Polyphenol Profile and Pharmaceutical Potential of Quercus spp. Bark Extracts.

Elansary Elansary,El-Ansary El-Ansary,El-Abedin El-Abedin,Szopa Szopa,Ekiert Ekiert,Yessoufou Yessoufou,Kubica Kubica,Mattar Mattar,Al-Yafrasi Al-Yafrasi

doi:10.3390/plants8110486

Elansary Elansary, El-Ansary El-Ansary + Show 7 more

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https://doi.org/10.3390/plants8110486

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Abstract

Targeted profiling of polyphenols in trees may reveal valuable sources of natural compounds with major applications in pharmacology and disease control. The current study targeted the profiling of polyphenols using HPLC-DAD in Quercus robur, Q. macrocarpa and Q. acutissima bark extracts. Free radical scavenging of each extract was investigated using antioxidant assays. Antimicrobial activities against a wide spectrum of bacteria and fungi were explored, as well as anticancer activities against different cancer cell lines. The HPLC-DAD analyses revealed the availability of several polyphenols in high amounts, including ellagic acid (in Q. robur) and caffeic acid (in Q. macrocarpa) in all three species. The bioactivity assay revealed high antioxidant activity in Q. robur compared to that of the other species, as well as phenolic standards. The three oak bark extracts showed clear antibacterial activities against most bacteria tested, with the highest antibacterial activities in the extracts of Q. robur. In addition, the three extracts showed higher antibacterial activities against Pseudomonas aeruginosa, Micrococcus flavus, and Escherichia coli compared to that of other bacteria. There were strong antifungal activities against some fungi, such as Aspergillus flavus, Penicillium funiculosum, and Penicillium ochrochloron. There were also noticeable anticancer activities against MCF-7, HeLa, Jurkat, and HT-29 cell lines, with the highest anticancer activity in the extracts of Q. robur. This is the first study that reveals not only novel sources of important polyphenols (e.g., ellagic acid) in Q. robur, Q. macrocarpa and Q. acutissima bark but also their anticancer activities against diverse cancer cell lines.

Highlights

Tree barks are widely used in traditional medicine to treat several diseases because of their medicinal properties grounded in the presence of phenolic compounds that can have antioxidant, antimicrobial, and anti-inflammatory activities [1,2,3]
The highest anticancer activity was found in the extracts of Q. robur compared to that of
This study demonstrated differences in secondary metabolite composition among the examined cortex extracts and is the first to document the phenolic acid profiles in these materials

Summary

Introduction

Tree barks are widely used in traditional medicine to treat several diseases because of their medicinal properties grounded in the presence of phenolic compounds that can have antioxidant, antimicrobial, and anti-inflammatory activities [1,2,3]. The best-known species in Europe is Quercus robur L. This plant occurs naturally in Europe, Asia, and North America and is used in traditional medicine for the treatment of diarrhea and inflammation [7]. The bark of Q. robur is listed in the official database of pharmaco-therapeutic plants by the European Medicine Agency [8]. Q. robur bark contains a high amount of tannins (hydrolyzable and condensed tannins) (8%–20%). These tannins are composed of either galloyl esters and their derivatives (gallotannins, ellagitannins, and complex tannins) or oligomeric and polymeric proanthocyanidins and can possess different interflavanyl couplings and substitution patterns (condensed tannins) [11,12]

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