Cytotoxicity of Portuguese Propolis: The Proximity of theIn VitroDoses for Tumor and Normal Cell Lines

Abstract

With a complex chemical composition rich in phenolic compounds, propolis (resinous substance collected by Apis mellifera from various tree buds) exhibits a broad spectrum of biological activities. Recently, in vitro and in vivo data suggest that propolis has anticancer properties, but is the cytoxicity of propolis specific for tumor cells? To answer this question, the cytotoxicity of phenolic extracts from Portuguese propolis of different origins was evaluated using human tumor cell lines (MCF7—breast adenocarcinoma, NCI-H460—non-small cell lung carcinoma, HCT15—colon carcinoma, HeLa—cervical carcinoma, and HepG2—hepatocellular carcinoma), and non-tumor primary cells (PLP2). The studied propolis presented high cytotoxic potential for human tumor cell lines, mostly for HCT15. Nevertheless, excluding HCT15 cell line, the extracts at the GI50 obtained for tumor cell lines showed, in general, cytotoxicity for normal cells (PLP2). Propolis phenolic extracts comprise phytochemicals that should be further studied for their bioactive properties against human colon carcinoma. In the other cases, the proximity of the in vitro cytotoxic doses for tumor and normal cell lines should be confirmed by in vivo tests and may highlight the need for selection of specific compounds within the propolis extract.

The Bioactive Potential of Functional Products and Bioavailability of Phenolic Compounds

“…The minimum obtained was recorded in the samples that contained high amounts of phenolic acids, which could be understood as a form of exo-protection. Low flavonoid concentration determined specificity, which corresponded to previous studies performed on other tumor and nontumor cells [42]. For A. linearis the balanced distribution of the two major phenolic acids corresponded to a maximum cell number.…”

Relationship between total phenolic contents and biological properties of propolis from 20 different regions in South Korea

“…The antiproliferative activity toward PC-3 cell line was reported in propolis from Brazil (optimal dose, 40 μg/mL) [ 50 ] and India (IC 50 , 41.8–134.5 μg/mL) [ 51 ]. The antiproliferative activity toward MCF-7 cell line was reported in propolis from Cuba (1–25 μg/mL) [ 52 ], India (13 μg/mL) [ 42 ] and (26.88–104 μg/mL) [ 51 ], Indonesia (47.45 μg/mL) [ 53 ], Java (37.8–276.45 μg/mL) [ 54 ], Malta (67 μg/mL) [ 55 ], Portugal (36–182 μg/mL) [ 56 ], and Turkey (125 μg/mL) [ 57 ]. The antiproliferative activity toward A549 cell line was reported in propolis from Cuba (IC 50 , 35.48–99.5 μg/mL) [ 58 ], India (10 μg/mL) [ 42 ], and Tunisia (200 μg/mL) [ 59 ].…”

“…For the AChE inhibition, negative correlation between the total phenolic and flavonoids content and IC 50 was reported in propolis samples from Morocco [ 32 ]. For the antiproliferative activity toward MCF-7 cell line, negative correlation between the total polyphenol content and IC 50 was reported, whereas positive correlation between the total flavonoid content and IC 50 was reported [ 56 ]. For the antimicrobial activity, strong correlation between the total phenolic and flavonoids content and MIC was reported in propolis from Spain [ 69 ], whereas no direct correlation between them was also reported in propolis from Brazil [ 68 ] and Greece and Cyprus [ 29 ].…”

Propolis: A Complex Natural Product with a Plethora of Biological Activities That Can Be Explored for Drug Development

“…In the last decades, several studies have demonstrated the biological and pharmacological actions of different worldwide propolis samples. The following sections summarize the recent published information about antibacterial and antifungal [ 6 , 7 , 56 – 59 ], antiviral [ 7 , 59 , 60 ], anti-inflammatory [ 61 ], antioxidant [ 62 – 64 ], immunomodulatory [ 6 , 65 , 66 ], and antitumor activities [ 8 , 17 , 23 , 64 , 66 , 67 ], revealing the interest of researchers in this bee product and its potential for the development of new drugs as well.…”