Estudo fitoquímico e biológico de Maytenus quadrangulata (Celastraceae)

Abstract

This work describes the phytochemical and biological study of leaves, branches, and roots of Maytenus quadrangulata (Celastraceae). The phytochemical study of the leaves and roots led to the isolation and structural identification of 41 compounds of which 31 are pentacyclic triterpenes. Among the triterpenes, fifteen belong to the friedelane skeleton (friedelan-3-one, friedelan-3β-ol, friedelan-3α-ol, friedelane-3,7-dione, 11β-hydroxyfriedelan-3-one, 3β-hydroxyfriedelan-7-one, 3α-hydroxyfriedelan-7-one, friedelane-2α,3α-diol, friedelane-3α,16β-diol, friedelane-3α,11β-diol, friedelane-3α,25-diol, 3α,29-diacetoxyfriedelane, 3α,11β-diacetoxyfriedelane, 3β,24-diacetoxyfriedelane, 3α,25-diacetoxyfriedelane, and 24-acetoxyfriedelan-3β-ol), ten belong to the lupane skeleton (lup-20(29)-en-3β-ol, 11α-hydroxylup-1:20(29)-dien-3-one, 11α-hydroxylup-20(29)-en-3-one, lup-20(29)-ene-3β,11α-diol, lup-20(29)-ene-1β,3β-diol, and lup-20(29)-ene-2α,3β,11α-triol, 2,3-seco-lup-20(29)-en-2,11α-olide-3-oic acid), two belong to the oleanane skeleton (3α-quadrangulanol and olean-9(11):12-dien-3β-ol), one is a quinonemethide (tingenone), and four are dimers (escutionin αA, 7,8-di-hydroescutionin αA, escutidin αA, and 7,8-di-hydroisoxuxuarin Eα). In addition to the triterpenes, two steroids (β-sitosterol and 3-O-β-D-glucosyl-β-sitosterol), two flavonoids (4'-O-methylepigallocatechin and 4'-O-methylcatechin 5-O-β-D-glucopyranoside), two naphthoquinones (lapachol and dehydro-α-lapachone), one phenolic aldehyde (syringaldehyde), one tropane derivative (4,8-dihydroxy-7-methyl-1-oxaspiro[2.6]nona-6,8-dien-5-one), one sesquiterpene macrocyclic alkaloid (8-O-desacetyleuonine), and one macrocyclic alkaloid derivative of spermidine (N(9)-acetyl-N(9)-desoxymaifoline) were isolated. Among the isolated compounds, eight are reported for the first time in the literature, including 3α,29-diacetoxyfriedelane, 3α,11β-diacetoxyfriedelane, 3α,25-diacetoxyfriedelane, 24-acetoxyfriedelan-3β-ol, 3α-quadrangulanol, lup-20(29)-ene-2α,3β,11α-triol, 2,3-seco-lup-20(29)-en-2,11α-olide-3-oic acid, and 4,8-dihydroxy-7-methyl-1-oxaspiro[2.6]nona-6,8-dien-5-one. It is worth noting that friedelane-3α,25-diol was isolated for the first time from a plant species. The methanolic extracts the leaves, branches, and roots, as well as the ethyl acetate extract of the roots, were analyzed by UHPLC-HRMS. A total of 53 compounds were identified putatively from this analysis, including flavonoids, triterpenes, alkaloids, glycosides, anthocyanins, sesquiterpenes and lipids. The study of the biological activities consisted of antiviral activity against Mayaro and Zika viruses, antifungal and antiproliferative activity against cancer cell lines. Extracts from the leaves and branches of M. quadrangulata showed anti-Zika and anti-Mayaro activities. In particular, the ethyl acetate extract of the leaves showed pronounced effects against Mayaro and Zika viruses, and the ethyl acetate extract of the branches exhibited significant effects against Zika virus. These extracts demonstrated low toxicity to Vero cells, with cytotoxic concentration (CC50) values higher than 953 µg/mL, potent inhibition with effective concentration (EC50) lower than 12 µg/mL, and high selectivity with indices higher than 79.