Curry Leaves Could Cure Prostate Cancer

Curry leaves don’t just satiate the taste buds, as scientists have discovered. There’s a new aspect to these leaves — the possibility of curing prostate cancer. Researchers from the Santiniketan-based Visva-Bharati University, Kolkata’s Indian Institute of Chemical Biology and Georgetown University Medical Centre in Washington, USA, have isolated mahanine — a plant-derived carbazole alkaloid from curry leaves — which has caused the mass death of prostate cancer cells through apoptosis, a type of controlled cell death mechanism.

“Mahanine did not cause death of liver cells, heart or skeletal muscle cells, indicating that this alkaloid selectively kills prostate cancer cells,” says Samir Bhattacharya, the lead researcher. “Mahanine promises a new chemotherapeutic option for prostate cancer treatment,” says Bikas C Paul, a co-researcher. Their findings were published in the journal The Prostate (Vol 66, No 12).

The research team exposed LNCaP and PC3, two types of cultured human prostate cancer cells, to mahanine-extracted and purified from curry leaves. The cancer cells were treated with one mg/ml, two mg/ml and three mg/ml mahanine for one, two and three days. And over 72 hours, at two mg/ml dose, mahanine reduced the viability of both types of cancer cells by 50 per cent. At three mg/ml dose, mahanine destroyed almost all the cancer cells within 48 hours. Studying the effects of mahanine on PC3 cancer cells, the team found that it inhibited the activity of AKT — a protein that fuels the growth of prostate cancer cells. It also blocked the generation of Bcl-xL — a type of protein that helps cancer cells survive.

“At 60 hours, mahanine completely abolished Bcl- xL,” says Bhattacharya. Reduction in the levels of Bcl-xL releases cytochrome c, a protein of mitochondria. Cytochrome C activates caspase, an enzyme that further accelerates the death of cancer cells without damaging any neighbouring healthy cells.

Mahanine has also been shown to cause the death of human leukaemic cells. “But the concentration of mahanine we used was well below the concentration used to kill leukaemic cells,” says Bhattacharya. “This suggests that prostate cancer cells are more sensitive to mahanine-induced cell death compared to leukaemic cells.”

Prostate cancer has been found to be one of the 10 leading male cancer cases in India. According to the population-based cancer registry, prostate cancer is on the rise in cities like Pune, Delhi, Chennai, Bangalore and Kolkata. In the US, prostate cancer is the second leading cause of death in men.

The above article was originally published in the science and technology section of Down To Earth, a science and environment fortnightly published from New Delhi, on December 31 2006 issue and written by this blogger.