Proanthocyanidins and Phenolic Compounds from the Twigs of Salix chaenomeloides and Their Anti-Lipogenic Effects on 3T3-L1 Preadipocytes.

The present study investigated potential bioactive natural products from the EtOH extract of Salix chaenomeloides twigs using column chromatography, leading to the isolation of six compounds ( 1 - 6 ), which were characterized as two proanthocyanidins, procyanidin B 2 ( 1 ) and procyanidin B 1 ( 2 ), and four phenolic compounds, 4-hydroxybenzoic acid β -D-glucosyl ester ( 3 ), di- O -methylcrenatin ( 4 ), p -coumaric acid glucoside ( 5 ), and syringin ( 6 ) by the comparison of their NMR spectra with the reported data and high-resolution (HR)-electrospray ionization mass spectroscopy (ESI-MS) analysis. We investigated the potential of six compounds ( 1 - 6 ) to inhibit adipogenesis in 3T3-L1 preadipocytes, which showed that the compounds ( 1 - 6 ) significantly reduced lipid accumulation in 3T3-L1 adipocytes without affecting cell proliferation. Notably, compound 1 demonstrated a remarkable 60% and 90% reduction in lipid levels with 50 and 100 µM treatments, respectively. Oil Red O staining results indicated that compound 1 significantly inhibits the formation of lipid droplets, comparable to the effect of T863, an inhibitor of triglyceride used as a positive control, in adipocytes. Compound 1 had no effect on the regulators PPARγ, C/EBPα, and SREBF1 of adipocyte differentiation in 3T3-L1 preadipocytes, but compound 1 activated the fatty acid oxidation regulator, PPARα, compared to the lipogenic-induced control. It also suppressed fatty acid synthesis by downregulating the expression of fatty acid synthase (FAS). Finally, compound 1 induced the mRNA and protein levels of CPT1A, an initial marker of mitochondrial fatty acid oxidation in 3T3-L1. This finding substantiates the anti-lipogenic and lipolytic effects of procyanidin B 2 ( 1 ) in 3T3-L1 preadipocytes, emphasizing its pivotal role in modulating obesity-related markers.