Study reveals natural anti-hypertensive property of yam


Yam (Dioscorea alata Linn) locally known as “ube” is abundantly found in tropical and subtropical countries. It is considered an important crop because of its excellent storage properties. It can be stored up to six months without refrigeration.

Yam is mainly grown for human consumption. It is processed into several food products such as yam flour and starch, confectioneries, cakes and pastries. The purple varieties are popularly used in the preparation of ice cream and other desserts.

Purple yam

However, aside from food uses, yam is also considered as source of natural ingredients for medicinal purposes.

A study funded by the Philippine Council for Health Research and Development of Department of Science and Technology (PCHRD-DOST) entitled Production and Evaluation of PRP-1 (Philippine Rootcrops Protein 1) – a Novel Anti-hypertensive Protein Isolated from Yam stated that locally produced yam can be a good source of alternative drug for the treatment of hypertension.

Hypertension or high blood pressure is a condition in which the blood pressure in the arteries is chronically elevated. The condition might lead to organ damage and several illnesses such as heart attack, stroke, heart failure, aneurysm or renal failure.

According to the World Health Organization (WHO), hypertension is one of the most prevalent causes of premature deaths to nearly 8 million people every year worldwide. WHO also estimates that there are about 1 billion people suffering from hypertension, two-thirds of these are from developing countries.

Commercial anti-hypertensive drugs are expensive – that is why the WHO recommends and encourages the use of plants as an alternative treatment for the disease.

According to Dr. Edgardo E. Tulin, chemistry professor of the Visayas State University (VSU) in Baybay City, Leyte and project leader of the study, yam is rich in different properties that can be used in many medicinal applications.

Given these natural properties in yam, the study evaluated PRP-1, the protein extracted from locally produced yam suspected to have anti-hypertensive content due to its angiotensin-converting enzyme (ACE) inhibitory function.

According to Dr. Tulin, the ACE inhibitors in yam prevent conversion of angiotensin I to angiotensin II, a compound that causes blood pressure increase in the body. ACE inhibitors are proteins that are usually found in commercial drugs primarily used for the treatment of hypertension.

The study also reported that yam can lower the rate of sugar absorption in the bloodstream and help regulate the body’s metabolism. It is also a good source of Vitamin B6 needed by the body to breakdown homocysteine. High levels of homocysteine in the blood are believed to increase the chances of having heart disease. Intake of vitamin B6 will reduce the risks of heart attack.

The study also evaluated the toxicity of PRP-1 in mice and showed no effects in both acute and chronic studies conducted. “Purified PRP-1 was not allergenic to mice. There were no signs of toxicity and no significant changes in the blood and in the internal organs of the test animals we observed,” said Dr. Tulin.

The study was able to extract 333 milligrams of PRP-1 in every 100 grams of yam tubers. “PRP-1 is a natural protein that can be used safely as a potential anti-hypertensive drug which is non toxic, inexpensive and has no side effects. The discovery of this naturally occurring protein in yam could bring the country an alternative medicine for the treatment of hypertension,” concluded Dr. Tulin.(Edmon Agron/PCHRD-DOST)


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