Dereplication of Aporphine Alkaloids by UHPLC-HR-ESI-MS/MS and NMR from Duguetia lanceolata St.-Hil (Annonaceae) and Antiparasitic Activity Evaluation

Abstract

Although the genus Duguetia is well known for producing alkaloids as chemical constituents, there are no reports of alkaloids identified in the species D. lanceolata. Thus, aiming to identify the chemical composition of this species, the dereplication of alkaloidic phase was performed by use of ultra-high performance liquid chromatography high resolution electrospray ionization tandem mass spectrometry (UHPLC-HR-ESI-MS/MS) and 1 H nuclear magnetic resonance (NMR). The chromatographic fractionation of the alkaloid extract from Duguetia lanceolata (Annonaceae) leaves afforded four fractions (I-IV) that were shown to be composed of aporphine alkaloids. 1 H NMR analysis and UHPLC-HR-ESI-MS/MS based dereplication allowed the identification of eight alkaloids: glaucine (1), norglaucine (2), isocorydine (3), N-methyllaurotetanine (4), oxoglaucine (5), liriodenine (6), lanuginosine (7), dehydroglaucine (8). Compounds 2, 3, 4, 6 and 7 were described for the first time in this species, while alkaloids 1, 5 and 8 are newly discovered in the genus Duguetia. Additionally, the antiparasitic activity of the four fractions was evaluated in vitro against Leishmania infantum and Trypanosoma cruzi. Fraction I, composed exclusively by 1, displayed activity against Leishmania infantum and Trypanosoma cruzi intracellular amastigotes, with half maximal inhibitory concentration (IC 50 ) values of 7.5 and 28.6 µg mL -1 , respectively. Fraction IV (constituted by 2, 3 and 4) showed activity against promastigotes of Leishmania infantum with IC 50 value of 50.0 µg mL -1 , while fraction II (constituted by 5 and 6) showed activity against trypomastigotes of Trypanosoma cruzi, with IC 50 values of 83.0 µg mL -1 . This work showed that fragmentation in UHPLC-HR-ESI-MS/MS combined with 1 H NMR analysis of fractions is useful for identifying alkaloids in mixtures. Additionally, it was also demonstrated the potential of aporphine alkaloids from Duguetia lanceolata St.-Hil (Annonaceae) in the search for new drug candidates for neglected diseases.

Application of effect‐directed analysis using TLC–bioautography for rapid isolation and identification of antidiabetic compounds from the leaves of Annona cherimola Mill.

“…According to their identification, bands 3–8 and 4 were assigned as alkaloids of the oxoaporphine type (Figure 3). Specifically, the fragmentation pattern of bands 3 and 8 is in line with the literature, showing the loss of CO with a fragment at m/z 248.0 [M + H‐28] + , followed by the loss of CH 2 O with a fragment at m/z 218.1 [M + H‐58] + 51–53 . It should be noted that in band 3, liriodenine inhibits α‐glycosidase and α‐amylase because it is present in LF‐1 and LF‐2, but in band 8, it only inhibits α‐amylase (Figure 1), which could be due to the different concentrations found in the fractions.…”

“…is in line with the literature, showing the loss of CO with a fragment at m/z 248.0 [M + H-28] + , followed by the loss of CH 2 O with a fragment at m/z 218.1 [M + H-58] + [51][52][53]. It should be noted that in band 3, liriodenine inhibits α-glycosidase and α-amylase because it is present in LF-1 and LF-2, but in band 8, it only inhibits α-amylase (Figure1), which could be due to the different concentrations found in the fractions.The MS/MS spectra of the protonated molecule at m/z 336.1 [M + H] + were consistent with dicentrinone.…”

“…The fragment ion at m/z 320.1 [M + H‐16] + has been previously reported for this alkaloid, 50,54 followed by the fragment at m/z 292.1 [M + H‐28] + caused by the loss of CO, and the loss of NH 3 to give the fragment at m/z 275.0 [M + H‐17] + 55 . In the case of oxoaporphine alkaloids, the amino group is conserved because it is part of an aromatic ring 52 …”

“…55 In the case of oxoaporphine alkaloids, the amino group is conserved because it is part of an aromatic ring. 52 Generally, in positive mode, aporphine alkaloids form protonated ions on the N of the isoquinoline nucleus. 51 Aporphine alkaloids and their derivatives are important constituents of Annona spp.…”

Evaluación de la actividad antioxidante in vitro de extractos de duguetia vallicola j.f. Macbr. – Annonaceae

“…Para el extracto de AcOEt, los valores son similares en ambos ensayos; mientras que, en el extracto de alcaloides totales, uno no es confiable y por tanto la comparación entre los valores no es óptima (ver tabla 1). (Fuentes, 2020;da Silva et al, 2007;Cunha, 2009;Ngouonpe et al, 2019;Dantas et al, 2020;Nardelli et al, 2021).…”