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The aqueous-acetone polyphenolic extract of the traditionally derived date syrup, known as "Rub El Tamer", was analyzed using RP-HPLC-DAD and ESI-MS. The phenolic content of the extract was 394.53 ± 1.13 mg per 100 g of syrup with caffeoylsinapylquinic acid as the most abundant compound (72.23%). The extract exhibited strong antioxidant activities as evaluated using the ABTS (2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)), DPPH (2,2-diphenyl-1-picrylhydrazyl) and FRAP (ferric reducing antioxidant power) methods. The extract antimicrobial potential against a range of microorganism strains showed that Staphylococcus aureus, Staphylococcus epidermidis, and Bacillus cereus were the most sensitive bacteria with MBC in the range of 0.5-0.05 mg/mL. Furthermore, in the presence of the syrup extract (8.18-131 μg/mL), the Human SH-SY5Y neuroblastoma and the 3T3 fibroblast cell lines showed dissimilar reduction of viability suggesting a higher cytotoxic effect against tumorigenic cells. Our results provide new insights into date syrup characterization which should stimulate further studies of this hot desert resource.

Quantitative and qualitative analyses of the yellow and red azarole phenolic extracts prepared from leaf, fruit peel/pulp, and syrup were comparatively investigated. The yellow azarole was found significantly richer in polyphenols than the red-fruit species. Hyperoside was the main phenolic in both yellow and red azarole leaves and only in yellow fruits, whereas procyanidin B2 was the major compound in red fruits. Yellow azarole leaf and fruit peel extracts exhibited the strongest antioxidant activities using DPPH (≈168 and 79 μmol TEAC/g fw, respectively) and FRAP (≈378 and 161 μmol Fe(2+)/g fw, respectively) assays. The highest antibacterial activities were recorded for the yellow azarole leaf and fruit peel extracts, especially against Staphylococcus aureus and Streptococcus faecalis . The low phenolic content of the syrups contrasted with their significant antioxidant and antimicrobial potentials, which were correlated to their hydroxymethylfurfural (HMF) (furan derivative amounts) content.

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Introduction Rosa species are known by their richness in bioactive compounds useful in cosmetic, perfumery, food and phytotherapy. These metabolites are influenced by several factors accordingly affecting the plant properties in different environments. Objective Exploration of polyphenolic composition and antioxidant activity of stem extracts from Rosa moschata Herrm., R. canina L. and R. sempervirens L. growing in different northern areas in Tunisia. Methods Phytochemical composition was carried out by means of high‐performance liquid chromatography diode‐array detector (HPLC‐DAD) and HPLC‐DAD‐ESI‐MS (electrospray ionisation mass spectrometry). Antioxidant activity was measured using the DPPH (1,1‐diphenyl‐2‐picrylhydrazyl) radical scavenging assay, the FRAP (ferric reducing antioxidant power) test, the TEAC (Trolox equivalent antioxidant capacity) and the ORAC (oxygen radical absorbance capacity) assays. Results Rosa stem profiles were dominated by flavonols but qualitative variation was recorded between sections (Caninae and Synstylae). Aromadendrin‐O‐hexoside‐deoxyhexoside, quercitrin and quercetin 3‐O‐glucoside were identified as the major compounds of R. sempervirens, R. moschata and R. canina, respectively. Quantitative differences were found between species, provenances and extracts either for the individual compounds or for the total phenolic contents. This variability was also highlighted in Rosa scavenger ability results. The highest mean values were recorded by methanolic extracts of R. moschata from Bizerte (TEAC and FRAP) and R. canina for DPPH. However, for ORAC assay, the most active extract was obtained by ethyl acetate from stems of R. canina. Conclusion Results allow concluding that stems of R. sempervirens, R. moschata and R. canina could present a new natural residual source of bioactive phytochemicals, to be employed as additives in pharmaceutical products or in cosmetic and food preparations.