Maphetu N, Unuofin JO, Masuku NP, Olisah C, Lebelo SL. Medicinal uses, pharmacological activities, phytochemistry, and the molecular mechanisms of Punica granatum L. (pomegranate) plant extracts: A review. Biomed Pharmacother. September 2022;153:113256. doi: 10.1016/j.biopha.2022.113256.
Pomegranate (Punica granatum, Lythraceae) is well-known for its pharmacological properties. Pomegranates have been consumed to treat various chronic diseases including cancer, heart diseases, diabetes, and obesity. The seeds have been used to improve male fertility, and other components have been used in cosmetics. Pomegranates have demonstrated anti-cancerous, anti-inflammatory, antiulcer, antidepressant, diuretic, cardioprotective, antidiarrheal, antioxidant, anti-obesity, and antidiabetic properties. The purpose of this review was to update ethnomedicinal uses, pharmacological activities, phytochemistry, and molecular mechanisms of pomegranate. Methodology, inclusion and exclusion criteria, and other details about the review process were not provided.
The purported medicinal qualities of pomegranate are due to the chemical profile of the plant parts. The bark is rich in tannins, proanthocyanins, anthocyanins, and terpenoids with demonstrated anti-inflammatory properties. The bark has been used to stop nose bleeds, speed recovery from sore throats, ulcers, and hoarseness as well as parasitic complaints such as malaria. The flowers contain tannins, terpenes, terpenoids, flavonoids, and organic oils. The flowers have been used to treat cardiovascular disorders, diabetes, and weight management. They have also been used to treat common bacterial infections. Alkaloids, flavonoids, and tannins are prevalent in pomegranate leaves. The leaves have been used to manage cholesterol, body weight, and diabetic nephropathy. Additionally, leaves were found to have antibacterial, anti-inflammatory, anti-cholinesterase, and cytotoxic properties. Leaf extracts have also been used to treat lice and dandruff.
The seeds are the most consumed plant part. They are rich in anthocyanins, tannins, fatty acids, flavonoids, ligands, and sterols. The seeds are most known for their antimicrobial, anti-cancerous, and antioxidant properties. The seeds are largely responsible for the juice, which is a source of vitamin C, potassium, phosphorus, calcium, manganese, zinc, and copper. Pomegranate peels make up 43% of the whole fruit. They are used medicinally for their anti-proliferative, anti-inflammatory, antioxidant, and anti-cancerous effects. The peels are comprised of alkaloids, anthocyanins, anthocyanidins, tannins, flavonoids, phenolics, proanthocyanins, sterols, terpenes, and xanthonoids.
Anthocyanins give pomegranate its color through the ripening process. Flavonoids contribute to the antimicrobial, antioxidant, anti-atherosclerosis, antiviral, anti-inflammatory, and anti-cancerous properties. Sterols function to reduce cholesterol absorption and low-density lipoprotein cholesterol (LDL-C). Terpenes and terpenoids are most abundant in essential oils and exhibit anticancer, antimicrobial, anti-inflammatory, antioxidant, and antiallergic properties. Juice consumption is associated with reducing fatigue and improving quality of life.
Several studies evaluated bioactive components using different extraction methods. Ethanol and aqueous extraction yield more bioactive compounds compared to other extracts. For instance, methanol extracts yielded phenolics including polyphenols, flavonoids, sterols, and polyterpenes. Studies show that pomegranate contains 17 types of amino acids, minerals, vitamin C, calcium, iron, phosphorus, retinol, riboflavin, and ferulic acid. Bark and roots extracts were shown to have anthelminthic, vermifuge, and antiparasitic properties.
Bioactive compounds vary based on cultivars, climatic conditions, and geographic location. Studies found that bioactive compounds are derived from the interrelationships between the plants and the environment. Additionally, medicinal benefits differed based on the plant part and extraction method used.
Several animal studies confirmed bioactive components. For example, pomegranate fruits used in skin care were shown to aid ultraviolet (UV)-induced products, anti-aging products, and coloring in bath products. Animal studies found that aqueous and alcohol leaf extracts improved hair growth, and alcohol leaf extracts provided anti-dandruff and anti-lice benefits. Anti-cancer benefits were demonstrated through animal models showing that pomegranate peel extracts interfere with tumor cell proliferation.
Owing to its alkaloid, polyphenol, and coumarin contents, pomegranate has been studied for is antiviral effects including anti-COVID-19 potential. Studies showed that pomegranate exhibited antiviral activity against human norovirus as well as inhibitory activity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and angiotensin-converting enzyme 2 (ACE2). COVID-19 is caused by SARS-CoV-2. Studies showed that pomegranate peel extract (PPE) inhibited SARS-CoV-2/ACE2 binding interaction, which could reduce viral infection.
Several human trials were conducted to determine the antidiabetic properties of pomegranate. An aqueous peel extract was found to inhibit chronic hyperglycemia oxidative stress. Methanol leaf extracts improved lipid metabolism, normalized serum albumin concentration, and decreased hyperglycemia.
Pomegranate has also been shown to have androgenic properties which may offer viability in treating male infertility. Pomegranate peels or rinds can be used as food additives or coloring agents.
The authors conclude that pomegranate has many benefits and that a diet rich in fruits and vegetables including pomegranate can provide numerous health benefits and reduce the risk of chronic diseases. However, they suggest a need for further studies to evaluate the efficacy and safety of pomegranate and its phytochemicals. Additionally, research should include exploration of the mechanisms of action required for development of natural drugs.
The authors declare no conflict of interest.
—Samaara Robbins