Metabolomics and molecular networking analyses in Arabidopsis thaliana show that extracellular self-DNA affects nucleoside/nucleotide cycles with accumulation of cAMP, cGMP and N6-methyl-AMP.

Extracellular DNA (exDNA) widely occurs in the environment due to release by either cell lysis or active secretion. The role of exDNA in plant-soil interactions has been investigated and inhibitory effects on the growth of conspecific individuals by their self-DNA have been reported. Transcriptome analysis in the model plant Arabidopsis thaliana showed a clear recognition by the plant roots of self- and nonself-exDNA, with inhibition occurring only after exposure to the former. In this study, an untargeted metabolomics approach was used to assess at molecular level the plant reactions to exDNA exposure. Thus, the effects on the metabolites profile of A. thaliana after exposure to self- and nonself-exDNA from plants and fish, were studied by NMR, LC-MS, chemometrics and molecular networking analyses. Results show that self-DNA significantly induces the accumulation of RNA constituents (nucleobases, ribonucleosides, dinucleotide and trinucleotide oligomers). Interestingly, AMP and GMP are found along with their cyclic analogues cAMP and cGMP, and in form of cyclic dimers (c-di-AMP and c-di-GMP). Also methylated adenosine monophosphate (m6AMP) and the dimeric dinucleotide N-methyladenylyl-(3'→5') cytidine (m6ApC) increased only in the self-DNA treatment. Such striking evidence of self-DNA effects highlights a major role of exDNA in plant sensing of its environment.

Antiviral Activity of Vitis vinifera Leaf Extract against SARS-CoV-2 and HSV-1.

Vitis vinifera represents an important and renowned source of compounds with significant biological activity. Wines and winery bioproducts, such as grape pomace, skins, and seeds, are rich in bioactive compounds against a wide range of human pathogens, including bacteria, fungi, and viruses. However, little is known about the biological properties of vine leaves. The aim of this study was the evaluation of phenolic composition and antiviral activity of Vitis vinifera leaf extract against two human viruses: the Herpes simplex virus type 1 (HSV-1) and the pandemic and currently widespread severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). About 40 phenolic compounds were identified in the extract by HPLC-MS/MS analysis: most of them were quercetin derivatives, others included derivatives of luteolin, kaempferol, apigenin, isorhamnetin, myricetin, chrysoeriol, biochanin, isookanin, and scutellarein. Leaf extract was able to inhibit both HSV-1 and SARS-CoV-2 replication in the early stages of infection by directly blocking the proteins enriched on the viral surface, at a very low concentration of 10 µg/mL. These results are very promising and highlight how natural extracts could be used in the design of antiviral drugs and the development of future vaccines.

Trifolium Repens Blocks Proliferation in Chronic Myelogenous Leukemia via the BCR-ABL/STAT5 Pathway.

Some species of clover are reported to have beneficial effects in human diseases. However, little is known about the activity of the forage plant Trifolium repens, or white clover, which has been recently found to exert a hepatoprotective action. Scientific interest is increasingly focused on identifying new drugs, especially natural products and their derivatives, to treat human diseases including cancer. We analyzed the anticancer effects of T. repens in several cancer cell lines. The phytochemical components of T. repens were first extracted in a methanol solution and then separated into four fractions by ultra-high-performance liquid chromatography. The effects of the total extract and each fraction on cancer cell proliferation were analyzed by MTT assay and Western blotting. T. repens and, more robustly, its isoflavonoid-rich fraction showed high cytotoxic effects in chronic myelogenous leukemia (CML) K562 cells, with IC50 values of 1.67 and 0.092 mg/mL, respectively. The block of cell growth was associated with a total inhibition of BCR-ABL/STAT5 and activation of the p38 signaling pathways. In contrast, these strongly cytotoxic effects did not occur in normal cells. Our findings suggest that the development of novel compounds derived from phytochemical molecules contained in Trifolium might lead to the identification of new therapeutic agents active against CML.

Paviosides A-H, eight new oleane type saponins from Aesculus pavia with cytotoxic activity.

A phytochemical analysis of Aesculus pavia has led to the isolation of eight novel triterpenoid saponins, based on oleane type skeleton and named paviosides A-H (1a, 1b-4a, 4b). On the basis of chemical, and 2D NMR and mass spectrometry data, the structures of the new compounds were elucidated as 3-O-[ß-D-xylopyranosyl (1 → 2)] [-ß-d-glucopyranosyl (1 → 4)]-ß-D-glucopyranosiduronic acid 21-tigloyl-22-acetyl barringtogenol C (1a), 3-O-[ß-D-xylopyranosyl (1 → 2)] [-ß-D-glucopyranosyl (1 → 4)]-ß-D-glucopyranosiduronic acid 21-angeloyl-22-acetyl barringtogenol C (1b), 3-O-[ß-D-xylopyranosyl (1 → 2)] [-ß-D-galactopyranosyl (1 → 4)]-ß-D-glucopyranosiduronic acid 21-tigloyl-22-acetyl barringtogenol C (2a), 3-O-[ß-D-xylopyranosyl (1 → 2)] [-ß-D-galactopyranosyl (1 → 4)]-ß-D-glucopyranosiduronic acid 21-angeloyl-22-acetyl barringtogenol C (2b), 3-O-[ß-D-xylopyranosyl (1 → 2)] [-ß-D-xylopyranosyl (1 → 4)]-ß-D-glucopyranosiduronic acid 21-tigloyl-22-acetyl barringtogenol C (3a), 3-O-[ß-D-xylopyranosyl (1 → 2)] [-ß-D-xylopyranosyl (1 → 4)]-ß-d-glucopyranosiduronic acid 21-angeloyl-22-acetyl barringtogenol C (3b), 3-O-[ß-D-xylopyranosyl (1 → 2)] [-ß-D-xylopyranosyl (1 → 4)]-ß-D-glucopyranosiduronic acid 21-tigloyl-22-acetyl protoaescigenin (4a), and 3-O-[ß-D-xylopyranosyl (1 → 2)] [-ß-D-xylopyranosyl (1 → 4)]-ß-D-glucopyranosiduronic acid 21-angeloyl-22-acetyl protoaescigenin (4b). The compounds showed cytotoxic activity on J-774, murine monocyte/macrophage, and WEHI-164, murine fibrosarcoma, cell lines. Among them, paviosides E-H (3a, 3b and 4a, 4b) showed higher activity with values ranging from 2.1 to 3.6 µg/mL. Structure-activity relationship studies indicated the positive effect on the activity of xylose unit in the place of glucose, while a little detrimental effect is observed when glucose is substituted by galactose. The aglycone structure and the presence of a tigloyl or an angeloyl group at C-21 do not affect significantly the inhibitory activity on both tested cell lines.