Imagine a world where the secrets of an ancient plant are unearthed, revealing a treasure trove of medicinal potential hidden within its leaves and flowers. Cannabis, a versatile and remarkable plant, has been utilized by humans for thousands of years, not only for recreational enjoyment but also for its health benefits. Recent research has taken a significant leap into the past, investigating the evolutionary roots of some of cannabis's most renowned bioactive compounds, including tetrahydrocannabinol (THC), cannabidiol (CBD), and cannabichromene (CBC).
In a groundbreaking study conducted by researchers at Wageningen University & Research in the Netherlands, an innovative method known as ancestral sequence reconstruction (ASR) was employed to shed light on long-lost enzymes responsible for producing these beneficial compounds in cannabis's ancestors. By ‘reviving’ these ancient enzymes, scientists could examine their functionalities and characteristics, thus bridging the gap between the past and present of this fascinating plant.
While delving into the evolutionary history of cannabis enriches our understanding of its development, the practical implications of this research cannot be overlooked. According to biosystematics scientist Robin van Velzen, these ancient enzymes demonstrate greater robustness and flexibility compared to their modern counterparts, making them promising candidates for future applications in biotechnology and pharmaceutical research.
Since prehistoric times, humans have cultivated cannabis for multiple purposes, ranging from food and textiles to medicine and pleasure. Today, it is recognized that cannabis can generate hundreds of cannabinoids, terpenes, flavonoids, and other phytochemicals, many of which possess unique therapeutic and psychoactive properties.
The focus of this recent study was on cannabinoid oxidocyclases, a specific type of enzyme crucial for transforming cannabigerolic acid (CBGA) into various cannabinoids, each with its own biological effects. These enzymes significantly affect the therapeutic efficacy of cannabis. Despite their critical role, cannabinoid oxidocyclases remain poorly understood. The researchers aimed to unravel their history by reconstructing their extinct ancestors.
In contemporary cannabis plants, the synthesis of THC, CBD, and CBC relies on distinct enzymes, each dedicated to producing one specific cannabinoid. However, the authors of the study propose that this specialization may not have existed millions of years ago. They suggest that through the resurrection and characterization of three ancestral cannabinoid oxidocyclases, they could experimentally validate the theory that the ability to metabolize CBGA arose in a recent ancestor of cannabis.
Utilizing ASR, which is informed by DNA sequences from modern plants, the team successfully reconstructed an ancestral gene from a series of related sequences, effectively breathing life into these ancient proteins. The findings indicate that the common ancestor of modern cannabinoid oxidocyclases was capable of synthesizing multiple cannabinoids simultaneously, a stark contrast to the specialized enzymes seen in current cannabis species, which evolved following gene duplications.
This discovery implies that the capacity to metabolize CBGA indeed originated in a recent ancestor of cannabis, suggesting that early cannabinoid oxidocyclases were versatile enzymes, generating precursors for various cannabinoids rather than focusing solely on one, as their modern relatives do. Additionally, the results confirm that the emergence of cannabinoid oxidocyclase activity occurred independently within the cannabis family as well as in other distantly related plants known for cannabinoid production, such as rhododendrons.
Interestingly, the study found that the reconstructed ancestral enzymes were easier to produce in microbial systems, such as yeast cells, compared to modern versions. This finding holds significance in light of the growing emphasis on utilizing biotechnological methods over traditional botanical approaches for cannabinoid production.
Robin van Velzen noted, "What once seemed evolutionarily 'unfinished' turns out to be highly useful." For instance, CBC is a cannabinoid known for its anti-inflammatory and pain-relieving properties, yet it's produced in minimal amounts by modern cannabis plants. An ancient enzyme identified in this study represents an ‘evolutionary intermediate’ that excels in the production of CBC.
Van Velzen pointed out that currently, no cannabis strain naturally possesses a high concentration of CBC. Therefore, introducing this enzyme into a cannabis plant could pave the way for the creation of innovative medicinal varieties.
This compelling research was published in the Plant Biotechnology Journal, marking a significant advancement in our comprehension of cannabis's evolution and its potential future applications in medicine.
