Analgesic effects of 1,2,3,4,6-penta-O-galloyl-β-D-glucose in an animal model of lipopolysaccharide-induced pain

Identification of potential anti-inflammatory components in Moutan Cortex by bio-affinity ultrafiltration coupled with ultra-performance liquid chromatography mass spectrometry

Moutan Cortex (MC) has been used in treating inflammation-associated diseases and conditions in China and other Southeast Asian countries. However, the active components of its anti-inflammatory effect are still unclear. The study aimed to screen and identify potential cyclooxygenase-2 (COX-2) inhibitors in MC extract. The effect of MC on COX-2 was determined in vitro by COX-2 inhibitory assays, followed by bio-affinity ultrafiltration in combination with ultra-performance liquid chromatography-mass spectrometry (BAUF-UPLC-MS). To verify the reliability of the constructed approach, celecoxib was applied as the positive control, in contrast to adenosine which served as the negative control in this study. The bioactivity of the MC components was validated in vitro by COX-2 inhibitor assay and RAW264.7 cells. Their in vivo anti-inflammatory activity was also evaluated using LPS-induced zebrafish inflammation models. Finally, molecular docking was hired to further explore the internal interactions between the components and COX-2 residues. The MC extract showed an evident COX-2-inhibitory effect in a concentration-dependent manner. A total of 11 potential COX-2 inhibitors were eventually identified in MC extract. The COX-2 inhibitory activity of five components, namely, gallic acid (GA), methyl gallate (MG), galloylpaeoniflorin (GP), 1,2,3,6-Tetra-O-galloyl-β-D-glucose (TGG), and 1,2,3,4,6-Penta-O-galloyl-β-D-glucopyranose (PGG), were validated through both in vitro assays and experiments using zebrafish models. Besides, the molecular docking analysis revealed that the potential inhibitors in MC could effectively inhibit COX-2 by interacting with specific residues, similar to the mechanism of action exhibited by celecoxib. In conclusion, BAUF-UPLC-MS combining the molecular docking is an efficient approach to discover enzyme inhibitors from traditional herbs and understand the mechanism of action.

Bio-guided study of the antinociceptive, anti-inflammatory, and free-radical scavenging capacity of the leaves of Rhus virens Lindh. ex A. Gray and its possible mechanism of antinociception

ETHNOPHARMACOLOGICAL RELEVANCE

Rhus genus is commonly known as sumac and widely used in the folk medicine. Rhus virens is a plant commonly used to treat diabetes or pain in the northern territory of Mexico. Even though R. virens is used in the folk medicine there is still a lack of evidence about the pharmacological effect of this species.

AIM OF THE STUDY

The aim of this study was to determine the antinociceptive, anti-inflammatory and antioxidant effect of R. virens through a bio-guided chemical separation.

MATERIALS AND METHODS

The aqueous, methanolic, and hexane extract of R. virens were obtained and tested in the formalin test, TPA-induced ear edema, and DPPH, ABTS, and FRAP assay. Also, possible interaction of pain pathways was studied using naloxone, bicuculline, L-NAME, ODQ, and glibenclamide in the formalin test in mice.

RESULTS

Rhus virens methanolic extract (30 mg/kg, p.o.) produced higher antinociceptive activity in both the early and late phases of the formalin test (35.0 and 52.9%, respectively). Also, pre-administration with naloxone, bicuculline, L-NAME, ODQ and glibenclamide prevented the antinociceptive effect of R. virens in the early phase of the formalin test. Meanwhile, only naloxone and bicuculline prevented the antinociceptive effect on the late phase of the formalin test. Chemical separation of methanolic extract allowed to isolate 1,2,3,4,6-penta-O-galloyl-glucopyranose (PGG), it was tested in the formalin test, producing an antinociceptive effect on the late phase of the formalin test. On the other hand, topical application of the derivatives of R. virens methanolic extract produced an anti-inflammatory effect in the TPA-induced ear edema, being PGG an anti-inflammatory molecule. Lastly, radical scavenging activity was higher in the extracts of higher polarity, comparable to the standard used Camellia sinensis.

CONCLUSIONS

In conclusion, R. virens produce an antinociceptive, anti-inflammatory and free-radical scavenging activity. The antinociceptive effect could be related to the opioidergic, GABAergic, and NO-GMPc-K + ATP channels pathways. These effects could be partially produced by the presence of PGG.

In vitro metabolic biomodulation of irinotecan to increase potency and reduce dose-limiting toxicity by inhibition of SN-38 glucuronide formation

OBJECTIVES

Colorectal cancer continues to have one of the highest incidents of occurrence with a rising rate of diagnosis among people under the age of 50. Chemotherapy with irinotecan results in severe gastrointestinal dose-limiting toxicity that is caused by the glucuronidated form of the active metabolite (SN-38G). This study evaluates herbal compounds and analogs to biomodulate the metabolism of IR to decrease dose-limiting toxicity while increasing the amount of the active metabolite.

METHODS

In vitro metabolism using human liver microsomes was conducted with white willow bark (WWB) extract, select specific components of WWB, and analogues to evaluate biomodulation of the IR metabolism. Samples were analyzed using liquid chromatography-tandem mass spectrometry to measure metabolites between reactions with and without herbals components.

RESULTS

WWB showed an optimal decrease (>80%) in SN-38G and a corresponding increase in SN-38 levels (128%) at a concentration of near 200 μg/mL. Tannic acid produced a 75% decrease in SN-38G with a 130% increase in SN-38 at 10 μg/mL, whereas the treatment with beta-pentagalloyl glucose and various analogues decreased SN-38G by 70% and increased SN-38 by 20% at 10 μg/mL.

CONCLUSIONS

These results suggest naturally occurring compounds from WWB may have the potential to increase potency by increasing the conversion of IR to SN-38 and decrease dose-limiting toxicity of IR chemotherapy by reducing glucuronidation of SN-38.

PGG impairs herpes simplex virus type 1 infection via blocking capsid assembly

Aim: Pentagalloylglucose (PGG), a hydrolyzable polyphenol was isolated from Phyllanthus emblica, which exhibited a strong inhibitory activity on HSV-1 infection, but its underlying mechanisms have not been completely delineated. Results/methodology: Using TEM, we first observed that PGG blocked the formation and maturation of HSV-1 capsid particles. Hence, we engaged in exploring the molecular mechanisms of PGG on the capsid assembly. At last, we found that PGG also blocked the relocalization of capsid proteins from the cytoplasm to the nucleus where the assembly took place. Conclusion: The current studies, for the first time, demonstrated acetylated microtubules were needed at this process of capsid proteins nuclear translocation. PGG also impairs herpes simplex virus type 1 infection by blocking capsid assembly.