Aqueous and ethanol extracts of different traditional Malaysian plants (Polygonum minus, Andrographis paniculata, Curcuma xanthorrhiza, Momordica charantia and Strobilanthes crispus) were evaluated for their antioxidant properties, total phenolic content and cytotoxic activity. Antioxidant activity was evaluated by using 1,1-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays. The results showed that ethanol extracts contain high antioxidant activities compared to aqueous extracts. The findings exhibited a strong correlation between antioxidant activity and the total phenol contents. In addition, all the plant extracts showed non-toxic effects against a normal human lung fibroblast cell line (Hs888Lu). Although traditionally aqueous extracts are used, we determined that ethanol extracts usually achieved better activity in the assays.

Orthosiphon stamineus is considered an important traditional folk medicine. In this study ethanol and aqueous extracts of O. stamineus were evaluated in vitro for their antioxidant, antimicrobial as well as for their immunomodulatory properties on human peripheral blood mononuclear cells (PBMCs). The DPPH radical scavenging method was used for the determination of antioxidant activity, while the antibacterial efficacy was investigated by both disc diffusion method and Minimum Inhibitory Concentration (MIC) against four bacterial strains (Gram-positive and Gram-negative). Furthermore, the immunomodulatory potential of the extracts was investigated through the MTT assay. Aqueous extract of O. stamineus exhibited significant free radical scavenging activity with IC₅₀ 9.6 µg/mL, whereas the IC₅₀ for the ethanol extract was 21.4 µg/mL. The best antimicrobial activity was shown by the aqueous extract of O. stamineus against Staphylococcus aureus, with inhibition zone of 10.5 mm and MIC value 1.56 mg/mL. Moreover, the results observed from the MTT assay showed that both plant extracts stimulated the PBMCs proliferation in vitro in a concentration-dependent manner, but the aqueous extract has remarkable activity against PBMCs. These findings indicate that O. stamineus showed high antioxidant activity and may be considered as an immunomodulatory agent.

Current anti-gastric ulcer agents have side effects, despite the progression and expansion of advances in treatment. This study aimed to investigate the gastroprotective mechanisms of Pithecellobium jiringa ethanol extract against ethanol-induced gastric mucosal ulcers in rats. For this purpose, Sprague Dawley rats were randomly divided into five groups: Group 1 (normal control) rats were orally administered with vehicle (carboxymethyl cellulose), Group 2 (ulcer control) rats were also orally administered with vehicle. Group 3 (positive control) rats were orally administered with 20 mg/kg omeprazole, Groups 4 and 5 (experimental groups) received ethanol extract of Pithecellobium jiringa ethanol extract at a concentration of 250 and 500 mg/kg, respectively. Sixty minutes later, vehicle was given orally to the normal control group, and absolute ethanol was given orally to the ulcer control, positive control and experimental groups to generate gastric mucosal injury. The rats were sacrificed an hour later. The effect of oral administration of plant extract on ethanol-induced gastric mucosal injury was studied grossly and histology. The level of lipid peroxidation (malondialdehyde—MDA), superoxide dismutase (SOD) and gastric wall mucus were measured from gastric mucosal homogenate. The ulcer control group exhibited severe gastric mucosal injury, and this finding was also confirmed by histology of gastric mucosa which showed severe damage to the gastric mucosa with edema and leucocyte infiltration of the submucosal layer. Pre-treatment with plant extract significantly reduced the formation of ethanol-induced gastric lesions, and gastric wall mucus was significantly preserved. The study also indicated a significant increase in SOD activity in gastric mucosal homogenate, whereas a significant decrease in MDA was observed. Acute toxicity tests did not show any signs of toxicity and mortality up to 5 g/kg. The ulcer protective effect of this plant may possibly be due to its preservation of gastric wall mucus along with increased SOD activity and reduction of oxidative stress (MDA). The extract is non-toxic, even at relatively high concentrations.

Adiponectin is a protein hormone secreted entirely by abdominal fat tissue. It exhibits various biological activities. The present study was performed to evaluate the effects of metformin alone or in combination with adiponectin on blood glucose, TG (triglyceride), CHOL (Total cholesterol), LDL (Low density lipoprotein) and HDL (High density lipoprotein) levels in mice and also to evaluate the anti-ulcerogenic activity of adiponectin against ethanol induced gastric mucosal injury in rats. Three groups of mice were gavaged with 1% volume/body weight high fat-sucrose. Metformin at a dosage of 250 mg/kg was added to the feed and a dosage of 2.5 mg/kg adiponectin was injected intraperitoneally (i.p). Blood glucose was measured at one hour intervals for five hours. Blood concentrations of TG, CHOL, LDL and HDL were also measured at the end of the fifth hour of the experiment. On the other hand, four groups of adult healthy rats were i.p. injected with distilled water, omeprazole 20 mg/kg, 2.5 mg/kg and 5 mg/kg adiponectin one hour before oral administration of absolute ethanol to generate gastric mucosal injury. After an additional hour the rats were sacrificed and the ulcer areas of the gastric walls were determined. Furthermore, an acute toxicity study has indicated no mortality with 5 mg/kg dose of adiponectin injected i.p in rats and no major clinical signs of toxicity were observed. The results indicate that the effect of a combination of metformin and adiponectin on blood glucose and HDL is quite effective. Histology of the gastric wall of negative control rats revealed severe damage of gastric mucosa, along with edema and leucocyte infiltration of the submucosal layer compared to rats pre-treated with either omeprazole or adiponectin extract where there was marked gastric protection along with reduction or inhibition of edema and leucocytes infiltration. The results suggest that combination of metfomin and adiponectin give a promising antidiabetic effect and also, adiponectin promotes ulcer protection as ascertained by the comparative decrease of ulcer areas, reduction of edema and leucocytes infiltration of the submucosal layer.