Extraction, Isolation and Purification of Kaempferol from <i>Cassia fistula</i> L. Flowers

Cassia fistula L., (CFL) (Fabaceae) commonly called the Golden Shower Plant has an abundance of phytopharmaceuticals. It has been used as the oldest natural sweetener. Due to its eminent ethno-medicinal values since ages, it has been used in Ayurveda, Chinese and Unani medicine for innumerable diseases and illnesses like cold, congestion, sore throat, jaundice, wound healing, typhoid, constipation, cancer, etc. Kaempferol (KP) is one such active metabolite present in CFL flowers that displays prominent bioavailability. In recent times, life-threatening diseases have escalated worldwide, which has shifted the focus from synthetic medicines to herbal medicines. In the present work, for the first time, the extraction of KP (a flavonoid, 3, 5, 7-trihydroxy-2-(4-hydroxyphenyl)-4H-1-benzopyran-4-one) from CFL flowers was done using methanol as solvent. High-Performance Liquid Chromatography (HPLC) was employed further for the isolation and purification of KP from CFL flowers. Spectral analysis such as Fourier Transformer Infrared Spectroscopy (FTIR), Liquid Chromatography-Mass Spectrometry (LC-MS), and Nuclear Magnetic Resonance (NMR) was conducted for the structural determination of isolated KP. Through Thin Layer Chromatography (TLC) fingerprinting, only 15% purity of KP was achieved, whereas by using HPLC this enrichment reached approximately 85-90%. By performing different spectral characterisations, isolated and purified KP was substantiated as the spectroscopic data obtained agreed well with the literature. Extraction, isolation, and purification of KP from CFL flowers offer a green alternative to explore the therapeutic utility of this important phytoestrogen for the development of several design and real-world applications in pharmaceutical material science for various biological activities.