Cytotoxic activity of steroidal glycosides from the aerial parts of Solanum torvum collected in Thua Thien Hue, Vietnam

Solanum torvum induces ferroptosis to suppress hepatocellular carcinoma

ETHNOPHARMACOLOGICAL RELEVANCE

Solanum torvum Sw. (ST) is used to clear heat toxins, promote blood circulation, and alleviate blood stasis. Therefore, this plant has traditionally been used as an ethnomedicine for common cold, chronic gastritis, and tumors.

AIM OF THE STUDY

This study aimed to elucidate the mechanism by which ST induces ferroptosis in hepatocellular carcinoma (HCC), the combination effect with lenvatinib, and the impact on lenvatinib-resistant cells.

MATERIALS AND METHODS

Cell viability assays were performed using different hepatoma cell lines treated with ST. Lipid peroxidation and iron assays were performed using flow cytometry. Molecules involved in the ferroptosis pathway were detected by Western blotting. Finally, a lenvatinib-resistant cell line was established to evaluate the antiproliferative effects of ST.

RESULTS

ST ethanol extract inhibited the growth of various hepatoma cell lines. A significant reduction in glutathione peroxidase 4 (GPX4) expression was observed following ST treatment, which was accompanied by increased lipid peroxidation and Fe2+ accumulation. ST induced ferroptosis mainly through heme oxygenase-1 (HO-1) expression. HO-1 knockdown reduced ST-induced lipid peroxidation and reversed GPX4 suppression. Acyl-CoA synthetase long-chain family member 4 (ACSL4) also participated in ST-induced ferroptosis. ST and lenvatinib combination showed an additive effect, and ST retained its potential anti-HCC efficacy in a lenvatinib-resistant cell line.

CONCLUSION

This study demonstrated that the ethanol extract of ST inhibits hepatoma cell growth by inducing ferroptosis. ST displayed an additive effect with lenvatinib in Hep 3B cells and showed remarkable anti-HCC activity in lenvatinib-resistant Hep 3B cells. Collectively, the study shows that ST might have the potential to reduce lenvatinib use in clinical practice and salvage cases of lenvatinib resistance.

Anti-MRSA mechanism of spirostane saponin in Rohdea pachynema F.T.Wang & tang

ETHNOPHARMACOLOGY RELEVANCE

Rohdea pachynema F.T.Wang & Tang (R. pachynema), is a traditional folk medicine used for the treatment of stomach pain, stomach ulcers, bruises, and skin infections in China. Some of the diseases may relate to microbial infections in traditional applications. However few reports on its antimicrobial properties and bioactive components.

AIM OF THE STUDY

To identify its bioactive constituents against methicillin-resistant Staphylococcus aureus (MRSA) in vitro and in vivo, and its mechanism.

MATERIALS AND METHODS

The anti-MRSA ingredient 6α-O-[β-D-xylopyranosyl-(1 → 3)-β-D-quinovopyranosyl]-(25S)-5α-spirostan-3β-ol (XQS) was obtained from R. pachynema by phytochemical isolation. Subsequently, XQS underwent screening using the broth microdilution method and growth inhibition curves to assess its antibacterial activity. The mechanism of XQS was evaluated by multigeneration induction, biofilm resistance assay, scanning electron microscopy, transmission electron microscopy, and metabolomics. Additionally, a mouse skin infection model was established in vivo.

RESULTS

26 compounds were identified from the R. pachynema, in which anti-MRSA spirostane saponin (XQS) was reported for the first time with a minimum inhibitory concentration (MIC) of 8 μg/mL. XQS might bind to peptidoglycan (PGN) of the cell wall, phosphatidylglycerol (PG), and phosphatidylethanolamine (PE) of the cell membrane, then destroying the cell wall and the cell membrane, resulting in reduced membrane fluidity and membrane depolarization. Furthermore, XQS affected MRSA lipid metabolism, amino acid metabolism, and ABC transporters by metabolomics analysis, which targeted cell walls and membranes causing less susceptibility to drug resistance. Furthermore, XQS (8 mg/kg) recovered skin wounds in mice infected by MRSA effectively, superior to vancomycin (8 mg/kg).

CONCLUSIONS

XQS showed anti-MRSA bioactivity in vitro and in vivo, and its mechanism association with cell walls and membranes was reported for the first, which supported the traditional uses of R. pachynema and explained its sensitivity to MRSA.

Bioactive triterpenoids from Solanum torvum fruits with antifungal, resistance modulatory and anti-biofilm formation activities against fluconazole-resistant candida albicans strains

Vulvovaginal candidiasis (VVC) is the second most common vaginal infection that affects women of reproductive age. Its increased occurrence and associated treatment cost coupled to the rise in resistance of the causative pathogen to current antifungal therapies has necessitated the need for the discovery and development of novel effective antifungal agents for the treatment of the disease. We report in this study the anti-Candida albicans activity of Solanum torvum 70% ethanol fruit extract (STF), fractions and some isolated compounds against four (4) fluconazole-resistant strains of C. albicans. We further report on the effect of the isolated compounds on the antifungal activity of fluconazole and voriconazole in the resistant isolates as well as their inhibitory effect on C. albicans biofilm formation. STF was fractionated using n-hexane, chloroform (CHCl3) and ethyl acetate (EtOAc) to obtain four respective major fractions, which were then evaluated for anti-C. albicans activity using the microbroth dilution method. The whole extract and fractions recorded MICs that ranged from 0.25 to 16.00 mg/mL. From the most active fraction, STF- CHCl3 (MIC = 0.25-1.00 mg/mL), four (4) known compounds were isolated as Betulinic acid, 3-oxo-friedelan-20α-oic acid, Sitosterol-3-β-D-glucopyranoside and Oleanolic acid. The compounds demonstrated considerably higher antifungal activity (0.016 to 0.512 mg/mL) than the extract and fractions and caused a concentration-dependent anti-biofilm formation activity. They also increased the sensitivity of the C. albicans isolates to fluconazole. This is the first report of 3-oxo-friedelan-20α-oic acid in the plant as well as the first report of betulinic acid, sitosterol-3-β-D-glucopyranoside and oleanolic acid from the fruits of S. torvum. The present study has demonstrated the anti-C. albicans activity of the constituents of S. torvum ethanol fruit extract and also shown that the constituents possess anti-biofilm formation and resistance modulatory activities against fluconazole-resistant clinical C. albicans isolates.

A new steroidal saponin from the aerial parts of Solanum torvum

A new steroidal saponin, torvoside R (1), was isolated along with torvoside Q (2) and macaoside (3) from dichloromethane soluble-portion of the aerial parts of Solanum torvum. Their chemical structures were elucidated using HRESIMS, 1 D- and 2 D-NMR as well as comparison with those reported in the literature. All isolated compounds (1 - 3) exhibited cytotoxicity against SK-LU-1, HepG2, MCF-7, and T24 cancer cell lines with IC₅₀ values ranging from 14.18 to 89.31 µg/mL.