Corrigendum to "Naturally occurring sesquiterpene lactones and their semi-synthetic derivatives modulate PGE2 levels by decreasing COX2 activity and expression" [Heliyon 5 (3) (March 2019) e01366].

[This corrects the article DOI: 10.1016/j.heliyon.2019.e01366.].

Naturally occurring sesquiterpene lactones and their semi-synthetic derivatives modulate PGE2 levels by decreasing COX2 activity and expression.

Plants of the Asteraceae family have been used in traditional medicine for centuries due to their main antimicrobial and analgesic activities. A liniment from Artemisia californica has recently been tested on patients affected by either acute pain or chronic pain conditions with great success. The aim of this study was to evaluate the anti-inflammatory activity of sesquiterpene lactones (SLs), representing the majority in the Asteraceae family. Leucodin, α-santonin and sclareolide (three SLs) were chosen to undergo chemical modifications. This pool of molecules underwent molecular modeling experiments using an in-house program, WATGEN, predicting the water network and its contribution to the overall affinity of the enzyme-ligand complex. The anti-inflammatory activity and the ability of compounds to modulate COX-2 expression have been evaluated in LPS-stimulated RAW 264.7 cells and in RIF-1 cells treated according to the Photodynamic Therapy (PDT) protocols using Photoprin (PH) as photosensitizer. Furthermore, commercially available assay kits were used to evaluate the concentration of PGE-2 and the direct inhibition of COX-2. All the tested molecules fit well in the enzyme binding pocket, but to get a substantial inhibition of the expression and activity of the enzyme as well as a reduction in the PGE2 concentration, high concentrations of the compounds are needed. The only exceptions being leucodin itself and FP6, one of the α-santonin derivatives, presenting a CF3 functional group. We believe that this class of compounds has some interesting potential in the treatment of pain and inflammation. Although, the activity seems to be due to a mechanism related to the expression of the COX enzymes rather than on a direct inhibition.

Rational drug design and synthesis of new α-Santonin derivatives as potential COX-2 inhibitors.

Sesquiterpene compounds are widely known for their numerous pharmacological activities. Herein the focus of the authors was on α-Santonin, a sesquiterpene lactone from the Artemisia genus: the aim was to determine whether α-Santonin could be considered in the treatment of inflammation and pain. To this purpose, a small series of derivatives was designed and screened in silico against the enzyme COX-2 along with the parent compound. Drug-likeness parameters were also assessed. The compounds were eventually synthesized, and few were tested to determine their efficacy in the inhibition of COX-2 activity and expression. Overall, compound A2 was the only one with a detectable inhibitory potential of COX-2 activity whilst two of its ether derivatives demonstrated improved ability in the inhibition of COX-2 expression.

Enhancement of Curcumin Bioavailability Via the Prodrug Approach: Challenges and Prospects.

Curcumin is a natural product with many interesting pharmacological properties. However, these are offset by the particularly poor biopharmaceutical properties. The oral bioavailability of curcumin in humans is very low, mainly due to low solubility, poor stability, and extensive metabolism. This has led to multiple approaches to improve bioavailability, including administration of curcumin with metabolism inhibitors, formulation into nanoparticles, modification of the curcumin structure, and development of curcumin prodrugs. In this paper, we focus on the pharmacokinetic outcomes of these approaches. Pharmacokinetic parameters of curcumin after release from prodrugs are dependent on the linker between curcumin and the promoiety, and the release itself may depend on the physiological and enzymatic environment at the site of cleavage. This is an area in which more data are required for rational design of improved linkers. Cytotoxicity of curcumin prodrugs seems to correlate well with cellular uptake in vitro, but the in vivo relevance is uncertain. We conclude that improved experimental and theoretical models of absorption of curcumin prodrugs, development of accurate analytical methods for simultaneous measurement of plasma levels of prodrug and released curcumin, and acquisition of more pharmacokinetic data in animal models for dose prediction in humans are required to facilitate movement of curcumin prodrugs into clinical trials.