In the ongoing quest to identify pain treatments with fewer adverse effects than those commonly used, researchers investigated the antinociceptive properties of a Chinese herb that has long been used for pain relief.
Plant extracts have been used to treat pain for centuries.
Perhaps most notable to western medicine are aspirin, which was initially developed from salicin, a chemical in willow bark , and opioids, which originated from the opium poppy.
In traditional Chinese medicine, the Corydalis yanhusuo (YHS) herb has been used to treat pain and inflammation for more than 1,000 years.
Corydalis yanhusuo is a species of genus Corydalis. Research has indicated that the alkaloiddehydrocorybulbine(DHCB), extracted from the roots of the plant, can be helpful in reducing neuropathic pain.Tetrahydropalmatine is a major constituent alkaloid which also has analgesic activity.
N-methyltetrahydroprotoberberines with κ-opioid receptor agonist activity have been isolated from C. yanhusuo.
“There is a growing interest in finding therapies that act not on one single target but instead are multi-targeted–we call this polypharmacology,” said study co-author Olivier Civelli, PhD, a professor of pharmacology, pharmaceutical sciences, and developmental and cell biology at the University of California Irvine
“YHS is a mixture of alkaloids that together can have a different analgesic effect than isolated drugs,” he told Clinical Pain Advisor.
Previous research demonstrated the antinociceptive properties of 2 isolated alkaloids of YHS, l-tetrahydropalmatine (l-THP) and dehydrocorybulbine (DHCB).3,4 Dr Cipelli and colleagues aimed to build on those findings by investigating the analgesic effects of the full YHS extract in rodent models of acute, inflammatory, and neuropathic pain.
Mice were administered different doses of either
- a vehicle solution, or
- a mixture of the isolated alkaloids l-THP and DHCB,
before being subjected to standardized tests
According to the results, YHS (500 mg/kg) showed significant antinociceptive effects in the tail-flick assay (P <.001), while a combination of its isolated compounds showed no such effect (P >.05).
Results from the other 3 assays indicate antinociceptive effects on acute, inflammatory, and neuropathic pain at a non-sedative dose (200 mg/kg), compared to the vehicle solution, which had no effect.
Further testing showed that daily administration of YHS for 7 days did not lead to tolerance of its antinociceptive effects, unlike morphine (P <.01).
“Another benefit is that, because YHS acts, at least in part, as an antagonist to the dopamine receptors, it should not display addictive properties, which is a major issue in pain management these days,” explained Dr Civelli.
Because “YHS is readily available as a supplement in the US, and it can be used by patients without prescription, clinicians could prescribe it as an adjunct therapy,” he added.
In future research, he would like to test the effects of combining YHS with commonly used analgesics to possibly prevent their overuse.
He noted that research on “natural medicine” is not well-received by institutions that support basic research, partially because of the relative novelty of poly-pharmacology, which is inherent to plant-based medicine.
This is exactly the problem with marijuana: to be most effective, the whole plant (or one of its organs) must be used in combination.
The Western ideal of a one-to-one correspondence of ingredient to effect cannot be used.
Instead, we have to accept that precise knowledge of the complex interactions of the various molecules in a plant substance may not be possible or necessary to benefit from it.
Wang L, Zhang Y, Wang Z, et al. The Antinociceptive Properties of the Corydalis yanhusuo Extract PLoS ONE. 2016; 11(9): e0162875. doi:10.1371/journal.pone.0162875.