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For thousands of years Ayurvedic medicine has utilized the galls of the pistachio tree to treat asthma, skin conditions and heart conditions. Now science is showing us the proof.
In Hawaii and parts of Asia, there is a local term for the activity of snacking on partially cracked shells and seeds of pistachio nuts along with a few other notable seeds such as apricot: "Crack seed."
One might appreciate the term "crack" with the fact that these nuts – together with the surrounding partially opened shell – are typically roasted and nicely flavored with salts and spices. They can be, well, sort of addictive, and the sweet-salty flavor of the shell often rivals the rich taste of the nut meat inside.
My point? Well, for starters, new research is finding that the galls and shells of the humble pistachio seed contain a special biochemical that has become of interest to pharmaceutical researchers.
It gets more interesting when we find that pistachio galls have been used for thousands of years in Ayurvedic medicine.
But why is pistachio research so important to pharmaceutical companies? Because a particular substance in pistachios blocks enzymes called phosphodiesterases. Phosphodiesterases are enzymes that will break apart phosphodiesters.
What's the big deal about phosphodiesters?
It just so happens that practically every protein is assembled using a phosphodiester backbone. This means that an enzyme that breaks apart phosphodiesters can really interrupt our metabolism.
Now not all phosphodiesterases are necessarily bad. In fact, our bodies produce and utilize these enzymes to help control and regulate processes. They are also used to help signal the ending and beginning of certain metabolic processes.
But phosphodiesterases are also involved in a number of disease symptoms and metabolic problems. This is why pharmaceutical companies are so interested in what are called selective phosphodiesterase-inhibitors.
Selective phosphodiesterase inhibitors
There are a number of nonselective phosphodiesterase inhibitors in nature, including caffeine and theobromine (green tea) among others. But selective phosphodiesterase inhibitors are considered more therapeutic because they halt some processes without interrupting others.
A clear example of a phosphodiesterase inhibitor drug is Sildenafil – branded as Viagra. By blocking the phosphodiesterase-5 enzyme, the drug opens certain blood vessels– particularly those involved in penile erection. But also many others.
Another phosphodiesterase is type 4 and this is related to diseases related to respiratory conditions – meaning the lungs and sinuses. Asthma, bronchitis and other airway conditions are typically rampant with phosphodiesterase-4.
This means that inhibitors that are selective to phosphodiesterase-4 have been found to open the airways and sinuses. This of course means a greater ability to breathe.
That's not all. Many skin conditions, such as psoriasis, also involve high phosphodiesterase-4 levels.
As such, drugs have been developed to inhibit this enzyme. These are modeled upon plant-produced inhibitors such as Luteolin produced by peanuts. And Mesembrine, isolated from the South African herb, Sceletium tortuosum – also called Kanna.
Drug examples of phosphodiesterase-4 inhibiting drugs include Roflumilast used to treat asthma, and Ibudilast - a bronchodilator also used for strokes. And let's not forget Apremilast, used for psoriasis.
Another important type of selective phosphodiesterase inhibitor blocks phosphodiesterase-1. Like phosphodiesterase-5, phosphodiesterase-1 is also involved in the contraction and relaxation of the smooth muscles, as they conduct calcium ions and an energy metabolite called cAMP.
This means blocking high phosphodiesterase-1 can also treat airway conditions and conditions related to high blood pressure.
One of the better known phosphodiesterase-1 inhibitors is Vinpocetine – a constituent of the periwinkle plant (Vinca minor). This has been shown to be useful for airway conditions, cardiovascular conditions and dementia.
Pistachio galls contain phosphodiesterase inhibitors
So hopefully you see why finding this type of therapeutic agent in the galls of the pistachio is a big deal.
Researchers from Italy's University of Salerno obtained some galls from the pistachio tree – Pistacia integerrima. They proceeded to grind them into a powder.
They proceeded to extract and analyze the extracts for their biochemical constituents. They found numerous medicinal compounds including sterols, triterpenoids and phenols – including naringenin found in citrus and others.
One of the main therapeutic agents found was pistagremic acid. This has been found in other research to reduce pain and inflammation.
Anyway, the researchers produced ten different extract fractions from the powder and analyzed them against phosphodiesterase-1. The powder extracts significantly inhibited phosphodiesterase-1.
They also demonstrated from other research on phosphodiesterase and phosphodiesterase inhibitors – given the traditional history in asthmatic treatment – that Pistacia integerrima also likely inhibits phosphodiesterase-5.
Other research has found pistachio essential oil also inhibits the 5-lipoxygenase enzyme – involved in pain and inflammation.
Ayurvedic medicine confirmed by science - once again
While this sounds like a lot of chemical gobbledygook, the research confirms a pistachio gall Ayurvedic remedy used for thousands of years.
Numerous varieties of the pistachio tree grow in Asia and notably in the Himalayan region. The tree likes higher elevations.
For thousands of years, Ayurvedic healers crushed the pistachio galls and boiled them up. They produced a concoction called Karkatshringi. Karkatshringi has been used for centuries to treat asthma, circulatory conditions and skin conditions.
The bonus is that medicinal plants such as pistachio also contain numerous other agents, which serve to balance and buffer the metabolic effects of their medicinal constituents.
Today much of the pistachio nuts are produced from rootstock of the Pistacia integerrima species, along with P. atlantica and P. terebinthus.
So do these benefits translate to the nuts?
The galls develop as an immune response by the pistachio tree. But the leaves, shells and nuts also contain many phenols and phytochemicals. While it appears these parts of the tree have not yet been tested for phosphodiesterase inhibition, it does appear they may contain at least some of the compounds that inhibit phosphodiesterase.
In a recent study published in the journal Nutrition, 60 adults with cholesterol problems ate 1.5 ounces of shelled pistachio nuts per day for three months. Testing before and after the period revealed the pistachio nut consumption significantly improved their lipids and blood sugar (glycemic) status. But they also showned significantly improved arterial function and decreased vascular stiffness - meaning they had healthier arteries.
Because vascular stiffness is directly related to smooth muscle function and thereby phosphodiesterase-1 and 5, it would be logical to assume that the nuts promote at least some of the same effects as the galls - but perhaps more gradually.
So – go ahead and "crack seed."
Abdur Rauf, Muhammad Saleem, Ghias Uddin, et al., "Phosphodiesterase-1 Inhibitory Activity of Two Flavonoids Isolated from Pistacia integerrima J. L. Stewart Galls," Evidence-Based Complementary and Alternative Medicine, vol. 2015, Article ID 506564, 6 pages, 2015. doi:10.1155/2015/506564
Rauf A, Uddin G, Siddiqui BS, Khan A, Khan H, Arfan M, Muhammad N, Wadood A. In-vivo antinociceptive, anti-inflammatory and antipyretic activity of pistagremic acid isolated from Pistacia integerrima. Phytomedicine. 2014 Oct 15;21(12):1509-15. doi: 10.1016/j.phymed.2014.07.015.
Shirole RL, Shirole NL, Kshatriya AA, Kulkarni R, Saraf MN. Investigation into the mechanism of action of essential oil of Pistacia integerrima for its antiasthmatic activity. J Ethnopharmacol. 2014 May 14;153(3):541-51. doi: 10.1016/j.jep.2014.02.009.
Kasliwal RR, Bansal M, Mehrotra R, Yeptho KP, Trehan N. Effect of pistachio nut consumption on endothelial function and arterial stiffness. Nutrition. 2015 May;31(5):678-85. doi: 10.1016/j.nut.2014.10.019.