Evaluation of Phenolic and Flavonoid Contents, Antioxidant Properties and Toxicity Study of Barringtonia racemosa (PUTAT) and Zingiber officinale (Ginger) Combined Ethanolic Extracts

Abstract

Oxidative stress, which occurs due to an imbalance between free radicals and antioxidants, has been connected to various health conditions such as cancer, cardiovascular diseases, neurological disorders, rheumatoid arthritis, and the aging process. The search for natural antioxidants derived from plants has become increasingly important as they tend to be safer and cause fewer side effects than manufactured medicines. In this study, we examine the phytochemical composition, determine the antioxidant activity, and evaluate the toxicity of single and combination Barringtonia racemosa and Zingiber officinale ethanolic leaf extracts. The crude extracts were prepared using ethanolic extraction. The Folin–Ciocalteu assay and aluminum chloride colorimetric assay were applied to determine the total phenolic (TPC) and total flavonoid (TFC) contents, respectively. The TPC values for B. racemosa and Z. officinale are 368.24±1.10mg GAE/g and 150.24±1.61mg GAE/g, respectively. The TFC values for B. racemosa and Z. officinale: 15.52±2.00mg QE/g and 47.05±0.67mg QE/g, respectively. We applied the DPPH radical scavenging assay to evaluate antioxidant activity, while the brine shrimp lethality assay (BSLA) and Artemia salina hatching assay were used to measure toxicity. Both plant extracts had significant levels of phenolic constituents but low flavonoid concentration. In the DPPH assay, the combined extract and B. racemosa alone resulted in an IC50 of 36.44±1.22µg/mL, and 21.83±1.38µg/mL, respectively. It showed very powerful antioxidant activity. The IC50 value of Z. officinale extract, which was higher (133.85±10.35µg/mL) denoting a moderate level of antioxidant activity equivalent to the reference standard, quercetin. Toxicity testing found that the combined extract and B. racemosa was mildly toxic than potassium dichromate, a known toxin, showing a positive safety profile resulted LC50 45.47±3.01µg/mL, and 99.55±30.96µg/mL, respectively and EC50 35.46±6.89µg/mL, and 73.93±1.27µg/mL, respectively. These findings represent that ethanolic leaf extracts of B. racemosa and Z. officinale, particularly when combined, may act as efficient natural antioxidants. Their high phenolic content most likely contributes to their bioactivity, indicating their potential as therapeutic agents against oxidative stress.