Influence of Seasonal Variation on Diosgenin Content in Costus speciosus (J. Koenig) Sm. Rhizome Quantified Through Validated RP-HPLC-PDA Method

Background Costus speciosus (J. Koenig) Sm. (Syn. Cheilocostus speciosus) is an ethnic anti-diabetic plant, used for its high diosgenin content. Objectives This study aimed to evaluate the seasonal variation of diosgenin content in Costus speciosus rhizome, quantified through validated RP-HPLC method. Materials and Methods The rhizomes were collected in four different seasons, such as rainy (August), autumn (October), winter (February) and summer (May), from Lucknow, India. The HPLC method validation was done in terms of linearity, precision, repeatability, accuracy, sensitivity and robustness. Results Diosgenin was separated under isocratic elution on an RP-HPLC column (4.6 × 250 mm, 5 µm) with a mobile phase consisting of methanol and water, eluted at retention time (Rt) of 18.396 min and content was calculated with the help of standard curve. The limit of detection and limit of quantification (LOQ) was found to be 522.68 and 1583.90 ng (nanogram), respectively. The diosgenin content varies significantly in different seasons. Conclusion The diosgenin content was found higher in rainy (193.97 µg/mg) season and was concluded to be optimum season for collection of rhizomes as quality raw material. Harvesting at optimal season may fulfill the commercial demand of diosgenin and may reduce the diosgenin-intended overexploitation of the species from the wild.