Ellagitannins and triterpenoids extracts of Anogeissus leiocarpus stem bark extracts: Protective effects against osteoarthritis.

Osteoarthritis (OA) is a complex joint disease characterized by persistent pain. Unfortunately, current pharmacological therapies are unsatisfactory and characterized by side effects, reason why new strategies are needed. We tested the efficacy of different classes of compounds, ellagitannins and olean-type triterpenoids, contained in Anogeissus leiocarpus extract (Combretaceae family) in comparison to ellagitannins of Castanea sativa extract in a rat model of osteoarthritis induced by the intra-articular injection of sodium monoiodoacetate (MIA). The decoction of stem bark of A. leiocarpus AL-DEC-TOT (300 mg/kg; 4.8% triterpenoids; 11.0% tannins), the butanol extract AL-BuOH-EXT (120 mg/kg; triterpenoids 20.9%; tannins 6.4%) and its correlated aqueous residue AL-Res-H2 O (300 mg/kg; triterpenoids 0.7%; tannins 8.7%) and the decoction of C. sativa, CS-DEC-TOT, (240 mg/kg; triterpenoids 0.65%; tannins 10.8%) were orally administered for two weeks starting from the day of the damage. Behavioural tests highlighted that all stem bark extracts of A. leiocarpus counteracted hypersensitivity development, reduced spontaneous pain, and improved motor skills. Histologically, AL-DEC-TOT, AL-BuOH-EXT and AL-Res-H2 O were effective in preventing joint alterations. In conclusion, all the extracts were effective demonstrating that both olean-type triterpenoid and ellagitannin fractions have anti-hypersensitivity and restorative properties running the stem bark extracts of A. leiocarpus as a candidate in the treatment of OA.

1H NMR and HPLC-DAD-MS for the characterization of ellagitannins and triterpenoids of less investigated Anogeissus leiocarpus DC (Combretaceae) stem bark.

Anogeissus leiocarpus DC is an evergreen tree, widely distributed in Asia and Africa. The stem bark is used in traditional medicine, and as chewing sticks and infusion. Nowadays, it is becoming increasingly important to define the phytochemical profile of less studied edible plants. Aim of this research was a first complete characterization of ellagitannins and triterpenoids profiles by HPLC-DAD-MS and 1H NMR and analyses. A total of 59 compounds were identified including 43 ellagitannins and 16 triterpenoids, mainly oleane derivatives and glycosylated forms. Among ellagitannins, roburin, vescalin and castalin were found for the first time. Tannins accounted for 38.9% whereas triterpenoids were 4.8%, both estimated on dry decoction. The decoction was preliminary tested against osteoarthritis in rats. The characterization of the main phytochemicals of Anogeissus leiocarpus DC stem bark decoction is a necessary step to evaluate nutraceutical properties, paving the way for possible food applications of this plant.