Protocatechuic acid / GSK‐3β Cancer Research Results

Protocatechuic acid (PCA; 3,4-dihydroxybenzoic acid) is a naturally occurring phenolic acid found in many fruits, vegetables, grains, medicinal plants and plant-derived foods. PCA also occurs as a metabolite of several dietary polyphenols and anthocyanins. It has demonstrated antioxidant, anti-inflammatory, neuroprotective, cardioprotective and anticancer activities in preclinical studies. In Alzheimer-related models, PCA has improved learning and memory, reduced amyloid-β deposition and neuroinflammation, attenuated oxidative stress and supported cholinergic and neurotrophic signalling. In APP/PS1 transgenic mice, PCA reduced amyloid deposition and inflammatory responses while improving cognitive deficits. More recent AD-model studies also report improvement of cognitive function through modulation of cholinergic synaptic signalling. In cancer models, PCA can suppress proliferation, migration and inflammatory signalling and promote apoptosis through mechanisms involving ROS regulation, NF-κB, PI3K/AKT, MAPK and mitochondrial apoptotic pathways. PCA is listed as a separate product because purified protocatechuic acid has been directly administered and studied independently of the botanical extracts from which it originates. (Example EGb 761) Current therapeutic evidence remains predominantly preclinical.
After ingestion, cyanidin anthocyanins are extensively degraded and metabolized to protocatechuic acid (PCA). That is why foods such as blackberries, blackcurrants, aronia, blood oranges, and black/purple rice can be important PCA sources even when their measured free PCA content is not especially high.

High PCA Sources

Black/purple rice bran  - High
Hibiscus / roselle      - High
Açaí                    - High
Black rice              - High
Purple rice             - High
Black wild rice         - Moderate
Blood orange            - High precursor source
Blackcurrant            - Moderate-high
Blackberry              - Moderate-high
Aronia / chokeberry     - Moderate-high
Dark cherries           - Moderate
Onion                   - Moderate
Potato                  - Moderate
Barley tea              - Moderate