Immunomodulatory Activity of a Traditional Sri Lankan Concoction of Coriandrum sativum L. and Coscinium fenestratum G

Abstract

Objective: To investigate the immunomodulatory activity of a traditional Sri Lankan concoction of Coriandrum sativum L. and Coscinium fenestratum (Gaertn.) Colebr., which is a Sri Lankan traditional medicine used to relieve inflammation and cold.

Methods: In vivo anti-inflammatory activity was tested using carrageenan-induced rat paw-edema model. Mechanism of anti-inflammatory activity was assessed by investigating the production of nitric oxide (NO), expression of iNOS enzyme, and reactive oxygen species (ROS) by rat peritoneal cells. The membrane stabilizing activity was also tested. The antibody response was determined by assessing the specific haemagglutination antibodies raised against sheep red blood cells.

Results: The three doses of freeze-dried concoction used ((human equivalent dose (HED)-183 mg/kg) 2 × HED and 1/2HED; n = 6 rats/group) showed significant inhibition of paw edema compared to water control at 3^rd-5^th hours (p < 0.05). Both HED and 1/2HED exhibited marked anti-inflammatory activity (72-83% inhibition at 4^th-5^th hours; p < 0.05). The HED of the concoction showed significant inhibition of NO (77.5 ± 0.73%, p < 0.001) and ROS production (26.9 ± 2.55%; p < 0.01) by rat peritoneal cells. Inhibition of NO production in the concoction treated rat peritoneal cells was confirmed by the lack of iNOS expression. The concoction also exhibited significant membrane stabilizing activity (IC₅₀ = 0.0006 μg/ml; p = 0.001). HED resulted in a significantly high induction of specific antibody production against SRBC antigens as detected by SRBC haemagglutination assay (mean day 14 titers 253.3 compared to control: 66.7) (p < 0.01).

Conclusions: The traditional Sri Lankan concoction of C. sativum and C. fenestratum demonstrated potent in vivo anti-inflammatory activity, significant reduction of ROS, and NO production by rat peritoneal cells and the lack of iNOS expression confirmed the low NO production. The increased membrane stability also supports the anti-inflammatory activity of the concoction. Further, this concoction induced a significantly high antibody response reflecting its immunostimulatory activity. Together these results scientifically validate the therapeutic use of the concoction of C. sativum and C. fenestratum in Sri Lankan traditional medicinal system for immunomodulatory effects.

Figure 1

The inhibition of rat paw edema by the concoction of C. sativum and C. fenestratum. Inhibition of paw volume was assessed from rats treated with 1/2HED, HED and 2HED of the concoction, indomethacin (5 mg/kg), and water. HED: Human equivalent dose. Values represent mean ± SEM; n = 6 rats per group.

Figure 2

Effect of the human equivalent dose (HED) of the concoction on NO production by rat peritoneal cells. NO production by peritoneal cells obtained from rats treated with HED of the concoction and prednisolone (10 mg/ml) and from control group was assessed. Data represents mean ± SEM.

Figure 3

NOS gene expression in peritoneal cells from carrageenan-injected rats orally administered with prednisolone, lane 1; water, lane 2; and the concoction, lane 3. iNOS: inducible NOS; nNOS: neuronal NOS; eNOS: endothelial NOS; GAPDH: glyceraldehyde-3-phosphate dehydrogenase.

Figure 4

Effect of the human equivalent dose (HED) of the concoction on ROS production by rat peritoneal cells. ROS production by peritoneal phagocytic cells harvested from rats treated with HED of the concoction, prednisolone (10 mg/ml), and water as control. Cells treated with diphenyleneiodonium chloride (DPI) used as in vitro positive control.

Figure 5

Membrane stabilizing activity of the concoction. Percent inhibition of haemolysis of rat red blood cells treated with the concoction and aspirin (positive control) was assessed. Data represent average from three repeat experiments, n = 6. Data represents mean ± SEM.