Validation of an optimized HPLC/UV method for the quantification of flavonoids in lotus

Flavonoids present in the leaves of lotus (Nelumbo nucifera) grown in different regions of South Korea (Yeongcheon, Haenam, and Seocheon) and at different harvest times (July to September) were determined. Flavonoid contents in lotus extracts were identified and analyzed using high-performance liquid chromatography (HPLC). The HPLC results revealed that the flavonoid contents of the lotus extracts varied at different harvesting times, with the highest content in July. Analysis of the flavonoid content in the leaves from the different regions showed the highest contents of isorhamnetin-3-O-glucoside, quercetin 3-O-glucuronide, and quercetin 3-O-glucoside in Yeongcheon, Korea, and highest contnts of rutin, myricetin, kaempferol 3-O-glucoside, and quercetin in Haenam, Korea. The HPLC method was validated and optimized to quantify quercetin 3-O-glucuronide; it showed good linearity (1000–62.5 µg/mL, r2 = 0.9999), accuracy (106%–108%), and precision (RSD ≤ 1.70%). Determination of flavonoid content in lotus is valuable for producing medicinal crops and identifying the optimal sources to increase the quantity of clinically available medicines.