Bioactive Components from Pistachios Reduce Adipogenesis and Suppress Inflammatory Gene Expression In Vitro
Authors: Grace Mary H , Esposito Debora , Xiong Jia , Timmers Michael , Komarnytsky Slavko , Lila Mary Ann 
Published: November 2023

The present study was designed to identify the natural bioactives present in pistachio kernel and skin responsible for adipocyte differentiation, antioxidant, anti‐inflammatory activities and effect on expression of proinflammatory marker cytokines, as well as to study the underlying mechanism involved, through measurement of mitochondrial bioenergetics and oxidative burst. Pistachio skin and kernel were extracted for non‐polar (NP) and polar (P) components. Bioassays with 3T3L1 mouse adipocytes demonstrated that all pistachio skin and kernel fractions decreased lipid accumulation up to 17%, and skin NP fraction had the highest activity. Bioassay guided fractionation of the skin NP indicated that the lipolytic activity was highest in the fraction consisting of linoleic acid (20%), linoleic acid (10%), and beta‐sitosterol (50%). Our results support the previously reported effects of sitosterol in regulation of glucose uptake, adipogenesis and lipolysis in adipocytes. Skin NP contains nearly 4 fold more sitosterol than kernels NP. In addition, skin NP accumulates 1.7 and 1.3 fold greater gamma‐tocopherol and beta‐carotene compared to kernel NP.

Radical scavenging assays indicated that pistachio skin and kernel NP and P fractions significantly inhibited ROS and NO production in lipopolysaccharide‐stimulated RAW 264.7 macrophages. Total phenolics, total flavonoids and total proanthocyanidins of skin P fraction were 260, 3.0, and 46.2 mg/g, respectively, and for kernel P fraction; 50.0, 0.7, and 1.8 mg/g, respectively. NP‐HPLC‐FLD and LC‐IT‐TOF‐MSn showed that skin accumulated high concentrations of proanthocyanidin components with different degree of polymerization and anthocyanin pigments, that were absent in the kernels. Gallic, protocatechuic acids, quercetin and eridictyol glycosides were main components of the kernel P fraction.

Gene expression profiles associated with inflammation (IL‐1b, INOS, COX2 and IL‐6) were characterized in in the LPS‐stimulated RAW264.7 macrophages after treatment with pistachio fractions. Results indicated that fractions with highest inhibitory activity were loaded with a combination of polyphenolic compounds, mostly flavonols and catechins. Inflammatory activation of macrophages induced a rapid non‐mitochondrial consumption of oxygen by NADPH oxidase‐2 (NOX‐2), which is known as the pro‐inflammatory oxidative burst. Skin NP components showed a strong inhibitory effect on the oxidative burst quantified as oxygen consumption rate (OCR). Taken together, these data suggested that immune cells treated with bioactives naturally present in pistachio skin had decreased capacity to launch a pro‐inflammatory response.

Our results indicate that pistachio and its bioactive molecules decrease inflammatory biomarkers as well as inhibit lipid accumulation. Results support the potential of pistachio to inhibit biomarkers associated with inflammation and obesity.

Support or Funding Information

The American Pistachio Growers