Comparison between Phenolic Content, Antioxidant, and Antibacterial Activity of Algerian and Turkish Propolis.

BACKGROUND: Propolis is a natural resinous material produced by honeybees. The biological activity and phenolic profile of propolis were largely studied all over the world. However, only a few investigations have been carried out on Algerian and Turkish propolis. The aim of the present study was to compare the phenolic content, antioxidant, and antibacterial activity of propolis samples collected from different localities of Algeria and Turkey. METHODS: Propolis extracts were performed using maceration in ethanol 80%. Total phenolic and flavonoid contents were determined. Antioxidant and antibacterial activities were evaluated using FRAP assay and the MIC was determined against four bacterial strains (S. aureus ATCC 25923, E. coli ATCC 25922, P. aeruginosa ATCC 27853 and K. pneumonia). RESULTS: TP varied from 19.51 ± 0.86 to 219.66 ± 1.23 mg GAE/g. Whereas, TF varied from 5.27± 0.07 to 74.57 ± 1.03 QE/g. All samples showed good ferric reducing antioxidant power ranging from 267.30 ± 4.77 to 2387.30 ± 44.15 µmol Trolox eq./g. All Algerian propolis samples displayed a more pronounced activity against S. aureus ATCC 25923 with MIC values ranging from 0,04 ± 0.00 mg/mL to 0.30±0.06 mg/Ml, with an activity 30 times more powerful than Anatolian propolis. While, Anatolian propolis samples were most active against P. aeruginosa ATCC 27853 with MIC values ranging from 0.20±0.00 mg/mL to 0.60±0.00 mg/Ml, with an activity 5 to 10 times more powerful than Algerian propolis. CONCLUSION: Algerian and Anatolian propolis possessed considerable phenolic and flavonoids contents. In addition, they exhibited interesting antioxidant and antibacterial activities. Our findings suggest that both propolis could be useful in the food and pharmaceutical industries.

Correlation between antioxidant activity and phenolic acids profile and content of Algerian propolis: Influence of solvent.

We aimed in the reported study to investigate the impact of using various solvents in the extraction of potentially active compounds from Algerian propolis. Phenolic and flavonoids contents in association with antioxidant activity of the tested extracts were evaluated. Moreover phenolic composition was determined using UFLC-MS/MS. The tested parameters varied according to the used solvent. Total phenolic and flavononid contents ranged from 0.81±0.16 to 8.97±0.25 EGA mg/g and from 0.57±0.01 to 3.53±0.84 EQ mg/g respectively. All the investigated extracts demonstrated notable antiradical and reducing activities. Ethyl acetate and n-butanol were found to contain the highest amounts of phenolic and flavonoid compounds and the strongest antioxidant properties. The antioxidant activity of propolis extracts appears to be largely influenced by total phenolic and flavonoid contents. Rutin, chlorogenic, ferulic, caffeic and gallic acids were found to be the main phenolic compounds in Algerian propolis. Our results suggest that Algerian propolis may be a poplar-type propolis.

GREEN TEA BEVERAGE AND EPIGALLOCATECIHIN GALLATE ATTENUATE NICOTINE CARDIOCYTOTOXICITY IN RAT.

Nicotine, the principal alkaloid in tobacco, induces a cellular damage on heart and cardiomyocyte culture. We investigate the protective role of green tea extract (GTE) against nicotine. Male albino rats were treated by injecting nicotine (1 mg/kg b.w. for 2 months) subcutaneously and thereby supplementing GTE 2% orally to them. The levels of plasma lipids, cardiac MDA (malondialdehyde) and catalase activity Mitogen-activated proteins kinases MAPKs were measured. The expression levels of (ERK 1/2, extracellular signal - regulated kinase 1/2 and P38 MAP kinase), endoplasmic reticulum stress (ERS)-related protein (GRP78 glucose regulated protein-78, HSP70 heat shock protein-70, CHOP C/EBP homologous protein), AIF (apoptosis-inducing factor) and VDAC (voltage-dependant anion channel) were evaluated by Western blot. In the in vitro study, the cardiomyocytes were exposed to nicotine (10 µM) and major GTE polyphenol epigallocatechin gallate EGCG (50 µM). Data showed that nicotine induced a significant increase on MDA levels, LDH (lactate dehy- drogenase) and aminotransferase activity compared with control. The heart sections of nicotine exposed-rats showed severe degenerative changes. Nicotine increased the expression of P38, but not ERK 1/2, ER stress-related proteins and AIF with no changes of VDAC. Concomitant GTE treatment significantly normalized and/or improved,the levels of MDA, enzymatic activity and histological injuries. The proteins expression was attenuated by GTE co-administration without any changes for VDAC. ERK 1/2 expression enhanced in GTE- treated groups. Exposure of cardiac cells to nicotine induced the expression of ERS markers and p38; the ERK 1/2 was highly expressed only in the presence of EGCG. It was suggested that green tea beverage can protect against nicotine toxicity by attenuating oxidative stress, endoplasmic reticulum stress and apoptosis. Otherwise, our results have showed that ERK1/2 and p38 are survival signaling pathways activated by GTE and EGCG.