Schisandra chinensis has the effect of reversing multidrug resistance in tumors
The crude extract of "Schisandra chinensis" and its active ingredient schisandrin A have a reversing effect on multidrug resistance, and can greatly increase the sensitivity of tumor cells to antitumor drugs. The structure of schisandrin A is different from all known multidrug resistance reversing agents, making it a Chinese herbal medicine with development prospects. This is a "new discovery" disclosed by Liu Gengtao, researcher at the Institute of Materia Medica, Chinese Academy of Medical Sciences, and academician of the Chinese Academy of Engineering, in his academic report at the "Guangzhou Pharmaceutical 2006 Cross-Strait Pharmaceutical (Yangcheng) Forum" held recently.
Liu Gengtao pointed out that cancer is one of the greatest killers of human health, with its mortality rate ranking among the top in China and second in the world. Multidrug resistance in tumor cells is currently one of the important reasons for the failure of clinical tumor chemotherapy. So-called "multidrug resistance" refers to tumor cells being inherently resistant, or having developed resistance after induction by chemotherapeutic drugs, to a series of antitumor drugs with different structures and mechanisms of action. Therefore, reversing the multidrug resistance of tumor cells so as to restore the sensitivity of tumor cells to chemotherapeutic agents has very important clinical value.
Academician Liu conducted a series of studies on "reversing resistance" with Schisandra chinensis, including in vitro experiments, nude mouse in vivo experiments, and antitumor experiments, confirming that the crude extract of Schisandra chinensis and its active ingredient schisandrin A have a very obvious effect in reversing multidrug resistance. In experiments on the enhancing effect of combined use with the antitumor drugs vincristine, paclitaxel, and doxorubicin in inhibiting the growth of mouse sarcoma S180, it was found that after the crude extract of Schisandra chinensis was used in combination with these three drugs, the tumor-inhibiting effects of all three drugs were enhanced to a certain degree, with tumor inhibition rates reaching 51.66%, 38.11%, and 53.05%, respectively. In mechanistic research, Academician Liu discovered four mechanisms: first, Schisandra chinensis can increase the accumulation of antitumor drugs in drug-resistant tumor cells, thereby enhancing efficacy; second, it can inhibit the expression of P-glycoprotein, suggesting that it exerts its effect at least in part by directly or indirectly interfering with the P-glycoprotein-mediated drug efflux pump; third, it can significantly increase the susceptibility of BEL7402 liver cancer cells to apoptosis induced by doxorubicin; fourth, the calcium antagonist VER can partially antagonize the increase in intracellular calcium mediated by the dihydropyridine calcium agonist BAYK8644, suggesting that schisandrin A itself has no calcium antagonist activity.
The above studies indicate that the mechanism by which the crude extract of Schisandra chinensis reverses multidrug resistance is mainly related to inhibiting P-glycoprotein and enhancing the apoptosis of drug-resistant tumor cells induced by antitumor drugs. Liu Gengtao stated that this research achievement has now applied for patent protection. He believes that Schisandra chinensis is very abundant in domestic resources and is worthy of continued research and development.