Table 3.

Summary of the functional properties of Phoenix dactylifera

Source of the sample (reference)	Study protocol	Findings
Saudi Arabia[3]	Commercially purchased date fruit from a market in Madinah	Flavonoid glycosides extracted from the date fruits had significant antibacterial activity against imipenem-resistant P. aeruginosa. The major flavonoids found in the extract were quercetin, luteolin, and apigenin.
Morocco[15]	Six varieties of ripe date fruits (Bouskri, Bousrdon, Bousthammi, Boufgous, Jihl, and Majhoul)	Bousrdon and Jihl had the highest antioxidant potentials based on their phenolic and flavonoid contents. Jihl had the highest antioxidant activity based on DPPH scavenging activity and a ferric-reducing power. Bousrdon and Jihl extracts had the strongest activities against select microbes including gram-positive (Bacillus subtilis, Bacillus cereus, Staphylococcus aureus) and gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Salmonella abony).
Mauritania[16]	Six varieties of ripening (Blah) and fully ripe (Tamr) date fruits: Ahmar dli, Ahmar denga, Bou seker, Tenterguel, Lemdina, and Tijib	The Blah stage had higher polyphenols and flavonoids from all varieties based on total phenolic and flavonoid contents. It also had the highest total antioxidant activity, and a high positive correlation was found between total phenolics and TEAC of the fruit methanolic extracts compared to the flavonoids, suggesting that phenolics were the major contributor to the antioxidant activity.
Malaysia[10]	Effects of chilling and storage on antibacterial properties and antioxidant capacities of Saudi Arabian cultivars (Mabroom, Safawi, and Ajwa) versus the Iranian cultivar (Mariami)	After storage at 20°C and 4°C for 5 weeks, Mariami had the highest TAC (3.18 and 1.40 mg cyd 3-glu/100 g DW, respectively), whereas Mabroom had the lowest TAC (0.54 and 0.15 mg cyd 3-glu/100 g DW, respectively). The TAC of all extracts increased after storage. The chilling of date palm fruits for 8 weeks before solvent extraction elevated the TPC of all date fruit extracts, except for methanolic extracts of Mabroom and Mariami. The TPC of all cultivar extracts decreased after 5 weeks of extract storage. IC50 values of all cultivar extracts increased after extract storage, except for the methanolic extracts of Safawi and Ajwa. Different cultivars exhibited different antibacterial properties. Only the methanolic extract of Ajwa exhibited antibacterial activity against all four bacteria tested: S. aureus, B. cereus, Serratia marcescens, and E. coli.
Sudan[17]	Six varieties of ripe date fruits (Barakawi, Gondaila, Jaw, Mishrig, Bittamoda, and Madini)	All date varieties were found to have good amounts of total polyphenols and total flavonoids (35.82–199.34 mg GAE/100 g and 1.74–3.39 mg catechin equivalent/100 g, respectively). Bittamoda and Madini had the highest TPC, whereas Bittamoda and Gondaila had the highest TFC. They also had high antioxidant activities including ferric-reducing antioxidant power (FRAP), chelation of Fe2+ ion, and scavenging of H2O2.
Algeria[18]	Seven varieties of ripe date fruits (Tantebouchte, Biraya, Degla Baidha, Deglet-Nour, Ali Ourached, Ghars, and Tansine)	All varieties had high polyphenols, flavonoids, and flavonols, although the methanolic extract of Ali Ourached cultivar had the highest
USA[19]	Six commercially available varieties of date fruits: Deglet Nour (Algeria), Deglet Nour (California), Deglet Nour (Tunisia), Shahia (Tunisia), Barni (Saudi Arabia), and Khudri (Saudi Arabia)	Total phenolic contents were found to be high (33–125 mg GAE/100 g dry weight), although Barni (Saudi Arabia) had the highest. Antioxidant activities were also found to be high based on DPPH, FRAP, and ORAC.
Oman[20]	Twenty-two varieties of date fruits (Fardh, Helali Oman, Manhi, Qush Basrah, Handal, Naghal, Qushbu Maan, Qushbu Norenjah, Qush Balquan, Qush Jabri, Seedi, Khasab, Khunaizi, Barshi, Qush Mamoor, Barni, Azad, Zabad, Khalas, Qush Tabak, Qush Lulu, and Halali Alhasa)	All varieties showed high antioxidant activity (40%–86%); Khasab, Khalas, and Fardh had the highest activities.
Saudi Arabia[21]	Two date fruit varieties (Al Sagey, Helwat Al Jouf, and Al Sour)	All varieties possessed potent antioxidant capacities because of their rich phenolic (caffeic acid, ferulic acid, protocatechuic acid, catechin, gallic acid, p-coumaric acid, resorcinol, chlorogenic acid, and syringic acid) and flavonoid (quercetin, luteolin, apigenin, isoquercitrin, and rutin) contents. Al Sagey cultivar possessed the strongest antioxidant capacities and the highest phenolic contents. Al Sagey and Helwat Al Jouf showed comparable glutathione and ascorbate redox status, whereas in Al Sour, glutathione redox status was the least.
UK[22]	Three commercially available date fruits (Deglet Nour, Khouat Allig, and Zahidi)	The majority of the total phenolic content (2058–2984 mg GAE/100 g) was assumed to be composed of flavonoids (1271–1932 mg CAE/100 g). These families of dietary phenolics may be the major ones responsible for the high antioxidant capacity reported in date seeds, which varied from 12540 and 27699 μmol TE per 100 g
Saudi Arabia[23]	Mosaifah variety fruit, seed, leaf, and bark were studied	The fruit had the highest antibacterial activity against S. aureus, Streptococcus pyogenes, E. coli, and P. aeruginosa. Carbohydrates, alkaloids, flavonoids, steroids, saponins, and +tannins were the major constituents identified.
Tunisia[24]	Three cultivars (Allig, Deglet Nour, and Bejo)	All cultivars showed strong antioxidant activities and contents, although Allig had the highest followed by Bejo and Deglet Nour. Antioxidant activities correlated positively with the total phenolic and flavonoid contents of the dates.
Tunisia[35]	Four cultivars (Gondi, Gasbi, Khalt Dhahbi, and Rtob Ahmar) of Tunisian date palm (Phoenix dactylifera L.) fruits at three maturation stages, Besser, Rutab, and Tamr	All cultivars showed highest antioxidant potentials (TPC, TFC, CTC, and AA) at Besser stage, and a significant correlation (P < 0.05) was found between the antioxidant activities and ripening. The major phenolics found were caffeic acid, ferulic acid, protocatechuic acid, and catechin for all cultivars.
Saudi Arabia[25]	Five cultivars (Helali, Medjool, Lonet-Mesaed, Khenazi, and Barhee) during different stages of ripening	The antioxidant capacity measured by the DPPH method and the antioxidant compound (phenols, tannins, and vitamin C) concentrations decreased from young stages through to the maturation and the ripening stages. The antioxidant capacity was highly positively correlated with the concentration of antioxidant compounds in most cultivars. The activities of the antioxidant enzymes, peroxidase, catalase, and polyphenol oxidase increased from the Hanabauk through to the Kimri and/or the Besser stage, on cultivar, and thereafter, declined at the ripening stages.
Algeria[26]	Ten cultivars (Mech Degla, Deglet Ziane, Deglet Nour, Thouri, Sebt Mira, Ghazi, Degla Beida, Arechti, Halwa, and Itima)	Ghazi, Arechti, and Sebt Mira possessed the strongest antioxidant capacities and the highest phenolic contents. Four phenolic acids (gallic, ferulic, coumaric, and caffeic acids) and five flavonoids (isoquercitrin, quercitrin, rutin, quercetin, and luteolin) were identified.
Tunisia[27]	Ten Tunisian date varieties (Smiti, Kenta, Bekrari, Mermella, Garn ghzal, Nefzaoui, Baht, Korkobbi, Bouhattam, and Rotbi)	Results showed that date fruit varieties were rich in soluble sugars, which varied from 35.57 (Smiti variety) to 77.88 g/100 g fresh weight (FW) (Korkobbi variety). Several minerals were also present in the following order: K, Ca, P, Mg, Na, Fe, Cu, Zn, and Mn. The potassium content reached 0.74 g/100 g dry weight in Smiti variety. For all date varieties, the phenol content did not exceed 9.70 milligram of GAE/100 g FW). The original antioxidant activity reached 31.86 mg of ascorbic acid equivalent antioxidant capacity/100 g FW for Garn ghzal variety. However, it was only 17.77 for the Nefzaoui.
Iran[28]	Ten date varieties (Khenizi, Sayer, Lasht, Kabkab, Maktoub, Gentar Shahabi, Majoul, Khazui, and Zahedi)	Among 10 different varieties, Khenizi showed the highest antioxidant activity with the FRAP value of 3279.48 μmol/100 g of the dry plant and DPPH inhibitory percentage of 56.61%. DPPH scavenging radical and FRAP values of some varieties including Khenizi, Sayer, Shahabi, and Maktub showed a significant increase and were comparable to α-tocopherol (10 mg/L). Shahabi variety with 276.85 mg GAE/100 g of the dry plant showed the highest total phenolic content compared to other varieties. There was no correlation between the accumulation of total phenol and antioxidant activity of extracts, explaining the existence of other antioxidant components in date fruits.
Saudi Arabia[29]	Three varieties (Khalas, Sukkari, and Ajwa)	Water extract has shown significantly higher contents of total phenols than alcoholic extract, especially in Ajwa (455.88 and 245.66 mg/100 g, respectively). However, phenolic profile indicated that Sukkari contained the highest rutin concentration (8.10 mg/kg), whereas catechin was approximately the same in Sukkari and Ajwa (7.50 and 7.30 mg/kg, respectively). Khalas was the variety with highest content of caffeic acid (7.40 mg/kg). A significant difference was indicated among extracts and varieties in suppressing lipid peroxidation. Sukkari and Ajwa have reduced the oxidation with 50% at lower concentration in water extract than alcoholic extract (0.63, 0.70 and 1.60, 1.43 mg/mL, respectively). Furthermore, high positive linear correlation was found between total phenols in water (r = 0.96) and alcohol (r = 0.85) extracts and inhibition of lipid oxidation activity. The compounds responsible for the activity were catechin (r = 0.96), and rutin (r = 0.74) in water extract, whereas this correlation decreased in alcoholic extract (r = 0.66) for catechin and very weak (r = 0.38) for rutin. No correlation was found between caffeic acid and lipid peroxidation in both extracts. Similar significant results were obtained with DPPH test, except with Sukkari, which showed no difference between aqueous and alcoholic extracts (4.30 and 4.10 mg/mL, respectively).
UK[30]	Date syrup from commercially available Khadrawi cultivar	DS has a high content of total polyphenols (605 mg/100 g) and is rich in tannins (357 mg/100 g), flavonoids (40.5 mg/100 g), and flavanols (31.7 mg/100 g), which are known potent antioxidants. Furthermore, DS and polyphenols extracted from DS, the most abundant bioactive constituent of DS, are bacteriostatic to both gram-positive and gram-negative E. coli and S. aureus, respectively. It has further been shown that the extracted polyphenols independently suppress the growth of bacteria at minimum inhibitory concentration (MIC) of 30 and 20 mg/mL for E. coli and S. aureus, and have observed that DS behaves as a prooxidant by generating hydrogen peroxide that mediates bacterial growth inhibition as a result of oxidative stress. At sublethal MIC concentrations, DS showed antioxidative activity by reducing hydrogen peroxide, and at lethal concentrations, DS showed prooxidant activity that inhibited the growth of E. coli and S. aureus. The high sugar content naturally present in DS did not significantly contribute to this effect.
Algeria[31]	Five cultivars (Deglet Nour [DN], Degla Baidha [DB], Ghars [Gh], Tamjhourt [Tam], and Tafezauine [Taf])	Total phenolic content ranged from 41.80 to 84.73 mg GAE/100 g and the total flavonoid content varied from 7.52 to 14.10 mg rutin equivalents (RE)/100 g. The antioxidant activities of methanolic extracts were evaluated in vitro using scavenging assays of DPPH radical, ABTS radical ion, and potassium ferricyanide complex as reducing power assay. Effective scavenging concentration (IC50) on DPPH radical ranged from 10.83 to 21.27 mg/L, the IC50 values decreased in the order DN > Tam > DB > Taf. ABTS radical cation scavenging activity (trolox equivalent 1.66–3.35 mM), the trolox equivalent antioxidant capacity values decreased in the order DN > Gh > DB > Tam > Taf. In the potassium ferricyanide complex assay, the antioxidant capacity of the extracts ranged between 2.06 and 4.21 mM ascorbic acid equivalents and the ascorbic acid equivalents antioxidant capacity values of the extracts decreased in the order Gh > Tam > DB > DN > Taf.
Tunisia[32]	Five cultivars (Beidh Hmam, Degla, Khalt Ahmar, Rtob, and Rtob Hodh) at different stages of ripening (Besser, Rutab, and Tamr).	Results showed that the content of these phytochemicals are very important at Besser stage and then decreased as the fruit ripening progressed, followed by a decrease in the antioxidant and the antibacterial activities. The analysis of the phenolic profile revealed the presence of 13 compounds. Caffeic, ferulic, and p-coumaric were detected as the major acids especially at Besser stage.
Egypt[33]	Commercially available ripe (Tamr) date variety	Water extract of Tamr stage date variety showed a higher content (14.80 mg GAE/g sample) of phenolic compounds than ethanol extract (10.31 mg GAE/g sample). High-performance liquid chromatography analysis showed the extracts contain high concentration of esculetin (15.11 and 17.30 mg/100 g) and tannic acid (2.85 and 1.79 mg/100 g). On the other hand, protocatechuic acid, catechol, pyrogallol, and cinnamic acid were not detected in both extracts. Moderate concentrations of gallic acid (7.51 and 5.28 mg/100 g), itaconic acid (6.40 and 5.91 mg/100 g), and traces of ferulic acid (0.15 and 0.22 mg/100 g) were detected. DPPH assay revealed a good antioxidant capacity of water extract, which was higher than that of ethanol extract. Antimicrobial data exhibited an impressive antibacterial activity for date extract. Date extract showed a strong antibacterial activity (for water and ethanol extracts) against E. coli (20 ± 0.57 and 16 ± 0.57 mm), Salmonella enterica (20 ± 0.54 and 14 ± 0.52 mm), and B. subtilis (18 ± 0.32 and 15 ± 0.23 mm) and moderate inhibition against S. aureus (8 ± 0.48 and 5 ± 0.52 mm) and Enterococcus faecalis (5 ± 0.36 and 2 ± 0.57 mm).
Tunisia[34]	Three cultivars (Deglet Nour, Allig, and Bejo) at full ripeness (Tamr stage)	The results revealed that second-grade dates reported three benzoic acids, five cinnamic acids, and two flavonoids, with the predominance of q-coumaric acid (1998.80 μg/100 g). The antimicrobial activities showed that the date extracts were active against gram-positive and gram-negative bacteria, showing marked activity against E. coli with an inhibition zone of 25 mm. Cytotoxicity assays showed that the date extracts were able to inhibit the proliferation of HeLa cell lines.

AA = antioxidant activities; CAE = catechin equivalents; CTC = condensed tannins content; DS = date syrup; DW = dry weight; ORAC = oxygen radical absorbance capacity; TAC = total anthocyanin content; TE = trolox equivalents; TEAC = trolox equivalent antioxidant capacity; TFC = total flavonoid content; TPC = total phenolic content