Extract from pomegranate peels and seeds shows anti-hypertensive properties

In a recent study published in the journal Nutrients, a team of Italian researchers investigated the efficacy of an extract obtained from the non-edible parts of pomegranates, using a sustainable and green method called hydrodynamic cavitation, in lowering cardiovascular risk due to hypertension using in vivo experiments in a rat hypertension model.

Study: Improved Cardiovascular Effects of a Novel Pomegranate Byproduct Extract Obtained through Hydrodynamic Cavitation. Image Credit: Tim UR/Shutterstock.com

Background

Pomegranates belong to the Punicaceae family and are widely cultivated in Asia, the Middle East, the Mediterranean region, North America, Australia, and Africa.

The fruit is known to have numerous health benefits and medical uses and contains various polyphenols such as tannins, anthocyanins, flavonoids; organic acids; phenolic acids such as gallic and ellagic acids; vitamins; terpenes; and tocopherols.

The main forms in which pomegranate is consumed for nutritional and nutraceutical purposes are as juice or jams made from the fleshy edible part of the fruit.

The non-edible part of the fruit constitutes approximately half of the weight of the fruit and is known to contain various beneficial bioactive compounds.

While the non-edible parts, such as the peel, have been used for tea, infusions, and as a spice, they constitute a significant portion of the waste generated by the food industry that processes pomegranates. The pomegranate seeds are also a rich source of fatty acids and sterols.

About the study

In the present study, the researchers evaluated the efficacy of a hydrodynamic cavitation-based extract obtained from the entire pomegranate fruit (PFE), as well as that obtained from the non-edible parts (PPE) that are generated as a waste byproduct during the juicing process in reducing cardiovascular risk.

The non-edible parts used in the hydrodynamic cavitation extraction included seeds and peel.

Hydrodynamic cavitation is believed to be a green, sustainable, and scalable model for extracting bioactive compounds and uses water as the solvent.

Real-scale applications have verified the method to be energy and time-efficient and effective in extracting high yields of bioactive compounds.

Furthermore, whole pomegranate hydrodynamic cavitation-based extracts have exhibited apoptotic and antiproliferative activity in in vitro experiments involving breast cancer cells.

Freeze-dried samples of PPE and PFE were chemically analyzed using high-performance liquid chromatography with diode-array detection to identify and quantify the phenolic compounds.

Additionally, the researchers investigated the chronic and acute anti-hypertensive effects and pharmacokinetic profile of both extracts using in vivo experiments involving phenylephrine (PE)-induced rat model of hypertension.

Rats with induced hypertension were orally administered either PPE, PFE, or ellagic acid while their vital functions were continuously monitored.

The pharmacokinetic profile included an assessment of the bioavailability and bioaccessibility through time-course measurements of plasma levels of urolithin A, punicalagin α, or ellagic acid.

Furthermore, the anti-hypersensitive effects of the extracts were determined through measurements of systolic blood pressure during the study, as well as a complete lipid analysis including total cholesterol, triglycerides, high-density lipoprotein, and low-density lipoprotein of the rats after the study period.

Ventricular and cardiac hypertrophy were assessed using explanted heart samples from euthanized animals, and histological analyses of the thoracic aorta were also conducted to assess endothelial integrity.

Additionally, enzyme-linked immunosorbent assay (ELISA) was used to assess transforming growth factor beta one and interleukin-6 levels.

Results

The results indicated that the hydrodynamic cavitation-based extract PPE obtained from the non-edible waste byproducts of pomegranate juicing showed similar efficacy as the extract obtained from the whole fruit using the same extraction method in reducing cardiovascular risk in rats with induced hypertension.

Furthermore, the bioaccessibility of the extract through the gastrointestinal route was also found to be high.

The extract from the non-edible parts of the pomegranate also exhibited anti-fibrotic and anti-inflammatory effects. Additionally, similar to Captopril, the reference hypertension drug, PPE showed a significant ability to inhibit systolic blood pressure increase at doses lower than that reported for ellagic acid.

The pharmacokinetic profile indicated significant levels of ellagic acid in the blood, but urolithin A and punicalagin α were not detected.

The researchers believe that the absence of urolithin A and punicalagin α in the blood might be due to the longer metabolism time needed from the former and the pre-systemic rapid metabolization of the latter.

Conclusions

Overall, the findings suggested that hydrodynamic cavitation-based extracts from pomegranate peels and seeds that are formed as the byproduct of the pomegranate juicing process have substantial levels of bioactive compounds that contain anti-hypertensive properties.

These extracts have high bioaccessibility in the intestine and exhibit comparable systolic blood pressure-lowering abilities as reference drugs.

These results highlight the potential nutraceutical and medicinal use of the non-edible parts of the pomegranate.