Assessment of polyphenol composition, antioxidant and antimicrobial properties of various extracts of Date Palm Pollen (DPP) from two Tunisian cultivars

Abstract

This study aimed to investigate and compare the total phenolic (TPC) and flavonoid (TFC) contents and antioxidant and antibacterial activities of different extracts recovered from Date Palm Pollen collected from Tunisian cultivars of Kerkennah (DPP-K) and Tozeur (DPP-T) using various solvents, including hexane, chloroform, ethyl acetate, acetone, ethanol and water. The results revealed that DPP-T had higher TPC than DPP-K for all solvent extracts, except for hexane, with a value of 237.74 ± 9.58 mg GAE/g for the water extract. The highest level of TFC (75.10 ± 4.37 mg QE/g) was recorded in the acetone DPP-T extract, which was about twice as high as that of DPP-K. A total of eight phenolic compounds were identified and quantified in both extracts by HPLC, namely gallic acid, catechin, caffeic acid, epicatechin, vanillic acid, coumarin, quercitin and rutin. The antioxidant activities of the extracts were screened using DPPH and β-carotene bleaching assays. The results indicated that the DPP-T acetone extract showed the best DPPH scavenging activity (IC 50 = 46.56 ± 0.28 µg/ml), with no activity being recorded for DPP-K. The DPP-T extract also showed significant effects in terms of the β-carotene test (28.12 ± 0.04 µg/ml) when compared to BHT as a reference standard. The extracts were screened for antimicrobial activity against 10 bacterial and 7 fungal strains, and the results showed that ethyl acetate DPP-K extract exhibited the strongest activity against L. monocytogenes and that the S. aureus strain was most sensitive to DPP-T, with MIC and MBC values of 0.98 mg/ml and 1.95 mg/ml, respectively. Both DPP-T and DPP-K showed strong inhibition effects on the growth of F. oxysporum. Further time kill assays demonstrated the potency of DPP-K and DPP-T ethyl acetate extracts to inhibit the growth of L. monocytogenes and S. aureus, respectively.Overall, the findings suggest that DPP could be considered a promising source of new natural antioxidant and antimicrobial agents for use in various food and pharmaceutical products and formulations. This suggested that the DPP extract is a good potential inhibitor of food 3 spoiling microbial growth and could be a highly effective therapeutic choice for human and plant infections.

Effects of Phoenix dactylifera pollen grains extract supplementation on post-thaw quality of Arabian stallion semen

“…On the other hand, α-tocopherol, one of the major sperm antioxidants, was established to be abundant in spermatozoa membrane (Suleiman et al, 1996;Surai et al, 2000) and protect sperm motility from oxidative harm (Brzezińska-Ślebodzińska et al, 1995). Besides, date palm pollen suspension was reported to have potent antimicrobial, antifungal and anti-toxicant activities (Aba Al-Khail et al, 2003;Shakibaa et al, 2011;Daoud et al, 2015) and these effects could improve postthawing semen quality through reduction of bacterial growth in the semen extender.…”

“…AlFarasi et al (2005) and Mansouri et al (2005) reported the potent antioxidant activity of the aqueous extract of dates which was attributed its inclusion to the wide range of phenolic compounds including p-coumaric, ferulic and sinapic acids, flavonoids and procyanidins. Palm pollen has also been recognised as a rich source of phytochemicals and nutrients mainly carotenoids and flavonoids (Daoud et al, 2015). Fresh pollen has a highly nutritive value as it is rich in mineral, multi-vitamins, sugars, lipids, growth factors and more than 100 enzymes and cofactors (Hassan, 2011).…”

Proximate analysis, mineral composition, phytochemical contents, antioxidant and antimicrobial activities and GC-MS investigation of various solvent extracts of cactus cladode

“…In this part, we used the same protocol as ascribed by Daoud et al (2015). Bacterial and fungal strains showing sensitivity to tested extracts are therefore selected to determine the minimum inhibitory and bactericidal/ fungicidal concentrations.…”

“…The kill-time analysis is often applied, by following the decrease of the bacterial cells growth, over time, due to the effect of a definite extract concentration as reported by our laboratory (Daoud et al, 2015). Each test was performed twice.…”

“…To investigate the mode of antimicrobial action, we used the same protocol as described by Daoud et al (2015).…”