Bioassay-guided fractionation, phospholipase A2-inhibitory activity and structure elucidation of compounds from leaves of Schumanniophyton magnificum

• Published in: Pharmaceutical biology Vol. 58; no. 1; pp. 1078 - 1085
• Main Authors: Joshua, Parker Elijah, Anosike, Chizoba Joy, Asomadu, Rita Onyekachukwu, Ekpo, Daniel Emmanuel, Uhuo, Emmanuel Nnaemeka, Nwodo, Okwesili Fred Chiletugo
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 01.01.2020; Taylor & Francis Ltd; Taylor & Francis Group
• Subjects: 14-Methyl pentadecanoic acid methyl ester; 3-ethylhexane; Acetic acid; anti-inflammatory; Bacillus cereus; Dichloromethane; enzyme inhibition; Erythrocytes; Ethyl acetate; Fractionation; Gas chromatography; hexadecanoic acid, ethyl ester; Inflammation; Infrared spectroscopy; Leaves; Mass spectroscopy; Methanol; n-Hexane; Palmitic acid; Phospholipase A2; Prednisolone; Rubiaceae; Venom
• ISSN: 1388-0209; 1744-5116
• DOI: 10.1080/13880209.2020.1839510

Schumanniophyton magnificum Harms (Rubiaceae) is used traditionally in Nigeria for the treatment of snake bites. Snake venom contains phospholipase A 2 (PLA 2 ) which plays a key role in causing inflammation and pain. To assess the anti-inflammatory effect of the methanol extract of Schumanniophyton magnificum (MESM) leaves through the inhibition of PLA 2 and investigate the compounds responsible for the effect. PLA 2 -inhibitory activity of MESM was assessed at concentrations of 0.1-0.8 mg/mL using human red blood cells as substrate. Prednisolone was used as the standard control. MESM was subsequently partitioned using n-hexane, dichloromethane, ethyl acetate and aqueous-methanol (90:10 v/v), after which PLA 2 -inhibitory activity of the partitions was determined. The best partition was subjected to chromatographic techniques and the fractions obtained were assessed for PLA 2 inhibition at 0.4 mg/mL. Compounds in the most active fraction were determined using Fourier-transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GC-MS). MESM significantly inhibited PLA 2 activity at 0.8 mg/mL (44.253%) compared to prednisolone (35.207%). n-Hexane partition (SMP1) proved more active with inhibition of 55.870% observed at 0.1 mg/mL. Fraction 1 (SMF1) showed the highest PLA 2 -inhibitory activity of 58.117%. FTIR studies revealed the presence of some functional groups in SMF1, and GC-MS confirmed the presence of 9 compounds which are first reported in this plant. Hexadecanoic acid, ethyl ester was identified as the major compound (24.906%). The PLA 2 -inhibitory activity of MESM suggests that its compounds may be explored further in monitoring anti-inflammatory genes affected by the venoms.