Phenolic Compounds Isolated and Identified from Amla ( Phyllanthus emblica ) Juice Powder and their Antioxidant and Neuroprotective Activities

Abstract

The edible fruit of Phyllanthus emblica (known as amla and Indian gooseberry) is widely used in Eastern traditional medicinal systems for a variety of ailments. Our group has previously reported that an amla juice powder shows neuroprotective effects in several in vitro and in vivo assay models but its chemical constituents and their neuroprotective activity remain unknown. Therefore, we conducted a phytochemical investigation of amla juice powder and evaluated the antioxidant and neuroprotective effects of the isolates. Ten phenolics (1–10), including gallic acid (1), five gallic acid derivatives (2–6), ellagic acid (7), and three ellagic acid derivatives (8–10), were isolated and identified with compounds 8–10 being reported from amla for the first time. All of the isolates showed antioxidant effects in the DPPH assay with IC₅₀ values ranging from 6-158.9 μM superior to the synthetic commercial antioxidant, butylated hydroxytoluene (IC₅₀ = 371.4 μM). In addition, compound 8 reduced β-amyloid-induced neurotoxicity in a transgenic Caenorhabditis elegans model by increasing their survival rate by 28.3% compared to the control group. This study adds to the growing body of evidence supporting the potential health benefits of amla and supports the functional food and nutraceutical applications of amla juice powder.