Elderberry (Sambucus nigra L.) Fruit Extract Alleviates Oxidative Stress, Insulin Resistance, and Inflammation in Hypertrophied 3T3-L1 Adipocytes and Activated RAW 264.7 Macrophages

Oxidative stress and inflammation in hypertrophied adipose tissue with excessive fat accumulation play a crucial role in the development of obesity and accompanying metabolic dysfunctions. This study demonstrated the capacity of elderberry fruit (EDB) extract to decrease the elevated production of reactive oxygen species in hypertrophied 3T3-L1 adipocytes. Treatment with the EDB extract resulted in modulation of mRNA expression and protein secretion of key adipokines in hypertrophied adipocytes. Expression of leptin and adiponectin was, respectively, down- and up-regulated. Moreover, glucose uptake stimulation was noticed in mature adipocytes, both sensitive to insulin and insulin resistant. This may suggest a positive effect of EDB extract on insulin resistance status. The extract was also found to alleviate the inflammatory response in activated RAW 264.7 macrophages by down-regulating the expression of proinflammatory genes (TNF-α, IL-6, COX-2, iNOS) and suppressing the enhanced production of inflammatory mediators (TNF-α, IL-6, PGE2, NO). In vitro experiments showed that the EDB extract could inhibit digestive enzymes, including α-amylase, α-glucosidase, and pancreatic lipase, leading to reduced intestinal absorption of dietary lipids and carbohydrates. Further in vivo studies could be postulated to support EDB as a functional food component for the prevention and treatment of obesity and metabolic-immune comorbidities.

Raspberry Polyphenolic Extract Regulates Obesogenic Signals in Hepatocytes

The aim of this in vitro study was to examine the effect of raspberry polyphenolic extract on the immune-metabolic molecular mechanisms activated by obesity-related signals in hepatocytes (HB-8965^®). Alterations in endosomal/lysosomal activity (neutral red uptake assay, NR), the expression of selected genes involved with lipid oxidation, and metabolism and inflammation processes in the liver were studied. Hepatocytes were treated with plasma collected from Wistar rats that were fed a high-fat diet (HF), raspberry polyphenolic extract (PP), serine-type protease inhibitors as an agonist of TLR4 (TD) or a combination of PP with HF or TD treatments. The PP added to the experimental treatments modulated hepatic immune-metabolic mechanisms through the upregulation of STAT1, ANGPTL4, and CD44, as well as considerably reducing the NR uptake and downregulation of COX-2 and the multifunctional protein AhR. The kinetic analysis of AhR expression revealed that HF-related molecular mechanisms activated AhR mRNA expression earlier than PP initiated the regulatory effect. In conclusion, PP might be considered a valuable dietary agent that regulates obesity-related signals in hepatocytes. Moreover, taking AhR kinetic behavior into consideration, it can be assumed that PP might modulate the severity of the HF-induced downstream metabolic signaling of AhR.