Potentiality of Roselle and Onion ( Allium Cepa ) Peel as Raw Materials for Producing Protocatechuic Acid in Tropical Malaysia: A Comparative Study

Protocatechuic acid from natural sources are widely used in human health. This study focuses on the presence of protocatechuic acid (PCA) in Rosselle (Hibiscus sabdariffa) and onion peel (Allium cepa). Collection of onion peel is difficult and amount is less than 1% in onion. Moreover, Malaysia is importing 100% from overseas. On the contrary, roselle is very common in tropical Malaysia and its calyx can be dried and preserved. Thin Layer Chromatography (TLC) and High Performance Liquid Chromatography (HPLC) were used to identify protocathechuic acid (PCA) from the samples. TLC was performed on 20×20 cm Silica gel 60 F₂₅₄ aluminum sheets as TLC plates with mixtures of water-methanol-formic acid as mobile phase. TLC recorded the presence of protocatechuic acid in both of the samples. HPLC analysis was performed on C-18 in 250×4.6 mm steel column with methanol-water-formic acid in 25:75:0.5 ratio as mobile phase. The flow rate of the mobile phase was 1.0 ml/min and protocatechuic acid was detected at 260 nm of wavelength. The quantities of protocatechuic acid determined by HPLC in rosselle and onion peel were 0.014 mg in 30 g of dried samples extract and 0.25 mg in 30 g of dried extract, respectively. The amount of protocatechuic acid in onion peel extract was eighteen times higher compared to Rosselle extract but considering availability of raw materials in Malaysia, roselle might be used as good source of PCA production with potential economic feasibility.