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Myrtaceae Juss. is a very large family of flowering plants, that are a valuable source of bioactive compounds. From the phytochemical point of view, apart from ubiquitous tannins, flavonoid derivatives and volatile oils, Myrtaceae plants are very rich in phloroglucinol derivatives, divided in two principal subclasses: oligomeric acylphloroglucinols and phloroglucinol-terpene adducts. Despite this large structural variability, many studies on phloroglucinols from the Myrtaceae have focused on unique bioactive acylphloroglucinol compounds, named myrtucommulones. Nevertheless, many studies also reported other interesting phloroglucinol derivatives. Therefore, in this review, a comprehensive description of the chemical features of acylphloroglucinols and meroterpenoid-acylphloroglucinols from the Myrtaceae family is presented along with their biological activities. Moreover, since myrtucommulones and their derivatives have become attractive targets for organic chemists, thanks to their structural features and biological activities, relevant approaches and synthetic procedures are herewith discussed.

A dereplication strategy using UPLC-QTOF/MSE, the HMAI method, and NMR spectroscopy led to the identification of five main steroidal saponins (1-5), including three previously unknown compounds named macroacanthosides A-C (3-5), in a bioactive fraction of Agave macroacantha. The major saponins were isolated, and some of them together with the saponin-rich fraction were then evaluated for phytotoxicity on a standard target species, Lactuca sativa. The inhibition values exhibited by the pure compounds were confirmed to be in agreement with the phytotoxicity of the saponin-rich fraction, which suggests that the saponin fraction could be applied successfully as an agrochemical without undergoing any further costly and/or time-consuming purification processes. The NMR data of the pure compounds as well as of those corresponding to the same compounds in the fraction were comparable, which indicated that the main saponins could be identified by means of this replication workflow and that no standards are required.

Plants are the everlasting source of a wide spectrum of specialized metabolites, characterized by wide variability in term of chemical structures and different biological properties such antiviral activity. In the search for novel antiviral agents against Human Immunodeficiency Virus type 1 (HIV-1) from plants, the phytochemical investigation of Scrophularia trifoliata L. led us to isolate and characterize four flavonols glycosides along with nine iridoid glycosides, two of them, 5 and 13, described for the first time. In the present study, we investigated, for the first time, the contents of a methanol extract of S. trifoliata leaves, in order to explore the potential antiviral activity against HIV-1. The antiviral activity was evaluated in biochemical assays for the inhibition of HIV-1Reverse Transcriptase (RT)-associated Ribonuclease H (RNase H) activity and HIV-1 Integrase (IN). Three isolated flavonoids, rutin, kaempferol-7-O-rhamnosyl-3-O-glucopyranoside, and kaempferol-3-O-glucopyranoside, 8–10, inhibited specifically the HIV-1 IN activity at submicromolar concentration, with the latter being the most potent, showing an IC50 value of 24 nM.

WOS: 000456899500016, PubMed: 30529825, In this study, ethyl acetate, acetone, ethanol and water extracts from flowers, stems and roots of Cistanche phelypaea (L.) Cout were appraised for radical scavenging activity (RSA) towards 1,1-diphenyl-2-picrylhydrazyl,2,2-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) and superoxide free radicals, and for metal chelating activities on iron and copper ions. The water extracts had the highest antioxidant activity, especially those from roots and flowers, and were further appraised for in vitro inhibition of enzymes implicated on the onset of human ailments, namely acetyl- (AChE) and butyrylcholinesterase (BuChE) for Alzheimer's disease, alpha-glucosidase and alpha-amylase for diabetes, and tyrosinase for skin hyper-pigmentation disorders. The extracts had a higher activity towards BuChE, and the roots extract had the highest capacity to inhibit tyrosinase. Samples showed a low capacity to inhibit carbohydrate hydrolysing enzymes, except for the root extract with a good inhibition on glucosidase. Samples were then characterized by NMR (1D and 2D): the main metabolites identified in the flowers extract were iridoid glycosides, in particular gluroside and bartsioside. In stems, phenylehanoid glycosides (PhGs) and iri doids were detected, especially acteoside. In roots were detected essentially PhGs, mainly echinacoside and tubuloside A. Docking studies were performed on the identified compounds. A favorable binding energy of tubuloside A to tyrosinase was calculated, and indicated this compound as a possible competitive inhibitor of alpha-glucosidase and tyrosinase. Our results suggest that C. phelypeae is a promising source of biologically-active compounds with health promoting properties for pharmaceutical and biomedical applications. (C) 2018 Elsevier B.V. All rights reserved., Foundation for Science and Technology (FCT, Portugal)Portuguese Foundation for Science and Technology; Portuguese National Budget funding through the CCMAR project [CCMAR/Multi/04326/2013]; FCTPortuguese Foundation for Science and Technology [IF/00049/2012, SFRH/BD/94407/2013, SFRH/BD/116604/2016], This work was supported by the Foundation for Science and Technology (FCT, Portugal) and by the Portuguese National Budget funding through the CCMAR/Multi/04326/2013 project. Luisa Custodio was supported by FCT Investigator Programme (IF/00049/2012). Catarina Guerreiro Pereira and Maria Joao Rodrigues acknowledges FCT for the PhD grants SFRH/BD/94407/2013 and SFRH/BD/116604/2016, respectively.