Indole Glycosides from Aqueous Fraction of Strychnos nitida

Steroidal alkaloids from the roots of Veratrum stenophyllum

Three new steroidal alkaloids, veratrasines A - C (1-3), along with ten known analogues (4-13) were isolated from the roots of Veratrum stenophyllum. Their structures were elucidated by NMR and HRESIMS data and comparison with the reported data in the literatures. A plausible biosynthetic pathway for 1 and 2 were proposed. Compounds 1, 3, and 8 showed moderate cytotoxic activity against MHCC97H and H1299 cell lines.

Molecular networking-based dereplication of strictosidine-derived monoterpene indole alkaloids from the curare ingredient Strychnos peckii

RATIONALE

Monoterpene indole alkaloids (MIAs) are a large group of biologically active compounds produced by hundreds of plant species in numerous plant families, such as Apocynaceae, Loganiaceae and Rubiaceae. Although this diversity is biosynthetically intermediated by strictosidine, there are no works focused on the fragmentation patterns under collision-induced dissociation of strictosidine-derived alkaloids.

METHODS

Initially, the alkaloid fingerprint of Strychnos peckii was established using leaf spray with tandem mass spectrometry (LS-MS/MS). Then, high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC/MS/MS) analyses were carried out to focus on the patterns of neutral losses in product ion scan experiments with the leaf aqueous extract. Finally, the product ion spectra from a set of presumable strictosidine-type derivatives were analyzed and organized via molecular networking (MN), and dereplicated by manual interpretation of MS/MS spectra.

RESULTS

LS-MS/MS allowed the tentative identification of strictosidine-derived alkaloids in the leaves of S. peckii, showing useful neutral losses for the dereplication of strictosidine analogues by HPLC/MS/MS experiments. The use of MN combined with manual interpretation of the fragmentation patterns highlighted characteristic fragmentation pathways, and allowed the tentative identification of strictosidine, desoxycordifoline, strictosidinic acid, 10-hydroxystrictosidine, 5-carboxystrictosidine, lyaloside, 3,4-dehydrostrictosidine and strictosidine lactam.

CONCLUSIONS

The use of MN combined with the analysis of the fragmentation patterns proved to be a useful strategy for the dereplication of strictosidine-derived MIAs from S. peckii, highlighting known and unprecedented structures, as well as useful diagnostic product ions. Therefore, this workflow is an effective approach for the characterization of strictosidine-type alkaloids in future dereplication works.

Antitumor Triterpenoid Saponin from the Fruits of Avicennia marina

The fruits of Avicennia marina are widely used for both medicine and food in Guangxi of China. As a part of our continuous effort to search for bioactive molecules from the plant, the fruits of A. marina were investigated, which has led to one new triterpenoid saponin (1) and 29 known compounds been isolated and their structures were established by using spectroscopic methods and comparing with literature data. The new triterpenoid saponin showed cytotoxicity against GSC-3# and GSC-18# with the IC50 values were 12.21 and 5.53 μg/mL respectively, and most of the known compounds had significant antioxidant capacity with the IC50 values ranging from 0.36 to 13.07 μg/mL.

Three New Pyridine Alkaloids from Vinca major Cultivated in Pakistan

Three new pyridine type alkaloids, (-)-vinmajpyridines A-C (1-3), along with two known alkaloids, have been isolated from the aerial parts of Vinca major cultivated in Pakistan. Their structures have been elucidated by means of NMR and HRESIMS spectroscopic data. The new alkaloids were evaluated for their cytotoxicity against glioma initiating cell lines (GITC-3^# and GITC-18^#), glioblastoma cell lines (U-87MG and T98G), and lung cancer cell line A-549, but none of them was active at 20 μg/mL concentration.