Isolation of a new iso-quinoline alkaloid and cytotoxicity studies of pure compounds and crude extracts of Ravenia spectabilis engl.

A new 2-quinolone alkaloid, iso-oligophyline (1), and two very unusual C34 terpenoids, proposed names ravespanol (2) and ravespanone (3), along with two known compounds, ß-sitosterol (4), and methyl linoleate (5), were isolated from the leaf extract of Ravenia spectabilis engl. Methyl linoleate constitutes the first report of isolation from this species. We have already reported the isolation of atanine (6), oligophyline (7), ravenoline (8), and arborinine (9) from the plant. Based on nuclear magnetic resonance (NMR) spectroscopy and mass spectrometric analysis, the structure of the isolated chemicals was determined. The crude fractions and four compounds (6,7,8 and 9) were evaluated for a cytotoxicity study on a panel of six human stomach cancer cell lines (SCL, SCL-6, SCL-37'6, SCL-9, K-3, N21) by MTT assay. Among the plant extracts and isolated compounds, petroleum ether fraction and compound 7 exhibited the highest cytotoxic activity against SCL and SCL-6 cells, where the IC50 values were 17.9 and 16.56 µM, respectively.

Isolation and In Silico Prediction of Potential Drug-like Compounds with a New Dimeric Prenylated Quinolone Alkaloid from Zanthoxylum rhetsa (Roxb.) Root Extracts Targeted against SARS-CoV-2 (Mpro).

A new dimeric prenylated quinolone alkaloid, named 2,11-didemethoxy-vepridimerine A, was isolated from the root bark of Zanthoxylum rhetsa, together with twelve known compounds. The structure of the new compound was elucidated on the basis of spectroscopic investigations (NMR and Mass). The interaction of the isolated compounds with the main protease of SARS-CoV-2 (Mpro) was evaluated using molecular docking followed by MD simulations. The result suggests that 2,11-didemethoxy-vepridimerine A, the new compound, has the highest negative binding affinity against the Mpro with a free energy of binding of -8.5 Kcal/mol, indicating interaction with the Mpro. This interaction was further validated by 100 ns MD simulation. This implies that the isolated new compound, which can be employed as a lead compound for an Mpro-targeting drug discovery program, may be able to block the action of Mpro.

Indole alkaloids from the leaves of Ravenia spectabilis engl. with activity against pancreatic cancer cell line.

Two previously undescribed indole alkaloids, 3-prenyl-5(3-keto-but-1-enyl) indole and 3-prenyl-indole-5-carbaldehyde, the structurally-related 3,5-diprenyl indole and four known alkaloids were isolated from the leaves of Ravenia spectabilis Engl. Structures were elucidated based on nuclear magnetic resonance (1D and 2D NMR) spectroscopic and mass spectrometric analysis. The previously undescribed compounds isolated were subsequently screened against the HeLa (human cervical cancer), MIA PaCa-2 (human pancreatic adenocarcinoma) and A549 (lung cancer) cell lines. Among the isolated compounds, 3,5-diprenyl indole was the most cytotoxic across all three cell lines (MIA PaCa-2 IC50 = 9.5 ± 2.2 µM). Molecular modelling studies suggested DNA intercalation as the mode of action of these compounds.