds

(Courtesy of Wikipedia, both figures, Ref. 4)

This essay will cover pomegranate's nutrient profile, antioxidant phytochemicals, current medical literature and research directions, and indicate the existing and possible future applications of pomegranate in functional foods.


There is very limited nutrition information for pomegranate. Although several reports exist on the web, they are all the same data which appear to derive from a single report by Nutritiondata.com (Ref. 2) summarized from the US Department of Agriculture -- the data used in this essay.

The simplest conclusion about the nutritional value of pomegranate aril is its relatively low yield of macronutrients and poverty of micronutrients, being a significant source only of vitamin C (10% RDI). Although numerous other nutrients were assayed, their values are so low that it is not useful to highlight them in this table. Even those listed are at levels lower than most fruits and vegetables.


Table 1. Macro- and Micronutrient Profile for Pomegranate Aril Pulp


per 100 g aril weight





Calories, total kcal



Carbohydrates, g



Fats, g



Protein, g



Dietary fiber, g



Water, g





Potassium, mg



Vitamin C, mg



Vitamin K, mg



Vitamin B6^, mg



Pantothenic acid, mg



Omega-6 fatty acids, mg



Phytosterols, mg





Data are normalized to 100 g of aril weight to allow comparisons with other superfruits; from Nutritiondata.com (Ref. 2)

RDI: Reference Dietary Intake, Institute of Medicine, US National Academies of Science

^ Pyridoxine

ne, no reference data established

However, the potential value of pomegranate as a health food from research to date appears to lie in its phytochemicals, particularly those with antioxidant functions (preliminary science indicates that health benefits may occur). Consequently, research to date is discussed below for what appears to be a unique pomegranate antioxidant phenolic group, punicalagins, and other flavonoids discovered in aril pulp.

Antioxidant phytochemicals


Almost unique in the plant world, the genus Punica has a limited number of species among which pomegranate is by far the most prevalent and individually researched.

Discovered first around 1990, a new type of flavonoid from pomegranate pericarp, now also found in its aril (the desirable food and juice source covering the seeds), has been called punicalagins, plural because there are numerous similar tannin-like structures in this class of phenolics. Punicalagins are often identified particularly in more recent research as form A or form B, and may have another subunit called punicalin. In these cases, a total punicalagins value may be reported in the phytochemical literature. This antioxidant now synonymous with pomegranate has been the subject of 35 medical research studies since 1990 including 27 reports within the past 6 years (PubMed dated January 12, 2007; Ref. 3).

As the chemistry of punicalagins became known, however, it was found to be not unique to pomegranate, but is also present in other plants, such as numerous species of the genus Terminalia, species chebula Retz. (“Fructus Chebulae”), myriocarpa, catappa and citrina (these are tropical flowering trees historically used in African traditional medicine for antiobiotic and antifungal purposes). Punicalagins have also been isolated from Cistus salvifolius (Mediterranean shrub) and Combretum molle (African shrub) (see Wikipedia, Ref. 4 for summaries).

Chemically, punicalagins are considered as tannins which hydrolyze during metabolism to yield ellagic acid, a flavonol of the phenolic superfamily of pigments often associated with tannins such as by the class called ellagitannins among which punicalagin is considered a member.

Consequently, an evaluation of the antioxidant value of pomegranate arils must include effects produced by ellagic acid, a much better studied phenolic in medical research to date (686 medical citations on PubMed, January 12, 2007). Ellagic acid, a recognized antioxidant of many types of berries, nuts, seeds and other plant foods, is under active scientific study as a potential anti-cancer agent.

Pomegranate also contains other antioxidants such as vitamin C, beta-carotene, catechins, gallocatechins, and anthocyanins such as prodelphinidins, delphinidin, cyanidin, and pelargonidin. ORAC of pomegranate juice is considered high, measured at 10,500 units per 100 grams (2002 assay, Brunswick Laboratories, Norton, MA; http://brunswicklabs.com).

Clinical trial status

According to a summary by the US National Institutes of Health (http://clinicaltrials.gov), there are currently three human clinical trials (January 2007) underway examining effects of pomegranate juice on prostate cancer and benign human prostate hyperplasia. Their titles, locations and trial phases are:

  • Effects of Pomegranate Juice or Extract on Rising PSA Levels in Men Following Primary Therapy for Prostate Cancer; M.D. Anderson Cancer Center, New York; phase II
  • Pomegranate Juice in Treating Patients With Rising Prostate-Specific Antigen Levels After Surgery or Radiation Therapy for Localized Prostate Cancer; Jonsson Cancer Center, Los Angeles; phase II
  • Randomized, Double Blinded, Trial of Pomegranate Tabs vs Placebo-Effects on Symptoms of Benign Prostatic Hyperplasia; University of California, Irvine; phase II and III

Clinical trials

The above reference to clinical trial activity places pomegranate juice in a special category of clinical study not occupied by many natural products, as the requirements to gain approval for clinical trials are very rigorous.

In phase II trials, treatment is given to a group of people (typically100-300) to examine preliminary signs of efficacy and safety, usually lasting two years. In a phase III trial, treatment is given to larger groups of people (1,000-3,000) to confirm effectiveness, monitor side effects, compare to commonly used treatments, and collect information that will ensure as much as possible the treatment can be used safely. As a trial “pivotal” to decision-making about the usefulness of the treatment, a phase III trial can last several years for such evaluation to be complete and the results analyzed by regulatory and clinical experts.

Research trends and potential health benefits

Scan of the research activity on pomegranate juice yields a broad range of scientific inquiry, including the following anti-disease topics: chemopreventive anticancer agent; anti-atherogenic; anti-thrombotic; anti-inflammatory; antimicrobial/antibiotic; wound and periodontal healing; dental and periodontal applications; antifungal; antimutagenic; reduction of high blood pressure; improvement of stress response in ischemic heart disease; stimulation of bone metabolism; inhibition of cholesterol synthesis and reduction of hyperlipidemia; anti-diabetic; relief from oxidative erectile dysfunction; stimulation of endothelial nitric oxide synthase and protection of nitric oxide against oxidative destruction; reduction of cardiac fibrosis; stimulation of immune functions; regeneration of epidermis and dermis cells; photochemopreventive protection against ultraviolet light (skin cancer application).

The following observations summarize the status of pomegranate as a “superfruit” and as a source of dietary antioxidants (punicalagins and ellagic acid):

  • flesh and juice of seed arils are the only edible portions of pomegranate fruit and the only sources of antioxidant phytochemicals being used in current beverage products and medical research
  • this situation contrasts with the mangosteen for which the edible fruit pulp (also a seed aril but lacking pigmentation) has no appreciable antioxidant value (Ref. 1). Mangoteen's antioxidant xanthones are extracted from its inedible exocarp
  • nutritionally, pomegranate arils are a poor source of calories, macronutrients or micronutrients and so are similar to the nutrient-poor aril of the mangosteen (Ref. 1). Neither of these species should be called a “superfruit” which implies nutrient richness and antioxidant strength


  • whether consumed as fresh pulp or as juices, the arils both of pomegranate and mangosteen provide pleasant, exotic fruit products currently growing in popularity
  • the pace of scientific medical research on pomegranate currently exceeds that for any other exotic fruit, indicating that its major antioxidant group – punicalagins – has significant potential to lower risk against various diseases

Article Continued - Review of Current Research >>

General References

  1. Gross PM, Crown I. Is mangosteen a superfruit? Nutrient and antioxidant properties, Natural Products Information Center, in press, 2007. Update by NPICenter, http://www.npicenter.com/anm/anmviewer.asp?a=17613&z=201
  2. Nutrition data for pomegranate, http://www.nutritiondata.com/facts-C00001-01c20Ws.html
  3. PubMed, http://pubmed.gov
  4. Wikipedia on pomegranate, http://en.wikipedia.org/wiki/Pomegranate

About the Author
Paul M. Gross, Ph.D., received his doctorate in physiology from the University of Glasgow, Scotland and was a post-doctoral fellow in neuroscience at the Laboratory of Cerebral Metabolism, National Institutes of Health, Bethesda, MD. A former Research Scholar for the Heart and Stroke Foundation of Ontario, he published 85 peer-reviewed journal reports and book chapters over a 25 year career in medical science, and was recipient of the Karger Memorial Award, Switzerland, for publications on brain capillaries. Dr. Gross is on the Steering Committee of the International Berry Health Association. He is senior author of a 2006 book on the goji berry entitled Wolfberry: Nature’s Bounty of Nutrition and Health (Booksurge Publishing, Amazon.com, http://wolfberry.org/) and is publisher of The Berry Doctor's Journal, http://berrydoctor.com where the public can obtain free information on berry science and nutrition.

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