Though widely regarded as unique to cannabis, there are a few other plants capable of producing their own phytocannabinoids that likewise interact with our endocannabinoid system. Many of these chemicals are technically lipophilic alkamides, but their interactions with cannabinoid receptors make them qualify as phytocannabinoids themselves.
Most surprisingly, a species of hops known as humulus yunnanensis var kriya, or humulus kriya for short, was found to have naturally occurring levels of THC and CBD in 1982. Genetically distinct from the better-known humulus lupulus, or the “beer hops” plant, it’s native to the Yunnan Province area of southwest China and northeast India, though populations stretch well into southern India as well.
After the discovery of cannabinoids in the herb, it was largely forgotten until 2018 when Dr. Bomi Joseph, a Food Safety advisor for the FDA and World Health Organization (WHO) dug up information on the herb at the India National Library on Botanical Medicines. Dr. Joseph’s work would conclude that the close growing habits of wild hops and cannabis varieties led to exchanges in these cannabinoids due to the plants’ genera being so closely related. Though originally having over 17,000 samples containing a variety of THC and CBD ratios, Dr. Joseph only kept and bred 6 plants with no THC and measurable amounts of CBD in them, eventually able to get the CBD levels up to 18% through selective breeding and later partnering with plant-based pharmaceutical companies in the US to offer non-cannabis CBD products.
Tuber melanosporum, or the black truffle, is a species of truffle native to southern Europe, and is among the most expensive mushrooms in the world. As the truffle ages, it produces large quantities of anandamide (AEA), an endocannabinoid that we naturally produce within our bodies, as well as the metabolic enzymes capable of breaking it down. Similarly to chocolate, the heightened levels of AEA may be directly responsible for the obsession many have for black truffles.
At least 3 species within the radula genus of liverwort have been known to produce cannabinoids as well. Radula marginata is native to New Zealand and is known as wairuakohu by the local Maori people, radula perrottetii is native to Japan, and radula laxiramea is native to Costa Rica. All have been found to produce a chemical called perrottetinenic acid (PETa), which when heated decarboxylates to perrottetinene (PET), in a similar manner to THCa decarboxylating to THC. Shockingly, despite a 300 million year evolutionary difference, at least one of the cannabinoids produced by these radula species appears to be extremely chemically similar to THC found in cannabis, and even mimics many of the same effects.
PET was first discovered in 1994, but its chemical structure wasn’t clarified until 2008 by an enantioselective total synthesis. Even then, similarities to THC weren’t discovered until 2018 by a group of researchers at the University of Bern in Switzerland. PET was found to actively bind to CB1 receptors and though its physiological effects are very similar to THC, its potency is much lower. The exact reason for the plant producing these chemicals is currently unknown.
Kava is a crop native to the Pacific Islands, and has been used in many native cultures including the Hawaiians, Samoans, Fijians and Pohnpeians. Kava produces up to 18 different chemicals called kavalactones, each with their own range of homologues. The primary kavalactone in kava is known as yangonin, which has shown a significant affinity for CB1 receptors, similar to THC, and may contribute to the desire and historical usage behind the traditional kava drink.
Camellia sinensis, a species of evergreen shrub in the camellia genus, is widely used for the production of tea. It’s typically harvested for white tea, yellow tea, green tea, oolong, dark tea, pu-erh tea, black tea and twig tea, typically harvested from a pool of over a thousand cultivars throughout East Asia. Camellia sinensis has been shown to produce a group of chemical compounds called flavan-3-ols, including gallocatechol (GC), epigallocatechin gallate (EGCG), epicatechin gallate (ECG), and catechin. GC has shown particular affinity for human cannabinoid receptors, and is considered a primary reason for green tea’s health benefits.
The echinacea genus of flowering plant, also known as coneflowers, are native to many areas in central North America and contained in the daisy family. Some species of echinacea have been known to produce chemical compounds known as alkylamides which have been found to be moderate cannabinoid agonists. These species include echinacea purpurea, or the eastern purple coneflower, echinacea angustifolia, or the narrow-leaved purple coneflower, and echinacea pallida, or the pale purple coneflower.
Thus far, at least 25 alkylamides have been identified in various echinacea species that interact with the endocannabinoid system, primarily CB2 receptors. These compounds are primarily found in the roots and flowers, but are produced throughout the plant’s structure. The most prominent of these compounds, and the one to receive the most study, is the cis/trans isomer dodeca-2E,4E,8Z,10E/Z-tetraenoic-acid-isobutylamide. Native American uses of the herbs go back thousands of years, and while clinical data on their effectiveness is lacking, they’ve historically been used for a variety of ailments including pain relief, toothaches, insect bites, burns, stomach cramps and snake bites.
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