Three stilbenes from pigeon pea with promising anti-methicillin-resistant Staphylococcus aureus biofilm formation activity.

Cajaninstilbene acid (CSA), longistylin A (LLA), and longistylin C (LLC) are three characteristic stilbenes isolated from pigeon pea. The objective of this study was to evaluate the antibacterial activity of these stilbenes against Staphylococcus aureus and even methicillin-resistant Staphylococcus aureus (MRSA) and test the possibility of inhibiting biofilm formation. The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of these stilbenes were evaluated. And the results showed that LLA was most effective against tested strains with MIC and MBC values of 1.56 µg/mL followed by LLC with MIC and MBC values of 3.12 µg/mL and 6.25 µg/mL as well as CSA with MIC and MBC values of 6.25 µg/mL and 6.25-12.5 µg/mL. Through growth curve and cytotoxicity analysis, the concentrations of these stilbenes were determined to be set at their respective 1/4 MIC in the follow-up research. In an anti-biofilm formation assay, these stilbenes were found to be effectively inhibited bacterial proliferation, biofilm formation, and key gene expressions related to the adhesion and virulence of MRSA. It is the first time that the anti-S. aureus and MRSA activities of the three stilbenes have been systematically reported. Conclusively, these findings provide insight into the anti-MRSA mechanism of stilbenes from pigeon pea, indicating these compounds may be used as antimicrobial agents or additives for food with health functions, and contribute to the development as well as application of pigeon pea in food science.

Three new glycosides from the stems of Eurya chinensis R. Br.

Two new phenolic glycosides (1 and 2), one known analogue (3), along with a new diterpene glucoside (4) were obtained from ethanolic extract of the stems of Eurya chinensis R. Br. The structures of these isolated compounds were identified by extensive analysis of HRESIMS and NMR spectroscopic data. The cytotoxicities of these compounds were evaluated on MCF-7, A549, HepG2, CaCo2 and 5-8 F cell lines by MTT method, but no obvious activities were observed.

The sesquiterpenes with the COVID-19 Mpro inhibitory activity from the Carpesium abrotanoides L.

The extract of the whole plant of Carpesium abrotanoides L. yielded four new sesquiterpenes including a novel skeleton (claroguaiane A, 1), two guaianolides (claroguaianes B-C, 2-3), and one eudesmanolide (claroeudesmane A, 4), together with three known sesquiterpenoids (5-7). The structures of the new compounds were elucidated by spectroscopic analysis especially 1D and 2D NMR spectroscopy and HRESIMS data. Additionally, all the isolated compounds were preliminarily evaluated for the inhibitive activity of COVID-19 Mpro. As a result, compound 5 showed moderate activity with an IC50 value of 36.81 µM and compound 6 exhibited a potent inhibitory effect with an IC50 value of 16.58 µM, while other compounds were devoid of noticeable activity (IC50 > 50 µM).

Four new stilbenes and one new flavonoid with potential antibacterial and anti-SARS-CoV-2 activity from Cajanus cajan.

Four new stilbenes (1-4) and one new flavonoid (5), named cajanines D-H, together with three known stilbenes (6-8) were isolated from the leaves of Cajanus cajan (L.) Millsp. (pigeon pea). The structures of these compounds were elucidated unambiguously on the basis of IR, 1D, and 2D NMR, as well as HRESIMS data. Structurally, stilbenes 1-4 bore an isopentyl side chain, and further hydroxylation of compounds 1-3 generated a greater variety of structural forms. Compound 5 was a flavonoid owning an isopentyl side chain. Besides, antibacterial activity of the isolated compounds against Staphylococcus aureus, Bacillus cereus, and Escherichia coli was studied in vitro. Compounds 1-8 were endowed with profound antibacterial activity. Among them, the MIC values of compounds 4, 6, and 7 against S. aureus were 1.56, 0.78, and 0.78 µg/mL, respectively, among which 6 and 7 had better antibacterial activity than the positive control Vancomycin with the MIC values of 1.56 µg/mL. Additionally, the anti-SARS-CoV-2 main protease activity of all the isolated compounds was evaluated, and it was worth mentioning that the IC50 values of compounds 5-7 were 8.27, 4.65, and 8.30 µM, respectively, being comparable to the positive control Ebselen. Our findings may provide valuable guidance for the application of stilbenes as lead compounds in the future for the development of drugs with antibacterial or anti-COVID-19 activity.

Four new eudesmane-type and one new eremophilane-type sesquiterpenes from the whole plant of Carpesium abrotanoides L.

The extract of the whole plant of Carpesium abrotanoides L. yielded five new sesquiterpenes including four eudesmanes (1-4) and one eremophilane (5). The new compounds were characterized by spectroscopic analysis especially 1D and 2D NMR spectroscopy and HRESIMS data. Structurally, both compounds 1 and 2 were sesquiterpene epoxides and 2 owned an epoxy group at C-4/C-15 position to form a spiro skeleton. Compounds 4 and 5 were two sesquiterpenes without lactones and 5 possessed a carboxy group in the molecule. Additionally, all the isolated compounds were preliminarily evaluated for the inhibitory activity against SARS-CoV-2 main protease. As a result, compound 2 showed moderate activity with an IC50 value of 18.79 µM, while other compounds were devoid of noticeable activity (IC50 > 50 µM).

Two new withanolides from the whole plants of Physalis peruviana.

Two new withaphysalin-type withanolides (18-O-ethylwithaphysalin R and 5-O-ethylphysaminimin C, 1 and 2), along with twelve known withanolides (3-14), were purified and identified from Physalis peruviana L. The chemical structures of these new isolates were elucidated through analyzing spectroscopic and HRESIMS data. All the obtained metabolites were appraised for their potential antiproliferative activity against the human breast cancer cell line MCF-7. Compound 7 was discovered to exhibit potent activity with an IC50 value of 3.51 µM and compounds 2, 6 and 14 showed weak cytotoxic effect.

Euryachincoside, a Novel Phenolic Glycoside with Anti-Hepatic Fibrosis Activity from Eurya chinensis.

Eurya chinensis has been recorded as a folk medicine traditionally used for treatment of a variety of symptoms. However, the phytochemical and pharmacological investigations of this plant are still scarce. A novel phenolic glycoside named Euryachincoside (ECS) was isolated by chromatographic separation from E. chinensis, and its chemical structure was identified by analysis of HRMS and NMR data. Its anti-hepatic fibrosis effects were evaluated in both HSC-T6 (rat hepatic stellate cells) and carbon tetrachloride (CCl4)-induced mice with Silybin (SLB) as the positive control. In an in vitro study, ECS showed little cytotoxicity and inhibited transforming growth factor-beta (TGF-ß)-induced Collagen I (Col1) along with alpha-smooth muscle actin (α-SMA) expressions in HSC-T6. An in vivo study suggested ECS significantly ameliorated hepatic injury, secretions of inflammatory cytokines, and collagen depositions. Moreover, ECS markedly mediated Smad2/3, nuclear factor kappa B (NF-κB) and nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathways both in vitro and vivo. These present findings confirmed that ECS is a novel phenolic glycoside from E. chinensis with promising curative effects on hepatic fibrosis, and its mechanisms may include decreasing extracellular matrix accumulation, reducing inflammation and attenuating free radicals via Smad2/3, NF-κB and Nrf2 signaling pathways, which may shed light on the exploration of more effective phenolic glycoside-based anti-fibrotic agents.

Peruranolides A-D, four new withanolides with potential antibacterial and cytotoxic activity from Physalis peruviana L.

BACKGROUND: Many drugs for anti-tumour have been developed, nevertheless, seeking new anticancer drug is the focus of ongoing investigation. Withanolides have been reported to possess potent antiproliferative activity. Literature findings revealed that a diversity of withanolides were obtained from Physalis peruviana, however, the antitumor activity of these bioactive compounds is still unclear. METHODS: The EtOAc fraction of P. peruviana were decolorized on Middle Chromatogram Isolated (MCI) Gel column, repeatedly subjected to column chromatography (CC) over sephadex LH-20, preparative High Performance Liquid Chromatography (HPLC) and silica gel to afford compounds. Their chemical structures of the new isolates were elucidated through analyzing spectroscopic and HRESIMS data. All these obtained metabolites were appraised for their potential antiproliferative activity against the human breast cancer cell line MCF-7 by MTT assay, and in vitro antibacterial activity of the isolated compounds (1-7) were evaluated against E. coli, B. cereus and S. aureus. Results: Four new withanolides, including one withaphysalin-type withanolide (peruranolide A, 1), two 13,14-seco-withaphysalins (peruranolides B-C, 2-3), as well as one normal withanolide (peruranolide D, 4), were purified and separated from P. peruviana L.. Compound 5 was discovered to exhibit potent cytotoxic effect with an IC50 value of 3.51 µM. In vitro antibacterial activities, compounds 1-7 had no obvious inhibitory activity against E. coli, but had moderate inhibitory activities against B. cereus and S. aureus. CONCLUSIONS: Our findings might offer valuable clues for the utilization of withanolides as lead compounds for antineoplastic or antibacterial drug development.