Piperine, a functional food alkaloid, exhibits inhibitory potential against TNBS-induced colitis via the inhibition of IκB-α/NF-κB and induces tight junction protein (claudin-1, occludin, and ZO-1) signaling pathway in experimental mice

BACKGROUND

Inflammatory bowel disease is a chronic immunoinflammatory disease of the gastrointestinal tract. Piperine, an alkaloid, has been reported to possess antioxidant, anti-inflammatory, antiapoptotic, and antiulcer potential.

AIM

To elucidate the plausible mechanisms of action of piperine on experimental trinitrobenzenesufonic acid (TNBS)-induced colitis by assessing various biochemical, molecular, histological, and ultrastructural modifications.

METHODS

Colitis was induced in male Sprague-Dawley rats via intrarectal instillation of TNBS. Then, the rats were treated with piperine (10, 20, and 40 mg/kg, p.o.) for 14 days.

RESULTS

TNBS induced significant (p < 0.05) colonic damage, which was assessed by disease activity index, macroscopic score, and stool consistency. The administration of piperine (20 and 40 mg/kg) significantly inhibited (p < 0.05) these damages. Treatments with piperine (20 and 40 mg/kg) notably inhibited (p < 0.05) the TNBS-induced elevation of oxido-nitrosative stress (superoxide dismutase, glutathione, malondialdehyde, and nitric oxide), 5-hydroxytryptamine, and hydroxyproline content in the colon. Furthermore, colonic inducible nitric oxide synthase (iNOs), tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β, IL-6, interferon-gamma, and cyclooxygenase-2 (COX-2) messenger RNA (mRNA) expressions were upregulated after TNBS instillation and piperine (20 and 40 mg/kg) significantly attenuated (p < 0.05) these elevated mRNA expressions. TNBS decreased the expressions of tight junction (TJ) protein (claudin-1, occludin, and zonula occludens-1 (ZO-1)) and increased the expressions of proapoptotic (caspase-1) protein. These expressions were markedly inhibited (p < 0.05) by piperine treatment. Histological and ultrastructural studies of transmission electron microscopy suggested that piperine significantly ameliorated (p < 0.05) TNBS-induced colonic aberrations.

CONCLUSION

Piperine ameliorated the progression of TNBS-induced colitis by modulating the nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor-alpha/nuclear factor-kappa B signaling pathway, thus inhibiting the overexpression of proinflammatory cytokines (TNF-α and IL's), COX-2, iNOs, oxido-nitrosative stress, and proapoptotic proteins (caspase-1) that may improve the expression of TJ protein (claudin-1, occludin, and ZO-1).

Diarylheptanoid, a constituent isolated from methanol extract of Alpinia officinarum attenuates TNF-α level in Freund's complete adjuvant-induced arthritis in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Rheumatoid arthritis (RA) is a chronic inflammatory and destructive joint disease that affects the worldwide population. Alpinia officinarum Hance (Zingiberaceae), rhizomes are widely used ethnobotanically as an anti-inflammatory, analgesic, and antioxidant agent in traditional medicine.

AIM

To investigate the efficacy and possible mechanism of isolated phytoconstituent from the methanol extract of A. officinarum (MEAO) rhizomes against Freund's complete adjuvant (FCA)-induced arthritis in rats. Furthermore, molecular docking was performed to study the binding mode of this compound into the active site of TNF-α.

MATERIALS AND METHODS

Diarylheptanoid was isolated from MEAO, well characterized (HPTLC, ¹H NMR, ¹³C NMR, and ESI-MS) and evaluated for its antiarthritic activity in female Wistar rats (170-200 g). Diarylheptanoid (5, 10 and 20 mg/kg, p.o.) was administered starting from day 12. Various behavioral, biochemical, molecular and histopathology parameters were evaluated. Molecular docking study was performed using Glide module integrated into Schrodinger molecular modeling software.

RESULTS

The structure and molecular weight of the isolated compound (diarylheptanoid) were confirmed by 1D and mass spectral data and characterized as 1-phenyl-5-hydroxy-7- (4''-hydroxy-3''-methoxyphenyl) heptane-3-one (i.e., 5-HPH) with molecular formula C₂₀H₂₄O₄. Administration of 5-HPH (10 and 20 mg/kg) significantly inhibited (p < 0.05) FCA induced increases in paw volume, joint diameter, thermal hyperalgesia and tactile allodynia. It also significantly decreased oxido-inflammatory markers (SOD, GSH, MDA, and TNF-α). FCA induced a histological alteration in ankle joint also attenuated by 5-HPH. Its Glide docking score was found to be -9.702 with binding energy (Glide energy) of -37.033 kcal/mol.

CONCLUSION

5-HPH may exhibit its anti-arthritic potential via inhibition of elevated oxido-inflammatory markers thus restoring the elevated hyperalgesia, allodynia and reducing destruction in synovial membrane and cartilage. Therefore, 5-HPH is a potential moiety bearing antioxidant and with anti-inflammatory properties to inhibit FCA-induced arthritis in rats. The results of the present investigation should enable the design of potent small-molecule inhibitors that inactivate TNF-α with high affinity and specificity.

Anti-inflammatory and antioxidant potential of Guaianolide isolated from Cyathocline purpurea: Role of COX-2 inhibition

BACKGROUND

Inflammation activated by oxidative stress can cause various diseases, such as asthma, rheumatoid arthritis, cancer, diabetes, etc. Plant constituents with sesquiterpene lactones possess antioxidant and anti-inflammatory properties.

AIM

To determine the antioxidant and anti-inflammatory potential of isolated phytoconstituent from Cyathocline purpurea Buch-Ham ex D (CP). Don in laboratory animals. Furthermore, to understand the interactions involved in the binding of this compound to cyclooxygenase-2 (COX-2) via computational docking.

METHODS

Phytoconstituent was isolated, purified and well characterized (using IR, NMR, and MS) from ethyl acetate fraction of CP methanolic extract. It was then evaluated for its in-vitro antioxidant activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydrogen peroxide (H₂O₂) and hydroxyl (OH) radical assays as well as in-vivo anti-inflammatory potential against carrageenan-induced paw edema model in rats. The molecular docking study was performed against the crystal structure of COX-2 to evaluate the binding potential of phytoconstituent towards this enzyme.

RESULTS

The isolated compound 6α-hydroxy-4 [14], 10 [15]-guainadien-8α, 12-olide (HGN) showed significant (p<0.001) antioxidant activity with IC₅₀ values of 76μg/mL. Administration of HGN (10 and 20mg/kg) significantly (p<0.001) reduced the increased paw volume after subplantar administration of carrageenan. It also exhibits good binding affinity towards with COX-2 with a docking score of -8.98 and Glide binding energy of -36.488kcal/mol shedding light on the potential mechanism of anti-inflammatory action.

CONCLUSIONS

The presence of hydroxyl group in HGN provides a credential to its in-vivo anti-inflammatory and in-vitro antioxidant activities. Furthermore, the good binding affinity of HGN for the active site of COX-2 may open novel vistas in therapeutic option with natural antioxidants like Cyathocline purpurea to treat various inflammatory disorders.

Ameliorative effects of Artemisia pallens in a murine model of ovalbumin-induced allergic asthma via modulation of biochemical perturbations

INTRODUCTION

Asthma is a chronic, heterogeneous airway disorder characterized by airway inflammatory and remodeling. Artemisia pallens has been reported to possess antioxidant, anti-inflammatory and Anti-allergic potential.

OBJECTIVE

To evaluate the anti-asthmatic effects of methanolic extract of Artemisia pallens (APME) against ovalbumin (OVA)-induced airway hyperresponsiveness (AHR) in rats.

MATERIALS AND METHOD

AHR was induced in male Sprague-Dawley rats (180-200g) by intraperitoneal (i.p.) injection of OVA and boosted with an identical OVA solution (s.c.) on day 7. Rats were either treated orally with vehicle (10mg/kg), montelukast (10mg/kg) or APME (100, 200 and 400mg/kg) for next 28days. At the end treatments, various biochemical, molecular (RT-PCR and ELISA analysis) and histological parameters were evaluated.

RESULTS

APME (200 and 400mg/kg) significantly attenuated (p<0.05) OVA-induced alteration in lung functions measured by Whole-body plethysmography. Increased Bronchoalveolar Lavage (BAL) fluid differential cell count, as well as total protein and albumin in BAL fluid and lungs, was significantly decreased (p<0.05) by APME. It also significantly attenuated (p<0.05) elevated lung oxido-nitrosative stress, myeloperoxidase, and serum IgE levels. OVA-induced down-regulation in lung Nrf2 and upregulation in TNF-α, IL-1β, IL-4, IL-6, TGF-β mRNA expression was significantly attenuated (p<0.05) by APME (200 and 400mg/kg) treatment. Histopathological analysis of lung tissue showed that APME treatment reduced OVA-induced inflammatory influx and fibrosis.

CONCLUSION

Artemisia pallens simultaneously orchestrate plethora of mechanisms viz. modulations of IgE, TGF-β, TNF-α, IL's and Nrf-2 levels to exhibit its anti-asthmatic potential in OVA-induced AHR in rats.