Small, naturally derived molecules are important targets of drug research and development and are models of chemical synthesis. Such molecules accounted for over 60% of the approved drugs and pre-New Drug Application candidates from 1989 to 1995 (1). Of the top 35 ethical drug sales worldwide, drugs derived from natural products accounted for 24% in 2001 and 26% in 2002 (2). Drug research and development is gaining insights from research on natural products, a new trend that combines traditional methods with new techniques in life science. In addition to research seeking to discover natural compounds through use of isolation techniques and structural determination methods, research to identify new sources of natural compounds and classify their functions and research to modify the structures of those compounds by biosynthetic or chemical manipulation will definitely expand the field of natural product chemistry. ...
Although important progress has been achieved in combating HIV/AIDs over the past 30 years, HIV/AIDs is still a serious threat to today's world. In China, figures on the incidence of this disease have painted a less than optimistic outlook. As the prevailing methods of preventing HIV/AIDS are all partially effective, novel and effective preventive interventions are needed in order to control the spread of the disease. Pre-exposure prophylaxis (PrEP) is one of the most promising prevention strategies and has garnered great attention worldwide. Current clinical trials on the efficacy and safety of this strategy have had some favorable results though major challenges around the world remain. Thus, China has taken an active part in the PrEP study to limit the prevalence of HIV/AIDS. This article describes the status of the PrEP study and discusses the opportunities and challenges encountered when implementing this strategy in China.
Creatinine (Crn) is one of the main intrinsic hydroxyl radical (•OH) scavengers and an ideal one for healthy or normal mammals, although this fact has not yet become widely accepted. Our results from urinary data estimated that ca. 0.4-0.6% of Crn is used daily to scavenge •OH in normal mammals [ca. 50 μmole and ca. 400 pmole of •OH in healthy subjects and normal rats, respectively]. In human subjects, Crn reacts non-enzymatically with •OH to form creatol (CTL: 5-hydroxycreatinine) and demethylcreatinine (DMC) in a one to one ratio, and CTL partially decomposes to methylguanidine (MG). And so, the scavenged mole of •OH by Crn is nearly equal to their molar total sum (CTL + MG + DMC) or 2 × (CTL + MG). The molar ratio of (scavenged •OH)/Crn in healthy subjects and normal rats are 4.4 and 6.0 mmole/mole, respectively, i.e. almost similar, but in patients with chronic kidney disease (CKD) the ratio increases up to ca. 60 mmole/mole in proportion to the severity of CKD. Since the level of Crn might not be enough to scavenge all •OH, and MG starts accumulating as a uremic toxin, Crn is not really the ideal scavenger. 5-Hydroxy-1-methylhydantoin (HMH, NZ-419), a Crn metabolite, is another antioxidant, having •OH scavenging ability, and has been shown to inhibit the progression of CKD in rats in stead of Crn, if sufficient amounts are given orally.
The peroxisome proliferator-activated receptor (PPAR) subtype specificity of GW501516, a well-known PPARδ-specific agonist, was studied by examining its effects on the expression of endogenous genes in primary hepatocytes and the liver of wild-type and PPARα-null mice. GW501516, like the PPARα-specific agonist Wy14,643, induced the expression of several PPAR target genes in a dose-dependent manner but this action was mostly absent in the cells and liver of PPARα-null mice. Results indicated that GW501516 acts as an efficient PPARα activator in the mouse liver.
We investigated the effects of a Chinese herbal medicine, Gosha-jinki-gan (GJG), on the regulation of insulin levels in rats fed a sucrose-rich diet (SRD). Normal Wistar rats in the SRD group were fed an SRD for 4 weeks. Increased dietary sucrose did not alter plasma glucose levels but it increased plasma insulin levels at 2 and 4 weeks in the SRD-fed rats relative to control rats that were fed standard chow. GJG treatment significantly suppressed the SRD-induced elevation in plasma insulin levels. These results suggest that GJG improves hyperinsulinemia caused by an SRD.
The sedative and anxiolytic potential of Leea indica (Burm. f.) Merr., a Bangladeshi tribal medicinal plant was studied for the first time. The crude methanol extract of L. indica leaves was evaluated for its central nervous system (CNS) depressant effect using rodent behavioral models, such as hole cross, open field and thiopental sodium induced sleeping time tests for its sedative properties and an elevated plus-maze (EPM) test for its anxiolytic potential, respectively. The methanol extract of L. indica at doses of 200 mg/kg, p.o. and 400 mg/kg, p.o., displayed a dose dependent suppression of motor activity, exploratory behavior (in hole cross and open field tests) and prolongation of thiopental induced sleeping time in mice; the highest CNS depressant effect was shown at a dose of 400 mg/kg, p.o. In the EPM test, both doses of methanol extract significantly (p < 0.01) increased exploration to and time spent by the treated mice in EPM open arms in a dose dependent manner. These results provide in vivo evidence that leaves of L. indica in general have significant sedative and anxiolytic effects. However, these results may rationalize the scientific basis for use of this plant in traditional medicine for treatment of anxiety and related disorders.
The purpose of this study was to compare the chondroprotective effects of chondroitin sulfate (CS)-hyaluronic acid (HA) (CS-HA) injection and HA injection in an experimental model of osteoarthritis. After induction of osteoarthritis in rabbits, 28 rabbits were randomized into four groups: control group, 'HA' group, 'CS' group, and 'CS-HA' group. After 7 days, rabbits in the control group, 'HA' group, 'CS' group and 'CS-HA' group were respectively treated with normal saline, HA, CS, or CS-HA injection in the knees. All animals were treated once weekly. The animals were treated continuously for 5 weeks. Histological and biochemical evaluations were performed. As shown by histological observation, CS-HA injection treatment showed a chondroprotective effect on osteoarthritis. However, the histological scores of 'HA' group and 'CS-HA' group were not significantly different (p > 0.05). The results of biochemical evaluation showed that the expression levels of IL-1β, TNF-α, TIMP-1 and NO in synovial fluid of treated groups were all different from the control group (p < 0.05). However, the expression levels of these biochemical molecules in three treated groups were not significantly different (p > 0.05). In conclusion, CS-HA injection showed no obvious advantage over HA injection in osteoarthritis treatment.
The immunosuppressive properties of an aqueous suspension of Withania somnifera (WS) root powder were investigated in a pristane induced female Balb/c model of a systemic lupus erythematosus (SLE) like disease. The course of disease is initiated by peritoneal inflammation caused by pristane which results in development of SLE like symptoms, i.e. autoantibody production, proteinuria, and nephritis within a period of five to six months. The model of SLE was established by injecting 0.5 mL of pristane intraperitoneally into female Balb/c mice (12-18 weeks old). WS root powder (500 mg and 1,000 mg per kg body weight) was administered orally from one month prior to disease induction and for the following 6 months. Parameters of inflammation like nitric oxide (NO), Interleukin 6 and tumour necrosis factor-α and reactive oxygen species (ROS) in serum and/or ascitic fluid were measured. Prophylactic administration of WS root powder (500 mg and 1,000 mg per kg body weight) potently inhibits the pro-inflammatory cytokines, NO, and ROS in the ascitic fluid as well as in serum. Therefore, our results indicate a preventive effect of WS root powder on the mouse model of lupus.
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