Phytochemical Screening, GC-MS Analysis, Antioxidant, Cytotoxicity, and Anti- Inflammatory Studies of Medicinal Plant Persicaria glabra Growing in Bangladesh

Technical Summary: Phytochemical Screening, GC-MS Analysis, and Biological Evaluation of Persicaria glabra from Bangladesh

Problem Statement
Persicaria glabra (Willd.) M.Gómez, commonly known as "Lal Kukri" or "Bihagni," is an aquatic to semi-aquatic medicinal plant widely used in the ethnomedicine of South Asia for treating skin infections, internal inflammation, and digestive ailments. While the aerial parts (leaves and stems) have received some scientific attention, systematic investigations into the root system remain limited. Roots, being in constant contact with waterlogged soil and environmental stressors, may possess unique defensive metabolites. This study addresses the gap in knowledge regarding the comparative phytochemical profile and biological potential of both the aerial and root parts of P. glabra growing in Bangladesh, aiming to scientifically validate its traditional uses.

Methodology
The research employed a multi-faceted approach involving collection, extraction, chemical profiling, and biological assays:

• Plant Material: Specimens were collected from Lawachara National Park, Moulvibazar, Bangladesh, in November 2024, and authenticated by the National Herbarium of Bangladesh (Voucher No. 94756).
• Extraction: Aerial parts (695 g) and roots (920 g) were shade-dried, powdered, and subjected to cold maceration using four solvents of increasing polarity: n-hexane, chloroform, ethyl acetate, and methanol.
• Phytochemical Screening: Qualitative tests were conducted to detect major secondary metabolite classes, including steroids, terpenoids, flavonoids, phenolics, alkaloids, quinones, coumarins, saponins, tannins, and carbohydrates.
• GC-MS Analysis: Gas chromatography-mass spectrometry was performed on n-hexane and chloroform extracts of both plant parts to identify volatile and non-polar constituents using NIST and Wiley spectral libraries.
• Biological Assays:
  • Antioxidant Activity: Evaluated via DPPH radical scavenging (IC50), Total Phenolic Content (TPC), Total Flavonoid Content (TFC), and Total Antioxidant Capacity (TAC).
  • Cytotoxicity: Assessed using the Brine Shrimp Lethality Test (Artemia salina) to determine LC50 values.
  • Anti-inflammatory Activity: Measured via the in vitro inhibition of egg albumin denaturation, compared against the standard drug diclofenac sodium.

Key Results

• Phytochemical Profile: Preliminary screening confirmed the presence of alkaloids, flavonoids, phenolics, terpenoids, quinones, and steroids across various extracts. Notably, saponins, tannins, and carbohydrates were predominantly found in methanol extracts.
• GC-MS Findings:
  • Aerial n-Hexane Extract: Identified 13 compounds, with (Z)-13-docosenamide being the major constituent (42.78%), followed by methyl-heneicosanoate (19.61%).
  • Root n-Hexane Extract: Identified 25 compounds, dominated by progesterone (24.18%), campesterol (10.52%), and 17β-hydroxy-17α-methyl-5α-androstan-3-one (8.77%).
  • Root Chloroform Extract: Identified 12 compounds, with 1,3,5-tris(trimethylsiloxy)benzene as the primary constituent (34.31%), followed by a benzodiazepine derivative and methyl tridecanoate.
• Antioxidant Activity:
  • The aerial chloroform extract demonstrated the highest radical scavenging activity (DPPH IC50 = 11.29 µg/mL), the highest total phenolic content (348.87 ± 4.24 mg GAE/g), and the highest total antioxidant capacity (548.81 ± 6.73 mg AAE/g).
  • The root ethyl acetate extract exhibited the highest antioxidant activity among root fractions (DPPH IC50 = 16.90 µg/mL).
  • Generally, phenolic and flavonoid contents were significantly higher in aerial parts compared to roots across all solvents.
• Cytotoxicity: Both aerial and root ethyl acetate extracts showed moderate cytotoxicity in the brine shrimp assay, with LC50 values of 34.77 µg/mL and 17.73 µg/mL, respectively. These were less potent than the positive control, vincristine sulfate (LC50 = 3.57 µg/mL).
• Anti-inflammatory Activity: Both plant parts exhibited strong anti-inflammatory potential via egg albumin denaturation inhibition. The aerial methanol extract showed the strongest activity (IC50 = 8.45 µg/mL), followed by the root methanol extract (IC50 = 12.81 µg/mL). While effective, these values were higher (less potent) than the standard diclofenac sodium (IC50 = 5.40 µg/mL).

Significance and Claims
The study concludes that Persicaria glabra is a rich source of therapeutic phytochemicals with significant pharmacological potential. The authors assert that the plant's aerial parts and roots contain bioactive secondary metabolites—including steroids, terpenoids, flavonoids, and specific compounds identified via GC-MS—that substantiate its traditional use in treating inflammation and oxidative stress.

The paper claims that the comparative evaluation fills a critical gap regarding the root system of P. glabra, revealing that while aerial parts are superior in total phenolic and flavonoid content, root extracts (particularly chloroform and ethyl acetate fractions) possess distinct bioactive profiles, including high concentrations of progesterone and other steroidal compounds. The findings provide new scientific data to support the folkloric applications of the plant and suggest its potential as a source for natural product drug discovery, specifically for antioxidant and anti-inflammatory agents. The authors emphasize that the study offers a foundational basis for further phytochemical exploration and pharmacological validation but does not propose immediate clinical applications or specific drug development pathways beyond these initial in vitro findings.