Now, sapota joins the list of fruits that have proven anticancer properties. Proof of principle study using human cancer cell lines and mice induced with breast cancer has shown that certain chemicals in sapota fruit can inhibit tumour progression.
The study was undertaken by a team of scientists from the Indian Institute of Science (IISc) Bangalore and the Institute of Bioinformatics and Applied Biotechnology, Bangalore. The results were published recently in the Nature group’s journal Scientific Reports .
Experiments were carried out using different human cancer cell lines and mice induced to develop breast cancer to test and verify the efficacy of the sapota fruit extract in inhibiting cancer cell proliferation.
In the case of human cells, the anti-tumour potency was pronounced in the case of leukaemia. Of the two different human leukaemia cancer cell lines studied, the effect was pronounced in one of them (NALM6). The viability was “significantly affected” in these cell lines after 48 hours of treatment at extract concentrations of 1 mg/ml onwards. “Over 80 per cent of cell death was observed at 2 mg/ml concentration,” the paper notes. As expected, the effect of the sapota fruit extract on normal cells was “limited” compared with cancer cells.
Mice induced with breast cancer and treated with the extract given through the oral route showed “significant reduction” in the tumour size. “In 50 per cent of mice studied, we could increase the lifespan by 3-fold,” said Sathees Raghavan, Associate Professor, Department of Biochemistry, IISc. “We can initiate cell death within six hours of treatment.”
The study showed that proliferation of cancer cells was inhibited by activating programmed cell death (apoptosis) and not by necrosis (killing of cancer cells).
There are two pathways through which programmed cell death can be achieved. While one is the intrinsic pathway (involving the mitochondria), the other is the extrinsic pathway (the effect is brought about from outside the cell).
“We found the extract activates the intrinsic pathway of apoptosis to kill the cancer cells,” Prof. Raghavan said. Mitochondria plays a critical role in activating apoptosis as several of the proteins responsible for cell death are present either within or outside the mitochondria. The cancer cells treated with the extract “collapsed” the transmembrane of the mitochondria.
A small haemoprotein was released following the collapse of the transmembrane and this initiated the activation of the intrinsic pathway of apoptosis.
While human leukaemia cell lines were studied, in the case of mice, the effect of the extract was studied on breast cancer cells. Explaining the reason for this, Prof Raghavan said: “In India it is difficult to develop B cell leukaemia in mice using human leukaemia.”
But it is pertinent to point out that breast cancer accounts for about 30 per cent of all cancers, worldwide , while leukaemia accounts for only four per cent of all cancers in the world.
For the study, the researchers had used sapota fruit extract. As a result, which chemical(s) or molecule(s) has the effect of activating apoptosis (programmed cell death) is not known.
“The next step is to purify the active component that causes the observed anticancer properties in sapota fruit,” he said.