Biological and chemical examination of Pittosporum phillyraeoides
Undertaken at the Institute of Pharmacy Department of Pharmaceutical Biology, Ernst-Moritz-Arndt University, Greifswald, Germany, July 2007
The leaves of Pittosporum phillyraeoides …. are called “Gumby Gumby” by the Australian Aboriginals, and used for medical treatments. For a long time it has been claimed that the plant has an effect on cancer and other diseases. Biological testing of the leaves/extracts on a cellular level in vitro was not done until now. Some preliminary phytochemical investigations were done about 20 years ago. This research contributes to a scientific verification for the use of P. phillyraeoides and showed the following results:
Morphological examination of the leaves
The dried leaves are yellow green, long and narrow, and have a weak aromatic fragrance. They taste bitter and cause some itching of the throat. Microscopy of a cross-section of the leave shows a dorsiventral leaf structure with druses in the mesophyll.
Qualitative phytochemical analysis
During screening investigations secondary plant substances were found:
- Saponins, probably belonging to the triterpen saponins.
- Other terpenoid compounds, probably as components of essential oils or as bitter principles.
- Phenols, as tannins and flavonoids, but other phenols are also possible.
- The presence of cumarins seems to be possible.
With respect to the exact chemical structure of the compounds more investigations are necessary.
Quantitative phytochemical analysis
The leaf showed a small content of 1.34% tannins, calculated as pyrogallol. Also the flavonoid content, determined with two different methods was fairly low with 0.54 and 0.54% respectively. The content of carbohydrates was 29.17%. Protein 4.53% and 6.24% lipids were found.
None of the tested extracts showed a noteworthy inhibition of the tested bacteria Staphylococcus aureus, Bacillis subtilis, Escherichia coli, Micrococcus flavus, Pseudomonas aeroginosa or of the fungus Candida maltosa.
Free radical scavenging activities
Many of the extracts showed only moderate radical binding capacity, compared to ascorbic acid. The most active extract was the methanol 80% extract.
The extracts showed in the neutral red assay weak to moderate cytotoxicity against FL cells and lung cancer cells of the cell line A427.
The following extracts showed the strongest suppression (IC50 values in the range of 83-119 µg/ml) of the growing A427 cells: hot water, methanol, methanol 80% and cold ethanol.
Effect of selected extracts on human blood leucocytes
The extracts effective against FL and the tumor cell line A427 (tea, cold ethanol and Amylase 1 day) were also tested on primary human leucocytes. Concentrations which were highly cytotoxic for FL and tumor cells, showed a stimulating effect on
the human blood cells (MTT test). Cytotoxic effects are only observed in far higher concentrations.
Immunmodulative properties of selected extracts
The extracts with cancer cell cytotoxicity were also tested for their (ability to boost the immune system).
Especially the Amylase treated (1day) extract, which imitates the process used by the Aboriginals for breaking down the leaves, and the tea, were noticeable for their cytotoxic effect as well as their immune stimulating effects.
Further investigations are necessary to identify the compounds which are responsible for the cancer cell cytoxicity and the immunomodulatory properties.
© S. H., Greifswald, July 2007. All Rights Reserved.