Ruellia simplex C. Wright (Acanthaceae): Antinociceptive, anti-inflammatory, and antidiabetic activities of a novel fatty acid isolated from its leaf extract

Ruellia simplex is a medicinal plant whose leaf is used to treat pains, inflammation, and diabetes in Nigeria. The current study was undertaken to determine the antinociceptive (analgesics), anti-inflammatory, and antidiabetic activities of a novel fatty acid isolated from the leaf extract of R. simplex. Isolation of a novel fatty acid from the most active fraction was carried out on silica gel column chromatography while, antinociceptive, anti-inflammatory, and antidiabetic activities of the isolated compound were evaluated by acetic acid, carrageenan, and alloxan-induced animal models respectively. The chemical structure of the new compound was elucidated by FT-IR, NMR, GC-MS, and LC-MS. The isolated fatty acid showed inhibition of pains by decreasing abdominal writhing in mice in dose dependent fashion as well as reduced paw volume in the carrageenan-induced paw edema in rats at IC50 = 12.5 ± 1.08 μg/ml and 10.21 ± 1.02 μg/ml, respectively, whereas the antidiabetic activity showed a dose dependent reduction in blood sugar levels with IC50 = 6.02 ± 0.01 μg/ml. The compound showed the following features: R-COOH functional group at 3327 wavelength cm-1 by FTIR; EI-MS [M]+* at m/z 467, peak area 62.231% and RT 14.086 min by GC-MS; singly charged fragments at m/z 116.1 and m/z 465.1, RT 1.31 min by LC-MS and eight proton signals consisting of singlets and multiplets (1H), thirty carbon atoms (13C) NMR data. From the study, the novel fatty acid from R. simplex extract was potentially active for the treatment of pains, inflammation, and diabetes.