In the early part of the 20th century, flavonoids had their first big moment. In 1936, the Hungarian physician István Rusznyák and biochemist Albert Szent-Györgyi published a study in the journal Nature on the health benefits of these non-intoxicating organic chemicals. Szent-Györgyi, who had also done important work on vitamin C and fumaric acid, won the Nobel Prize for Medicine the following year.
Early research showed exciting possibilities for flavonoids, highlighting the anti-inflammatory, antioxidant, anti-viral, and anti-cancer effects that continue to intrigue modern researchers. Flavonoids even earned the nickname “Vitamin P,” although the expression has since gone out of style.
Yet much like terpenes, another lesser-known class of chemicals found in the cannabis plant, flavonoids have also struggled for official recognition as medicines — neither the U.S. Food and Drug Administration (FDA) nor the European Food Safety Authority (EFSA) has approved any health claim for flavonoids or approved any as pharmaceutical drugs.
But with cannabis research seemingly on the verge of a renaissance, the plant’s once-obscure compounds are benefitting from the spotlight. Which could mean big things for these intriguing secondary metabolites also found in the plant, and their exciting — and mostly unharnessed — potential.
As with terpenes (like limonene) and even some cannabinoids (like beta-caryophyllene), flavonoids are not unique to cannabis — and vitexin is no exception. The chemical compound is also found in the passion flower, chaste trees, black bamboo leaves, pearl millet, and hawthorn. Many of these plants are known for their various anti-inflammatory and disease-avoidant powers, effects in which vitexin is thought to play a prominent role.
Hawthorn, whose active ingredients are primarily thought to be the flavonoids vitexin and rutin, has long been valued in Europe as a cardiac tonic. In a 2018 review of past studies published in the journal Integrative Medicine, hawthorn was evaluated as a preventative against heart failure. Though the results of the review were mostly promising, it also included a study whose “puzzling and quite concerning” results indicated a rise in heart failure rates — although this may be an anomaly, as hawthorn is generally considered quite safe and side effect-free.
There were also numerous circulatory benefits ascribed to hawthorn in past animal and human studies, such as increased coronary artery blood flow, enhanced pumping efficiency of the heart, a lengthening of the refractory period, and slightly lowered blood pressure.
A good amount of research has addressed the use of another vitexin-heavy plant, passion flower. Native to the Americas and Asia, psychoactive species of the plant family have long been used by Native Americans for their anxiolytic and sedative properties. Germany’s Commission E — the authority for traditional, folk and herbal medicines — has approved passion flower in the treatment of nervousness and insomnia.
Another plant remedy, the tetradium daniellii which grows wild in the forests of China and Korea, also features vitexin. Long used in Chinese and Korean traditional medicine for headaches, the healing of gastric ulcers and relief from dermatitis, the plant has not attracted much attention from the Western natural medicine community. This will likely change in the future, as it is also implicated in the treatment of Alzheimer’s disease.
There has been some scientific research on vitexin’s neuroprotectivity, like a 2018 collaborative review in the journal BioMed Research International. Led by researchers in Brazil and India, the study pointed to vitexin as a compound of interest in the treatment of neurodegenerative diseases. Where typical treatment regimens focus mainly on relieving symptoms, vitexin seems to counteract the processes that induce neurodegeneration, such as redox imbalance, neuroinflammation, abnormal protein aggregation, reduction of cognitive abilities, and motor impairment.
More research out of Brazil addressed vitexin’s specific aptitude in preventing the cell toxicity that comes with Alzheimer’s disease. In a 2015 study published in the journal Food and Chemical Toxicology, scientists found that the flavonoid could protect the brain’s PC12 cells from attack by Aβ peptides, which are one of the chief causes of the neurodegeneration that accompanies Alzheimer’s.