## 4 Discussion
The TPC of the 100% methanol extract of the date seeds found in this study is higher than that reported for 14 varieties of Iranian date seeds [11] but was lower than that of the methanolic extract of some Tunisian date seeds [49]. These results revealed that it is hard to find a certain solvent system that extracts all phenolic compounds; therefore, employing an organic solvent alone or water can be more efficient in extracting most of the phenolic components of date seed samples. Similar to the TPC, Ruthana showed a significantly high total flavonoid content (TFC) while Qatarah showed the lowest. The results showed that 100% methanol was the most effective solvent, followed by the mixture of methanol:ethanol:water (40:40:20) and methanol 50% for the extraction of the TFC from date seed varieties, whereas water was the least efficient for TFC extraction. The TFC values of the date seeds were in agreement with those reported by [16] for the Saudi date seeds but higher than those of the Tunisian date seed varieties [40]. The high flavonoid yield of the mixture could be attributed to the high polarity of the solvent, which favors the extraction of flavonoids [49]. The Ruthana seed exhibited the highest TPC and TFC, ranging from 53.64 to 93.36 mg GAE/g and 21.89 to 59.89 mg CE/g, respectively, depending on the solvent system compared to the others. These values are higher than those of the Ajwa seed TPC and TFC, which range from 31.55 to 39.32 mg GAE/g and 18.4 to 29.56 mg CE/g, respectively [50], but lower than those of the Sukkari date seed, which contained 98.1 mg GAE/g phenolic and 70 mg CE/g flavonoids [16]. Several factors, including the date variety, geographic location, soil, sunlight, analytical and extraction methods, as well as the solvent system, might be responsible for the variation in the phenolic and flavonoid contents of the date seeds. The phenolic compounds in seeds are affected by the ripening stages of dates; they increase in the Rutab stage and decline progressively as the dates mature to the Tamr stage, and this was attributed to their embryo-protective effect, while at the Tamr stage, these compounds are broken down [11,31]. Carotenoids are major phytochemicals that act as colorants, vitamin precursors, and antioxidants. In the seed, carotenoid presence is necessary for the synthesis of abscisic acid, a phytohormone that regulates plant growth and development and significantly affects plant defense against bacteria and fungus. Carotenoids were found to protect against the lipid peroxidation of the membranes during seed aging and loss of viability [51]. Both the total carotenoids and anthocyanin levels contribute to the antioxidant activity of date seeds. The total carotenoid content (TCC) of the three date seeds reported in this study is higher than that of the Emirati date seed varieties [52]. The total anthocyanin content (TAC) of the three date seed varieties is in agreement with a previous study that revealed the TAC in Deglet Nour seed [53] but is higher than the TAC values of some Tunisian date seed varieties [47]. Similar to the other bioactive compounds, carotenoid and anthocyanin content were reported to vary according to cultivars, ripening stages, storage conditions, and postharvest processing [54]. Date seed was reported to contain higher antioxidant activity than date fruit [44]. The antioxidant activity of the seeds was reported to increase until the Rutab stage and then decrease in the Tamr stage due to a decrease in phenolic compounds, mainly because of polyphenol oxidase activity [55]. In plant extracts, the antioxidant activity is determined by using DPPH free radical scavenging activity and TRP, which are associated with the presence of antioxidant molecules that neutralize free radical chains by donating a hydrogen atom. This study found significant antioxidant activity differences among the tested cultivars, similar to the phenolic and flavonoid content. A strong correlation between the phenolic components and the antioxidant activity of the date seeds was observed in this study.