A new phenylpropanoid glycoside from the bark of Streblus ilicifolius (Vidal) Corner

Megastigmane glycosides from Streblus ilicifolius (S.Vidal) Corner and their anti-inflammatory activity

Twelve undescribed megastigmane glycosides, streilicifolosides A-L (1-12), together with 8 known analogues (13-21) were isolated from the leaves of Streblus ilicifolius (S.Vidal) Corner. Their plannar structures were elucidated using extensive NMR spectroscopic methods (1D and 2D-NMR spectroscopy), and HRESIMS spectroscopic data analyses. The absolute configurations of the undescribed compounds were determined by the glucose-induced shift-trend, calculated and experimental circular dichroism spectroscopy. All the compounds were tested for inhibitory effects on the production of NO in LPS-treated RAW264.7 cells, and streilicifoloside E and platanionoside D exhibited potent anti-inflammatory activity comparable to that of the positive control, with IC₅₀ values of 26.33 and 21.84 μM, respectively. Furthermore, these two compounds markedly decreased the secretion of PGE2 and TNF-α and inhibited the expression of COX‒2, iNOS and NF-κB/p65 in LPS-induced RAW264.7 cells in a dose-dependent manner. In addition, the structure-activity relationships of the isolates were also discussed. The results suggest that streilicifoloside E and platanionoside D could be used as potential candidates for the development of new anti-inflammatory agents.

Strebluses E-H, four new stilbene-like derivatives from the stems of Streblus ilicifolius

Following bioactivity-guided isolation, four new stilbene-like derivatives, named Strebluses E-H, were isolated from the EtOAc-soluble fraction of the stems of Streblus ilicifolius (Moraceae). Their chemical structures were elucidated based on NMR spectroscopic data interpretation and optical rotation calculation. Streblus E possesses potent tyrosinase inhibitory activity with an IC₅₀ value of 0.1 μM. Oxy-tyrosinase has two bound Cu²⁺ ions and a peroxide group in the binding site, which has a role in the catalytic oxidation. Thus, a docking study of Streblus E with oxy-tyrosinase was performed to analyze the ligand-protein interactions. With in silico modelling, the S value and the ligand-protein interactions suggested that Streblus E showed lower binding affinity for oxy-tyrosinase than that of Streblus C.

Tyrosinase Inhibitors from the Stems of Streblus Ilicifolius

Two new stilbene derivatives, named strebluses C and D, were isolated from the EtOAc-soluble fraction of the stems of Streblus ilicifolius (Moraceae). Its absolute configuration was elucidated based on NMR spectroscopic data interpretation and optical rotation calculation. Streblus C possesses strong tyrosinase inhibitory activity with an IC₅₀ value of 0.01 μM. Docking studies of 1 and 2 with oxy-tyrosinase were carried out to analyze their interactions. The analysis of the docked poses confirmed that 1 showed better binding affinity for oxy-tyrosinase than that of 2.

Two new derivatives of 8-prenyl-5,7-dihydroxycoumarin from the stems of Streblus ilicifolius (S.Vidal) Corn

From the EtOAc-soluble extract of the stems of Streblus ilicifolius (Moraceae), two new secondary metabolites named strebluses A (1) and B (2) were isolated. Their chemical structures have been concluded based on the chemical derivatisation and the spectroscopic interpretation. All compounds have been tested for their tyrosinase inhibitory activity. They showed weaker inhibitory activity than that of kojic acid (IC₅₀, 44.6 µM).

Two new amide glycosides with anti-inflammatory activity from the leaves of Streblus ilicifolius (Vidal) Corner

Two new amide glycosides, streblusoamides A (1) and B (2), along with 11 known compounds (3-13) were isolated from the leaves of Streblus ilicifolius. The structures of the isolates were elucidated by spectroscopic methods. All of the isolates were tested for inhibition of NO production in lipopolysaccharide (LPS)-induced RAW 264.7 cells to investigate their anti-inflammatory effects. The results revealed that compounds 1, 5 and 6 moderately inhibited the release of NO production with IC₅₀ values ranging from 50.90 μM to 64.79 μM.