Date Published: April 19, 2019
Publisher: Public Library of Science
Author(s): Siriwan Ongchai, Chatchadawalai Chokchaitaweesuk, Patiwat Kongdang, Siriwadee Chomdej, Kittisak Buddhachat, Ming-Chang Chiang.
Senna species and anthraquinone derivatives generated by these organisms, rhein and aloe-emodin, exert anti-inflammatory effects. These species present a similar morphology but produce different ingredients when they are used as medicinal products. In this study, a DNA barcoding- (Bar-) high-resolution melting (HRM) technique was developed using internal transcribed sequence 2 (ITS2) to differentiate between Senna alata and Senna tora as a result of significant differences in their melting profiles. We used this approach for confirmation of S. alata and S. tora raw materials, and we examined the chondroprotective properties of the ethanolic extracts of S. alata and S. tora using a porcine model of cartilage degradation induced by a combination of interleukin-17A (IL-17A) and IL-1β. We found that both Senna ethanolic extracts, at a concentration of 25 μg/mL, effectively prevented cartilage degradation. Rhein and aloe-emodin were present in the extract of S. alata but not in that of S. tora. We observed a reduction in the release of sulfated glycosaminoglycans (S-GAGs) and hyaluronic acid (HA) into media in both treatments of Senna extracts, which indicated proteoglycan preservation in explant tissues. These results suggest that neither rhein nor aloe-emodin are the main factors responsible for cartilage-protecting properties. Taken together, results show that both S. alata and S. tora are promising for further development as anti-osteoarthritic agents and that Bar-HRM using ITS2 could be applied for species confirmation with Senna products.
Osteoarthritis (OA) involves joint degeneration, especially in the elderly, and is caused by proinflammatory cytokines (e.g., interleukin-1 (IL-1), tumor necrosis factor α (TNFα), oncostatin M (OSM), IL-6, and IL-17), leading to an imbalance in the biochemical processes in articular cartilage [1–3]. Cytokines IL-1β and IL-17A are detected in synovial fluid (SF) of rheumatoid arthritis (RA) and OA patients [3–5]. These compounds are well known to be involved in the inflammatory process and cartilage degradation, by which IL-17A strongly synergizes with other inflammatory cytokines (e.g., IL-1, TNFα, IL-6) to stimulate cartilage collagen and proteoglycan breakdown via matrix-degrading enzymes (e.g., matrix metalloproteinase (MMP) 1, 3, and 13) [1–3, 6]. Current OA therapy is only moderately effective as a treatment option, especially with pain relieving drugs (e.g., non-steroid anti-inflammation drugs with adverse effects) [7, 8]. Presently, disease-modifying osteoarthritis drugs (DMOAD) have been extensively studied for the ability to halt the structural disease progression of OA and also to improve symptoms and/or function . Naturally-derived or occurring ingredients from medicinal plants are a promising source for drug discovery for DMOAD.
Taken together, we report several significant findings. (i) Presently, commercial Senna products distributed on the market are available in various forms, including powder, dried, ground leaves, or stem cuttings, which can lead to difficult species delimitation. Bar-HRM using ITS2 is required to ensure the quality of herbal medicinal plant products for consumers’ health. Our results show that Bar-HRM using ITS2 serves as a promising tool, given that it is a reliable, highly sensitive, economic, and a rapid method to authenticate S. alata and S. tora from their raw materials and even in commercial products. (ii) Both ethanolic extracts of S. alata and S. tora possess a anti-cartilage destruction from the cytokine (IL-1β- and IL-17A) induction by halting matrix degradation such as proteoglycan although the absence of rhein and aloe-emodin was seen in S. tora. This evidence indicated that the anthraquinones in Senna might not be a major bioactive compound responsible for chondroprotection in porcine cartilage.