Phytochemical analysis, antioxidant and toxicity evaluation of ethanolic Gnetum gnemon L. leaf extracts-A potential natural food additive

Abstract

The primary aims of this study were to assess the antioxidant activity and evaluate the toxicity of ethanolic Gnetum gnemon L. leaf extracts. The ultimate goal was to identify this extract as a promising natural antioxidant in the food industry. The total phenolic content (TPC) was determined, and the antioxidant activities were assessed using the 2,2-diphenyl-1-picrylhydryzyl (DPPH) test, ferric reducing antioxidant power (FRAP) assay, and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay. Liquid Chromatography-Mass Spectrometry (LC-MS) was employed to ascertain the bioactive components accountable for antioxidant activity, whereas the brine shrimp mortality assay was conducted to evaluate toxicity. The extract's TPC exhibited the highest value at 39.4 ± 2.69 mg GAE/g. The DPPH and ABTS assays demonstrated scavenging activity, with IC50 values of 2.51 ± 0.26 mg/mL and 5.02 ± 0.30 mg/mL, respectively. The FRAP assay measured the ferric-reducing antioxidant power activity yielding a value of 696.67 ± 13.56 μmol TEAC/g DW. LC-MS study detected the existence of 11 different non-volatile compounds, including furaneol, traumatic acid, gentiatibetine, tryptophan, anofinic acid, diosmetin, petunidin 3-O-glucoside, rhapontigenin, allixin, [10]-gingerol, and salidroside. These specific chemicals in the G. gnemon leaf extract may have played a role in its antioxidant action. The LC50 of the leaf extract was determined to be 41.08 mg/mL, indicating that it exceeds the threshold of 1 mg/mL. This implies that the extract is not hazardous and poses no threat to human health when consumed. Thus, the ethanolic extract of G. gnemon leaf can be confirmed as a natural antioxidant agent suitable for creating natural additives that protect food from spoilage and counteract oxidative degradation during storage and processing.