A new study offers one of the most comprehensive studies ever conducted on the chemical origin of the unique “skunk-like” smell of cannabis. The study shows that an entirely new family of sulfur compounds is responsible for the novel odor and that these molecules are chemically similar to the aroma compounds in garlic.
While much current cannabis research is focused on understanding the effects of cannabinoids like tetrahydrocannabinol (THC) or cannabidiol (CBD), there are many other molecules in this deeply complex plant. This new research was specifically focused on understanding the chemical source of the unique pungent aroma of cannabis.
Hundreds of different flavorings can be found in cannabis. Many of them belong to a class of compounds known as terpenes, which are responsible for many distinctive plant smells like pine or lavender, and experimental cannabis growers often play with different concentrations of terpenes to create hybrid strains with unique scents. It was previously hypothesized that terpenes were responsible for the iconic “smell” of cannabis, but the difficulty of analyzing all of the potential aromatic compounds in this plant has limited robust studies.
“To solve this problem,” the researchers explain in their newly published study, “we used a specially designed, comprehensive 2-dimensional gas chromatography (2DGC) system with three detectors working at the same time: A time-of-flight mass spectrometer (TOF-MS) , Flame ionization detector (FID) and sulfur chemiluminescence detector (SCD). “
The new research particularly focused on molecules known as volatile sulfur compounds (VSCs). These sulfur-containing organic compounds are strongly associated with other pungent plant odors like hops and garlic. The iconic spray from skunks is also known to contain a number of potent VSCs. Given that the pungent aroma of cannabis is informally referred to as a “skunk,” it seemed reasonable to find out which VSCs in the plant could be associated with this highly specific odor.
“Combining multiple detectors together with 2DGC to analyze cannabis gave us the tools we needed to analyze data and identify trends between certain compounds and the flavors of different cannabis strains,” explains lead author of the new study, Iain Oswald. “Our data conclusively establish a connection between this new family of VSCs in cannabis and their pungent aroma.”
The new study describes several VSCs that have never been identified in nature before. Analysis of some particularly harsh cannabis strains revealed direct links between higher concentrations of VSCs and “skunk-like” scents.
“I have suspected for years that we are missing something in our understanding of this plant,” says another co-author of the study, Josh Del Rosso. “Although terpenes have been hailed as the main source of the pungent cannabis odor, we now know that this is this new class of VSCs.”
A look at the molecular similarities between these newly discovered cannabis compounds and those in garlic
An interesting finding from the study was the chemical similarity of these newly discovered cannabis VSCs compared to some VSCs found in garlic. Previous research has linked some garlic health benefits to these specific VSCs, so the compelling hypothesis is that these newly discovered cannabis VSCs may have potential medicinal benefits.
“I hope our results can serve as a stepping stone to help other researchers find out whether these compounds add even more medicinal properties to cannabis than we ever imagined,” notes Del Rosso.
Research has shown that while these VSCs are very volatile, if properly processed, they can remain highly present in some extracts. And analysis of some cannabis extracts found that VSCs are still present in these formulations in a wide variety of concentrations.
Another aspect of the study measured VSC levels during the plant’s growth cycle and after harvest. The highest concentrations of VSCs were detected at the end of the plant’s growth cycle, with a peak at the end of an 11-day post-harvest healing process.
Importantly, the concentrations of VSCs decreased rapidly when the hardened plant was stored. Ten days after curing, the levels of these VSCs had decreased significantly. Kevin Koby, another researcher on the project, says these results provide producers with valuable insight if they are looking to maximize VSC levels in future cannabis products.
“These results prove that cannabis producers are racing against time to get quality products into the hands of their customers,” says Koby. “Hopefully our results will create a new standard for growers and traders to preserve and protect these key connections – regardless of processing, packaging and storage time requirements.”
The study offers cumulatively strong evidence of the chemical origins behind the uniquely pungent odor of cannabis. It also points to compelling new research avenues into the potential medical benefits of these newly discovered compounds.
The new research was published in the journal ACS Omega.