In continuation of our natural and medicinal research programme on tropical rainforest plants, a bioassay guided fractionation of ethanolic extract of leaves of Canarium patentinervium Miq. (Burseraceae Kunth.) led to the isolation of scopoletin (1), scoparone (2), (+)-catechin (3), vomifoliol (4), lioxin (5), and syringic acid (6). All the compounds exhibited antiacetylcholinesterase activity with syringic acid, a phenolic acid exhibiting good AChE inhibition (IC50 29.53 ± 0.19 μ g/mL). All compounds displayed moderate antileishmanial activity with scopoletin having the highest antileishmanial activity (IC50 163.30 ± 0.32 μ g/mL). Given the aforementioned evidence, it is tempting to speculate that Canarium patentinervium Miq. represents an exciting scaffold from which to develop leads for treatment of neurodegenerative and parasitic diseases.
The high potential of quinoline containing natural products and their derivatives in medicinal chemistry led us to discover a novel series of compounds 6-23 based on the concept of molecular hybridization. Most of the synthesized analogues exhibited potent leishmanicidal potential. The most potent compound (23, IC50=0.10±0.001μM) among the series was found ∼70 times more lethal than the standard drug. The current series 6-23 conceded in the development of fourteen (14) extraordinarily active compounds against leishmaniasis. In silico analysis were also performed to probe the mode of action while all the compounds structure were established by NMR and Mass spectral analysis.
Molecular hybridization yielded phenyl linked oxadiazole-benzohydrazones hybrids 6-35 and were evaluated for their antileishmanial potentials. Compound 10, a 3,4-dihydroxy analog with IC50 value of 0.95 ± 0.01 μM, was found to be the most potent antileishmanial agent (7 times more active) than the standard drug pentamidine (IC50 = 7.02 ± 0.09 μM). The current series 6-35 conceded in the identification of thirteen (13) potent antileishmanial compounds with the IC50 values ranging between 0.95 ± 0.01-78.6 ± 1.78 μM. Molecular docking analysis against pteridine reductase (PTR1) were also performed to probe the mode of action. Selectivity index showed that compounds with higher number of hydroxyl groups have low selectivity index. Theoretical stereochemical assignment was also done for certain derivatives by using density functional calculations.