Hypericum triquetrifolium and H. neurocalycinum as Sources of Antioxidants and Multi-Target Bioactive Compounds: A Comprehensive Characterization Combining In Vitro Bioassays and Integrated NMR and LC-MS Characterization by Using a Multivariate Approach

Abstract

Hypericum triquetrifolium and H. neurocalycinum were evaluated for their phytochemical content and in vitro bioactivity. NMR analyses were performed on the methanol extract of the aerial parts of H. triquetrifolium to establish the main classes of phytoconstituents. Then, LC-DAD-MSn analyses were performed in order to compare the composition of aerial parts and roots extracts of both Hypericum species, obtained using either methanol or water as solvents. Results, processed using multivariate data analysis, showed a significantly higher phenolic content of methanol extracts compared to water extracts, while minor qualitative differences were observed between the two. Distinctive flavonoid and PAC patterns were observed for H. triquetrifolium and H. neurocalycinum, and specific compounds were exclusively detected in one or the other species. Specifically, the phloroglucinols 7-epiclusianone, hyperfirin and hyperforin were present only in H. neurocalycinum, while hyperforin was detected only in H. triquetrifolium. Extracts were assayed using different in vitro tests to evaluate their antioxidant properties and their inhibitory activity against several enzymes, showing significant antioxidant and metal chelating activities. Furthermore, inhibitory properties against acetylcholinesterase, butyrylcholinesterase and tyrosinase were observed. Multivariate approaches were used to correlate biological data with the phytochemical composition of the different extracts. The results, showing positive correlations between specific chemical constituents and the measured bioactivities, represent preliminary data that could guide future studies aimed at isolating bioactive constituents from H. neurocalycinum and H. triquetrifolium for further pharmacological evaluations.

Biological Activity of Genus Hypericum Sect. Hypericum Species—H. tetrapterum, H. maculatum subsp. immaculatum, H. triquetrifolium

“…The evaluated Hypericum extracts have demonstrated modest inhibitory activity of α-amylase when compared to acarbose, which was used as the positive control, but strong anti-α-glucosidase activity (Table 2). The obtained results correspond to previous studies [12,18,25,35] and indicate a strong, statistically significant correlation (p < 0.05) between anti-α-glucosidase activity and quantified amounts of quercetin (r = −0.80), epicatechin (r = −0.78) and phenolic acids (gallic and chlorogenic acid). Phenolic compounds have been recognized as inhibitors of the aforementioned enzymes, while in the case of α-amylase, the proposed mechanism includes the interaction of hydroxyl groups with amino acid residues at the active site (Glu233) [36].…”

“…A number of drugs have been developed with the aim of modifying the activity of these enzymes that are vital in the pathophysiology of some of the frequent diseases. The obtained results have demonstrated moderate anticholinesterase and anti-MAO-B activity of the examined Hypericum extracts, with IC 50 values in the range 606.03-1304.04 µg/mL and 47.81-59.25 µg/mL, respectively (Table 2), which are in accordance with previous studies of these species [18], as well as H. perforatum extracts [2,12,25]. It can be easily noticed that the IC 50 values obtained for galantamine and selegiline under identical experimental conditions are significantly lower, which questions the acute effects of Hypericum extracts as inhibitors of AChE and MAO-B.…”

“…The evaluated Hypericum extracts have exhibited a strong scavenging potential of DPPH radical, with RSC 50 values in the range 1.93-3.54 µg/mL, which was also demonstrated in the previously conducted studies [16][17][18][19] and is further confirmed by the IC 50 values obtained for quercetin dihydrate and propyl gallate (Table 2). Although there were reports stating that hypericins could be responsible for the antioxidant effect of Hypericum species [20], it is much more likely that this activity is a result of phenolic acids and flavonoid presence [19].…”

Novel Signposts on the Road from Natural Sources to Pharmaceutical Applications: A Combinative Approach between LC-DAD-MS and Offline LC-NMR for the Biochemical Characterization of Two Hypericum Species (H. montbretii and H. origanifolium)

“…We previously used the analysis of methanol extract by NMR as a screening technique with other Hypericum species to drive the further investigations obtained by LC-MS [ 38 ]. To improve that approach, which suffers from the limited resolving power of NMR when directly applied to very complex mixtures as crude extracts, in this paper, we decided to perform fractionation of the extracts.…”

Cytotoxic and Antioxidant Activity of Hypericum perforatum L. Extracts against Human Melanoma Cells from Different Stages of Cancer Progression, Cultured under Normoxia and Hypoxia

“…The particularly strong antioxidative effect of HpEx2 (the most polyphenol-rich and with the highest DPPH-scavenging activity) may be associated with the phenolic antioxidant activity, based on free radical scavenging. Reports suggest that hyperforin has a weak effect on DPPH inhibition, but some phenolic compounds, such as p -cumaroylquinic acids, quercetin, rutin, adhyperforin, and some procyanidin derivatives, are probably responsible for the majority of DPPH scavenging, like in other Hypericum species [ 36 , 56 ]. In the studied HpExs, DPPH scavenging activity correlates with total phenolic compounds, similar to the results obtained by Marreli et al [ 45 ].…”