PRIMARY AND SECONDARY METABOLITE CONTRIBUTING TO THE CHEMOTAXONOMY OF NINE ALOE SPECIES GROWN IN SOUTHWESTERN HIGHLANDS OF SAUDI ARABIA

This research was conducted to investigate the primary and secondary metabolites that contribute to the chemosystematics of nine Aloe species in the Sarawat Mountains.Nine Aloe species were collected from different locations in the Kingdom of Saudi Arabia (Taif, Al-Baha, Abha and Jazan) to reassess their taxonomic position.A. armatissima had the highest protein content (106.98 mg g -1 ), while A. brunneodentata had the highest carbohydrate content (4.05 mg g -1 ).On the other side, the lowest of protein and carbohydrate contents (35.19 and 0.25 mg g -1 ) were recorded in the tissues of A. parvicoma and A. fleurentiniorum, respectively.The results of the analysis of the secondary metabolites indicated significant variations of alkaloids, cardiac glycosides, flavonoids, and phenolic compounds among the shoots of the nine studied Aloe species.It was found that A. hijazensis had the highest value of phenolic compound, but the lowest of alkaloids (25.02 and 2.30 mg g -1 , respectively).On the contrary, A. parvicoma had the highest alkaloid content and the lowest phenolic compound content (13.08 and 4.21 mg g -1 , respectively).Moreover, the highest cardiac glycoside and flavonoid contents (21.09 and 18.04 mg g -1 ) were recorded in the shoots of A. fleurentiniorum and A. castellorum, respectively, while the lowest contents (9.07 and 6.33 mg g -1 ) were recorded in A. brunneodentata and A. armatissima.In conclusion, the total chemical constituents of the nine Aloe species indicated that all the study species were greatly different except for A. castellorum and A. hijazensis (cluster A); and A. fleurentiniorum, A. sabaea and A. abhaica (cluster B), which are notably similar in their chemical constituents.