An aqueous propolis extract rich in organic acids but traces of flavonoids protects against radiation induced intestinal mucositis

Intestinal mucositis is a frequent side effect encountered in patients undergoing radiotherapy that limits continuation of treatment. Intestinal mucositis was shown to be largely prevented by natural products possessing anti-inflammatory or anti-oxidant properties, including extracts of propolis containing a high proportion of flavonoids [1 – 3]. A specially formulated aqueous extract of propolis (PWE) has been prepared in such a way to preclude the inclusion of flavonoids but contain mostly organic aromatic acids (Propharma A/S, Blistrup, Denmark) in order to study whether it would still protect against radiation-induced intestinal mucositis. The condition was induced in rats by exposing them individually to gamma radiation doses varying from 4 to 8 Gray from a ¹³⁷Cs source. PWE was administered orally a few days before and 2 days after exposure. Rats were sacrificed 24h later, intestinal segments were examined histologically and homogenates were used to assess relevant biochemical parameters reflecting intestinal injury.

Irradiation led to a rise in the histological damage score, a rise in tissue TNF-α and TBARS, and a decrease in sucrase, alkaline phosphatase, GSH and cholecystokinin as well as a decrease in plasma citrulline. The findings reflect a decrease in intestinal functional activity caused by radiation. PWE preserved the intestinal integrity and largely protected against the changes induced in the histology damage score and all parameters measured, possibly as a result of the antioxidant and anti-inflammatory action of its organic acid content. Furthermore, evidence of apoptosis was shown histologically at the higher radiation exposure levels, but PWE was also able to show anti-apoptotic effects, albeit at high dose levels of the extract. The results lend support to the potential therapeutic usefulness of PWE in patients undergoing radiotherapy to limit the side effects on the gastrointestinal tract.

Acknowledgment:

The contribution of Dr. Jens Nielsen, Propolis Research Centre, Propharma A/S (Blistrup, Denmark) for providing PWE and for his valuable advice is gratefully acknowledged.

References:

[1] El-Ghazaly MA et al. Int J Radiat Biol 2011; 87: 1045 – 1051

[2] Khayyal MT et al. Phytomedicine 2014; 21: 1390 – 1399

[3] Khayyal MT et al. Environ Toxicol Pharmacol 2015; 40: 901 – 906