Isolation and characterization of protocatechuic acid from Pterospermum acerifolium (L.) (F. Sterculiaceae) cultivated in Iraq

Pterospermum acerifolium is a perennial plant known as the dinner plant tree, belonging to the Sterculiaceae family. All parts of the plant are rich in phytochemical compounds, which are known for their various pharmacological properties. This study aimed to identify, isolate and structurally elucidate bioactive polyphenolic compounds-specifically protocatechuic acid-from Pterospermum acerifolium cultivated in Iraq, using a combination of chromatographic and spectroscopic techniques. Initially, the removal of fat and wax from plant material was achieved through maceration in n-hexane solvent for three days, followed by extraction using a Soxhlet apparatus with 85 % methanol. The extract was subsequently partitioned with ethyl acetate, yielding 2.6 g of the resulting fraction. The ethyl acetate fraction was analyzed using High-Performance Liquid Chromatography (HPLC) to identify protocatechuic acid. A sharp peak appeared at a retention time of 9.00 min, corresponding to that of the standard protocatechuic acid analyzed under the same conditions. Confirmation of the compounds’ identity was further supported by the spiking technique, in which the addition of the reference standard to the sample resulted in an enhanced peak at 9.09 min, confirming the presence of protocatechuic acid. Structural elucidation of the isolated compound was carried out using complementary spectroscopic techniques. FTIR analysis displayed distinct absorption bands indicative of functional groups characteristic of protocatechuic acid (3335, 1675, 1524, 1423, 1302) cm-1. Additionally, LC-MS/MS analysis yielded molecular ion signals and fragmentation patterns that aligned with those of the authentic standard, further confirming the compounds’ identity, m/z (154, 137, 109, 93 and 77). The analytical results confirmed the presence of protocatechuic acid in the ethyl acetate fraction. Given its known pharmacological significance, this compound is likely a key contributor to the therapeutic potential of Pterospermum acerifolium. These findings offer a valuable foundation for phytochemists and pharmacologists interested in isolating and developing novel bioactive agents from this medicinal plant.