Comparative Antioxidant and GC–MS Profiling of Phyllanthus emblica L. and Curcuma longa L.: Implications for Microplastic-Induced Hepatotoxicity

Abstract

Phyllanthus emblica and Curcuma longa are two medicinal herbs commonly used with their biological properties linked to phenolic, flavonoid and volatile constituents. In this study, the total flavonoid content (TFC), total phenolic content (TPC), ABTS and DPPH radical-scavenging activity and gas chromatography-mass spectrometry (GC-MS) profile of the authenticated powdered materials were compared. Each spectrophotometric assay was repeated three times, and the percentage inhibition was computed directly from the absorbance. When the 50% response was bracketed, IC50 values were computed by local linear interpolation. The data of the GC-MS were processed in the Agilent MassHunter and compared with the NIST 23 mass-spectral library. P. emblica exhibited a TPC of 43.12 ± 0.24 mg gallic acid equivalents/100 mg, compared with 2.69 ± 0.23 mg/100 mg for C. longa. TFC values were 23.87 ± 0.37 and 22.86 ± 0.36 mg quercetin equivalents/100 mg, respectively. At 25 µg/mL, DPPH inhibition reached 81.43 ± 0.08% for P. emblica and 31.66 ± 0.12% for C. longa. The DPPH IC50 value of P. emblica was 12.86 ± 0.01 µg/mL While C. longa exhibited weaker inhibition compared to P. emblica, with the DPPH activity by 50% even at the tested concentration. ABTS IC50 values were 11.13 ± 0.04 and 31.46 ± 0.31 µg/mL, respectively. The TFC responses and the C. longa TPC response were below the lowest standards and should be interpreted with caution. In case of P. emblica, 37 integrated peaks and 45 library annotations were obtained and for C. longa, 23 integrated peaks and 31 library annotations were obtained from GC-MS analysis. The tentative identification of representative compounds in P. emblica and C. longa were alpha-pinene, dill ether and 2-caren-4-ol, and furfural, 1,2,3-benzenetriol, trans-cinnamic acid and ar-turmerone, respectively. Retention indices and authentic standards were not available and therefore compound assignments were tentative. In Summary, the present study compares the phytochemical composition, antioxidant activity, and GC–MS profiles of Phyllanthus emblica and Curcuma longa. P. emblica exhibited markedly higher phenolic content and radical-scavenging activity, while C. longa showed distinct volatile constituents. These findings provide a chemical basis for evaluating their complementary roles in mitigating oxidative stress and hepatotoxicity associated with microplastic exposure.