Discovery of immunosuppressive Lupane-type Triterpenoids from Hypericum longistylum

The phytochemistry study of Hypericum longistylum afforded one new degraded lupane-type triterpenoid, triterhyper A (1), and seven known congeners (2-8). The structures of those natural products were identified by extensive spectroscopic techniques and single crystal diffraction tests. Notably, triterhyper A (1) possessing an unusual 28-nor-lupane skeleton. More significantly, compounds 1-3 exhibited potential inhibitory effects on murine splenocytes proliferation stimulated by anti-CD3/anti-CD28 monoclonal antibodies (mAbs) and lipopolysaccharide (LPS), with IC₅₀ values ranging from (4.56 ± 0.45) μM to (18.34 ± 2.34) μM, highlighting that those isolates as potential lead compounds in the development of immunosuppressive drugs for autoimmune disease treatment.

Anti-BACE1 and Antimicrobial Activities of Steroidal Compounds Isolated from Marine Urechis unicinctus

The human β-site amyloid cleaving enzyme (BACE1) has been considered as an effective drug target for treatment of Alzheimer’s disease (AD). In this study, Urechis unicinctus (U. unicinctus), which is a Far East specialty food known as innkeeper worm, ethanol extract was studied by bioassay-directed fractionation and isolation to examine its potential β-site amyloid cleaving enzyme inhibitory and antimicrobial activity. The following compounds were characterized: hecogenin, cholest-4-en-3-one, cholesta-4,6-dien-3-ol, and hurgadacin. These compounds were identified by their mass spectrometry, ¹H, and ¹³C NMR spectral data, comparing those data with NIST/EPA/NIH Mass spectral database (NIST11) and published values. Hecogenin and cholest-4-en-3-one showed significant inhibitory activity against BACE1 with EC₅₀ values of 116.3 and 390.6 µM, respectively. Cholesta-4,6-dien-3-ol and hurgadacin showed broad spectrum antimicrobial activity, particularly strongly against Escherichia coli (E. coli), Salmonella enterica (S. enterica), Pasteurella multocida (P. multocida), and Physalospora piricola (P. piricola), with minimal inhibitory concentration (MIC) ranging from 0.46 to 0.94 mg/mL. This is the first report regarding those four known compounds that were isolated from U. unicinctus and their anti-BACE1 and antimicrobial activity, highlighting the fact that known natural compounds may be a critical source of new medicine leads. These findings provide scientific evidence for potential application of those bioactive compounds for the development of AD drugs and antimicrobial agents.