However formulation E was adjudged as having the best acceptable taste. Considering the components of the formulations, the syrup served as a sweetener and vehicle for the liquid formulation, citric acid and glycerin served to improve the sweetening effect of the syrup while ethanol served as sweetener and a preservative. 9 Though the formulations: AZD5363 mouse B, C, D. and E were sufficiently masked,

but on the basis of the taste result, formulation E can be said to be the best masked which could be due to the presence of glycerin, citric acid and ethanol which provides the formulation with extra sweet taste in addition to the sweet taste of syrup. Based on the physical appearance after 10 weeks of storage it could be deduced that the plant might contains natural preservative since formulation A did not show any sign of spoilage after 10 weeks. This is in agreement with earlier work.10 However it was observed that only formulation B had signs of microbial SCR7 manufacturer spoilage. This could be due to absence of ethanol and citric acid which could have helped

to augment the natural preservative present in P. amarus. The various formulations of P. amarus also showed in vitro scavenging activity of DPPH radical at 0.1 mg/ml when compared to the control that retained the violet colour of DPPH after 20 min observation ( Fig. 2). Taste masking is an important technique that has been used to prevent unpalatable drugs from

interacting with the taste buds to eliminate or reduce negative sensory response such as the bitter taste of the extracts of P. amarus. 11 The formulation of the extract as a herbal syrup is aimed at developing a liquid oral formulation that is palatable and acceptable. The characteristic bitter taste is produced when the extract binds to G-protein coupled receptors on the surface of the taste over cell of the tongue. This then prompts the protein subunits of alpha, beta, and gamma to split and activate an enzyme that converts a precursor within the cell into a secondary messenger. This secondary messenger causes the release of calcium ions (Ca++) from the endoplasmic reticulum of the taste cell. The resulting build-up of calcium ions within the cell leads to depolarization and neurotransmitter release. It is this signal that is sent to the brain and is interpreted as a bitter taste.12 The pleasant taste of the extract in formulation C is due to the effective blocking of the taste receptors. This has been accomplished by the presence of the combination of ethanol and sucrose in the formulation. Ethanol acted as a taste masking agent by competing for the taste channel thereby reducing the net effect of the bitter stimuli of the extract by the characteristic burning sensation of ethanol.