Antihyperglycemic activity of Tectona grandis Linn. bark extract on alloxan induced diabetes in rats

Antioxidant, Anti-Inflammatory and Anti-Diabetic Activities of Tectona grandis Methanolic Extracts, Fractions, and Isolated Compounds

Tectona grandis is a traditional Dai medicine plant belonging to the Lamiaceae family, which can be used to treat malaria, inflammation, diabetes, liver disease, bronchitis, tumors, cholelithiasis, jaundice, skin disease and as an anti-helminthic. To find more novel therapeutic agents contained in this medicinal plant, the antioxidant, anti-inflammatory and anti-diabetic activities of T. grandis methanolic extract, fractions and compounds were evaluated. In this study, 26 compounds were isolated from the leaves and branches of T. grandis. Their structures were identified based on extensive spectral experiments, including NMR, ESI-MS and comparison with published spectral data. Among them, compounds 1–2, 4–6, 9–14 and 16–22 were reported for the first time for this plant. The antioxidant activity screening results showed that compounds 5, 15 and 23 had potent antioxidant capacities, with SC50 values from 0.32 to 9.92 µmol/L, 0.92 to 1.10 mmol Trolox/L and 1.02 to 1.22 mmol Trolox/L for DPPH, ABTS and FRAP, respectively. In addition, their anti-inflammatory effects were investigated by releasing TNF-α, IL-1β and IL-6 through the use of mouse monocytic macrophages (RAW 264.7). Compounds 1, 13, 18 and 23 had the effects of reducing the expression of inflammatory factors. Compounds 13 and 18 were reported for the first time for their anti-inflammatory activities. Furthermore, the methanolic extract (ME), petroleum ether extract (PEE) and EtOAc extract (EAE) of T. grandis showed significant glucose uptake activities; compounds 21 and 23 significantly promoted glucose uptake of 3T3-L1 adipocytes at 40 µM. Meanwhile, compounds 4, 5 and 7 showed significant inhibitory activities against α-glucosidase, with IC50 values of 14.16 ± 0.34 µmol/L, 19.29 ± 0.26 µmol/L and 3.04 ± 0.08 µmol/L, respectively. Compounds 4 and 5 were reported for the first time for their α-glucosidase inhibitory activities. Our investigation explored the possible therapeutic material basis of T. grandis to prevent oxidative stress and related diseases, especially inflammation and diabetes.

Antihyperglycemic and antioxidant activity of Clitorea ternatea Linn. on streptozotocin-induced diabetic rats

Ethanol extract of Clitorea ternatea Linn. (EECT) was evaluated for its antihyperglycemic and antioxidative activity in normal and streptozotocin-induced diabetic rats. Antihyperglycemic activity of EECT was studied in normal fasted and glucose fed hyperglycemic and epinephrine induced hyperglycemic rats by estimating fasting serum glucose (FSG) by glucose oxidisae or peroxidase enzymatic method. Antioxidant activity of EECT was studied by assaying lipid peroxide/Thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD), total nitric oxide, catalase (CAT) and glutathione levels in diabetic rats. The EECT (200 and 400 mg/kg) showed significant antihyperglycemic activity by decreasing FSG in all hyperglycemic models except epinephrine induced hyperglycemic rats; in which improvement in FSG was observed only with EECT in 400 mg/kg dose, whereas significant decrease in TBARS (P < 0.001), nitric oxide (P < 0.001) and significant increase in SOD (P < 0.001), CAT (P < 0.01) and reduced glutathione levels (P < 0.001) was observed in animals treated with EECT (200 and 400 mg/kg) compared to diabetic control group. The results indicated that EECT has remedial effects on hyperglycemia and oxidative stress in diabetic rats.

Multifunctional properties of polysaccharides from Dalbergia sissoo, Tectona grandis and Mimosa diplotricha

Three water-soluble polysaccharides were isolated and purified from the leaves of Dalbergia sissoo Roxb. (DSLP), bark of Tectona grandis L. f (TGBP) and seeds of Mimosa diplotricha var. diplotricha Sauvalle (MDSP). Antioxidant and moisture preserving activities of these three polysaccharides were investigated using in vitro methods. The antioxidant activities studied include superoxide (O2(*-)), 1,1-diphenyl-2-picrylhydrazyl (DPPH*), 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS(*+)), hydroxyl (OH(-)), nitric oxide (NO*), N,N-dimethyl-p-phenylenediamine (DMPD(+)) radical scavenging activities, ferric ion (Fe(3+)) reducing ability, ferrous ion (Fe(2+)) chelating and lipid peroxidation activities. The study revealed higher activity of TGBP in all antioxidant assays than DSLP and MDSP. Further, the three polysaccharides showed effective moisture retention properties in comparison with hyaluronic acid and glycerol.

Protective effect of salidroside from Rhodiolae Radix on diabetes-induced oxidative stress in mice

It has been confirmed that diabetes mellitus (DM) carries increased oxidative stress. This study evaluated the effects of salidroside from Rhodiolae Radix on diabetes-induced oxidative stress in mice. After induction of diabetes, diabetic mice were administered daily doses of 50, 100 and 200 mg/kg salidroside for 28 days. Body weights, fasting blood glucose (FBG), serum insulin, TC (total cholesterol), TG (triglyceride), malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) were measured. Results showed that salidroside possessed hypoglycemic activity and protective effects against diabetes-induced oxidative stress, which could significantly reduce FBG, TC, TG and MDA levels, and at same time increase serum insulin levels, SOD, GPx and CAT activities. Therefore, salidroside should be considered as a candidate for future studies on diabetes.