Leishmanicidal Potential of Hardwickiic Acid Isolated From Croton sylvaticus

Abstract

Leishmania is a parasitic protozoon responsible for the neglected tropical disease Leishmaniasis. Approximately, 350 million people are susceptible and close to 70,000 death cases globally are reported annually. The lack of effective leishmanicides, the emergence of drug resistance and toxicity concerns necessitate the pursuit for effective antileishmanial drugs. Natural compounds serve as reservoirs for discovering new drugs due to their chemical diversity. Hardwickiic acid (HA) isolated from the stembark of Croton sylvaticus was evaluated for its leishmanicidal potential against Leishmania donovani and L. major promastigotes. The susceptibility of the promastigotes to HA was determined using the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide/phenazine methosulfate colorimetric assay with Amphotericin B serving as positive control. HA showed a significant antileishmanial activity on L. donovani promastigotes with an IC 50 value of 31.57± 0.06 µM with respect to the control drug, amphotericin B with IC 50 of 3.35 ± 0.14 µM). The cytotoxic activity was observed to be CC 50 = 247.83 ± 6.32 µM against 29.99 ± 2.82 µM for curcumin, the control, resulting in a selectivity index of SI = 7.85. Molecular modeling, docking and dynamics simulations of selected drug targets corroborated the observed antileishmanial activity of HA. Novel insights into the mechanisms of binding were obtained for trypanothione reductase (TR), pteridine reductase 1 (PTR1), and glutamate cysteine ligase (GCL). The binding affinity of HA to the drug targets LmGCL, LmPTR1, LdTR, LmTR, LdGCL, and LdPTR1 were obtained as-8.0,-7.8,-7.6,-7.5,-7.4 and-7.1 kcal/mol, respectively. The role of Lys16, Ser111, and Arg17 as critical residues required for binding to LdPTR1 was reinforced. HA was predicted as a Caspase-3 stimulant and Caspase-8 stimulant, implying a possible role in apoptosis, which was shown experimentally that HA induced parasite death by loss of

Homology Modeling, de Novo Design of Ligands, and Molecular Docking Identify Potential Inhibitors of Leishmania donovani 24-Sterol Methyltransferase

“…Due to the unavailability of an experimentally elucidated 3D structure for Ld SMT, molecular modeling techniques were used to predict a reasonably accurate protein structure ( Crentsil et al., 2020 ). Modeller version 10.2 ( Eswar et al., 2008 ) was employed in building the 3D structure using three different templates: i) the 3BUS template was used to generate five models of the Ld SMT ( Eswar et al., 2008 ), ii) the protein structure with PDB ID 4PNE was also used to model five different structures of the Ld SMT ( Eswar et al., 2008 ), and iii) multitemplate homology modeling was employed to generate five structures of the Ld SMT ( Eswar et al., 2008 ).…”

Antinociceptive effect of plant-based natural products in chemotherapy-induced peripheral neuropathies: A systematic review

“…(−)-Hardwickiic acid (C 20 H 28 O 3 ) is a diterpene isolated and extracted from the Croton calcifornicus plant with potential analgesic effect ( Crentsil et al, 2020 ). The compound was effective in significantly relieving the mechanical allodynia of rats induced to peripheral neuropathy with PTX at the dose tested (2 µg/5 µl, i.th.).…”

Biologically Active Diterpenoids in the Clerodendrum Genus—A Review

“…Harwickiic acid (44) was first isolated from Sindora sumatrana MIQ fruits [ 73 ]. This clerodane-type diterpenoid, obtained from the stem bark of Croton sylvaticus , was found to demonstrate significant antileishmanial activity against L. donovani promastigotes with an IC 50 of 31.57 µM, as well as cytotoxic activity against RAW 264.7 (CC 50 = 247.83 μM) [ 74 ]. Harwickiic acid (44) , isolated from C. inerme aerial parts, together with crolerodendrum B (42) and uncinatone (9) also demonstrates strong antioxidant activity measured as DPPH radical-scavenging activity; these compounds have been found to have respective ED 50 values of 11.3 µM (44) , 17.6 µM (42) and 10.1 µM (9) [ 70 ].…”