No abstract

Twenty new chebulic acid and brevifolincarboxylic acid derivatives, including eight optically pure or achiral compounds (1–7 and 14) and six pairs of enantiomers (8a/8b–13a/13b), along with nine known analogues (15–23), were isolated from an EtOH extract of the aerial parts of Euphorbia hirta. The absolute configurations of the new compounds were assigned based on single-crystal X-ray diffraction analysis and comparison of the experimental and calculated ECD data. Racemic or scalemic mixtures of 8–13 were isolated, and their enantiomers were analyzed by chiral-phase HPLC-ECD measurements. Compound 12 possesses an unprecedented 2H-cyclopenta­[de]­chromene-2,5­(4H)-dione scaffold. Compounds 12, 20, and 23 displayed moderate inhibitory effects against lipopolysaccharide-induced nitric oxide production in BV-2 microglial cells, while all the isolates exhibited significant DPPH radical scavenging activities with EC50 values of 2.2–15.8 μM.

Three new tyramine-type alkamides (1–3), three new natural products (4–6), five new N-acylated/formylated aporphine alkamides with different ratios of rotational isomers (7–11), and 20 known alkamides (12–31) were isolated from an EtOH extract of the stems and leaves of Piper puberulum. The absolute configurations of compounds 7, 8, and 10 were determined by single-crystal X-ray diffraction analysis. In the biological activity assay, compounds 3, 5, and 10–23 displayed inhibitory effects against lipopolysaccharide-induced NO release in BV-2 microglial cells, exhibiting IC50 values of 0.93–45 μM.

Two pairs of cycloneolignane enantiomers, piperhancins A and B (1 and 2, respectively), along with two enantiomeric pairs of biosynthetic related neolignanes, hancinone C (3) and piperhancin C (4), were isolated from the stems of Piper hancei. Compound 1 is an unprecedented 1′,2:1,2′-dicyclo-8,3′-neolignane. Their structures and absolute configurations were elucidated by spectroscopic analyses, X-ray diffraction, and electronic circular dichroism calculations. Among all of the isolates, compounds (+)-1, (−)-1, (+)-2, (−)-2, and (+)-3 could significantly inhibit the production of nitric oxide secreted by lipopolysaccharide (LPS)-induced neuroinflammation in BV-2 microglial cells, with IC50 values of 1.1–26.3 μM. In addition, compound (−)-1 could decrease the mRNA levels of iNOS, IL-6, and TNF-α induced by LPS in BV-2 microglial cells.

In the present investigation, a series of ferrocene-based Schiff bases 5a-m were synthesized by the condensation of various chalcones 3a-m with S-benzyl dithiocarbazate in absolute ethanol using catalytic amount of glacial acetic acid, and characterized by element analysis, 1 H NMR, 13 C NMR, and IR. The synthesized compounds were screened for their in vitro antimicrobial activity against four bacterias (Staphylococcus aureus ATCC 9144, Bacillus cereus ATCC 11778, Escherichia coli ATCC 25922, and Pseudomonas aeruginosa ATCC 43288) and two fungals (Aspergillus niger ATCC 9092 and Aspergillus fumigatus ATCC 46645) strains. The Schiff bases 5g, 5h, and 5m against Gram-positive bacterial (E. coli and P. aeruginosa) strains was found to be higher than that for the standard drug. They are potential new drugs in antibacterial activity aspects in further days.