Anti-Arthritis Effect of Ethanol Extract of Sacha Inchi (Plukenetia volubilis L.) Leaves Against Complete Freund's Adjuvant-Induced Arthritis Model in Mice

Abstract

Sacha inchi (Plukenetia volubilis L.) is a well-known oleaginous plant used as food source and traditional medicine by indigenous people for a long time. This study was conducted to evaluate anti-arthritis effect of ethanol extract of Sacha inchi leaves and provide scientific evidence to develop the new anti-arthritis remedy from Sacha inchi. Rheumatoid arthritis model was established by injection of complete Freund's adjuvant into right hind footpads of mice and three doses of ethanol extract of Sacha inchi leaves (100, 200 and 300 mg/kg body weight) were used for treatment. The severity of arthritis was evaluated by measuring the ankle diameter and arthritic score, hematological and biochemical parameters (erythrocytes, leukocytes, lymphocytes, monocytes, granulocytes counts, erythrocyte sedimentation rate, C-reactive protein and rheumatoid factor). The pro-and anti-inflammatory cytokines (TNF-α, INF-γ, IL-1β, IL-6, and IL-10) and the histology change of joint were also examined. All three doses of extracts significantly alleviated ankle diameter and arthritic score. Furthermore, the extracts could ameliorate the alternation of inflammatory cytokines as well histological features of CFA-induced mice. The efficacy of extract dose of 300 mg/kg body weight is comparable with reference drug (Mobic, 0.2 mg/kg body weight). This study indicates Sacha inchi leaf extract as the promising remedy for treatment of arthritis.

Keywords: Animal Model; Anti-Arthritis Effect; Antioxidants; Inflammatory Cytokines; Plukenetia volubilis.

Figure 1

The ethanol extract preparation. Sacha inchi leaves collected from medicinal plant farm in Pleiku city, Gialai province, Vietnam. The leaves were dried until reaching moisture about 10%–12% and ground into powder. The powder was soaked in ethanol, then the extract was obtained through multiple step filtration. The filtrate was subsequently concentrated in a vacuum rotary evaporator.

Figure 2

The therapeutic effect of EtPV on ankle diameters, arthritis score in mice with CFA-induced arthritis. (A) Ankle diameters, (B) Arthritis scores. Values were expressed as Mean ± SD (n = 6) and the letters a, b, c and d denote the significant difference among groups.

Figure 2

The therapeutic effect of EtPV on ankle diameters, arthritis score in mice with CFA-induced arthritis. (A) Ankle diameters, (B) Arthritis scores. Values were expressed as Mean ± SD (n = 6) and the letters a, b, c and d denote the significant difference among groups.

Figure 3

Macroscopic examination of experimental mice. Representative pictures of paws mice from each group (control, CFA-induced RA model, CFA-Mobic, CFA-EtPV₁₀₀/EtPV₂₀₀/EtPV₃₀₀) were presented. Briefly, the paw of RA mice was redness, swelling, and oedematous, whereas treatment with Mobic/EtPV₁₀₀/EtPV₂₀₀/EtPV₃₀₀ showed significant differences and alleviation of paw swelling.

Figure 4

The therapeutic effect of EtPV and Mobic on histopathological features of joints (stained with hematoxylin and eosin); Symbols: B = Bone; C = Cartilage; CE = Cartilage erosion; SP = Synovial space; SH = Synovial hyperplasia; P = Pannus; → cellular infiltration. Adjuvant-induced arthritis group is characterised by a distinct bone and cartilage erosion, synovial hyperplasia and pannus formation, destruction of joint structure with immune cells infiltration, whereas Mobic or EtPV treatment reduces the immune cells infiltration and improves the joint structure.

Figure 5

The therapeutic effect of EtPV on concentration of: (A) TNF-α and IL-1β, and (B) IFN-γ, IL-6 and IL-10 in mice with CFA-induced arthritis. Values were expressed as Mean ± SD (n = 6) and the letters a, b, c, and d denote the significant difference among groups.

Figure 5

The therapeutic effect of EtPV on concentration of: (A) TNF-α and IL-1β, and (B) IFN-γ, IL-6 and IL-10 in mice with CFA-induced arthritis. Values were expressed as Mean ± SD (n = 6) and the letters a, b, c, and d denote the significant difference among groups.