Isolation and structure elucidation of anti-malarial principles from Terminalia mantaly H. Perrier stem bark

Abstract

Emergence of malaria parasite resistance to drugs has raised global public health concerns for a compelling need to develop improved malaria therapy. This study is a bio-guided isolation of triterpenoid antimalarial compounds from Terminalia mantaly. Methanol extract of the plant was subjected to column chromatography, and eluted with a ternary solvent system gradient-wise. Two compounds, 1 and 2, were isolated and characterised by spectroscopic data (IR, 1H and 13C NMR, COSY, HMQC, HMBC) and by comparison with literature. Isolated compounds were investigated for antimalarial property by spectrophotometric determination of inhibition of β-Hematin formation, absorbance taken at 405 nm. Results were analysed using Graghpad Prism® (6.0) and presented as mean IC50±SEM. Statistical significance, determined using Student’s t-test and one-way ANOVA, set at p-value of 0.05. Quantitative β-Hematin formation inhibitory activities gave IC50±SEM values of (compound 1; 4.434±0.47), (compound 2; 5.140±4.2) with (chloroquine; 0.335±0.1 mg/ml). Compound 1 was identified as 2,3,19,23-tetrahydroxyolean-12-en-28-oic acid glucopyranoside (arjunglucoside I), and compound2 as its aglycone, 2,3,19,23-tetrahydroxyolean-12-en-28-oic acid (arjungenin). This study provided credence for folkloric use of Terminalia mantaly to treat malaria, and this observed activity was probably due to these isolated triterpenoids.Keywords: β-Hematin, triterpenoids, nuclear magnetic resonance spectroscopy

Synthesis of enantiomerically pure (d) – doxylamine using a novel chiral auxiliary

“…This process is complicated to operate and requires costly chiral reagents and a longer reaction time with tedious workup (Nilesh, 2016). Thus, this study supports the synthesis of drugs as also reported in other studies (Bamba et al, 2021;Samuel and Adekunle, 2021;Kouamé et al, 2021;Chawe et al, 2021).…”

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“…Unfortunately, the precise mechanism of action is currently unexplained. The possible mechanism of triterpenoids as antimalarial action includes their impacts on mitochondrial membrane potential and the reduction of β-haematin synthesis [31][32][33]. Triterpenoid (betulinic acid) antimalarial activity is assumed to be related to its ability to engage the PfATP6 protein, which regulates calcium ion transportation and affects the host-parasite selectivity [34].…”