Bioactivity-guided isolation of the antidiabetic principle in Pterocarpus Santalinoides leaf extract

Abstract Pterocarpus santalinoides is used in Nigerian ethnomedicine to treat diabetes mellitus. This study aimed to establish the antidiabetic property of the plant, and isolate and characterize its active principle. Dried and pulverized leaves (500 g) of P. santalinoides were extracted with 1.8 L of 80 % hydromethanol by cold maceration. The dried extract (10 g) was partitioned into n-hexane, ethyl acetate (EtOAc), n-butanol, and water. Antidiabetic activitiy-guided isolation by column chromatographic separation of the EtOAc soluble and purification of the sub-fractions by repeated preparative thin layer chromatography (pTLC) yielded a C-glycosyl flavonoid, identified as isovitexin. The chemical structure was elucidated based on high-resolution mass spectroscopy, 1D, and 2D nuclear magnetic resonance spectroscopic analyses. Alloxan-induced diabetic rat model was adopted for antidiabetic screening. The extract of P. santalinoides (100-200 mg/kg), fraction F4 (50 mg/kg), sub-fraction F4.3 (10 mg/kg), and the semi-purified compound F4.3.2 (5 mg/kg) significantly (p<0.05) reduced the fasting blood glucose of alloxan-induced diabetic rats, causing 48.4, 69.4, 57.7 and 64.5 % antidiabetic activity respectively, compared with > 68 % recorded in glibenclamide (2 mg/kg) control. These results reveal that isovitexin is the antidiabetic principle in P. santalinoides

Evaluation of Antimicrobial Activities of Fractions of Plant Parts of Pterocarpus santalinoides

Aims: The study aims to investigate the antimicrobial activities of the leaves, seeds, bark, and root of Pterocarpus santalinoides plant. Study Design: Agar well diffusion and Agar well dilution methods were used to test the preliminary antimicrobial and minimum inhibitory/bactericidal/fungicidal concentrations respectively of Pterocarpus santalinoides plants. Place and Duration of Study: Department of Pharmaceutical Microbiology and Biotechnology, Faculty of Pharmaceutical Sciences, Nnamdi Azikiwe University, Agulu Campus, Nigeria, between February – October, 2017. Methodology: Primary extraction and fractionation of the plant parts were undertaken with methanol, butanol, ethyl acetate, and n-hexane. Agar diffusion method for the primary antimicrobial screening on Muller-Hinton agar (bacteria) and Sabouraud dextrose agar (fungi) were used to assess the antimicrobial activities of the sixteen (16) samples on some microbial isolates namely Salmonella typhi, Escherichia coli, Candida albicans, Aspergillus niger, Microsporon canis, and Trichophyton rubrum. The minimum Inhibitory concentration (MIC), minimum bactericidal/fungicidal concentration (MBC/MFC) and percentage inhibition diameter growth (PIDG) of the samples that yielded positive activity were also evaluated. Results: Twelve (12) samples exhibited inhibitory activity on at least one or more of the test isolates. The MIC range observed for the extracts and fractions that yielded positive activity was 12.5 – 100 mg/ml. The n-hexane fraction of the plant root indicated the best value of 12.5 mg/ml against M. canis. The best MBC/MFC value of 25 mg/ml was observed with the ethyl acetate fraction of the bark (against E. coli and M. canis) and the n-hexane fraction of the root (against M. canis). The result showed S. typhi to be the most sensitive organism to the metabolites of P. santalinoides. Extended-spectrum activity was observed with the ethyl acetate fraction of the bark against three (3) of the test isolates namely S. typhi, E. coli and M. canis. The determination of PIDG values for the test organisms against the plants’ extracts/fractions showed that crude methanol extract (28.57%) and ethyl-acetate fraction (0.14%) of the leaves, butanol fraction (0.14%) of the root (all against S. typhi) were the most potent test samples. Conclusion: The results indicated that the plant parts may have potential medicinal values and confirmed its use in traditional medicine.

Phytochemical and Antimicrobial Evaluation of Leaf-extracts of Pterocarpus santalinoides.

Aim: This study was undertaken to examine the phytochemical constituents and antimicrobial activity of leaf-extracts of Pterocarpus santalinoides, a plant with wide application in Igede people’s traditional medicine against microbial infections. Methodology: Successive extraction of leaves of this plant at room temperature using petroleum ether, ethyl acetate, butanol, ethanol and water was carried out. These extracts were phytochemically screened qualitatively for the presence of alkaloids, flavonoids, saponins, tannins and terpenoids using established literature procedures. Agar well diffusion technique was used to screen the extract for antimicrobial activity. MICs, MBCs and MFCs for the various extracts were determined by the tube dilution technique. Graded concentrations of the extract solutions in Mueller Hinton broth were used for the tests. MBCs and MFCs were done to establish the nature of antimicrobial activity of these extracts. Results: Qualitative phytochemical screening of leaf-extracts of P. santalinoides revealed presence of alkaloids, flavonoids, terpenoids, saponins-glycosides and tannins (except ethanol extract that contained no tannins). These extracts inhibited growth of test organisms, and implies antimicrobial activity on E. coli, P. mirabilis, S. typhi, S. aureus and C. albicans. Zones of inhibition ranged from 17-24 mm. The MICs ranged from 5.0 mg/ml to 10 mg/ml while MBCs and MFCs ranged from 10 mg/ml to 20 mg/ml. Ethanol extracts showed the widest zone of inhibition followed by aqueous extracts (24 mm and 21 mm, respectively). Conclusion: These results lend support to the ethnomedicinal applications of this plant by the Igede people of North Central Nigeria, in treating infections caused by these test organisms which are human pathogens. The ethanol extract in particular, may be exploited as a possible antimicrobial agent for the management of infectious pathogenic diseases caused by these microorganisms.