TiO2 nanoparticles: green synthesis, characterization, and investigation of antimicrobial properties, and developmental toxicity in zebrafish (Danio rerio) embryos

The present study was designed to green synthesize titanium dioxide nanoparticles (G-TiO2 NPs) using Salacia reticulata leaf extract as a reducing and capping agent to assess antidiabetic, anti-inflammatory, and antibacterial effects as well as toxicity evaluation in zebrafish. Besides, zebrafish embryos were employed to study the effect of G-TiO2 NPs on embryonic development. Zebrafish embryos were treated with TiO2 as well as G-TiO2 NPs at four different concentrations, i.e., 25, 50, 100, and 200 µg/ml for 24-96-hour post-fertilization (hpf). The SEM analysis of G-TiO2 NPs confirmed that the size was in the range of 32-46 nm and characterized by EDX, X-ray diffraction (XRD), FTIR, UV-vis spectra. During 24-96-hour post-fertilization (hpf), the results showed that 25-100 µg/ml of TiO2 and G-TiO2 NP instigated developmental acute toxicity in these embryos, causing mortality, hatching delay, and malformation. TiO2 and G-TiO2 NPs exposure induced axis bent, tail bent, spinal cord curvature, yolk-sac, and pericardial edema. Exposure of larvae to the highest concentrations of 200 μg/ml TiO2 and G-TiO2 NPs caused maximum mortality at all time points and reached 70% and 50%, respectively, at 96 hpf. Besides, both TiO2 and G-TiO2 NP revealed antidiabetic and anti-inflammatory effects in vitro. In addition, G-TiO2 NPs exhibited antibacterial effects. Taken together, this study provided a valuable insight into the synthesis of TiO2 NPs using green methods and the synthesized G-TiO2 NPs possess moderate toxicity and potent antidiabetic, anti-inflammatory and antibacterial activities.

(Kothala Himbutu)

BACKGROUND

Decoctions of the root and stem of the medicinal plant Salacia reticulata is an indigenous remedy for diabetics and its complications in Sri Lanka. In diabetics, the formation of advanced glycation end products (AGEs) leads to many pathologies. Nevertheless, the anti-protein-glycation property of this plant is poorly documented. This study reports the anti-protein-glycation and radical scavenging potential of various plant parts of S. reticulata.

METHODS

Hot water extracts (2g dried powder/50 ml) of root, stem, leaf, twigs, and fruits at various concentrations (15.6 to 500.0 µg/ml) were subjected to anti-glycation and glycation reversing assays in vitro. 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay was used for free radical scavenging property.

RESULTS

Various plant parts of S. reticulata showed anti-protein-glycation and free-radical scavenging activities. IC50 for the anti-glycation activity of root, stem, leaf, twigs, and fruit extracts were 11.92 ± 1.14, 35.18 ± 2.79, 113.3 ± 1.91, 149.59 ± 1.06, and 1120.37 ± 229.48 µg/ml respectively. IC50 of Rutin was 21.88 ± 2.82 µg/ml. EC50 of the root, stem, twigs, and leaf extracts for glycation reversing was 102.09 ± 6.23, 116.99 ± 5.82, 154.45 ± 5.79, and 278.78 ± 14.19 µg/ml respectively. The EC50 values for the radical scavenging activity of leaf, stem, and roots were 26.4±4.7, 9.0±1.2, and 9.1±1.3 respectively. Root had significantly (p<0.05) high activity for all the parameters tested.

CONCLUSION

Salacia reticulata possess anti-glycation, glycation-reversing, and free radical scavenging activities. Other than root and stem, the leaves and twigs too may be a useful source for anti-diabetic bioactive molecules.

Salacia reticulata Extract Suppresses Fat Accumulation by Regulating Lipid Metabolism

The excessive storage of triglycerides in adipose tissue is a characteristic feature of obesity, which arises from an imbalance between energy intake and expenditure. In this study, we aimed to explore the potential anti-obesity effects of Salacia reticulata extracts (SC) in a high-fat diet (HFD)-induced in obese mice and 3T3-L1 adipocytes, with a specific focus on understanding the underlying lipid mechanisms. Mice were fed with a normal diet (NC; normal control), HFD (60% high-fat diet), Met (HFD containing metformin 250 mg/kg b.w.), SC25 (HFD containing SC 25 mg/kg b.w.), SC50 (HFD containing SC 50 mg/kg b.w.), or SC 100 (HFD containing SC 100 mg/kg b.w.) for 12 weeks. Notably, SC supplementation led to significant reductions in body weight gain, adipose tissue weight, adipose tissue mass, and adipocyte size in HFD-fed mice. Furthermore, SC supplementation exerted inhibitory effects on the adipogenesis and lipogenesis pathways while promoting lipolysis and thermogenesis pathways in the adipose tissues of HFD-fed mice. In vitro experiments using 3T3-L1 cells demonstrated that SC treatment during the differentiation phase suppressed adipogenesis and lipogenesis, whereas SC treatment after differentiation, activated lipolysis and thermogenesis. Collectively, these findings indicate that SC exhibits a direct influence on the lipid metabolism of adipocytes, making it an effective candidate for weight loss interventions.

Pleiotropic effects of Salacia reticulata and Simvastatin on oxidative stress and insulin resistance in a rat model

BACKGROUND

The present study investigated the effects of Salacia reticulata and simvastatin on oxidative stress and insulin resistance in Sprague-Dawley (SD) rats. We compared the protective effect of a methanolic extract of Salacia reticulata (SR) with simvastatin (SVS) in rats fed a high-fat diet (HFD).

METHODS AND RESULTS

Male Sprague-Dawley rats were divided into the following five different groups: control (C), C+SR, HFD, HFD+SR, and HFD+SVS. High-fat diet fed rats showed hyperglycemia, hyperinsulinemia, hyperleptinemia, dyslipidemia, and hypoadiponectinemia after 90 days. Treatment of high-fat diet fed rats with SR/SVS significantly (p < 0.05) reduced high-fat diet induced increases in plasma triglycerides, total cholesterol, very-low-density lipoprotein (VLDL), low-density lipoprotein (LDL) and decreased high- density lipoprotein (HDL) accompanied by an increase in lipid peroxidation (LPO) and protein oxidation. In addition, a significant decrease in the activities of antioxidant enzymes and enzymes of the polyol pathway was observed in rats fed high-fat diet. SR was found to be more effective than SVS. Moreover, infiltration of inflammatory cells and fibrosis in the liver of high-fat diet fed rats by SR/SVS were also prevented.

CONCLUSIONS

The present study confirms that SR/SVS may be a new and promising remedial approach because of its beneficial effects on the pathophysiological processes of obesity and related metabolic disorders.

Additive effects of Kothala himbutu (Salacia reticulata) extract and a lactic acid bacterium (Enterococcus faecalis YM0831) for suppression of sucrose-induced hyperglycemia in an in vivo silkworm evaluation system

Using a silkworm evaluation system, we previously evaluated various substances that suppress postprandial hyperglycemia. Enterococcus faecalis YM0831, a lactic acid bacterium that inhibits glucose uptake by the human intestinal Caco-2 cell line, exhibited hyperglycemia-suppressing effects in the silkworm system. In the present study, we found that Kothala himbutu (Salacia reticulata) extract, a traditional medicine containing α-glucosidase inhibitors, suppressed sucrose-induced hyperglycemia in the silkworm system. Moreover, combined oral administration of lactic acid bacteria YM0831 with Kothala himbutu extract had stronger suppressive effects on sucrose-induced hyperglycemia than single administration of either component. These findings suggest that the silkworm system provides a simple way to evaluate the effects of supplements on the suppression of blood glucose level induced by sucrose ingestion.

A subchronic oral toxicity study of Salacia reticulata extract powder in rats

The safety of Salacia plant (Salacia reticulata) extract powder, which is used in Ayurvedic medical practices, was studied in a dose range-finding subchronic toxicity study in Crl:CD Sprague–Dawley rats. Male and female rats were randomly assigned to 4 treatment groups and were treated by oral gavage with 0, 10, 65, and 400 mg/kg body weight/day of the powder for 91 days. Body weight, food consumption, and clinical signs were assessed during the treatment period. Urinalysis, hematology, blood chemistry, and organ weights were determined one day after the final treatment. The animals were euthanized at the end of the treatment and were examined for necropsy and histopathological purposes. No adverse toxicity was observed in the Salacia powder-treated groups with a No Observed Adverse Effect Level of ≧400 mg/kg body weight/day in both male and female SD rats.

Anti-diabetic and Anti-hyperlipidemic Effects and Safety of Salacia reticulata and Related Species

Extracts of Salacia reticulata Wight (Hypocrataceae) roots, stems, and leaves have been used in Asia for hundreds of years for the folkloric treatment of diabetes and other health problems. Constituents that have been identified as exhibiting anti-diabetic effects include salacinol, kotalanol, ponkorinol, salaprinol, and their corresponding de-0-sulfonated compounds. Mangiferin, kotalagenin 16-acetate and various proanthocyanidin oligomers have also been isolated. Studies indicate that Salacia extracts modulate multiple targets that influence carbohydrate and lipid metabolism including α-glucosidase, aldose reductase, pancreatic lipase, peroxisomal proliferator-activated receptor-α, glucose transporter-4 mediated glucose uptake, and angiotensin II type 1 receptor. Furthermore, Salacia extracts exhibit free radical scavenging, antioxidant and hepatoprotectant activities. In human studies, Salacia extracts have been shown to decrease plasma glucose and insulin levels, decrease HbA1c, and modulate serum lipid levels with no adverse effects being reported. Similar results have been demonstrated in rat and mouse models as well as in vitro systems. Safety of S. reticulata and other Salacia species as S. oblonga and S. chinensis in rats and mice indicate that extracts are exceedingly safe. No clinical studies have examined the effects of Salacia extracts on human weight loss, although weight loss and decreases in weight gain have been demonstrated in animal models. Because of the large number of pharmacologically active compounds, it is difficult to establish standards for extracts.

Effects of the Sri Lankan medicinal plant, Salacia reticulata, in rheumatoid arthritis

Salacia reticulata is a native plant of Sri Lanka. In the traditional medicine of Sri Lanka and India, Salacia reticulata bark is considered orally effective in the treatment of rheumatism, gonorrhea, skin disease and diabetes. We have investigated, both in vivo and in vitro, whether the leaf of Salacia reticulata (SRL) can ameliorate collagen antibody-induced arthritis (CAIA) in mice as the rheumatoid arthritis (RA) model. The mice were fed a lard containing chow diet (AIN-93G) or the same diet containing 1% (w/w) SRL powder. All mice were bred for 23 days. On day 7 or 14 after LPS injection, mice were killed, and tissue and blood samples were collected. Histological analysis was performed, and serum levels of inflammatory mediators and the mRNA levels of inflammation-related genes and osteoclast-related genes were measured. SRL treatment ameliorated the rapid initial paw swelling, inflammatory cells infiltration, skeletal tissues damage, osteoclast activation and the mRNA levels for osteoclast-related genes compared with the CAIA mice. However, the serum and mRNA levels of inflammatory mediators did not differ between the CAIA mice and the SRL-treated mice. SRL might reduce the inflammatory cells induction and skeletal tissue degradation by CAIA by the regulating osteoclastogenesis.