Chemical diversity during ontogeny of Piper auritum (Kunth)

Piper auritum a is shrub belonging to Piperaceae family, native to Central América and widely used in folk medicine and culinary (Ampforo et al., 1987). Despite the numerous studies carried out in its essential oil (Caballero-Gallardo et al., 2014), there is no further information on the phytochemical composition of this species. This work aims to characterize the metabolite diversity from different organs (leaves, roots, and fruits) of this species as well as to determine the differences in the metabolic profile during its ontogeny. The general fractionation of crude extracts included a partition between dichloromethane-water with the polar fraction being further purified by flash CC, RP-CC and semi-preparative HPLC. The resulting fractions or pure compounds were analyzed by HPLC-DAD-ESI-HRMS as well as by 1H and 13C NMR (1D and 2D). Thirty compounds were identified, apart of the asarone and safrole (Parmar et al.,1997), which were described from essential oils by several authors, the fractions contain the amides pellitorine (8) and 1-cinnamoylpyrrolidine (11); phenylpropanoids dillapiole (9), elemicin (5), and isoasarone (21); the aristolactams cepharanone A (3) and B (4) (Hänsel and Leuschke., 1975), the piperolides 4,6-dimethoxy-5-E-phenylbutenolide (1), 4,6-dimethoxy-5-Z-phenylbutenolide (2) and a novel cyclobutane-photodimer (6) of the piperolides. The seven major compounds from fruits were characterized as the C-glycosyl-flavonoids: 6"-O- glucosylvitexin (23), orientin (24), vitexin-2"-rhamnoside (25), vitexin and scoparin (26), margaritene (27), trematin (28) and isoembigenin (29). While most of these compounds were also found in leaves and fruit fractions, the adult leaves and seedlings showed a similar profile contrasting from that observed for P. gaudichaudianum (Gaia et al., 2014). Most of these compounds were reported for the first time for the family and the overall data indicated that P. auritum has a complex phytochemical composition based on the production of secondary compounds from different classes of natural products.