Abstract
In traditional medicine, Carica papaya leaf has been used for a wide range of therapeutic applications including skin diseases and cancer. In this study, we investigated the in vitro cytotoxicity of aqueous and ethanolic extracts of Carica papaya leaves on the human oral squamous cell carcinoma SCC25 cell line in parallel with non-cancerous human keratinocyte HaCaT cells. Two out of four extracts showed a significantly selective effect towards the cancer cells and were found to contain high levels of phenolic and flavonoid compounds. The chromatographic and mass spectrometric profiles of the extracts obtained with Ultra High Performance Liquid Chromatography-Quadrupole Time of Flight-Mass Spectrometry were used to tentatively identify the bioactive compounds using comparative analysis. The principal compounds identified were flavonoids or flavonoid glycosides, particularly compounds from the kaempferol and quercetin families, of which several have previously been reported to possess anticancer activities. These results confirm that papaya leaf is a potential source of anticancer compounds and warrant further scientific investigation to validate the traditional use of papaya leaf to treat cancer.
Highlights
A book entitled “The most wonderful tree in the world—the papaw tree (Carica papaia)”, published some 100 years ago, contains many anecdotes relating to the cure of breast, liver or rectal cancer after “treatment” with Carica papaya preparations [1]
Different parts of the Carica papaya plant have been used as traditional medicine for the treatment of skin infections and wound healing in general, and this widespread use has been scientifically validated [9,10,11], no information is available on the activity of this plant on skin cancer
The effects of Carica papaya leaf extracts have previously been reported being tested on the growth of different cancer cell lines: breast, stomach, lung, pancreatic, colon, liver, ovarian, cervical, neuroblastoma, lymphoma, leukaemia and other blood cancers [12,13,14]; to our knowledge, no skin cancer cell lines have been tested
Summary
A book entitled “The most wonderful tree in the world—the papaw tree (Carica papaia)”, published some 100 years ago, contains many anecdotes relating to the cure of breast, liver or rectal cancer after “treatment” with Carica papaya preparations [1]. In contrast to the limited number of studies that have been done to evaluate the effects of papaya extracts on cancer, the abundance in Carica papaya of phytochemicals with reported anticancer activities, such as carotenoids (in fruits and seeds), alkaloids (in leaves), phenolics (in fruits, leaves, shoots) and glucosinolates (in seeds and fruits), suggests that there are opportunities for new research to evaluate the anticancer potential of this medicinal plant [7]. The effects of Carica papaya leaf extracts have previously been reported being tested on the growth of different cancer cell lines: breast, stomach, lung, pancreatic, colon, liver, ovarian, cervical, neuroblastoma, lymphoma, leukaemia and other blood cancers [12,13,14]; to our knowledge, no skin cancer cell lines have been tested. Our aim was to preliminarily identify the bioactive compounds using liquid chromatography-quadrupole time-of-flight-mass spectrometry (LC-QToF-MS)
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