Fatty oil from Securidaca inappendiculata exerted therapeutic effects on adjuvant-induced arthritis in mice via suppression on fibroblast-like synoviocyte

Abstract

Securidaca inappendiculata Hassk. (SI) is a medicinal plant used to treat rheumatoid arthritis (RA) in South China. A substantial amount of fatty oil was isolated from SI (SIF), however little knowledge about its chemical composition and medicinal potentials was obtained. In this study, we analyzed its chemical composition with methyl esterification based GC-MS method, and investigated the therapeutic potentials on adjuvant-induced arthritis (AA) in mice. MTT and western-blot methods were employed to investigate its effects on proliferation rate and protein expressions in MH7A cells, respectively. It was revealed SIF was mainly comprised of saturated and monosaturated fatty acids, and the two predominant compounds were palmitic acid (36.89%) and oleic acid (31.12%). Treatment with SIF at 100 mg/kg resulted in significant alleviation of AA severity in mice, together with reduced synovial hyperplasia and inflammatory infiltration in joints, and decreased levels of sialic acid, malondialdehyde and alkaline phosphatase in serum. Results from immunohistochemical assays hinted the protective effects of SIF on joints were associated to the inhibition on production of some pathological factors in synovium, including IL-1β, TNF-α and MMP-9. SIF inhibited the proliferation of MH7A cells in a concentration dependent manner, and abrogated phosphorylation of p65 in vitro. These evidences collectively suggested SIF could suppress the pathological functions of fibroblast-like synoviocyte, and protect joints from destruction under AA conditions.

Keywords: Chemical composition; GC-MS; MH7A cells; Rheumatoid arthritis.

Figure 1

Chemical composition of SIF. Compound 1–34 represented 1 Benzoic acid, 2 Octanoic acid, 3 Nonanoic acid, 4 Nonane, 5‐methyl‐5‐propyl‐, 5 Decanoic acid, 6 Phenol, 2,5‐bis(1,1‐dimethylethyl), 7 Dodecanoic acid, 8 Tridecanoic acid, 12‐methyl‐, 9 Methyl tetradecanoate, 10 Benzyl Benzoate, 11 9‐Dodecenoic acid, 12 Pentadecanoic acid, 13 2‐Pentadecanone, 6,10,14‐trimethyl, 14 9‐Hexadecenoic acid (Z)‐, 15 Hexadecanoic acid, 16 Benzenepropanoic acid, 3,5‐bis(1,1‐dimethylethyl)‐4‐hydroxy‐, 17 Dibutyl phthalate, 18 Hexadecanoic acid, ethyl este, 19 Heptadecanoic acid, 20 9,12‐Octadecadienoic acid (Z,Z)‐, 21 9‐Octadecenoic acid (E)‐, 22 9‐Octadecenoic acid (Z)‐, 23 Octadecanoic acid, 24 Ethyl Oleate, 25 Octadecanoic acidethyl ester, 26 Nonadecanoic acid, 27 9,12,15‐Octadecatrienoic acid, 28 11‐Eicosenoic acid, 29 Eicosanoic acid, 30 Heneicosanoic acid, 31 Docosanoic acid, 32 Phthalic acid, 2‐ethylhexyl hexyl ester, 33 Tricosanoic acid, 34 Tetracosanoic acid, respectively.

Figure 2

Effects of SIF on the progression of AA in mice. A, periodic changes of arthritis score and body weight of mice; B, weight indexes of inflammatory paw and immune organs. Statistical significance: **p < 0.01 and *p < 0.05 compared with AA models.

Figure 3

Effects of SIF on pathological conditions of AA in mice. A, histological examination of ankle joints, a‐f represented AA model, vehicle, SIF (high), SIF (medium), SIF (low), LEF respectively, black arrow (horizontal): bone and cartilage erosion, red arrow (vertical): inflammatory infiltration into synovium and subcutaneous tissues; B, levels of pathogenic factors involved in joints degradation in serum. Statistical significance: **p < 0.01 and *p < 0.05 compared with AA models.

Figure 4

Effects of SIF treatments on local expressions of IL‐1β, TNF‐α and MMP‐9 in synovium (investigated by immunohistochemical method).

Figure 5

Inhibitory effects of SIF on proliferation and activation of p65 signaling in MH7A cells. A, morphological and structural changes of cells induced by SIF at the concentration of 100 μg/ml, pictures of a‐b were taken at 0, 15, 30, 60 h after the treatment respectively; B, the proliferation inhibitory effect of SIF on MH7A cells revealed by MTT assays; C, effects of SIF on the expression of p65 and p‐p65 in MH7A cells; quantification of results from western‐blot assay. Statistical significance: **p < 0.01 compared with vehicle control.