Geraniin exerts cytoprotective effect against cellular oxidative stress by upregulation of Nrf2-mediated antioxidant enzyme expression via PI3K/AKT and ERK1/2 pathway.

BACKGROUND: Geraniin, an active compound with remarkable antioxidant activity, was isolated from Geranium sibiricum. The present study aimed to investigate whether geraniin has the ability to activate Nrf2, induce antioxidant enzyme expression and protect cells from oxidative damage. METHODS: The cells were pretreated with geraniin for 24h and exposed to hydrogen peroxide (H2O2) for 4h. Intracellular reactive oxygen species (ROS) levels, mitochondrial membrane potential and apoptosis were measured. We also investigated intracellular glutathione (GSH) levels and changes in nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated signaling cascade in cells treated with geraniin. RESULTS: We investigated the protective effects of geraniin against H2O2-induced apoptosis in HepG2 cells. Geraniin significantly reduced H2O2-induced oxidative damage in a dose dependent manner. Further, geraniin induced the expression of heme oxygenase-1 (HO-1), NAD(P)H quinone oxidoreductase-1 (NQO1) and level of glutathione (GSH) in a concentration- and time-dependent manner, and increased Nrf2 nuclear translocation. The Nrf2-related cytoprotective effects of geraniin were PI3K/AKT and extracellular signal-regulated protein kinase1/2 (ERK1/2) pathway-dependent. However, inhibitors of PI3K/AKT and ERK1/2 (LY294002 or U0126) not only suppressed geraniin-induced nuclear translocation of Nrf2 but also abolished the expression of HO-1, NQO1 and GSH. CONCLUSIONS: These results demonstrated that geraniin induced Nrf2-mediated expression of antioxidant enzymes HO-1 and NQO1, presumably via PI3K/AKT and ERK1/2 signaling pathways, thereby protecting cells from H2O2-induced oxidative cell death. GENERAL SIGNIFICANCE: Geraniin, at least in part, offers an antioxidant defense capacity to protect cells from the oxidative stress-related diseases.

A pilot-scale homogenization-assisted negative pressure cavitation extraction of Astragalus polysaccharides.

This paper reported a new, green and effective extraction technique for polysaccharides, namely homogenization-assisted negative pressure cavitation extraction (HNPCE), which succeeded in the extraction of Astragalus polysaccharides (APs). Central composite design and kinetic model were applied to optimize the extraction conditions, and the optimal parameters were obtained as follows: homogenization time 70s, negative pressure -0.068MPa, extraction temperature 64.8°C, ratio of water to material 13.4 and extraction time 53min. The proposed method exhibited considerable predominance in terms of higher APs yield (16.74%) with much lower temperature and shorter duration, as against the reported hot water extraction method (14.33% of APs yield with 100°C and 3h). Moreover, FT-IR results showed that HNPCE method did not alter the primary structure of polysaccharides. Furthermore, the pilot-scale application of HNPCE was successfully performed with 16.62% of APs yield. Thus, HNPCE is an excellent alternative method for the extraction of polysaccharides from Astragalus or other plant materials in industry.

Microwave-assisted aqueous enzymatic extraction of oil from pumpkin seeds and evaluation of its physicochemical properties, fatty acid compositions and antioxidant activities.

Microwave-assisted aqueous enzymatic extraction (MAAEE) of pumpkin seed oil was performed in this study. An enzyme cocktail comprised of cellulase, pectinase and proteinase (w/w/w) was found to be the most effective in releasing oils. The highest oil recovery of 64.17% was achieved under optimal conditions of enzyme concentration (1.4%, w/w), temperature (44°C), time (66 min) and irradiation power (419W). Moreover, there were no significant variations in physicochemical properties of MAAEE-extracted oil (MAAEEO) and Soxhlet-extracted oil (SEO), but MAAEEO exhibited better oxidation stability. Additionally, MAAEEO had a higher content of linoleic acid (57.33%) than SEO (53.72%), and it showed stronger antioxidant activities with the IC50 values 123.93 and 152.84, mg/mL, according to DPPH radical scavenging assay and ß-carotene/linoleic acid bleaching test. SEM results illustrated the destruction of cell walls and membranes by MAAEE. MAAEE is, therefore, a promising and environmental-friendly technique for oil extraction in the food industry.

Biodiesel from Forsythia suspense [(Thunb.) Vahl (Oleaceae)] seed oil.

In the present work, Forsythia suspense seed oil (FSSO) was investigated for the first time as an alternative non-conventional feedstock for the preparation of biodiesel. The FSSO yield is 30.08±2.35% (dry weight of F. suspense seed basis), and the oil has low acid value (1.07 mg KOH/g). The fatty acid composition of FSSO exhibits the predominance of linoleic acid (72.89%) along with oleic acid (18.68%) and palmitic acid (5.65%), which is quite similar to that of sunflower oil. Moreover, microwave-assisted transesterification process of FSSO with methanol in the presence of potassium hydroxide catalyst was optimized and an optimal biodiesel yield (90.74±2.02%) was obtained. Furthermore, the fuel properties of the biodiesel product were evaluated as against ASTM D-6751 biodiesel standards and an acceptable agreement was observed except the cetane number. Overall, this study revealed the possibility of FSSO as a potential resource of biodiesel feedstock.