Hibiscus leaf is a rich source of polyphenols which are thought to have hypolipidemic (lipid-lowering) and antioxidant effects.
However the scientists, led by Chun-Tang Chui from the Institute of Biochemistry and Biotechnology in Taiwan, claimed that this was the first study focusing on the polyphenols and their anti-melanoma mechanisms.
Melanoma is the least common but most fatal form of skin cancer and is resistant to most forms of treatment including chemotherapy. Rates of melanoma have doubled in the past 20 years.
“Melanoma has become an increasingly important public health issue and novel treatment options have become an important medical need,” say the researchers.
“Regarding the effect of Hibiscus leaf in vitro and in vivo studies, the effect of the polyphenolic extract in cancer is rarely reported. Thus, it is important to evaluate the potential of Hibiscus leaf polyphenols (HLP) as a functional food for anticancer.”
Chui et al. said that hibiscus leaf was consumed as a vegetable in Africa but ignored elsewhere around the world. They suggested that based on these results, published in the Journal of Food Science, HLP may be a useful anti-melanoma agent.
Using human melanoma cells, mice melanoma cells and normal human skin fibroblasts as a control, the researchers treated them with various concentrations of HLP for 24 hours in order to determine the effect on the cancer cells as well the mechanisms behind this.
They found that HLP, and in particular the polyphenol epicatechin gallate (ECG), had an inhibitory effect on the growth of both the human and mouse cancer cells – inhibiting 50% of cancer cell viability when treated for 24 hours at a 250 microgram (μg) per millilitre (mL) dose. Significantly, the normal human skin cells did not change.
“These findings indicate that the HLP is likely to be a useful chemotherapeutic agent to eliminate cancer cells without significant harmful effects on normal cells,” said the researchers.
They also found that HPL and ECG led to “dose dependent and significant” levels of cancer cell death in the human cancer cells, in two ways – apoptosis, or programmed cell death and autophagy, or the catabolic breakdown of cells.
The scientists have called for more research into the extraction methods to yield a maximum amount of HLP.
They used methanol, hexane and ethyl acetate to extract the polyphenols from dried hibiscus sabdariffa leaves at 50°C.
Source: The Journal of Food Science
Article published online ahead of print: 17 Feb 2015, DOI: 10.1111/1750-3841.12790
“Hibiscus sabdariffa Leaf Polyphenolic Extract Induces Human Melanoma Cell Death, Apoptosis, and Autophagy”
Authors: Chun-Tang Chiu, Shu-Wen Hsuan et al.