Solenostemma argel (Argel) is a traditional perennial edible herb that is commonly used in folkloric medicine for the treatment of rheumatic pain, inflammation, bronchitis, cold, diabetes, gastrointestinal cramps, and urinary tract infections. No previous reports traced the mechanistic activity of this plant for treatment of rheumatoid arthritis in relation to its chemical constituents.
The present study was designed to substantiate the anti-arthritic potential of S. argel and identification of its secondary metabolites responsible for the action using ultra-performance liquid chromatography coupled to high resolution mass spectrometry (UPLC/HRMS).
The air-dried powder of S. argel was subjected to liquid-liquid fractionation method to yield polar metabolites fraction (PMF) and nonpolar metabolites fraction (NPMF) where the metabolites that represent each fraction were identified using UPLC/HRMS. The in-vitro anti-arthritic effects of both fractions were tested using protein denaturation, membrane stabilization and proteinase inhibition assays, in addition to in-vitro enzyme inhibition assays of COXs, LOX and collagenases. Adjuvant-induced arthritis (AIA) model was also established to evaluate their anti-arthritic effects in-vivo at two doses (200 and 400 mg/kg) in compared to the standard ibuprofen (5 mg/kg). Physical changes with hind paw edema and body weight gain as well as the assessment of serum rheumatoid biomarkers, inflammatory cytokines, oxidative stress markers, and the activity of hyaluronidase and β-glucouronidase enzymes were studied. The histopathological study of ankle and knee joints and immunohistochemistry of caspase-3 and TNF-α in joint synovium were also examined.
The PMF significantly (P < 0.05) reduced paw edema, serum rheumatoid markers, pro-inflammatory mediators, degeneration enzymes of cartilage and bone, and oxidative stress biomarkers. Interestingly, flavonoid glycosides and phenolic acids dominated the polar fraction, which showed the promising anti-arthritic activity of Argel compared to the NPMF which was dominated by pregnane glycosides.
Since arthritis is a chronic disease and there are imperative needs for a lifelong treatment with desirable pharmacological action and lower cost than the currently approved synthetic drugs having severe side effects, the PMF of Argel could be used as a potent anti-rheumatic agent.