Abstract
Oxidative stress plays a relevant role in the progression of chronic conditions, including cardiometabolic diseases. Several Cameroonian plants, including spices, are traditionally used as herbal medicines for the treatment of diseases where oxidative stress contributes to insulin resistance, like type 2 diabetes mellitus. This study evaluated the antioxidant capacity and the effects on oxidative-stress-induced impairment of glucose uptake of 11 Cameroonian spice extracts. H2O2-induced reactive oxygen species (ROS) production by human HepG2 cells was significantly reduced by 8/11 extracts. The most effective extracts, Xylopia parviflora, Echinops giganteus, and Dichrostachys glomerata, showed a concentration-dependent ROS-scavenging activity, which involved Nrf2 translocation into the nucleus. Xylopia parviflora, Tetrapleura tetraptera, Dichrostachys glomerata, Aframomum melegueta, and Aframomum citratum extracts showed the highest antioxidant capacity, according to oxygen radical absorbance capacity (ORAC) (2.52–88 μM Trolox Eq/g of extract), ferric-reducing antioxidant power (FRAP) (40.23–233.84 mg gallic acid Eq/g of extract), and total phenol (8.96–32.96% mg gallic acid Eq/g of extract) assays. In HepG2 cells, glucose uptake was stimulated by 4/11 extracts, similarly to insulin and metformin. H2O2-induced oxidative stress reduced glucose uptake, which was rescued by pretreatment with Xylopia aethiopica, Xylopia parviflora, Scorodophloeus zenkeri, Monodora myristica, and Dichrostachys glomerata extracts. The ROS-scavenging ability of the spice extracts may reside in some secondary metabolites observed by phytochemical profiling (reverse-phase high-performance liquid chromatography coupled to a diode array detector (HPLC-UV-DAD)). Further studies are needed to better clarify their biological activities and potential use to control oxidative stress and promote insulin sensitivity.
Highlights
Oxidative stress is recognized as an important pathophysiological factor leading to molecular and cellular tissue damage [1]
This study investigated the antioxidant potential of 11 selected spice extracts from Cameroon and evaluated some associated molecular mechanisms and their ability to modulate glucose uptake in a cell-based model system after exposure to oxidative stress
Since these plant extracts may exhibit a relevant antioxidant activity [6,9,10], they could represent a specific countermeasure to control excessive reactive oxygen species (ROS) generation, which is linked to insulin resistance in different pathological conditions [22,23]
Summary
Oxidative stress is recognized as an important pathophysiological factor leading to molecular and cellular tissue damage [1] It plays a relevant role in the process of aging and in the pathogenesis of cardiometabolic disorders, including obesity, type 2 diabetes mellitus (T2DM), metabolic syndrome, and insulin resistance [2]. The ingestion of dietary antioxidants from foods, herbs, and spices is the most recommended approach to counteract macromolecular damage by oxidative stress, and the search for natural compounds able to contrast oxidative stress is of major interest In this regard, plant-derived products are widely used in Africa for the treatment of many ailments and traditionally constitute the first line of health support for about 70–80% of the population [6]. The efficacy of some traditional medicines for the treatment of several ailments has been demonstrated, questions about their safety of use and toxicity have emerged, highlighting the need for a detailed characterization of the efficacy/safety balance [8]
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