Research on the application of the HPLC/PDA method to enhance the quality standards of Folium nelumbinis based on the bioactive nuciferine and quercetin 3-O-glucuronide

This study enhances quality control standards for Folium Nelumbinis, a medicinal herb in the Vietnamese and Chinese Pharmacopeias. Current standards are insufficient for accurately quantifying key bioactive compounds, nuciferine and quercetin 3-O-glucuronide, which are vital for the plant's pharmacological effects. The quality control standards include sensory characteristics, microscopic features, powder examination, physicochemical properties, limits for heavy metals, and qualitative. Additionally, simultaneous quantification of nuciferine and quercetin 3-O-glucuronide was achieved using HPLC on a GL Inert Sustain C18 column (250 mm × 4.6 mm, 5 μm). The mobile phase, consisting of acetonitrile (A) and 0.1 % triethylamine in water at pH 6.5 adjusted with 30 % acetic acid (B), was used with a flow rate of 1 mL/min and a detection wavelength of 270 nm. A 200 mg Folium nelumbinis powder was extracted with 6.0 mL of methanol and 1 % hydrochloric acid (6:4, v/v) via ultrasonication at 40 kHz and 500 W for 7 min, followed by centrifugation at 6000 rpm for 7 min (repeated three times). Physico-chemical standards studied are moisture content (8.74 %, w/w), impurities (0.74 %, w/w), fragmentation ratio (1.07 %, w/w), and ash content (6.50 %, w/w). The linearity of the calibration curve ranged from 12 to 48 μg/mL for nuciferine and 4–16 μg/mL for quercetin 3-O-glucuronide, and the square of the regression coefficient (r²) was 0.9990 and 0.9954, respectively. The limit of detection and quantification values were determined as 0.45 μg/mL and 1.50 μg/mL for nuciferine and 0.15 μg/mL and 0.50 μg/mL for quercetin 3-O-glucuronide. This research successfully establishes high-quality control standards for Lotus leaves in accordance with WHO guidelines and the Vietnamese Pharmacopoeia V. The validated HPLC method ensures precise and reliable quality control, supporting research consistency and practical herbal medicine application.