Elucidation of the betalainic chromoalkaloid profile of Pilosocereus catingicola (Grke) Byles Rowley subsp. salvadorensis (Werderm.) Zappi (Cactaceae) from Paraba, Brazil

The cacti are important plant genetic resources of the Brazilian semiarid region, with potential for the extraction of bioactive compounds such as flavonoids and alkaloids. The objective of this research was to characterize and quantify the chemical constituents of Pilosocereus catingicola (Gurke) Byles & Rowley subsp. salvadorensis (Werderm.) Zappi occurring in caatinga in the Westland of Paraiba, Brazil. We collected roots, stems and fruit of plants growing in populations at Arara, Areial and Boa Vista. Chemical characterization of the different plant tissues showed that roots and stems of P. catingicola contained steroids, flavonoids and saponins whereas fruit was dominated by high levels of betalainic chromoalkaloids (betalains). Tests performed to optimize extraction of betalains from P. catingicola fruit showed highest yields were from freeze-dried nuts extracted for 95 min, with the crude extract stored at -20°C for a maximum of 48 h. The betalains of all fruit samples were dominated by betacyanins with much lower amounts of betaxanthins observed in each population. Numerous betacyanin constituents were detected in fruit extracts, with the key constituents identified as betanin and phyllocactin. The Arara population yielded relatively more betaxanthins compared to plants from the Areial and Boa Vista regions.   Key words: Betacyanin, betanin, betaxanthin, caatinga, cactus, facheiro, phyllocactin.