Characterization of Phenolic compounds from leaf extracts of Bidens Pilosa L. Var. Radiata and evaluation of their antacid potential in Artificial Stomach Model

Abstract

Several studies reveal that Gastric Ulcer Disease (GUD) is one of the most prevalent gastrointestinal diseases affecting 5-10% of the population worldwide. Antacids have been used in the management of GUD. However, due to the side effects of synthetic antacids such as hypersensitivity reactions, nutritional deficits and bone marrow suppression, an alternative antacid with fewer side effects which is eco-friendly is needed. Therefore the aim of this study was to characterize phenolic compounds in extracts of Bidens pilosa leaves and evaluate the antacid potential in a modified artificial stomach model. Specific objectives were to: determine phytochemical composition of extracts of B. pilosa leaves, characterize the phenolic compounds from B. pilosa leaves and to evaluate the neutralizing effect of extracts of B. pilosa leaves. Extraction was done using soxhlet apparatus. Phytochemicals present were determined using calorimetric method. Classical column chromatography was used for fractionation and thin layer chromatography (TLC) was used to merge the fractions with the same retention factors, while solid phase extraction (SPE) was used for the clean-up. FTIR with a range between (4000-400 cm-1), UV-visible spectroscopy and GC-MS/MS were used for characterization. The pH of B. pilosa fractions with concentrations 800 and 400 mgkg-1bw-1, representing high dose (HD) and low dose (LD) respectively, and their neutralizing effects on artificial gastric acid were determined and compared to water and sodium bicarbonate (standard). A modified model of Vatier’s artificial stomach was used to determine the time taken to neutralize the artificial gastric acid. The neutralization capacity in vitro was determined with a classical titration method based on Fordtran’s model. Phytochemical analysis of each extract showed the presence of saponins, alkaloids, phenols, tannins, cardiac glycosides and flavonoids. Dichloromethane: methanol extract (1:1) showed the highest total phenolic and flavonoid content of 288.7 ± 1.27 mg GAE/g and 274.7 ± 2.02 mg QE/g extract respectively. Phenolics were in abundance while the other compounds were in low yields thus were not considered further. FT-IR spectral data showed a broad peak absorption in the range 3300-3200 cm-1 and was attributed to O-H stretch, 1150-1085 cm-1 C-O stretch, 1000-650 cm-1 C=C bend, 1440-1395 cm-1 O-H bend, 1650-1580 cm-1 N-H bend. Some of the phenolic compounds identified by GC-MS/MS were; 2,4-Di-tert-butylphenol, 2,6-Bis (tert-butyl)phenol, 3,5-ditert-butylphenol and 2,5-bis(1,1-Dimethylethyl)phenol. All treatments including HD and LD B. pilosa fractions and sodium bicarbonate showed significant acid neutralizing effects with (P<0.01 and P<0.05) when compared with water. The duration for consistent neutralization and neutralization capacities of fractions of B. pilosa HD and LD were significantly higher with (P<0.01) than those of water. HD and LD B. pilosa fractions were consistently active in the artificial stomach model and possessed potent antacid effects. In conclusion, the results obtained showed the presence of phenolic compounds in the B. pilosa leaf extracts which were responsible for the observed antacid activity. This study recommends B. pilosa leaf extract as an effective alternative to sodium bicarbonate that is commonly used and known to have side effects like alteration in systematic pH.