Pharmacognostic and physicochemical evaluation, HPLC analysis and antiproliferative properties of Kigelia africana (Lam.) Benth

Abstract

Introduction/Objective of study: Kigelia africana (Bignoniaceae) is enriched with bioactive constituents and has thus found various uses in African folklore. This study aims to evaluate the pharmacognostic, physicochemical, chromatographic and antiproliferative properties of K. africana.
Methodology: Standard methods were used to determine the qualitative microscopy, moisture content, ash and extractive value. Furthermore, HPLC analysis was conducted on the samples in order to detect and quantify some phenolic compounds (gallic acid, chlorogenic acid, rutin, ferulic acid, caffeic acid and quercetin). The Sorghum bicolor model was used for the antiproliferative assay. All experiment was carried out in triplicates.
Results: Microscopy revealed amphistomata with the presence of non-glandular unicellular, uniseriate trichomes on K. africana leaf. Cellulose, tannins, calcium oxalate crystals on the leaf and stem bark, while the roots lacked calcium oxalate crystals. Ash contents were leaf (21.8 ± 0.1) %w/w, stem bark (4.8 ± 0.03)%w/w and root (3.9 ± 0.2)%w/w. Moisture content was (10.5 ± 0.5) %w/w and (9.5 ± 0.2) %w/w for the root and leaf parts, respectively. All values were within WHO limits for crude drugs. The stem bark and root parts contained more water-soluble constituents than alcohol soluble constituents. From the results of HPLC analysis the leaf, stem bark and root extracts gave 24 peaks, 16 peaks and 30 peaks, respectively, a few peaks matched with reference compounds- quercetin, caffeic acid, ferulic acid and rutin. Results of antiproliferative assay showed that methotrexate was significantly (p ˂ 0.05) more effective than the stem bark (from 2-64 mg/mL) with inhibitions ranging from 72.0 ± 1.4% - 90.0 ± 2.4% and root extracts (from 4 – 64 mg/mL) that had inhibitions ranging from 50.3 ± 1.5% - 97.7 ± 0.4% but comparable with leaf extract (from 16 mg/mL - 64 mg/mL) with inhibitions ranging from 68.4 ± 0.8% - 99.0 ± 0.1%.
Conclusion: Further information which can be included in an official monograph of the plant for its proper identification and quality control has been provided by this study. Kigelia africana exhibited effective antiproliferative activities and the presence of phenolic compounds.