FORMULATION STRATEGY FOR THE PRE-CLINICAL AND EFFICACY EVALUATION OF HERBAL PRODUCTS WITH MEDICINAL PROPERTIES

EA Tembe-Fokunang, I. Horan, Charles Fokunang

Abstract


Introduction

Natural products constitute a major source of therapeutics, accounting for about 40% of all new US drug approvals in the decade to 2010 and more than 60,000 plant species are exploited for their medicinal properties. A specific category of these compounds are herbal medicines which are assuming a greater clinical and commercial importance in line with a growing interest in traditional and  alternative medicines in many developed countries. Despite the fact that herbal medicines now represent more than US 56 billion in sales per year in Europe, with the exception of a guideline on the quality of herbal preparations, there are no uniform regulatory criteria.

Objective of Study: This study aims at formulating a hierarchical strategy for evaluating complex mixtures of ethanolic extracts for dermal application by using an initial analytical screen followed by an in vitro toxicology and in vitro modeling of possible activity.

Materials and Methods: A combination of UV/VIS, FTIR, GC-MS, polarimetry, and amino acid (AA) techniques applied to ultrafiltrates and Sephadex column fractions was used for the identification of major active species in the complex. The use of MTT, SRB and NR cytotoxicity assays with organotypic cells was also applied to permits a rapid evaluation of gross toxicity which when applied in conjunction with separation methods allowed the activity to be associated with components of known molecular weight. Determination of mutagenic and antiseptic potential of the extract was assessed by virtue of Ames assay and disinfectant assays respectively. Finally, a highest order potential toxicity and possible mechanisms of efficacy action was evaluated using specific 3D culture models based on primary cells.

Results: The protein and carbohydrate content of the herbal extract and the final product showed a significant variation. The herbal extract showed a protein content of 25.17±1.3mg/ml while the final product had a significant reduced protein content of 0.044±0.0mg/ml. For sugar content Herbal extract had a reducing sugar of 235±35.0 mg/ml as compared to 15.33± 2.55mg/ml. Protein purification procedures identified two different proteins the molecular weights of which were estimated as follows: The herbal extract using ultrafiltration showed a molecular weight of 38914±1,266 kDa. Although UV/VIS analysis is not diagnostic for a particular compound a number of absorptive peaks were evident in the 200-220nm region which is indicative of flavones (phenolic structures). Acid hydrolysis indicated the presence of polysaccharides/hydrolysable glycosides, also the precipitation of phlobaphenes were indicative of the presence of tannins. Ames assay:  results showed no mutagenic potential of the extract with and without metabolic activation, these results also achieved significance at a 95% confidence level. However it was observed that at high concentrations a bactericidal effect was induced. A disinfectant assay using E. coli, S. aureus, S. typhimurium and C. sporogenes proved the herbal extract to contain antibiotic constituents, although its cell killing properties were influenced by final ethanol concentration


Keywords


pre-clinical, efficacy evaluation, herbal products, medicinal properties

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