Strawberry-Tree Honey Induces Growth Inhibition of Human Colon Cancer Cells and Increases ROS Generation: A Comparison with Manuka Honey

Abstract

Honey is a natural product known to modulate several biological activities including cancer. The aim of the present study was to examine the phytochemical content and the antioxidant activity of Strawberry tree (Arbutus unedo) honey (STH) and its cytotoxic properties against human colon adenocarcinoma (HCT-116) and metastatic (LoVo) cell lines in comparison with Manuka (Leptospermum scoparium) honey (MH). Several unifloral STH and MH were analyzed for their phenolic, flavonoid, amino acid and protein contents, as well as their radical scavenging activities. STH from the Berchidda area showed the highest amount of phenolic, flavonoid, amino acid and protein content, and antioxidant capacity compared to MH. Both STH and MH induced cytotoxicity and cell death in a dose- and time-dependent manner in HCT-116 and LoVo cells, with less toxicity on non-cancer cells. Compared to MH, STH showed more effect at lower concentrations on HCT-116 and LoVo cells. In addition, both honeys increased intracellular reactive oxygen species (ROS) generation. In HCT-116 cells, STH and MH induced similar ROS production but in LoVo cells STH induced a higher percentage of ROS compared to MH. Our results indicate that STH and MH can induce cell growth inhibition and ROS generation in colon adenocarcinoma and metastatic cells, which could be due to the presence of phytochemicals with antioxidant properties. These preliminary results are interesting and suggest a potential chemopreventive action which could be useful for further studies in order to develop chemopreventive agents for colon cancer.

The Influence of In Vitro Gastrointestinal Digestion on the Anticancer Activity of Manuka Honey

“…Gelam honey was able to inhibit 50% of cell growth of HT-29 with a dose of 36.2 mg/mL after 72 h [33]. Lower results were obtained with Strawberry tree honey, which showed an IC 50 of HCT-116 equal to 13.34 mg/mL at 24 h, 9.48 mg/mL at 48 h and 8.76 mg/mL at 72 h [34]. Even more inferior were the results obtained by Imtara et al, which achieved IC 50 values around 2 mg/mL with different types of honey from Morocco and from Palestine after 72 h of treatment of HCT-116 [35].…”

“…The double role of ROS is well known; these compounds have a deleterious effect if produced in physiological conditions, while in pathological conditions, like cancer, these species can help to induce apoptosis, and therefore program cell death [39]. There are several works in which the treatment of colorectal cancer cells with different types of honey caused a similar pattern in the production of intracellular ROS: strawberry tree honey induced a greater accumulation of ROS in both HCT-116 than in the LoVo cells [34] and a commercial honey of Indian origin caused the same increase in HCT-116 and HT-29 [40]. Similar results were found with a multifloral honey and honeydew honey, which managed to increase ROS levels in gastric adenocarcinoma cells in a concentration-dependent manner [41].…”

Correlation of Antioxidant and Antiproliferative Activity of Amla and Ginger

“…Accumulating evidence suggests that many dietary factors like antioxidants (polyphenols) are used alone or in combination with traditional/conventional chemotherapy to prevent or treat cancer [26][27][28][29][30][31][32][33][34][35]. Crude and processed plant extracts are studied extensively to evaluate its role in treatment as chemopreventive drug or to use in combination that can synergistically improve the outcome of current chemotherapy and lower the toxicity [36][37][38].…”

The phenolic profile of strawberry tree (Arbutus unedo L.) honey

“…Strawberry tree honey showed high total phenolic content (1038 mg GAE kg -1 ) and strong DPPH scavenging activity (3.32 mmol TE kg -1 ) in accordance with previous studies. 4,5,[21][22][23][24][25][26][27] Moreover, strawberry tree honey was the richest in total phenols when compared to other honeys (e.g., eucalyptus, sunflower, lavender, thyme, rosemary, orange, lime, acacia, black locust, coriander, chestnut, asphodel and thistle). 21,[23][24][25]27,28 CONCLUSION Hyphenated techniques that combine chromatographic with high resolution and high mass accuracy spectral methods, such as UHPLC-LTQ OrbiTrap MS 4 , are very useful in getting information about phenolic structures with high reliability.…”