Galloyl Group in B-type Proanthocyanidin Dimers Was Responsible for Its Differential Inhibitory Activity on 3T3-L1 Preadipocytes due to the Strong Lipid Raft-Perturbing Potency

Abstract

The effects of three B-type proanthocyanidin (PA) dimers covering procyanidin B2 (B-0g), procyanidin B2 3′-O-gallate (B-1g), and procyanidin B2 3,3′-di-O-gallate (B-2g) on 3T3-L1 preadipocyte differentiation and the underlying mechanisms were investigated. The results showed that digalloylated B-type PA dimers (B-2g) strongly inhibited 3T3-L1 preadipocyte differentiation through disrupting the integrity of the lipid raft structure and inhibiting the expression of peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer-binding protein alpha (C/EBPα) and then downregulating the expression of acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS) factors, followed by B-1g, while B-0g had little effect. The different inhibitory effects were mainly due to the difference in the B-type PA dimer structure and the ability to interfere with lipid rafts. The greater the galloylation degree of B-type PA dimers, the stronger the ability to disrupt the lipid raft structure and oppose 3T3-L1 preadipocyte differentiation. In addition, galloylated B-type PA dimers had greater molecular hydrophobicity and topological polarity surface area and could penetrate into the lipid rafts to form multiple hydrogen bonds with the rafts by molecular dynamics simulation. These findings highlighted that the strong lipid raft-perturbing potency of galloylated B-type PA dimers was responsible for inhibition of 3T3-L1 preadipocyte differentiation.

Targeting Lipid Rafts as a Rapid Screening Strategy for Potential Antiadipogenic Polyphenols along with the Structure–Activity Relationship and Mechanism Elucidation

“…There is increasing evidence which suggests that the structure and function of the lipid rafts play important roles in the cellular biological activities. , For example, changes in the structure of the lipid rafts could affect the differentiation of the 3T3-L1 preadipocytes into mature adipocytes, thereby interfering with the whole-body fuel homeostasis . Furthermore, the results of our earlier studies showed that the effects of polyphenols with different biological activities on the structure of lipid rafts also differed. , Therefore, we inferred that the lipid rafts could fill this gap by linking the properties of chemical substances with their biological activities and offering a better interpretation for the SAR of polyphenols. To test this assumption, we first correlated the interaction between several polyphenols and the lipid rafts with their differentiation-inhibitory effects on 3T3-L1 preadipocytes and found that these interactions and effects were highly positively correlated.…”

“…In contrast, the epicatechin-(4β → 8, 2β → O → 7)-epicatechin (A-type EC dimer) displayed a minimal effect on the lipid raft structure of 3T3-L1 preadipocytes and showed a rather low inhibitory effect . Importantly, our previous results showed that polyphenols at physiological concentrations could significantly interfere with the structural integrity of lipid rafts, thereby exerting the ability to inhibit 3T3-L1 preadipocyte differentiation . Therefore, we hypothesized that lipid rafts might be an attractive target for explaining the mechanism underlying the pleiotropic actions of polyphenols as well as for screening bioactive polyphenols.…”

“…Recently, we found that in silico tools, such as molecular dynamic simulations (MDSs), were a valuable tool to elucidate the mechanism of action of bioactive molecules and study the interactions between bioactive compounds and lipid rafts. ,, Furthermore, the specific physicochemical parameters, such as the binding process, binding site, interaction energy, and so on, can be obtained because MDSs take the motion of molecules into account. Thus, the MDS has also great advantages in the study of the SAR.…”

“…8 Importantly, our previous results showed that polyphenols at physiological concentrations could significantly interfere with the structural integrity of lipid rafts, thereby exerting the ability to inhibit 3T3-L1 preadipocyte differentiation. 33 Therefore, we hypothesized that lipid rafts might be an attractive target for explaining the mechanism underlying the pleiotropic actions of polyphenols as well as for screening bioactive polyphenols. Similar to the elucidation of the mechanisms that mediate the effect of lipid rafts, the study of the structure−activity relationship (SAR) of polyphenols remains challenging because of the great diversity in the chemical structure of polyphenols and the lack of reliable or accurate research tools.…”

The galloyl moiety enhances inhibitory activity of polyphenols against adipogenic differentiation in 3T3-L1 preadipocytes

“…As mentioned previously, 22 the mature lipid droplets were marked with Oil Red O (ORO) dye. Differentiation was monitored under a Nikon microscope and quantified at 490 nm by an eluting stain in 100% isopropyl alcohol.…”