Evaluation of the Plant Extracts of an Anti-Tubercular Herbal Remedy

Ximenia americana root bark (Olacaceae) and Pavetta crassipes (Rubiaceae) leaf used in Nigerian traditional medicine were tested individually against clinical isolate of Mycobacterium tuberculosis by Lowenstein - Jensen method. Crude aqueous extracts of X. americana and P. crassipes exhibited minimum inhibitory activity (MIC) of 100 μg/mL and 200 μg/mL respectively. Sequential screening with solvents of different polarities was used in evaluation tests to readily locate the source of the activity against tuberculosis and for conditions related to skin diseases since it was readily available. In general, antimicrobial screening of crude extracts gave MICs ranging from 31.25 μg/mL to > 5 mg/mL, with X. americana methanol extract being most active at 31.25 μg/mL against Staphylococcus aureus. In an effort to determine possible mechanisms of action, synergistic interaction studies between standard antibiotics and plant extracts were carried out with some synergy being observed between X. americana extract and streptomycin. Hexane (MIC 60.6 μg/mL) and dichloromethane (MIC 30.5 μg/mL) fractions of X. americana exhibited 94.3 % and 96.4 % inhibition against M. tuberculosis H37HRv (virulent strain) while P. crassipes hexane fraction had 86.7% inhibition at > 64 μg/mL. Using HPLC, TLC, GC, 1D and 2D-NMR as well as mass spectral analyses it was possible to identify rutin and 5-O- caffeoyl quinic acid methyl ester from P. crassipes. It proved extremely difficult to identify compounds from LC and TLC fractions from the non-polar extracts of X. americana responsible for anti-TB activity. There was some spectroscopic evidence from these fractions for closely related phytosterol esters and individual compounds such as stigmast- 3, 5 - diene, stigmastane oleate and β-sitosterol. Subsequent LC work with refractive index detection and SFC with evaporative light scattering data confirmed that the difficulties in assignment arose from the presence of non-UV absorbing non-volatile co-eluting compounds. Preparative xviii SFC or SFC-MS with the aid of the NIST database would have been needed for identification. Overall, these results lend some credence to the claims of the Nigerian remedy and potentially could be a source of assay biomarkers for monitoring its safety, efficacy and quality as required by IRCH (International Regulatory Co-operation for Herbal Medicines)

Evaluation of the plant extracts of an anti-tubercular herbal remedy

Ximenia americana root bark (Olacaceae) and Pavetta crassipes (Rubiaceae) leaf used in Nigerian traditional medicine were tested individually against clinical isolate of Mycobacterium tuberculosis by Lowenstein - Jensen method. Crude aqueous extracts of X. americana and P. crassipes exhibited minimum inhibitory activity (MIC) of 100 μg/mL and 200 μg/mL respectively. Sequential screening with solvents of different polarities was used in evaluation tests to readily locate the source of the activity against tuberculosis and for conditions related to skin diseases since it was readily available. In general, antimicrobial screening of crude extracts gave MICs ranging from 31.25 μg/mL to > 5 mg/mL, with X. americana methanol extract being most active at 31.25 μg/mL against Staphylococcus aureus. In an effort to determine possible mechanisms of action, synergistic interaction studies between standard antibiotics and plant extracts were carried out with some synergy being observed between X. americana extract and streptomycin. Hexane (MIC 60.6 μg/mL) and dichloromethane (MIC 30.5 μg/mL) fractions of X. americana exhibited 94.3 % and 96.4 % inhibition against M. tuberculosis H37HRv (virulent strain) while P. crassipes hexane fraction had 86.7% inhibition at > 64 μg/mL. Using HPLC, TLC, GC, 1D and 2D-NMR as well as mass spectral analyses it was possible to identify rutin and 5-O- caffeoyl quinic acid methyl ester from P. crassipes. It proved extremely difficult to identify compounds from LC and TLC fractions from the non-polar extracts of X. americana responsible for anti-TB activity. There was some spectroscopic evidence from these fractions for closely related phytosterol esters and individual compounds such as stigmast- 3, 5 - diene, stigmastane oleate and β-sitosterol. Subsequent LC work with refractive index detection and SFC with evaporative light scattering data confirmed that the difficulties in assignment arose from the presence of non-UV absorbing non-volatile co-eluting compounds. Preparative xviii SFC or SFC-MS with the aid of the NIST database would have been needed for identification. Overall, these results lend some credence to the claims of the Nigerian remedy and potentially could be a source of assay biomarkers for monitoring its safety, efficacy and quality as required by IRCH (International Regulatory Co-operation for Herbal Medicines).EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Anti-mycobacterial assessment and characterization of 5-O-caffeoylquinic acid methyl ester and rutin from Pavetta crassipes

Pavetta crassipes leaf (Fam. Rubiaceae) is used as part of a combination herbal remedy for the treatment of tuberculosis (TB) and other respiratory infections in Nigerian ethno medicine. However, little scientific data is available to support the use in ethnomedical therapy so the objective of the study was to assess the antitubercular property and to identify the bioactive components. The dried powdered leaf was sequentially extracted with solvents to obtain hexane, dichloromethane, methanol and water extracts. Following which, the extracts were then screened against Mycobacterium aurum, a rapidly growing saprophytic mycobacterium species for activity. The methanol extract exhibited inhibitory activity at an MIC value of 250 µg/mL against M. aurum and two known polyphenolic compounds were isolated as 5-O-caffeoylquinic acid methyl ester and quercetin-3-rutinoside (rutin). Reversed phase semi-preparative HPLC, mass spectrometry and 1H and 13C NMR techniques were utilized in isolating and characterizing the two components. The assignments of the structures were consistent with data from the literature. The study has shown that the methanol extract has some activity and hyphenation of LC-MS can be used for the isolation of polyphenols from the methanol fraction without a rigorous purification process

Eudragit E100 and Polysaccharide Polymer Blends as Matrices for Modified-Release Drug Delivery II: Swelling and Release Studies

Purpose: To compare the effects of two states of polymer/polymer blending (dry and aqueous/lyophilized) of locust bean gum with Eudragit® E100 and sodium carboxymethylcellulose on swelling and drug (levodopa) release from their tablet matrices.Methods: Sodium carboxymethylcellulose (SCMC), Eudragit® (E100) and locust bean (LB) were blended in their dry (as purchased) state or modified by aqueous blending and subsequent lyophilization prior to use as tablet matrices. The tablets were evaluated for swelling and in vitro drug release. Furthermore, in vivo absorption was predicted from the in vitro release data by convolution method.Results: E100 matrices exhibited little or no swelling while the matrices of SCMC and LB and their blends exhibited a degree of swelling > 180 %. Aqueous blending and lyophilization modulated the rate of release from matrices formulated with LB, SCMC and their polymer/polymer blends. Drug release profiles of the lyophilized polymer/polymer blends matrices were dissimilar to those of the dry polymer/polymer blends. Formulations F1aq, F2aq and F3aq exhibited fairly uniform absorption in the first 8 h, indicating the possibility of producing a steady delivery of drug.Conclusion: Polymer blending of LB, SCMC and E100, achieved by aqueous blending and lyophilization, enhances the performance of the matrices thereby exhibiting controlled levodopa release with no burst effect and the tablets retained their three-dimensional network.Keywords: Controlled release, Drug delivery, Eudragit, Locust bean, Levodopa, Matrix, Polymer blend, Sodium carboxymethylcellulos

Eudragit E100 and Polysaccharide Polymer Blends as Matrices for Modified-Release Drug Delivery I: Physicomechanical Properties

Purpose: To compare the effects of two states of polymer/polymer blending (dry and aqueous/lyophilized) on the physicomechanical properties of tablets, containing blends of locust bean gum (LB) with Eudragit® E100 (E100) and sodium carboxymethylcellulose (SCMC) as matrices.Methods: LB, SCMC and E100 were blended in their dry (as purchased) state or modified by aqueous blending and subsequent lyophilization, prior to use as matrices in tablets. The polymer blends were characterized by infra-red spectroscopy (FTIR), flow and compressibility tests, as well as physicomechanical analysis of their tablets.Results: No significant variations were noticeable in the FTIR peaks of the individual polymers in the dry and the aqueous/lyophilized states. Aqueous/lyophilized blending of the polymers resulted in better flow properties. The aqueous/lyophilized matrices were denser with improved mechanical strength and the tablets were harder than those produced from dry blended polymers.Conclusion: Dry blending of LB with E100 and SCMC greatly improved the physicomechanical properties of the tablets. This was further enhanced by aqueous/lyophilized blending.Keywords: Drug delivery, Polymer blend, Eudragit, Locust bean gum, Levodopa, Sodium carboxymethylcellulose, Matrix, Physicomechanical propertie

Pharmaceutical Properties and Applications of a Natural Polymer from Grewia mollis

The use of naturally occurring biocompatible materials has been the focus of recent research activity in the design of dosage forms for immediate and controlled release formulations. Grewia gum is an intracellular gum obtained by extraction from the inner stem bark of the shrub Grewia mollis (Malvaceae). It grows abundantly (wild or cultivated) in the middle belt region of Nigeria, and the mucilage has been used by indigenes of this belt as thickener in soups. Grewia gum has been investigated for potential applications in pharmaceutical dosage forms. The industrial extrapolation of the applications of the gum has, however, been slowed by the limited structural, toxicological, and stability data available on the gum. This paper highlights ethnobotanical uses of G. mollis shrub and discusses the structural features, functional properties, and applications of grewia gum with emphases on its pharmaceutical potentials