More effective than Adriamycin
In 1997, Purdue University published information with promising news that several of the Annonaceous acetogenins were " . . . not only are effective in killing tumors that have proven resistant to anti-cancer agents, but also seem to have a special affinity for such resistant cells." In several interviews after this information was publicized, the head pharmacologist in Purdue's research explained how this worked. As he explains it, cancer cells that survive chemotherapy can develop resistance to the agent originally used as well as to other, even unrelated, drugs.
This phenomenon is called multi-drug resistance (MDR). One of the main ways that cancer cells develop resistance to chemotherapy drugs is by creating an intercellular pump which is capable of pushing anticancer agents out of the cell before they can kill it. On average, only about two percent of the cancer cells in any given person might develop this pump--but they are the two percent that can eventually grow and expand to create multi-drug-resistant tumors. Some of the latest research on acetogenins reported that they were capable of shutting down these intercellular pumps, thereby killing multi-drug-resistant tumors. Purdue researchers reported that the acetogenins preferentially killed multi-drug-resistant cancer cells by blocking the transfer of ATP--the chief source of cellular energy --into them.
A tumor cell needs energy to grow and reproduce, and a great deal more to run its pump and expel attacking agents. By inhibiting energy to the cell , it can no longer run its pump. When acetogenins block ATP to the tumor cell over time, the cell no longer has enough energy to operate sustaining processes - and it dies. Normal cells seldom develop such a pump; therefore, they don't require large amounts of energy to run a pump and, generally, are not adversely affected by ATP inhibitors. Purdue researchers reported that 14 different acetogenins tested thus far demonstrate potent ATP-blocking properties (including several found only in graviola). They also reported that 13 of these 14 acetogenins tested were more potent against MDR breast cancer cells than all three of the standard drugs (adriamycin, vincristine, and vinblastine) they used as controls.
In an 1976 plant screening program by the National Cancer Institute, graviola leaves and stem showed active toxicity against cancer cells and researchers have been following up on these findings since. Thus far, specific acetogenins in graviola and/or extracts of graviola have been reported to be selectively toxic in vitro to these types of tumor cells: lung carcinoma cell lines; human breast solid tumor lines; prostate adenocarcinoma; pancreatic carcinoma cell lines; colon adenocarcinoma cell lines; liver cancer cell lines; human lymphoma cell lines; and multi-drug resistant human breast adenocarcinoma. Researchers in Taiwan reported in 2003 that the main graviola acetogenin, annonacin, was highly toxic to ovarian, cervical, breast, bladder and skin cancer cell lines at very low dosages saying; “. . . annonacin is a promising anti-cancer agent and worthy of further animal studies and, we would hope, clinical trials.”
An interesting in vivo study was published in March of 2002 by researchers in Japan, who were studying various acetogenins found in several species of plants. They inoculated mice with lung cancer cells. One third received nothing (the control group), one third received the chemotherapy drug adriamycin, and one third received the main graviola acetogenin, annonacin (at a dosage of 10 mg/kg). At the end of two weeks, five of the six in the untreated control group were still alive and lung tumor sizes were then measured. The adriamycin group showed a 54.6% reduction of tumor mass over the control group—but 50% of the animals had died from toxicity (three of six). The mice receiving annonacin were all still alive, and the tumors were inhibited by 57.9%—slightly better than adriamycin—and without toxicity. This led the researchers to summarize; “This suggested that annonacin was less toxic in mice. On considering the antitumor activity and toxicity, annonacin might be used as a lead to develop a potential anticancer agent.”
Now that scientists have the ability to recreate this chemical and several other active acetogenins in the laboratory, the next step is to change the chemical just enough (without losing any of the antitumorous actions in the process) to become a novel chemical which can be patented and turned into a new patented cancer drug. (Naturally-occurring plant chemicals cannot be patented.) Thus far, scientists seem to be thwarted again—every time they change the chemical enough to be patentable, they lose much of the antitumorous actions.
In the meantime, many cancer patients and health practitioners are not waiting… they are adding the natural leaf and stem of graviola to their cancer treatment regimen
Sloan Kettering
http://www.mskcc.org/cancer-care/herb/graviola