Polyphenol Profile and Pharmaceutical Potential of Quercus spp. Bark Extracts

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.

Mammillaria Species—Polyphenols Studies and Anti-Cancer, Anti-Oxidant, and Anti-Bacterial Activities

“…Samples were vouchered at Alexandria (Hosam0001030-1037). Stems (3 replications) were dried using lyophilization (freeze dryers Labconco, Kansas City, MO, USA), then powdered [1,2]. The powder (0.2 g DW, dry weight), was put in 15 mL tubes, then subjected to extraction with methanol (10 mL, Chempur, Poland) by sonication (2 × 30 min at 30 • C) in an ultrasonic bath (Sonic-2, POLSONIC).…”

“…The stem extracts were studied by HPLC-DAD method [1,2,45,46] using the Merck-Hitachi liquid chromatograph (LaChrom Elite) with a DAD detector (L-2455) in a ultraviolet (UV)-visible spectra range of 200-400 nm (detection wavelength for all compounds was set at 254 nm). The Purospher RP-18e (250 × 4 mm; 5 µm, Merck) column was used and the temperature was set at 25 • C. The mobile phase consisted of A-methanol, B-methanol: 0.5% acetic acid 1:4 (v/v).…”

“…Antiproliferative and cytotoxic effects of stem extracts were tested on MCF-7, HeLa, Jurkat, and HT-29, as well as HEK-293 (human normal cells) [1, 2,16]. Extracts were solubilized in DMSO (1%).…”

“…DPPH, β-carotene bleaching [48] and FRAP [2,49] assays were used. For DPPH, the wavelength of 517 nm was used to determine the absorbance.…”

Abundant Extractable Metabolites from Temperate Tree Barks: The Specific Antimicrobial Activity of Prunus Avium Extracts

“…However, recent studies have highlighted the diversity of biologically active metabolites that can be extracted from barks and upgraded as input materials in high value-added sectors [9][10][11][12]. Bark truly constitutes for every tree its first defense line against external attacks, particularly against infectious agents, and in this sense, is expected to produce compounds, notably polyphenols, potentially as antibacterial drug leads [13].…”