Chemistry Featured

The Origin of Cannabis’ Skunk-Like Aroma Uncovered

– Find out why the discovery of a new family of volatile sulfur compounds unlocks a whole new avenue of cannabis research.

For years, the cannabis science community has been befuddled by what compounds give cannabis its trademark “skunky gasoline” aroma. I’m guessing that you know what I’m speaking of — that powerful scent that’s nearly impossible to miss as it wafts through the air or can easily be detected in potent edibles.

As a chemist and the co-founder of ABSTRAX, I have forever been obsessed with getting to the bottom of what’s behind it and have assumed that it is intrinsically linked to the plant’s power/benefits to humanity.

In an effort to find answers, I collaborated with Iain Oswald, PhD (our Principal Scientist), Dr. T.J. Martin (our Director of Research and Development), Mario Guzman (cultivator of Bacio Gelato), and Josh Del La Rosso (cultivator of OC Kush). [1] The result of our efforts far superseded what we thought possible, as we uncovered an entirely new family of compounds responsible for this scent.

In fact, it was discovered that key volatile sulfur compounds (VSCs) – organic compounds containing sulfur – directly correlate to the pungent aroma of cannabis.

 

The Power of Two-Dimensional Gas Chromatography

The collaborative effort began by using two-dimensional gas chromatography (2DGC) coupled with mass spectrometry, flame ionization detection, and sulfur chemiluminescence.

The combination of multiple detectors, in tandem with 2DGC to analyze cannabis, gave us the tools needed to parse through data and identify trends between certain compounds and the aromas of various cannabis cultivars. Our data conclusively establishes a link between this new family of VSCs in cannabis and its pungent aroma.

Gas chromatography is typically used when analyzing the volatile species of various samples – whether flowers, food, or even beverages. However, cannabis presents a uniquely complex case due to the wide variety and number of aroma compounds present. 2DGC alleviates this issue by allowing for a greater separation of eluents.

This minimizes co-elution and allows for easier identification of the chemical species. Furthermore, the use of sulfur chemiluminescence – a method of detecting only compounds with sulfur atoms within their structure – provides an easy way to identify these compounds in the data. This is especially helpful in situations where compounds are in exceedingly low concentrations, including those discovered in this study.

Much like Cannflavins are prenylated flavonoids found specifically in cannabis, some of these newly discovered ‘cannasulfur compounds’ also appear to be highly specific prenylated VSCs to cannabis. It is interesting to see a common chemical theme within entirely different classes of compounds produced by this plant.

 

What This Discovery Means for the Present and Future

The study results provide a starting point for further studies to be conducted that will be multidisciplinary in nature.

For instance, the realization that certain cultivars may produce these compounds, while others do not, provides an opportunity to determine if this is due to genetic differences or otherwise.

For example, Bacio Gelato has the highest concentration of VSCs that we’ve measured in cannabis. This differs from Black Jack, which has no measurable VSCs. For Guzman, this finding was fascinating as it confirmed everything he had instinctively thought about some of the cultivars he has bred over time.

“They are some of the most pungent and medicinal on the market, and these compounds are the reason Gelato and subsequent crosses are some of the most potent and highly sought after out there,” shared Guzman.

Likewise, Josh Del Rosso, the originator of OG Kush, was equally excited about the new discoveries. “I have suspected for years now that we were missing something in our understanding of this plant,” said Del Rosso. “Although terpenes have been hailed as the major source of the pungent scent of cannabis, we now know that it is this new class of VSCs.”

Del Rosso also noted that perhaps the most exciting result from the study was the correlation between the chemical structure of VSCs found in garlic and cannabis.

The prenyl functional group that is found in each VSC measured is chemically similar to the allyl group found in garlic with a few modifications. These VSCs in garlic offer some of its strongest health benefits and suggest that the VSCs in cannabis may likewise possess similar activity.

Collectively, our hopes are that the results of the study can be a springboard to help other researchers determine if these compounds endow cannabis with even more medicinal properties than ever imagined.

 

VSCs Can Transfer from State to State

Beyond the discovery of VSCs, it was discovered that the compounds can translate from the flower state to extracts such as butane hash oil (BHO), a popular cannabis concentrate found in vapes.

Their high volatility makes them prone to evaporation, so we weren’t sure how they would translate into cannabis extracts. However, we confirmed that cannabis extracts can indeed contain these compounds in reasonable concentrations if processed correctly.

We were pleasantly surprised to see high levels in the sample we measured, especially if these compounds possess beneficial medicinal properties.

 

The Race Against Time

Lastly, the study measured VSCs as a function of plant growth.

We found that the concentrations of these compounds increase substantially at the end of the plant’s growth and reach a maximum immediately after the curing process. Surprisingly, the concentrations of most VSCs dropped substantially after even just a week of storage.

These results reveal that cannabis producers are racing against time when it comes to getting quality products into customers’ hands.

Hopefully, our results will establish a new standard for cultivators and distributors to help preserve and protect these key compounds — regardless of the rigors of processing, packaging, and time on the shelf.

Most importantly, it will help brands maximize their products and literally push cannabis quality to the next level.

 

Reference

[1] Oswald IWH, Ojeda MA, Pobanz RJ, et al. Identification of a New Family of Prenylated Volatile Sulfur Compounds in Cannabis Revealed by Comprehensive Two-Dimensional Gas Chromatography. ACS Omega. 2021;6(47):31667-31676. [journal impact factor = 3.512; times cited = 1]

About the author

Kevin Koby and Iain W.H. Oswald PhD, ABSTRAX

Kevin Koby and Iain W.H. Oswald PhD, ABSTRAX

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