Qualitative and Quantitative Estimation of Total Phenolic and Flavonoid Content in Aqueous and Ethanolic Extracts of Moringa oleifera Leaves: A Comparative Laboratory Study

Abstract

Background: Moringa oleifera Lam. (drumstick), a fast-growing tree widely cultivated and consumed across South India, is increasingly valued as a nutraceutical and functional food owing to its dense complement of polyphenolic antioxidants. The efficiency with which these moderately polar phenolics and flavonoids are recovered depends strongly on the polarity of the extraction solvent, yet solvent selection is often made without systematic comparison.

Objective: To qualitatively screen the phytochemical classes present in M. oleifera leaf extracts and to quantitatively compare total phenolic content (TPC) and total flavonoid content (TFC) between aqueous and ethanolic extracts under standardised laboratory conditions.

Methods: In this laboratory-based comparative phytochemical study, aqueous and ethanolic leaf extracts were prepared and subjected to standard qualitative phytochemical tests. TPC was estimated by the Folin–Ciocalteu assay against a gallic acid calibration curve (mg gallic acid equivalents [GAE]/g extract) and TFC by the aluminium chloride colorimetric assay against a quercetin calibration curve (mg quercetin equivalents [QE]/g extract). Three independent analytical replicates were analysed per extract per assay. Data are expressed as mean ± standard deviation (SD) and compared using independent-samples t-tests, with 95% confidence intervals (CI) and Cohen's d; p < 0.05 was considered significant.

Results: Both extracts were qualitatively rich in flavonoids, phenolics, tannins, terpenoids, glycosides and carbohydrates. TPC was substantially higher in the ethanolic extract (125.02 ± 2.80 mg GAE/g) than the aqueous extract (79.92 ± 3.07 mg GAE/g; mean difference 45.10 mg GAE/g; t = 18.797, df = 4, p = 0.001; 95% CI 38.44–51.76; Cohen's d = 15.35). TFC was likewise higher in the ethanolic extract (70.98 ± 0.36 mg QE/g) than the aqueous extract (39.35 ± 2.21 mg QE/g; mean difference 31.63 mg QE/g; t = 24.470, df = 4, p = 0.001; 95% CI 28.04–35.22; Cohen's d = 19.98).

Conclusion: Ethanolic extraction recovered approximately 1.6-fold more phenolics and 1.8-fold more flavonoids than aqueous extraction, with very large effect sizes, indicating that ethanol (or hydroethanol) is preferable to water for recovering M. oleifera leaf polyphenols in low-cost South Indian nutraceutical and functional-food applications.