‘Fundamental’ herb reverses drug resistance of cancer cells

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February 16, 2008  
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wu-wei-zi1.jpgCM NEWS – One of the 50 fundamental traditional Chinese medicinal herbs, Wu wei zi (???), contains substances that could “remarkably” reverse multidrug resistance of cancer cells, according to a study done at Standford University.wu-wei-zi1.jpg

Fructus Schizandrae (wu wei zi, ???) is commonly used as a tonic in traditional Chinese medicine. Recently, wu wei zi was found to significantly improve liver dysfunction in chronic hepatitis patients.

What is wu wei zi? Fructus Schizandrae is a deciduous woody vine and is dioecious, meaning individual plants are either male or female, thus both male and female plants must be grown. It is very tolerant to shade. Its Chinese name comes from the fact that its berries possess all five basic flavours: salty, sweet, sour, pungent (spicy), and bitter.

Its berries are used in traditional Chinese medicine, where it is considered one of the 50 fundamental herbs. They are most often used in dried form, and boiled to make a tea. Medicinally it is used as a tonic and restorative adaptogen with notable clinically documented liver protecting effects. The primary hepatoprotective (liver protecting) and immuno-modulating constituents are the lignans schizandrin, deoxyschizandrin, gomisins, and pregomisin, which are found in the seeds of the fruit. It should not be used by pregnant women.

During the early 1980’s Chinese doctors began researching Schizandra as a treatment for hepatitis, based on its potential for liver-protective effects.

Lignans schizandrins have been found to prevent liver damage, stimulate liver repair, and stimulate normal liver functioning. Schizandrins are claimed to inhibit and even reverse the destruction of liver cells by stimulating the production of cytochrome p-450 which is a protein involved in extramitochondrial electron transport in the liver. In another study, schizandrins have scavenging effects on active oxygen radicals.

What does wu wei zi treat according to traditional Chinese medicine?

  • stops asthmatic cough
  • treats spermatorrhea
  • treats chronic hepatitis
  • treats night sweats
  • promotes saliva
  • quenches thirst
  • calms emotion and palpitation
  • helps prevent insomnia
  • helps prevent liver damage
  • help liver to metabolize drugs
  • improves efficiency of brain activities
  • lowers blood pressure
  • as an anti-oxidant
  • as a tonic for shen (kidney)

The study done by researchers at the department of oncology of Standford University was to assess the reversal effect of five schizandrins and crude extract from Fructus Schizandrae on multidrug resistance of cancer cells.

According to the researchers, chemically, the five schizandins are derivatives of dibenzo-(a, c)-cyclooctene lignan with distinct structures differing from any known multidrug resistance reversal agents.

The researchers applied various concentrations of the wu wei zi extract and schizandrins to a panel of resistant cancer cell lines. Drug sensitivity, accumulation of chemotherapeutic substance, expression of P-glycoprotein and protein kinase C (PKC), and apoptosis (cell death) were determined in vitro.

What is p-glycoprotein? P-glycoproteins are part of a larger family of efflux transporters found in the gut, gonads, kidneys, biliary system, brain and other organs. They appear to have developed as a mechanism to protect the body from harmful substances.

P-glycoproteins play a large role in the distribution and elimination of many clinically important therapeutic substances.

What is protein kinase C? Protein kinase C is a subgroup of protein kinases. PKC catalyzes the phosphorylation of tyrosine residues in certain proteins. A protein which stimulates angiogenesis, e.g. of solid tumours, called Vascular Endotheelial Growth Factor (VEGF), depends in part on activation of a protein which is a receptor for VEGF.

The activation is achieved by phosphorylation of the VEGF receptor, which is catalyzed by a protein kinase C. Drugs which inhibit protein kinase C can promote death of tumour cells which depend on VEGF-mediated angiogenesis (spreading of cancer).

The researchers found that the tested five compounds showed various levels of multidrug resistance reversal activity, of which, schizandrin A (Sin A) was the most potent one.

By inhibiting both the function and expression of p-glycoproteins and total protein kinase C, the five schizandrins and crude extract from wu wei zi and their active compenent Sin A have have remarkable reversal effect on multidrug resistance in cancer cells.

[Cancer Chemother Pharmacol. 2008 Feb 13]