Antimicrobial Property of Picralima nitida Stem Bark Extract in Cream Formulations

Abstract

The effects of formulation variables on the antimicrobial activities of the basic fraction (BF) of the methanol extract of the stem bark of Picralima nitida Stapf. Th. & H. Durrant (Apocynaceae) in cream preparations were studied using a 2³ factorial experimental design. The individual and interaction effects of nature of humectant (N), concentration of humectant (C), and time of storage of cream preparation (S) on the effectiveness of the BF cream preparations, as measured by the diameter of zone of inhibition (mm) against Staphylococcus aureus and Microsporum canis, were evaluated. The effects of the variables depended considerably on the amount of BF in the formulation. The nature of humectant (N) generally had the highest effects on the antimicrobial activity of the creams with a positive increase in activity with changes from glycerin to propylene glycol. On the other hand, changing the concentration of humectant (C) from a "low" to a "high" level (from 5% to 10%, w/w) in the formulation also generally increased the antimicrobial activity of the BF creams. The time of storage (S) exhibited the least influence, but with the creams generally losing some activity after 12 months. The interaction effects of the variables on the antimicrobial effectiveness of the BF cream formulations appeared to be generally low. In clinical trials, the 10% w/w BF cream formulation generally exhibited impressive effectiveness against skin conditions of pityriasis versicolor, tinea pedis interdigitalis, tinea capitis, and tinea corporis. More work, however, is required to develop the BF into a clinically useful antimicrobial agent.

Keywords: :

• Basic Fraction
• Cream Formulation Variables
• Picralima Nitida
• Topical Antidermatophyte Activity