An optimized method for extracting corosolic acid from loquat leaves

To extract corosolic acid from loquat leaves for medical use. Loquat leaves were boiled in water to remove the water-soluble substances followed by 3 cycles of extraction with 25% aqueous methanol for 30 min and then by 95% aqueous methanol for 1 h at 80 degrees celsius;. After cooling at room temperature and filtration, the extract was treated with activated carbon to remove chlorophyll, and the liquid was filtered and concentrated to allow precipitation. The sediment was washed to obtain the total crude triterpene acid, which was further dissolved with methanol and purified by high-performance liquid chromatography (HPLC). The fractions including corosolic acid were collected, concentrated with vacuum distillation, and dried to obtain corosolic acid product, which was analyzed with HPLC. HPLC analysis of the extracts showed that the percentages of corosolic acid were 4.66%, 2.42%, and 24.18% in crude corosolic acid extracted with methanol, boiling water, and 95% aqueous methanol, respectively. After purification with HPLC, the purity of corosolic acid in the product exceeded over 80%. The optimal extraction method, which is convenient and cost-effective, is established for extracting corosolic acid from loquat leaves for medical use.