Animal models to test drugs with potential antidiabetic activity

Although medicinal plants have been historically used for diabetes treatment throughout the world, few of them have been validated by scientific criteria. Recently, a large diversity of animal models has been developed to better understand the pathogenesis of diabetes mellitus and new drugs have been introduced in the market to treat this disease. The aim of this work was to review the available animal models of diabetes and some in vitro models which have been used as tools to investigate the mechanism of action of drugs with potential antidiabetic properties. In addition, a MEDLINE/PUBMED search for articles on natural products, pancreatectomy and diabetes mellitus treatment published between 1996 and 2006 was done. In the majority of the studies, natural products mainly derived from plants have been tested in diabetes models induced by chemical agents. This review contributes to the researcher in the ethnopharmacology field to designs new strategies for the development of novel drugs to treat this serious condition that constitutes a global public health.     

Antioxidant activity of Antrodia camphorata on free radical-induced endothelial cell damage

AIM OF THE STUDY: Antrodia camphorata (A. camphorata) is well known in Taiwan as a traditional Chinese medicine. The purpose of this study is to evaluate the antioxidant activity of Antrodia camphorata on free radical-induced endothelial cell damage. MATERIALS AND METHODS: In this study, a human umbilical vein endothelial cell (EC) culture system was used to evaluate the effects of the fermented culture broth of A. camphorata (FCBA) and aqueous extracts of mycelia from A. camphorata (AEMA) against the oxidative cell damage induced by the free-radical generator AAPH. RESULTS: The present investigations show that FCBA (25-100 microg/mL) and AEMA (50-200 microg/mL) effectively protect the ECs from damage after exposure to 15 mM AAPH for 16h. However, cell viability was not affected in ECs under controlled conditions after FCBA or AEMA treatment. An increase in EC prostacyclin (PGI(2)) production in response to AAPH exposure was positively and negatively correlated with cell damage and FCBA/AEMA concentration, respectively. Both FCBA and AEMA treatment significantly inhibited AAPH-apoptotic cell death in the ECs, as evidence by reduced DNA fragmentation, cytochrome c release, caspase-3 activation, and dysregulation of Bcl-2 and Bax. Moreover, the AAPH-induced reductions in EC SOD activity and protein levels are prevented by FCBA and AEMA. CONCLUSION: Our findings suggest that A. camphorata possesses antioxidant properties and improves endothelial function, further offering effective protection from atherosclerosis.     

Anti-inflammatory effects of hydroalcoholic extract and two biflavonoids from Garcinia gardneriana leaves in mouse paw oedema

Garcinia gardneriana (Planch. & Triana) Zappi (Clusiaceae) is widely distributed in Brazil and used in folk medicine to treat inflammation, pain, and urinary tract and other infections. However, very few studies have analyzed these therapeutic effects. In this study, the anti-inflammatory effects of the hydroalcoholic extracts from Garcinia gardneriana (HEGG) and some of its isolated biflavonoids were evaluated. The results showed that HEGG from the leaves, bark and seeds reduced carrageenan-induced mouse paw inflammation, in addition to diminishing the myeloperoxidase activity in the stimulated tissues. The reduction of neutrophil infiltration by treatment with the HEGG from leaves was confirmed by histology. The leaf extract also reduced the paw oedema evoked by bradykinin, histamine, prostaglandin E2 and 12-O-tetradecanoylphorbol acetate. However, it partially decreased substance P and compound 48/80-caused paw oedema, without any influence on the arachidonic acid-induced oedema. Both of the isolated compounds, fukugetin and GB-2a, prevented the carrageenan-induced paw oedema. In conclusion, this study showed important anti-inflammatory effects of HEGG through its interaction with different intracellular signaling pathways, without interfering with the formation of arachidonic acid (AA) metabolites. These characteristics, in addition to the wide distribution and culturing ease of the plant, confirm its popular use and highlight its promise in the development of new anti-inflammatory drugs.     

Antiparkinson drug--Mucuna pruriens shows antioxidant and metal chelating activity

Parkinson's disease is a neurodegenerative disorder for which no neurorestorative therapeutic treatment is currently available. Oxidative stress plays an important role in the pathophysiology of Parkinson's disease. The ancient Indian medical system, Ayurveda, traditionally uses Mucuna pruriens to treat Parkinson's disease. In our earlier studies, Mucuna pruriens has been shown to possess antiparkinson and neuroprotective effects in animal models of Parkinson's disease. The antioxidant activity of Mucuna pruriens was demonstrated by its ability to scavenge DPPH radicals, ABTS radicals and reactive oxygen species. Mucuna pruriens significantly inhibited the oxidation of lipids and deoxyribose sugar. Mucuna pruriens exhibited divalent iron chelating activity and did not show any genotoxic/mutagenic effect on the plasmid DNA. These results suggest that the neuroprotective and neurorestorative effect of Mucuna pruriens may be related to its antioxidant activity independent of the symptomatic effect. In addition, the drug appears to be therapeutically safe in the treatment of patients with Parkinson's disease.     

Proliferative responses in the placenta after endotoxin exposure in preterm fetal sheep

OBJECTIVES: Antenatal infections are associated with an increased risk of perinatal morbidity and mortality. Systemic application of endotoxins to the fetus results in an increase in placental vascular resistance and chronic reduction in umbilical blood flow. We studied morphological alterations of the placenta in response to fetal inflammation in the preterm sheep. STUDY DESIGN: Therefore, 14 fetal sheep were chronically instrumented at a mean gestational age of 107+/-1 days (term is 147 days). Four days after surgery fetuses received 100 ng lipopolysaccharide (LPS; n=8) or saline (control; n=6) intravenously. Fetal heart rate and arterial blood pressure were monitored continuously while blood gases and acid-base balance were measured at time points 0, +1, +3, +6, +12, +24, +48 and +72 h. Three days after LPS application placental cotyledons were analyzed by immunohistochemistry and morphometry. Different primary antibodies like AE 1 and AE 3 against cytokeratins were used. Secondary antibodies were visualized with 3-amino-9-ethylcarbazole (AEC) or using the Vectastain kit (Vector Laboratories, Burlingame, CA). Double staining was carried out first by utilizing Vectastain kit (black), followed by AEC staining (red). Counterstaining was performed with haematoxylin. RESULTS: Fetal tachycardia and hypertension were induced transiently during the first 12h after LPS application. Fetuses suffered from mild hypoxaemia while acidemia was absent. Morphometry revealed a non-significant shift in the relation of maternal and fetal placental compartments towards the maternal parts in response to LPS treatment. Endotoxin induced an increased proliferation in both compartments of the placenta with a 3.2-fold increase on the maternal and a 1.8-fold increase on the fetal side. CONCLUSIONS: Systemic endotoxin exposure of the preterm fetal sheep leads to a change in the gross organization of the placenta and changes in the proliferation patterns in both placental compartments. These rearrangements inside the placenta may disturb its organ function and subsequently lead to fetal morbidity associated with the fetal inflammatory response syndrome and chronic placental dysfunction, respectively.     

The clinical analysis of poor ovarian response in in-vitro-fertilization embryo-transfer among Chinese couples

Purpose To explore the prevalence, predictor of clinical pregnancy and possible aetiology of poor ovarian response (POR) in in vitro fertilization–embryo transfer (IVF–ET) in Chinese. Methods A total of 4,600 retrieval oocyte cycles were finished between July 1, 2004 and April 30, 2006. Poor ovarian responses were observed in 426 patients of 472 cycles undergoing IVF, which were selected on the same retrieve oocyte day as the control group. The outcome of IVF–ET and the common markers of ovarian reserve were compared. Results The patients had previous ovarian surgery in 64 cycles of 472 poor ovarian response cycles. The group with poor ovarian response has significant differences in comparison with the control group in age (36.6 ± 4.2 vs 33.3 ± 4.04), ovarian surgeries (13.6 vs 2.8%), dose of gonadotrophin (58.5 ± 15.8 vs 40.6 ± 17.0), fertilization rate (71.5 vs 86%) and pregnancy rate (14.8 vs 36.7%). In the group with poor ovarian responses, clinical pregnancy rate declined significantly in women aged >40 years than in those aged ≤40 years (2.8 vs 18.5%, P < 0.001). The age, basal serum follicle stimulating hormone (FSH), basal serum luteinizing hormone (LH), basal oestradiol (E2) concentrations, FSH to LH ratio and the antral follicle count (AFC) are the common markers of ovarian reserve in our center. We found that there were significant differences in age, basal FSH, FSH-to-LH ratio and the antral follicle count. But no statistical significant differences were observed in basal oestradiol concentration and basal serum LH when comparing the two groups. Binary logistic regression analysis was used to study the relation among age, FSH, LH, E2, AFC and clinical pregnancy, and the age (odds ratio, 0.863; 95% confidence interval, 0.805–0.925; p = 0.000) was the only variable selected. Conclusion Our data show that the prevalence of poor ovarian response in Chinese is 11.9%. Previous ovarian surgery is associated with poor ovarian responses. The pregnancy rate of women with poor ovarian response is low in IVF–ET, especially the decline in clinical pregnancy rate of women aged >40 years became accelerated. Correct identification of those who are at risk for POR prior to stimulation is helpful in tailoring the best stimulation protocol to individual patients. Chronological age significantly improved the prediction of clinical pregnancy of poor ovarian responders.     

Evaluation of sperm selection procedure based on hyaluronic acid binding ability on ICSI outcome

PURPOSE: To compare the efficiency of routine sperm selection method with HA-selection procedure for fertilization rate, embryo development, implantation and pregnancy rates as well as evaluating the relationship between HA-binding ability with sperm protamine deficiency and DNA fragmentation. METHODS: Semen samples were obtained from the 50 couples undergoing ICSI. The percentage of fertilization rate, cleavage and quality of embryos compared between two procedures (routine sperm selection and HA-binding selection). The semen samples were assessed for DNA fragmentation and protamine deficiency by sperm chromatin dispersion (SCD) test and Chromomycin A3 (CMA3) staining, respectively. RESULTS: A significant inverse correlation was observed between percentage of HA binding with protamine deficiency, DNA fragmentation and abnormal sperm morphology (P < 0.05). Furthermore, in current study, oocytes inseminated by HA sperm selection procedure had significantly higher fertilization rate (P < 0.05). While the pregnancy and implantation rates were insignificantly increased. CONCLUSION: The results suggest that normal sperm have higher chance to bind HA and therefore, HA sperm selection procedure may select sperm with normal protamine content and low DNA fragmentation, but to confirm the effect of HA sperm selection on the ICSI outcome requires further studies.