Triphala is a traditional herbal formulation consisting of dried fruits originating from three medicinal plants, namely Terminalia chebula, Terminalia bellerica and Phyllanthus emblica. It is used in folk medicine for the treatment of headaches, dyspepsia and leucorrhoea. There are some reports regarding Triphala's pharmacological effects including its anti-cancer, radioprotective, hypocholesterolaemic, hepatoprotective and anti-oxidant activities. The most important components of these plants are the tannins and gallic acid which they contain. Gallic acid being a compound with tannin structure existing in the Triphala fruit. In this research, the gallic acid content contained in the three plants constituting Triphala was determined. Plant fruits were purchased from available Iranian markets. Milled and powdered fruits from each plant were extracted with 70% acetone and subjected to a reaction with rhodanine reagent in the process forming a colored complex. The complex's absorbance was measured at 520 nm and the amount of gallic acid was determined using its calibration curve. According to the results, the highest amount of gallic acid was observed in Phyllanthus embelica (1.79-2.18%) and the lowest amount was found in Terminalia chebula (0.28-0.80%). Moreover, differences between plant samples from different markets places were found to be statistically significant (p < 0.05). These differences can possibly be due to the source of plant preparation, storage condition and period of Triphala storage. In general, the rhodanine assay is a simple, rapid and reproducible method for the standardization of Triphala as gallic acid.
Keywords: Gallic acid; Phyllanthus emblica; Rhodanine assay; Terminalia bellerica; Terminalia chebula; Triphala.