Investigation of antiarthritic potential of Plumeria alba L. leaves in acute and chronic models of arthritis

Abstract

Aim: The present investigation was designed to evaluate antiarthritic potential of fractions of hydroalcoholic extract from leaves of P. alba.

Materials and methods: Plumeria alba L. leaves were extracted with hydroalcohol (30 : 70) to obtain hydroalcoholic extract of P. alba. This extract was further fractionated with solvents ethyl acetate and n-butanol to obtain EAPA and BPA, respectively. These fractions were tested against formaldehyde and Freund's complete adjuvant (FCA) induced arthritis. Arthritis assessment, paw volume, body weight, motor incoordination, and nociceptive threshold were measured. On day 21, the animals were sacrificed and histopathology was done.

Results: The 100 and 200 mg/kg doses of EAPA and BPA caused a significant (P ≤ 0.05-0.01) reduction in paw swelling in both models. Erythrocyte sedimentation rate (ESR) and spleen weight decreased significantly (P < 0.01) in arthritic rats treated with extracts. There was significant (P < 0.05) improvement in thymus weight in EAPA treated rats whereas significant (P < 0.01) improvement was also seen in haemoglobin level (Hb) in diclofenac treated group. Motor incoordination and nociceptive threshold were also significantly (P ≤ 0.05-0.01) improved.

Conclusion: The present study suggests that Plumeria alba L. has protective activity against arthritis and supports the traditional use of P. alba for rheumatism and other inflammatory diseases.

Figure 1

HPTLC fingerprinting of stigmasterol, BPA, and EAPA showing the Rf value.

Figure 2

HPLC fingerprinting of stigmasterol (a), EAPA (b), and BPA (c) showing the presence of stigmasterol in the extract.

Figure 3

Effects of EAPA and BPA on formaldehyde-induced paw edema. Values are plotted as the mean ± SEM, n = 6, in each group; significant reduction in paw volume was analysed by one-way analysis of variance followed by Dunnett's multiple comparisons test using GraphPad Instat software; *P < 0.05 and **P < 0.01 compared to formaldehyde control.

Figure 4

Morphological representations of rat paw after subplantar administration of FCA. (a) Vehicle control; (b) FCA treated rats; (c) EAPA (100 mg/kg); (d) BPA (200 mg/kg); (e) diclofenac (4 mg/kg) treated rats.

Figure 5

Effects of EAPA and BPA on arthritic score in FCA model. Values are plotted as the mean ± SEM, n = 6, in each group; decreased arthritis score was analysed by one-way analysis of variance followed by Dunnett's multiple comparisons test using GraphPad Instat software; *P < 0.05 and **P < 0.01 compared to FCA control.

Figure 6

Effects of EAPA and BPA on body weight in FCA model. Values are plotted as the mean ± SEM, n = 6, in each group; significant reduction in body weight was analysed by one-way analysis of variance followed by Dunnett's multiple comparisons test using GraphPad Instat software; *P < 0.05 and **P < 0.01 compared to FCA control.

Figure 7

Effects of EAPA and BPA on (a) ipsilateral paw and (b) contralateral paw. Values are plotted as the mean ± SEM, n = 6, in each group; significant reduction in paw volume was analysed by one-way analysis of variance followed by Dunnett's multiple comparisons test using GraphPad Instat software; *P < 0.05 and **P < 0.01 compared to FCA control.

Figure 8

Effects of EAPA and BPA on (a) fall-off time (s) and (b) pain threshold (s). Values are plotted as the mean ± SEM, n = 6, in each group; significant reduction in fall-off time and pain threshold were analysed by one-way analysis of variance followed by Dunnett's multiple comparisons test using GraphPad Instat software; *P < 0.05 and **P < 0.01 compared to FCA control.

Figure 9

Histology of the arthritis developing 21 days after immunization with FCA compared with unimmunized Sprague-Dawley rats. (a) Vehicle control; (b) FCA control; (c) EAPA (100 mg/kg); (d) BPA (200 mg/kg); (e) diclofenac (4 mg/kg). Magnification ×100; thickness: 5 μ.