What is hashishene? Examining the unique chemistry of hashish

For hundreds if not thousands of years, human beings have been separating glandular trichomes from cannabis plants, pressing them into shapes, and allowing them to cure like fine wines as a product known as hashish, or hash. But what do we know about the chemical transformation that takes place when trichomes are separated from the plant and turned into hashish?

Is hash, or hashish, really all that different from the cannabis flower? Ask any true cannabis connoisseur and they will tell you that hash absolutely has a unique quality compared to cannabis flower. But how? Why?Recently, researchers made a discovery that begins to answer these pressing questions about why hash is so different from cannabis flower, and it may have a lot to do with terpenes. It turns out that when hash is made and allowed to cure, a chemical transformation takes place that changes the common cannabis terpene myrcene into a unique monoterpene not actually found in the resins when they are on the living plant. This terpene has been rightfully dubbed – hashishene.

So, what is hashishene?

Hashishene is a common name for the molecule 5,5-dimethyl-1-vinylbicyclo[2.1.1]hexane. As far as scientists know so far, it is only found in aged hash from the chemical transformation of myrcene, a common cannabis terpene. It was named by the team of scientists who discovered it in 2014. 1

These kinds of chemical transformations are not new or surprising. It is well known that myrcene can transform into other terpenoids like geraniol and linalool. But those terpenoids are generally found even in low concentrations on the cannabis plant itself. So far, hashishene has only been found in aged hash. 2

Why does hash degrade?

Myrcene and other terpenes transform because of several main factors – air, light, heat, and pressure – all over time. What is interesting about hashishene is that it is not an alcohol terpenoid but is rather a true terpene consisting of only carbon and hydrogen atoms. 3

This tells us that hashishene is not an oxidative product of myrcene, and air is likely not driving this conversion. Rather it is more likely that light, heat and pressure, over long periods of time, are driving the chemical transformation from myrcene to hashishene. The researchers that discovered hashishene refer to it as a photolytic product, meaning that photons of light work to slowly transform the molecule without oxidizing it. However it is formed, there is such little research on hashinene, it is not clear how long it takes to be produced, and in what quantities.

What are the effects of hashishene?

Studying the effects of terpenoids is a precarious endeavor. In theory, it would be relatively easy to isolate hashishene, give it to rodents, and see what happens. But it’s much more challenging to study how trace concentrations of that terpene contribute to the synergistic effects of a very complex mixture of terpenoids and cannabinoids when given to a human. That being said, researchers have only just recently identified and isolated this compound; there are no known publications that demonstrate how hashishene might affect cells, tissues or rodents – much less, people.

What does hashishene mean for consumers?

For now, until we learn more about how hashishene affects the body, the presence of hashishene in a product means very little for consumers beyond the fact that this compound is one of the unique constituents of hashish. If a consumer is hoping to get effects similar to those of hashish, it might be important that hashishene be included in the formulation – but we honestly do not know how important hashishene may or may not be to overall subjective cannabis experiences. 

In addition to the fact that we do not know how this terpene affects the body, there are currently no commercial cannabis testing laboratories that can even measure it in samples. Chemical reference standards for hashishene only became available in recent years, and until customers demand to know how much hashishene is in their hash, cannabis testing labs are not necessarily motivated to add the chemical to their terpene test methods (which is not as simple a feat as it seems!).

What does hashishene mean for extract producers?

For producers seeking to produce hash with high levels of hashishene, it would be advantageous to find starting material that is relatively abundant in myrcene over other terpenes. This will hypothetically provide a good starting substrate to build hashishene as the hash ages. 

The hash should be protected from exposure to air. This was traditionally accomplished by tightly pressing hash into balls or bricks and then wrapping them with plastic wrap or other wrappings. Some cultures would even bury the wrapped hash for added protection and pressure. If you can manufacture hash that can be compressed, air-sealed and allowed to rest in a gentle warm environment, hashishene should form.

What about the other terpenes in hash?

The same research group that identified hashishene in aged hash also made other observations about terpenes, including a number of rare caryophyllene and humulene derivatives that were present in the samples. Several of these derivatives are not commonly found in nature. Because beta-caryophyllene and humulene (which is actually alpha-caryophyllene) are the most abundant sesquiterpenoids in cannabis, it would definitely make sense to look at the transformations of these terpenoids to find more unique markers of pressed hash. 4

Beyond this individual study, others have attempted to try to understand why pressed hash is markedly different from cannabis resin on cured flower. The late hash guru Frenchy Cannoli organized a collaborative effort called the Trichome Research Initiative that involved examining the chemical transformation of pressed hash over the course of six months. The findings were made publicly available and tell us a little bit about what might make hash so unique when compared to cured cannabis flower.

Cannabinoid Results from Frenchy Cannoli Trichome Research Initiative Project

First, the cannabinoid concentrations changed as one would expect. THCA values started out high and went down as delta-9-THC values increased via decarboxylation. Likewise, there is an increase in THCV that was noted in the cannabinoid data from this study. This is almost assuredly the result of decarboxylation of THCVA, which was not measured in the study. Likewise, CBC levels also increased, likely due to ongoing decarboxylation of CBCA, which was also not measured.

When zooming out and looking at Total THC or Total CBD, those values remain largely unchanged in the hash. We can see a little evidence of further THC transformation in the form of CBN – THC’s most stable degradation byproduct. As time pressed on, CBN levels in pressed hash begin to rise, and by 6 months had gone from undetectable levels to about 0.1% CBN. 

Based on Frenchy’s study, It would appear the changes in cannabinoids over time are marginal and that it is more than the cannabinoid transformations alone that make hash special. So, what about the terpenes?

Unfortunately, this study did not monitor the presence or concentrations of hashishene in samples. However, several commonly occurring terpenoids, including myrcene, were monitored. As would be expected, many of the concentrations of terpenes measured decreased over time, signifying that they were either volatilizing away from the sample, or they were transforming into other compounds not being measured.

Terpene Results from Frenchy Cannoli Trichome Research Initiative Project

Monoterpenes like myrcene, pinene, or limonene that are true terpenes, consisting of only carbon and hydrogen, show more signs of loss or degradation than alcohol terpenoids. Because none of the terpenoids measured increased significantly in concentration over time, if these terpenoids are transforming rather than volatilizing (evaporating away), they are transforming into compounds that most cannabis testing labs are not measuring.

The bottom line on hashishene

The Trichome Research Initiative study and the Marchini et al study are just glimpses into a broader investigation that needs to be done to really understand why hash hits different than cannabis flower – or even other of extracts like hash oils, sauces, and distillates. If nothing else, Frenchy’s study helps us understand that there is a lot going on with the chemistry of cannabis that is taking place outside of the spotlight that current commercial testing laboratories can shine.

Terpenoids appear to be slowly changing as hash ages (Image by Jason Wilson, MS)

The limited research on hashishene tells us that there are definitely interesting chemical transformations happening to both monoterpenes and sesquiterpenes in hashish, and that hashishene is probably just one of several, if not many, unique terpenoids that form in aged hashish that are not otherwise commonly found in nature. 

Thanks to some of this groundbreaking work, we have a glimpse into the frontier of hash science. Perhaps one day traditional hashish will command a new value among enthusiasts and connoisseurs as it gets easier and easier to point to the science that sets hash apart from other types of cannabis concentrates.

The post What is hashishene? Examining the unique chemistry of hashish appeared first on The Cannigma.

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