Anatomical, Phytochemical and Toxicological Characterization of Drynaria quercifolia (L.) J.Sm Rhizome Scales

Abstract

Background and Aims: The rhizome of Drynaria quercifolia (L.) J.Sm. is traditionally consumed after removal of the outer scale layer; however, the scientific basis of this practice remains unclear. The present study aimed to elucidate the anatomical, phytochemical and toxicological characteristics of the rhizome scales to understand their functional significance and justify their traditional exclusion prior to medicinal use. Study Design: Experimental laboratory-based study integrating anatomical observation, phytochemical screening, spectroscopic characterization and bioassay-based toxicological evaluation. Place and Duration of Study: PG and Research Department of Botany, Government Arts College, Coimbatore, Tamil Nadu, India, between September 2023 and March 2024. Methodology: Rhizome scales of D. quercifolia were collected from Kolli Hills, Tamil Nadu and subjected to macroscopic and microscopic examination. Aqueous extracts were prepared following traditional infusion methods. Preliminary phytochemical screening was conducted using standard qualitative tests. Functional groups were identified through Fourier Transform Infrared (FT-IR) spectroscopy. Toxicological evaluation was performed using Artemia salina lethality assay, Daphnia magna acute toxicity assay and Allium cepa root tip assay, each conducted in triplicate to assess cytotoxic and genotoxic effects. Results: Microscopic analysis revealed a uniseriate epidermal layer with multicellular non-glandular trichomes and thick-walled marginal cells, indicating a structurally specialized protective tissue. Phytochemical screening confirmed the presence of alkaloids, sterols and carbohydrates. FT-IR analysis showed prominent O–H stretching (3317 cm⁻¹), free hydroxyl groups (3657 cm⁻¹) and C–O functional groups, indicating predominance of polar constituents. Toxicological assays demonstrated moderate cytotoxicity in Artemia salina with LC₅₀ of 175 µg/mL. The Daphnia magna assay showed an EC₅₀ of approximately 1350 µg/mL with concentration-dependent morphological abnormalities. In the Allium cepa assay, mitotic activity decreased progressively, with mitotic index reduced to 12.82% at 1500 µg/mL and chromosomal stickiness observed at higher concentrations. Conclusion: The rhizome scales of Drynaria quercifolia represent a structurally and chemically distinct outer tissue layer containing defense-associated metabolites with measurable biological reactivity. These findings provide experimental evidence supporting the traditional removal of rhizome scales prior to medicinal use, as the scale layer contains defense-associated metabolites exhibiting measurable cytotoxic and antimitotic activity.