In vitro antiproliferative activity of partially purified Trigona laeviceps propolis from Thailand on human cancer cell lines

Supawadee Umthong,Chanpen Chanchao,Songchan Puthong,Preecha Phuwapraisirisan

doi:10.1186/1472-6882-11-37

Supawadee Umthong, Chanpen Chanchao + Show 2 more

Open Access

https://doi.org/10.1186/1472-6882-11-37

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Abstract

BackgroundCancers are some of the leading causes of human deaths worldwide and their relative importance continues to increase. Since an increasing proportion of cancer patients are acquiring resistance to traditional chemotherapeutic agents, it is necessary to search for new compounds that provide suitable specific antiproliferative affects that can be developed as anticancer agents. Propolis from the stingless bee, Trigona laeviceps, is one potential interesting source that is widely available and cultivatable (as bee hives) in Thailand.MethodsPropolis (90 g) was initially extracted by 95% (v/v) ethanol and then solvent partitioned by sequential extractions of the crude ethanolic extract with 40% (v/v) MeOH, CH2Cl2 and hexane. After solvent removal by evaporation, each extract was solvated in DMSO and assayed for antiproliferative activity against five cancer (Chago, KATO-III, SW620, BT474 and Hep-G2) and two normal (HS27 fibroblast and CH-liver) cell lines using the MTT assay. The cell viability (%) and IC50 values were calculated.ResultsThe hexane extract provided the highest in vitro antiproliferative activity against the five tested cancer cell lines and the lowest cytotoxicity against the two normal cell lines. Further fractionation of the hexane fraction by quick column chromatography using eight solvents of increasing polarity for elution revealed the two fractions eluted with 30% and 100% (v/v) CH2Cl2 in hexane (30DCM and 100DCM, respectively) had a higher anti-proliferative activity. Further fractionation by size exclusion chromatography lead to four fractions for each of 30DCM and 100DCM, with the highest antiproliferative activity on cancer but not normal cell lines being observed in fraction# 3 of 30DCM (IC50 value of 4.09 - 14.7 μg/ml).ConclusionsT. laeviceps propolis was found to contain compound(s) with antiproliferative activity in vitro on cancer but not normal cell lines in tissue culture. The more enriched propolis fractions typically revealed a higher antiproliferative activity (lower IC50 value). Overall, propolis from Thailand may have the potential to serve as a template for future anticancer-drug development.

Highlights

Cancers are some of the leading causes of human deaths worldwide and their relative importance continues to increase
Antiproliferation of ethanol crude extract From 90 g of T. laeviceps propolis a yield of 18 g (20%) of crude ethanol extract was obtained as a sticky brownish to dark brown resin with a distinctive smell
When assayed in vitro on the five cancer and two normal cell lines, using the MTT assay, the IC50 values for the five cancer cell lines ranged from 1.9-fold lower (SW620 and BT474) to only 1.04-fold lower (Hep-G2) than that for the control HS27 cell line (Table 1)

Summary

Introduction

Cancers are some of the leading causes of human deaths worldwide and their relative importance continues to increase. Chemotherapy is one of the most widely used approaches for the treatment of many cancers, but the long-term use of chemotherapy can lead to drug resistance via several different mechanisms, such as gene mutation, DNA methylation and histone modification. These resistance mechanisms have been reported to play important roles in the resistance of cancers to Propolis, one of the economic natural products from bees, is an interesting source for several bioactivities, such as antimicrobial as well as anti-cancer. Propolis has been long used as a dietary supplement for disease prevention [7], since it can provide antimicrobial activity, including antiviral activity [8], anti-inflammatory [9], immunomodulatory [10], antitumor [11] and antioxidant effects [12]

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