If you have ever sat there, smoking a nice dark purple, and wondered to yourself, “What makes this purple so darkly colored,” then what you are really asking is, what are flavonoids? Read on to learn the basics of these powerful chemicals responsible for some of the flavors, colors, and medical benefits of the food we eat and the cannabis we ingest.
Discovery of Flavonoids
The discovery of flavonoids is directly linked to the isolation and identification of vitamin C (ascorbic acid) by the Hungarian Nobel-prize winning researcher Albert Szent-Györgyi during the 1930s. Dr. Szent-Györgyi originally named this new class of chemicals “Vitamin P” because of their capillary permeability, which gave them benefits for fighting scurvy, a major health scourge.
Flavonoids – Not Just Flavors, Colors Too
Despite the name “flavonoid” being very similar to the word “flavor,” and them being widespread through a range of commonly eaten foods, they actually play a limited role in the flavors of what we eat, generally imparting a bitter, undesirable flavor, often masked by other flavors. For example, “Cocoa … is particularly rich in flavonoids—specifically, flavanols … Although flavanols impart a bitter astringent flavor to foods, the flavor is frequently masked in chocolates by aggressive processing and the addition of other flavors.” In addition to flavanols, another subclass of flavonoids is flavanones, which “are responsible for the bitter taste of the juice and peel of citrus fruits.”
Another subclass of flavonoids of note are “anthocyanins,” which are not flavors, but pigments in plants. Anthocyanins occur predominantly in the outer cells of dark red, blue, and purple colored fruits such as blueberries, raspberries, red grapes, and black currants. Anthocyanins can even change color depending on the pH; if they are in an acidic condition, anthocyanins appear as red but once the pH increases they turn blue. Interestingly, the “cyan” color range, which is one of the root words in “anthocyanin,” is actually the spectrum of bright, greenish-blue colors, like teal, not dark colors like sanguine or plum.
Anthocyanins – Why Purples Are Purple
As we just discussed, anthocyanins are what make plants have a purple hue, and that is no different with cannabis. In addition to the pH influencing the color, it additionally changes based on the structure of the anthocyanins, the light while the plant is growing, and the temperature. I’ve heard from many growers that it takes very cold temperatures for purple cultivars to actually become purple, but it seems like there are other techniques that can be employed when growing to influence color (i.e. soil pH). Research using LED lights has shown that using the right spectrum of light can alter anthocyanin production.
The Role of Flavonoids in Nature
In plants, flavonoids act in a similar manner to terpenes, attracting pollinators, serving as messengers, or as defenses against a range of environmental stressors and predatory animals (herbivores, insects, etc). It has been proposed that flavonoids can also act as defense against UV light (think of them as plant sunblock) but this has not been confirmed.
Flavonoids in Cannabis
Even though they exist widely in nature, flavonoids are one of the less well-studied groups of chemicals in cannabis. Research has shown that “More than 20 flavonoids have been identified in C. sativa, most of which are flavone (apigenin and luteolin) and flavonol (kaempferol and quercetin) aglycones and glycosides.” Research has also shown that, as with hashishene, cannabis has some unique flavonoids found almost nowhere else, cannflavin A, B, and C; though Cannflavin A has “been identified in Mimulus bigelovii, a plant in the Phrymaceae family.”
Potential Medical Benefits of Flavonoids
While flavonoids have been demonstrated to have a range of medical benefits, they have limited bioavailability due to “limited absorption, extensive metabolism, and rapid excretion.” Broadly speaking, flavonoids are effective free radical scavengers in test tubes, but they are present in minute amounts compared to other antioxidants like vitamin C. It is believed that part of their antioxidant activity is a result of their ability to bind (chelate) metal ions, specifically for iron and copper, which can catalyze free radical production.
Beyond their antioxidant properties, studies have shown that the dietary intake of flavonoids leads to a lower risk of cardiovascular disease. Similarly, the dietary intake of flavonoids has been shown to have benefits for people with diabetes, specifically, consumption of berries rich in anthocyanins is beneficial to people with type 2 diabetes. Another area that benefits from dietary flavonoids is cognitive impairments due to aging. Finally, while various flavonoids in animal models have been found to inhibit the growth of some cancers, that data is not “convincing evidence that high intakes of dietary flavonoids are associated with substantial reductions in human cancer risk.”
While studies on cannflavins are limited, they have hinted at numerous medical benefits, “most notably as an anti-inflammatory agent.” There have been specific studies looking at Cannflavin A, which has been shown to be both a neuroprotective against Alzheimer’s disease and have anti-cancer effects against bladder cancer which were synergistic to cannabinoids like THC and CBD.