Therapeutic potential of russelioside B as anti-arthritic agent in Freund's adjuvant-induced arthritis in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Caralluma species are traditional edible herbs used in folkloric medicine as antidiabetic, antioxidant, antipyretic, antirheumatic, anti-inflammatory and anthelmintic agents. C. quadrangula was selected in this study to document the traditional use of the genus as anti-rheumatic treatment and the possible mechanisms of action.

AIM OF THE STUDY: The higher mortality rates and shorter survival among the patients suffering from rheumatoid arthritis (RA) led to the increased interest on searching for new treatments for RA. Russelioside B (RB), a major pregnane glycoside found in C. quadrangula, was evaluated as a new anti-rheumatic agent.

MATERIALS AND METHODS: The n-butanol fraction of C. quadrangula was chromatographed on a silica gel column to isolate RB. The adjuvant-induced arthritis (AIA) model was established in rats by intradermal injection of complete Freund's adjuvant (CFA) to evaluate its anti-arthritic effect. Ibuprofen was used as a reference drug. Forty rats were randomly divided into 5 groups (n = 8): normal (NOR); CFA model (CFA); ibuprofen, 5 mg/kg; RB, 25 mg/kg and RB, 50 mg/kg. The treatments were initiated from day 16 when AIA model was established and continued up to day 40. Serum diagnostic rheumatoid markers, inflammatory cytokines, oxidative stress biomarkers, cartilage and bone degeneration enzymes were assessed.

RESULTS: RB at 50 mg/kg b. wt., showed significant decreases in the activities of hyaluronidase and β-glucouronidase enzymes as well significant decreases in the levels of proinflammatory cytokines as nuclear factor-kappa-B (NF-κB), tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) compared to the CFA group; 11.04 ± 0.61 pg/mg protein, 4.35 ± 0.25 pg/mg protein, 3.32 ± 0.13 pg/mg protein & 2.75 ± 0.14 pg/mg protein for RB, 50 mg/kg b. wt. group vs. 25.33 ± 2.13 pg/mg protein, 25.65 ± 2.1 pg/mg protein, 22.20 ± 1.34 pg/mg protein & 13.27 ± 1.40 pg/mg protein for the arthritic group, respectively. The total antioxidant capacity (TAC) was significantly restored to normal values in RB, 50 mg/kg treated rats (4.01 ± 0.09 nmol/mL vs. 3.71 ± 0.27 nmol/mL) and the levels of myeloperoxidase (MPO) reduced by 10-folds of the CFA arthritic group. Bone histomorphometry revealed that RB treatment significantly attenuated the CFA-induced bone loss in a dose-dependent manner.

CONCLUSIONS: These findings suggested that the anti-arthritic effect of RB was mediated through the reduction of the rheumatoid markers, anti-inflammatory and antioxidant action, inhibition of cartilage and bone degenerative enzymes as well as attenuation of bone loss and osteoclastogenesis.