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. 2025 Jan-Feb;16(1):101049.
doi: 10.1016/j.jaim.2024.101049. Epub 2025 Jan 18.

Anti-inflammatory activity and selective inhibition of iNOS gene expression by a polyherbal formulation

Boyagoda Vidanelage Loshini Ravima Ranaweera  1 , Daniya Edward  2 , Jayamini Chathurika Harasgama  2 , Ajita Mahendra Abeysekera  3 , Ovitigala Vithanage Don Sisira Jagathpriya Weerasena  2 , Shiroma Mangalika Handunnetti  2
Affiliations

Anti-inflammatory activity and selective inhibition of iNOS gene expression by a polyherbal formulation

Boyagoda Vidanelage Loshini Ravima Ranaweera et al. J Ayurveda Integr Med. 2025 Jan-Feb.

Abstract

Background: Link Samahan® (LS), a product of Link Natural Products (Pvt) Limited, Sri Lanka contains extracts of 14 medicinal plants. It is used as a prophylactic against cold and cold related symptoms. It has immunomodulatory activity, specifically enhancing the humoral immune response.

Objective: To investigate the anti-inflammatory activity (AIA) of LS and related mechanisms.

Materials and methods: In vivo AIA was assessed by the inhibition of carrageenan-induced rat paw-edema. Mechanisms of AIA were assessed in vitro by the inhibition of reactive oxygen species (ROS) and reactive nitrogen species (RNS) production and expression of inducible nitric oxide synthase (iNOS) gene using rat peritoneal cells.

Results: LS showed an increasing inhibition in rat paw-edema up to 5 h compared to the biphasic pattern exhibited by the reference drug, Indomethacin. Inhibition by LS at the 1st and 3rd-5th hours (44.7% and 73.0-74.6%) was comparable to indomethacin (47.4% and 83.6-76.5%; p > 0.05) whereas at the 2nd hour, LS exhibited a significantly higher inhibition compared to indomethacin (66.7% vs 28.6%; p < 0.05). LS treatment significantly inhibited the ROS (superoxide; 47.2 ± 0.86%; p < 0.05) and RNS (nitrite; 54.0 ± 0.40%; p < 0.05) production in rat peritoneal cells. Further, specific inhibition of iNOS gene expression in rat peritoneal cells resulted in a significant reduction in RNS production whereas LS had lesser or no inhibitory effect on endothelial NOS and neuronal NOS gene expression.

Conclusion: LS has potent anti-inflammatory activity and selective inhibition of iNOS activity. AIA of LS shown here supports its use as a prophylactic against cold and cold related symptoms.

Keywords: Anti-inflammatory activity; Link Samahan®; Polyherbal formulation; Reactive nitrogen species; Reactive oxygen species; iNOS.

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Conflict of interest statement

Conflict of interest Ajita Mahendra Abeysekera is an advisor to Link Natural Products (Pvt) Ltd. Other authors declare that they have no conflicts of interest.

Figures

Fig. 1
Fig. 1
The percentage inhibition of paw-edema by LS and indomethacin treated rats. Values represents mean ± SEM, n = 6 rats per group; (n = 6). ∗ Percentage inhibition of paw-edema by LS was significant compared to that of indomethacin (5 mg/kg). Significance level (p < 0.05).
Fig. 2
Fig. 2
O2− levels produced by phagocytic cells of rats treated with water, LS and prednisolone (10 mg/kg). Phagocytic cells of water treated rats were then treated with DPI used as the in vitro positive control. Values represents mean ± SEM, n = 6 rats per group; (n = 6). ∗Concentration was significant compared to that of water control; Significance level (p < 0.05).
Fig. 3
Fig. 3
Nitrite levels produced by phagocytic cells of rats treated with water, LS and prednisolone (10 mg/kg). Phagocytic cells of water treated rats were then treated with NMMA (1 mM) used as the in vitro positive control. Values represents mean ± SEM, n = 6 rats per group; (n = 6). ∗Level was significant compared to that of water control; Significance level (p < 0.05).
Fig. 4
Fig. 4
Analysis of NOS gene expression in peritoneal cells obtained from carrageenan injected rats following the oral administration of samples. (A) RT-PCR amplification of NOS and GAPDH genes. Lane 1 – Prednisolone, Lane 2 - Water, Lane 3 – LS. iNOS: inducible NOS; nNOS: neuronal NOS; eNOS: endothelial NOS; GAPDH: glyceraldehyde-3-phosphate dehydrogenase. (B) Relative intensity of target genes (iNOS, nNOS and eNOS); (∗ indicates p < 0.001).
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