CHEMICAL CONTENT, ANTI-OXIDANT AND ANTI-BACTERIAL POTENCY STABILITY IN SELECTED MALAWIAN AQUEOUS HERBAL FORMULATIONS

Abstract

Herbal formulations are stored in various containers for different durations which may lead to variations in their chemical profiles and pharmaceutical activities. This work evaluated the stability of selected aqueous herbal formulations during storage in plastic bottles and clay pots as done by some practitioners in Zomba, Malawi. Formulations were analyzed over a maximum period of 30 storage days for physico-chemical parameters, phytochemical presence, changes in metal concentrations and total phenolic content (TPC). Stability of antioxidant potential was determined by both electron transfer (ferric reducing assay) and proton donation (hydrogen peroxide scavenging assay). Anti-bacterial activity of the formulations was determined using the well-diffusion method against E- coli strains. Physico-chemical parameters and metal concentrations increased with storage duration and were higher in formulations stored in clay pot containers (P≤0.05). Formulation pH decreased with storage duration but was comparable between containers. Highest antibacterial activity was observed on day 5, with a 13mm growth inhibition zone against E.coli strains. This antibacterial activity was 59% of the activity of erythromycin (250mg). Increases in TPC, antioxidant potential and antibacterial activity were influenced by storage duration and not container material. This study showed that the monitored aqueous herbal formulations are not stable during storage and that the best combined medicinal effect can be achieved on day four with observance of hygienic principles.