Oxidative stress plays a key role in the pathogenesis of various diseases. Antioxidants protect the cells and tissues from oxidative stress by scavenging free radicals and reactive oxygen species. These antioxidants may be endogenous or exogenous. Plants are considered as potential and powerful exogenous source of antioxidants. Astragalus species (spp.), especially Astragalus membranaceus, have a long history of medicinal use in traditional Chinese medicine. Specifically, constituents of the dried roots of Astragalus spp. (Radix Astragali) provide significant protection against heart, brain, kidney, intestine, liver and lung injury in various models of oxidative stress-related disease. Different isolated constituents of Astragalus spp., such as astragalosides, flavonoids and polysaccharides also displayed significant prevention of tissue injury via antioxidant mechanisms. In this article, the antioxidant benefits of Astragalus spp. and its isolated components in protecting tissues from injury are reviewed, along with identification of the various constituents that possess antioxidant activity.

Oxyresveratrol, an active ingredient of Artocarpus lakoocha, is known to possess anti-inflammatory and immunomodulatory properties. Current study investigates the immunomodulatory effect of oxyresveratrol in mouse model of ethanol-induced ulcer. Anti-ulcer effect was determined using histopathological evaluation (H&E staining) and different tests like, gastric ulcer scoring, ulcer index, total acid secretion, and gastric pH. The mRNA expression levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), nuclear factor-kappaB (NF-ĸB), cyclooxygenase-1 (COX-1), cyclooxygenase-2 (COX-2) and trefoil factor 2 (TFF-2) were evaluated using reverse transcription polymerase chain reaction (RT-PCR). The data showed marked percentage inhibition of erosion, hemorrhage, fibrinoid necrosis, inflammatory infiltrate, and ulcer in low (30 mg/kg b.w.) and high dose (50 mg/kg b.w.) groups of oxyresveratrol. Treatment with oxyresveratrol inhibited ulcer score and ulcer index as compared with disease control group. Oxyresveratrol significantly increased gastric pH (P < 0.001) and attenuated total acid (P < 0.001) secretion. RT-PCR analysis showed significant suppression in the mRNA expression levels of IL-6 (P < 0.001), TNF-α (P < 0.01), NF-ĸB (P < 0.001), and COX-2 (P < 0.05) in oxyresveratrol treated groups, while COX-1 expression levels were found unaltered. Treatment with oxyresveratrol significantly elevated (P < 0.01) the expression levels of cytoprotective TFF-2 levels. Similar Immunomodulatory and anti-ulcer effects were found with ranitidine treatment, which was used as a reference drug. In conclusion, oxyresveratrol possess significant anti-ulcer property which might be attributed to attenuated expression levels of IL-6, TNF-α, NF-ĸB, and COX-2 and elevated expression levels of TFF-2.

Thymoquinone (TQ), the most important active principle of Nigella sativa is known to have anti-inflammatory, analgesic, antimicrobial and antioxidant properties. The present study was designed to see the anti-arthritic effect of TQ in rat model of arthritis. In the current research, anti-arthritic effect of TQ was determined in Freund's Complete Adjuvant (FCA)-induced arthritic rats by measuring TLRs expression levels. The mRNA expression levels of toll-like receptor 2 (TLR2), toll-like receptor 4 (TLR4), interleukin-1 (IL-1), nuclear factor-kappa B (NFκB) and tissue necrosis factor-α (TNF-α) were measured by reverse-transcription polymerase chain reaction. Arthritic signs were observed by macroscopic criteria. Hematoxylin and Eosin staining was used to perform ankle joint histopathology and agglutination method was used for measuring C-reactive protein (CRP) levels. Rheumatoid factor, alanine transaminase, aspartate aminotransferase, urea and creatinine were also determined in serum. TQ treatment reduced the macroscopic arthritic score, levels of CRP, synovial inflammation, pannus formation and bone erosion. It also reduced the mRNA levels of TLR2, TLR4, IL-1, NFκB and TNF-α. Methotrexate, used as a reference drug also significantly decreased their expression levels. TQ also normalized the hematological markers and did not depict any signs of hepatotoxicity and nephrotoxicity as determined by serum levels of alanine transaminase, aspartate aminotransferase, urea and creatinine. Our results showed that TQ possesses significant anti-arthritic activity which can be due to its anti-inflammatory and immunomodulatory effects. Results indicate that TQ has got the potential to ameliorate rheumatoid arthritis by downregulating TLR2, TLR4, TNF-α, IL-1, and NFκB expression levels.

Ginger has been used commonly in the traditional system of medicine for the treatment of respiratory disorders. The present study investigates the immunosuppressive activity of ginger by using the mouse model of ovalbumin-induced allergic asthma. Treatment with ethanol extract (500 mg/kg) and aqueous extract (720 mg/kg) of rhizomes, and methylprednisolone (5 mg/kg) was initiated 1 week after second sensitization of mice with ovalbumin and continued for 7 d. RT-PCR followed by gel electrophoresis and ELISA were used for the evaluation of mRNA expression levels and protein levels of Th2 type markers, respectively. Lung tissue histopathology was conducted by using H&E and PAS staining. We observed significant reduction in goblet cell hyperplasia (0.83 ± 0.17 and 1.0 ± 0.26), infiltration of inflammatory cells in airways (0.67 ± 0.33 and 1.0 ± 0.37), and edema with vascular congestion (1.0 ± 0.26 and 1.2 ± 0.17) by both ethanol and aqueous extracts, respectively. A highly significant reduction of total and differential count of eosinophils and neutrophils in BALF, and eosinophil count in blood were also observed. Both extracts significantly inhibited Th2-mediated immune response, which is evident by a decrease in mRNA expression levels of IL-4 and IL-5. Protein levels of IL-4 and IL-5 in BALF, along with total serum IgE levels, were also significantly suppressed by both extracts. Our study validated the traditional use of ginger in respiratory disorders and suggests that ginger reduces allergic airway inflammation, possibly by the suppression of Th2-mediated immune response.