Abstract Detail

Systematics

Almeida, Odair [1], Kamikawachi, Renan [2], Carrara, Virgínia [2], Vilegas, Wagner [1].

A chemotaxonomic point of view on some epiphytic cacti from Hylocereeae and Rhipsalideae.

The Cactaceae comprises about 1866 species, native to the Americas and generally inhabit arid or semi-arid environments. However, Among the cacti, Selenicereus (=Hylocereus) and Rhipsalis have gained some attention due to the difficulty of the well-defined classification. Other approaches, in addition to molecular and morfo-anatomical data, may be fundamental to support the current classifications. Chemotaxonomy is a phylogenetic approach based on information about the biochemical composition, therefore, it represents an alternative to the taxonomic questions. Thus, this study aimed to evaluate the chemical composition of Selenicereus and Rhipsalis spp in order to contribute with chemotaxonomic information to support the current classifications.Five species of Selenicerus and eleven species of Rhipsalis were collected, the samples were dried out. The dry material (100 mg) was extracted with 1 mL of methanol in an ultrasonic device for 10 min, and then it was centrifuged at 3,000 rpm for 5 min. The supernatant material was collected, filtered in a Sep-Pak C18 cartridge, dried and dissolved to a concentration of 1 mg/mL. The stock solution (1 mg/mL) was dissolved at concentrations of 5 µg/mL for analysis of direct injection in mass spectrometer (FIA-ESI-IT-MS) and 500 µg/mL for analysis of ultra performance liquid chromatography coupled to mass spectrometer (UPLC-MS). We have found, so far, the major substances present in Selenicereus are flavonoids with up to five saccharide units linked to aglycone, the aglycone varied between apigenin, kaempferol, quercetin and methylated quercetin. Conversely, the major substances present in Rhipsalis are triterpene saponins with up to four saccharide units linked to aglycone, the aglycone showed the skeleton of oleanolic acid and in some small substitutions was observed by methylation, hydroxylation or methoxylation. Flavonoids are substances associated with the photoprotection of plants and may be related to the natural environment of Selenicereus, they are products derived from the biosynthetic pathways of xiquimic acid and acetyl coenzyme A. On the other hand, triterpenic saponins have antiherbivory and antifungal activities for plants and are originating the biosynthetic pathways of mevalonic acid and deoxyxylulose phosphate. From a chemotaxonomic point of view, these results show completely different biosynthetic pathways between these two groups of epiphytic cacti, suggesting distant evolutionary lines and corroborating the phylogenetic branches established for the subfamily Cactoideae. Therefore, chemical analyzes of the secondary metabolites produced by the Cactaceae family provide information on the evolutionary branches of this family and can assist in the taxonomic definition of the species.

1 - São Paulo State University - UNESP, Praça Infante Dom Henrique, São Vicente, Sao Paulo, 11330900, Brazil
2 - São Paulo State University - UNESP, Araraquara, Sao Paulo, Brazil

Keywords:
Flavonoids
Saponins
Mass Spectrometry
secondary metabolites.

Presentation Type: Poster
Session: P3, Systematics Posters
Location: Virtual/Virtual
Date: Wednesday, July 21st, 2021
Time: 5:00 PM(EDT)
Number: P3SY005
Abstract ID:505
Candidate for Awards:None