Chemical and dereplication studies of Palicourea tomentosa (Aubl.) Borhidi and their antimicrobial and anticholinesterase activities

Abstract

Palicourea tomentosa (Aubl.) Borhidi (Rubiaceae, Palicoureeae), earlier classified as Psychotria poeppigiana Müll. Arg., is used in folk medicine for a variety of diseases. Biological studies on the plant describes their vasorelaxant, antiplasmodial, antitumoural and anticholinesterase activities. To expand the knowledge on the chemical and biological potential of this species, in this work, phytochemical and dereplication studies, as well as antimicrobial and anticholinesterase evaluation of Palicourea tomentosa were carried out. Phytochemical investigation deals with the isolation of lutein (1), a mixture of dehydrovomifoliol (2) and megastigma-4,7-dien-3-one (3), loliolide (4), 5,13-epoxy-9-hydroxy-megastigma-7-en,3-one (5), vomifoliol (6), asperuloside (7), 3-O-p-coumaroylquinic acid (8), and a mixture of the pyrrolizidinoindoline alkaloids hodgkinsine (9), chimonanthine (10) and psychotriasine (11). The ultra-high performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC HRMS/MS) based on molecular networking dereplication of dichloromethane fraction led to putative identification of other two megastigmanes, one terpene lactone and three carotenoids, besides seven triterpenes and four indole alkaloids. The dichloromethane, ethyl acetate and hydromethanol fractions of P. tomentosa were able to inhibit Candida albicans with minimum inhibitory concentrations (MICs) of 125, 250 and 125 µg mL-1, respectively. The methanol crude extract, dichloromethane and alkaloid fractions inhibited selectively the butyrilcholinesterase (BuChE) at percentages of 63.09, 60.39 and 56.22%, respectively.

Keywords

• Palicourea tomentosa
• pyrrolizidinoindoline alkaloids
• megastigmanes
• antimicrobial activity
• anticholinesterase activity