Written by: Jim Hole, Atlas Growers VP of Cultivation
A cannabis plant is like a chemical factory. Each day, it generates thousands of phytochemicals (plant manufactured chemicals) within its cell walls.
The sum total of all of these chemical reactions, and the resulting products, is referred to as the plant’s ‘metabolism’. The majority of these phytochemicals are called ‘primary metabolites’ with the big three metabolites comprised primarily of carbohydrates, proteins and fats that are required in large quantities for both plant growth and reproduction. But cannabis, like all plants, also produce secondary metabolites. And while these compounds have no known role in growth nor development - and are created in much smaller concentrations than the primary metabolites - they are still fundamentally important for keeping plants healthy.
One of the most important roles that some of these secondary metabolites play is to defend plants from attack by both small and large herbivores, ranging from microscopic fungi to large grazing animals. As anyone older than three years of age knows, plants can’t run. As a result, they have no choice but to ‘stand’ and fight by waging a chemical battle with organisms via some of these specialized secondary metabolites. Granted, some plants, have a great deal of success fighting some of their larger enemies with formidable defensive structures like thick, sharp thorns or tough bark but it’s the secondary metabolites that can tip the scale in the plant’s favor when they are under attack from microbe and insect pests. One such category of these enemy fighting chemicals that are commonly found in cannabis – and many other plant species – is a large group of secondary metabolites called ‘terpenoids’.
The name terpenoid is derived from the first compounds isolated from ‘turpentine’- the resins found in conifers like spruce and pine. At last count, there were nearly 15,000 identified terpenoids making them the largest and most diverse group of organic compounds found in plants. Terpenoids range from latex (found in natural rubber) to beta carotene found in plants like carrots. The name terpenoid encompasses two categories of plant chemicals: terpenes and terpene-related compounds with terpenoid being a convenient catch-all term.
Cannabis like many other terpenoid producing plants, metabolizes terpenoids in specialized structures called glandular trichomes (hairs). Cannabis terpenoids occur in greatest concentration on trichome tips in ball-like or ‘capitate’ structures. Terpenoids are, typically, highly aromatic and the fragrances emitted by cannabis plants are due a combination of various terpenoids. Many people believe that it’s the psychoactive and medicinal compounds like THC and CBD that give cannabis its characteristic odour yet these two compounds are, by and large, odourless.
Terpenoids can be divided into a number of sub-categories depending both on the number of carbon atoms they contain and the arrangement of the carbon atoms in each terpenoid’s molecular structure. For example, 15 carbon types are called sesquiterpenes whereas those with 40 carbon atoms are referred to as tetraterpenes. Carotenoids are an example of 40 carbon tetraterpenes and are responsible for giving tomatoes - and many autumn leaves - their beautiful red hue!
Other common terpenoids are alpha-pinene found in pine resin, sage and eucalyptus; caryophyllene that is common in both black pepper and hops; and myrcene that is a constituent of thyme, parsley, mango.
Watch out for Part 2 of our terpenoids blog next week.