HPLC-PDA and in vivo anti-inflammatory potential of isorhamnetin-3-O-β-D-glucoside from Zygophyllum simplex L

Ethnopharmacological relevance: Inflammation is a biological process in response to injury, resulting in altered blood flow, increased vascular permeability, tissue destruction, and the production of reactive oxygen species (ROS) and inflammatory mediators. Zygophyllum simplex L., a medicinal plant traditionally used in the Arabian Peninsula for inflammatory disorders, has demonstrated promising in vitro anti-inflammatory activity due to its phenolic content. Additionally, the ethyl acetate fraction has exhibited notable in vivo anti-inflammatory effects.

Study objective: This research aimed to evaluate the in vivo anti-inflammatory effects of a Z. simplex plant extract and its principal ethyl acetate isolate, isorhamnetin-3-O-β-D-glucoside (Isor-3-Glu). The study seeks to develop a straightforward and robust HPLC method for quantifying Isor-3-Glu within the total methanolic extract of Z. simplex.

Materials and methods: The total methanol extract of Z. simplex was successively partitioned with a variety of organic solvents and the ethyl acetate fraction was used to isolate Isor-3-Glu on a Sephadex LH-20 column. The in vivo anti-inflammatory activity was investigated using carrageenan-triggered inflammation in rats. Histological features and immunohistochemical expression of cyclooxygenase-2 (COX-2) and tumor necrosis factor-alpha (TNF-α) were analyzed, and the levels of interleukins (IL-1β and IL-6) as well as prostaglandin E2 (PGE2) of the paw tissues were examined by qRT-PCR and ELISA, respectively. Quantification of Isor-3-Glu was achieved using an HPLC-PDA method.

Results: Isor-3-Glu considerably (p < 0.05) lowered the weight of the paw edema. The histological abnormalities were improved, and the percentage of the COX-2 and TNF-α immunoreactive cells substantially decreased in the Isor-3-Glu-treated group in comparison with the positive control and Z. simplex extract group. Isor-3-Glu significantly ameliorated PGE2, IL-1β, and IL-6 levels. A straightforward and dependable HPLC technique was established for quantifying Isor-3-Glu in the total extract. The proposed methodology effectively determined Isor-3-Glu in less than 5 min. The calibration curve exhibited a linear relationship over the concentration range of 1.0-40.0 μg/mL, with a correlation coefficient (r) ≥ 0.9995. The developed method demonstrated a high level of sensitivity, with a detection limit as low as 0.139 μg/mL. The concentration of Isor-3-Glu in the total extract of Z. simplex was determined to be 0.05% w/w of dry extract.

Conclusion: Isor-3-Glu could be considered a promising anti-inflammatory compound that necessitates future clinical research. Isor-3-Glu was accurately quantified using a meticulously developed and optimized HPLC-PDA technique.