Rusliza Basir

Receptor for Advanced Glycation End Products and Its Involvement in Inflammatory Diseases

The receptor for advanced glycation end products (RAGE) is a transmembrane receptor of the immunoglobulin superfamily, capable of binding a broad repertoire of ligands. RAGE-ligands interaction induces a series of signal transduction cascades and lead to the activation of transcription factor NF-κB as well as increased expression of cytokines, chemokines, and adhesion molecules. These effects endow RAGE with the role in the signal transduction from pathogen substrates to cell activation during the onset and perpetuation of inflammation. RAGE signaling and downstream pathways have been implicated in a wide spectrum of inflammatory-related pathologic conditions such as arteriosclerosis, Alzheimers disease, arthritis, acute respiratory failure, and sepsis. Despite the significant progress in other RAGE studies, the functional importance of the receptor in clinical situations and inflammatory diseases still remains to be fully realized. In this review, we will summarize current understandings and lines of evidence on the molecular mechanisms through which RAGE signaling contributes to the pathogenesis of the aforementioned inflammation-associated conditions.

An investigation of the anti-inflammatory and analgesic effects of Orthosiphon stamineus leaf extract.

Anti-inflammatory and analgesic activities of a standardized Orthosiphon stamineus methanol:water (50:50 vol/vol) leaf extract (SEOS) were evaluated in animal models. Oral administration of SEOS at doses of 500 and 1,000 mg/kg significantly reduced the hind paw edema in rats at 3 and 5 hours after carrageenan administration (P < .01 and P < .01; P < .01 and P < .05, respectively). SEOS (1,000 mg/kg, p.o.) also produced significant (P < .05) analgesic activity in both the acetic acid-induced writhing test and the formalin-induced licking test (late phase) in mice and rats, respectively. However, SEOS showed no effect on the tail flick and hot plate tests in mice. The results of the present study support the proposal that O. stamineus has anti-inflammatory and non-narcotic analgesic activities. These findings justify the traditional use of the plant for treating pain and inflammation.

Antioxidant and hepatoprotective effects of Orthosiphon stamineus Benth. standardized extract.

Orthosiphon stamineus (OS), Benth. (Lamiaceae) is widely used in Malaysia for treatments of various kidney and liver ailments. In the experiment, DPPH* radicals scavenging, Fe(3+)-induced lipid peroxidation inhibiting activities and trolox equivalent antioxidant capacity (TEAC) of methanol/water extract of Orthosiphon stamineus (SEOS) were determined. The results indicated that SEOS exhibited antioxidant, lipid peroxidation inhibition and free radical scavenging activities. The hepatoprotective activity of the SEOS was studied using CCl(4)-induced liver toxicity in rats. The activity was assessed by monitoring liver function tests through the measurement of alanine transaminase (ALT) and aspartate transaminase (AST). Furthermore, hepatic tissues were also subjected to histopathological studies. Pretreatment of SEOS (125, 250, 500 and 1000 mg/kg p.o.) dose-dependently reduced the necrotic changes in rat liver and inhibited the increase of serum ALT and AST activities. The results of the present study indicated that the hepatoprotective effect of Orthosiphon stamineus might be ascribable to its antioxidant and free radical scavenging property.

HPLC and Anti-Inflammatory Studies of the Flavonoid Rich Chloroform Extract Fraction of Orthosiphon Stamineus Leaves

The aim of the present study was to verify the anti-inflammatory activity of Orthosiphon stamineus leaf extracts and to identify the active compound(s) contributing to its anti-inflammatory activity using a developed HPLC method. Active chloroform extract of O. stamineus was fractionated into three fractions using a dry flash column chromatography method. These three fractions were investigated for anti-peritoneal capillary permeability, in vitro nitric oxide scavenging activity, anti-inflammatory and nitric oxide (NO) inhibition using carrageenan-induced hind paw edema method. The flavonoid rich chloroform extract fraction (CF2) [containing sinensetin (2.86% w/w), eupatorin (5.05% w/w) and 3’-hydroxy-5,6,7,4’-tetramethoxyflavone (1.101% w/w)], significantly reduced rat hind paw edema, NO and decreased dye leakage to peritoneal cavity at p < 0.05. IC50 of in vitro NO scavenging of CF2 was 0.3 mg/mL. These results suggest that the anti-inflammatory properties of these CF2 may possibly be due to the presence of flavonoid compounds capable of affecting the NO pathway.

Orthosiphon stamineus Leaf Extract Protects Against Ethanol-Induced Gastropathy in Rats

Orthosiphon stamineus Benth., which is used as a gastroprotective herbal remedy in Malaysia, was assessed for its anti-ulcerogenic activity against ethanol-induced ulcers in rats. Fifty percent methanol was used to extract the oven-dried O. stamineus leaves. The extract was then lyophilized with a rotary evaporator and freeze-dried. Oral administration of O. stamineus methanolic extract (OSME) (125, 250, 500, and 1,000 mg/kg) was found to significantly decrease the ulcer index (P < .01, P < .001, P < .001, and P < .001, respectively). Histological study of a section of the rat stomach also showed a marked improvement in the gastric mucosal damage in groups receiving OSME. In order to further investigate the gastroprotective mechanism of OSME, mucus secretion and lipid peroxidation level were estimated in vitro and ex vivo. OSME exhibited dose-dependent stimulation of mucus secretion (r = 0.718, P < .001) and inhibition of lipid peroxidation in rat gastric mucosal homogenates (both in vitro [r = 0.819, P < .05] and ex vivo [r = 0.981, P < .05]). It was concluded that the gastroprotective mechanism of OSME was partly due to its ability to inhibit lipid peroxidation and stimulate gastric mucus secretion.

Role of Different Pfcrt and Pfmdr-1 Mutations in Conferring Resistance to Antimalaria Drugs in Plasmodium falciparum

Emergence of drugs resistant strains of Plasmodium falciparum has augmented the scourge of malaria in endemic areas. Antimalaria drugs act on different intracellular targets. The majority of them interfere with digestive vacuoles (DVs) while others affect other organelles, namely, apicoplast and mitochondria. Prevention of drug accumulation or access into the target site is one of the mechanisms that plasmodium adopts to develop resistance. Plasmodia are endowed with series of transporters that shuffle drugs away from the target site, namely, pfmdr (Plasmodium falciparum multidrug resistance transporter) and pfcrt (Plasmodium falciparum chloroquine resistance transporter) which exist in DV membrane and are considered as putative markers of CQ resistance. They are homologues to human P-glycoproteins (P-gh or multidrug resistance system) and members of drug metabolite transporter (DMT) family, respectively. The former mediates drifting of xenobiotics towards the DV while the latter chucks them outside. Resistance to drugs whose target site of action is intravacuolar develops when the transporters expel them outside the DVs and vice versa for those whose target is extravacuolar. In this review, we are going to summarize the possible pfcrt and pfmdr mutation and their role in changing plasmodium sensitivity to different anti-Plasmodium drugs.

Flavonoids eupatorin and sinensetin present in Orthosiphon stamineus leaves inhibit inflammatory gene expression and STAT1 activation.

Cytokines and other inflammatory mediators, such as prostaglandin E₂ (PGE₂) and nitric oxide (NO) produced by cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS), respectively, activate and drive inflammation and therefore serve as targets for anti-inflammatory drug development. Orthosiphon stamineus is an indigenous medicinal plant of Southeast Asia that has been traditionally used in the treatment of rheumatoid arthritis, gout, and other inflammatory disorders. The present study investigated the anti-inflammatory properties of Orthosiphon stamineus leaf chloroform extract (CE), its flavonoid-containing CE fraction 2 (CF2), and the flavonoids eupatorin, eupatorin-5-methyl ether (TMF), and sinensetin, identified from the CF2. It was found that CE (20 and 50 µg/mL) and CF2 (20 and 50 µg/mL) inhibited iNOS expression and NO production, as well as PGE₂ production. Eupatorin and sinensetin inhibited iNOS and COX-2 expression and the production of NO (IC₅₀ 5.2 µM and 9.2 µM for eupatorin and sinensetin, respectively) and PGE₂ (IC₅₀ 5.0 µM and 2.7 µM for eupatorin and sinensetin, respectively) in a dose-dependent manner. The extracts and the compounds also inhibited tumor necrosis factor α (TNF-α) production (IC₅₀ 5.0 µM and 2.7 µM for eupatorin and sinensetin, respectively). Eupatorin and sinensetin inhibited lipopolysaccharide (LPS)-induced activation of transcription factor signal transducers and activators of transcription 1α (STAT1α). Furthermore, eupatorin (50 mg/kg i. p.) and sinensetin (50 mg/kg i. p.) inhibited carrageenan-induced paw inflammation in mice. The results suggest that CE and CF2, as well as the known constituents of CF2, i.e., eupatorin and sinensetin, have meaningful anti-inflammatory properties which may be utilized in the development of novel anti-inflammatory treatments.

Antioxidant and Toxicity Studies of 50% Methanolic Extract of Orthosiphon stamineus Benth

The present study evaluated the antioxidant activity and potential toxicity of 50% methanolic extract of Orthosiphon stamineus (Lamiaceae) leaves (MEOS) after acute and subchronic administration in rats. Superoxide radical scavenging, hydroxyl radical scavenging, and ferrous ion chelating methods were used to evaluate the antioxidant properties of the extract. In acute toxicity study, single dose of MEOS, 5000 mg/kg, was administered to rats by oral gavage, and the treated rats were monitored for 14 days. While in the subchronic toxicity study, MEOS was administered orally, at doses of 1250, 2500, and 5000 mg/kg/day for 28 days. From the results, MEOS showed good superoxide radical scavenging, hydroxyl radical scavenging, ferrous ion chelating, and antilipid peroxidation activities. There was no mortality detected or any signs of toxicity in acute and subchronic toxicity studies. Furthermore, there was no significant difference in bodyweight, relative organ weight, and haematological and biochemical parameters between both male and female treated rats in any doses tested. No abnormality of internal organs was observed between treatment and control groups. The oral lethal dose determined was more than 5000 mg/kg and the no-observed-adverse-effect level (NOAEL) of MEOS for both male and female rats is considered to be 5000 mg/kg per day.

Delta-9-Tetrahydrocannabinol (∆9-THC) Induce Neurogenesis and Improve Cognitive Performances of Male Sprague Dawley Rats

Neurogenesis is influenced by various external factors such as enriched environments. Some researchers had postulated that neurogenesis has contributed to the hippocampal learning and memory. This project was designed to observe the effect of Delta-9-tetrahydrocannabinol (∆9-THC) in cognitive performance that influenced by the neurogenesis. Different doses of ∆9-THC were used for observing the neurogenesis mechanism occurs in the hippocampus of rats. The brains were stained with antibodies, namely BrdU, glial fibrillary acidic protein (GFAP), nestin, doublecortin (DCX) and class III β-tubulin (TuJ-1). The cognitive test was used novel-object discrimination test (NOD) while the proteins involved, DCX and brain-derived neurotrophic factor (BDNF), were measured. Throughout this study, ∆9-THC enhanced the markers involved in all stages of neurogenesis mechanism. Simultaneously, the cognitive behaviour of rat also showed improvement in learning and memory functions observed in behavioural test and molecular perspective. Administration of ∆9-THC was observed to enhance the neurogenesis in the brain, especially in hippocampus thus improved the cognitive function of rats.

Meta-analysis of biomarkers for severe dengue infections

Background Dengue viral infection is an acute infection that has the potential to have severe complications as its major sequela. Currently, there is no routine laboratory biomarker with which to predict the severity of dengue infection or monitor the effectiveness of standard management. Hence, this meta-analysis compared biomarker levels between dengue fever (DF) and severe dengue infections (SDI) to identify potential biomarkers for SDI. Methods Data concerning levels of cytokines, chemokines, and other potential biomarkers of DF, dengue hemorrhagic fever, dengue shock syndrome, and severe dengue were obtained for patients of all ages and populations using the Scopus, PubMed, and Ovid search engines. The keywords “(IL1* or IL-1*) AND (dengue*)” were used and the same process was repeated for other potential biomarkers, according to Medical Subject Headings terms suggested by PubMed and Ovid. Meta-analysis of the mean difference in plasma or serum level of biomarkers between DF and SDI patients was performed, separated by different periods of time (days) since fever onset. Subgroup analyses comparing biomarker levels of healthy plasma and sera controls, biomarker levels of primary and secondary infection samples were also performed, as well as analyses of different levels of severity and biomarker levels upon infection by different dengue serotypes. Results Fifty-six studies of 53 biomarkers from 3,739 dengue cases (2,021 DF and 1,728 SDI) were included in this meta-analysis. Results showed that RANTES, IL-7, IL-8, IL-10, IL-18, TGF-b, and VEGFR2 levels were significantly different between DF and SDI. IL-8, IL-10, and IL-18 levels increased during SDI (95% CI, 18.1–253.2 pg/mL, 3–13 studies, n = 177–1,909, I2 = 98.86%–99.75%). In contrast, RANTES, IL-7, TGF-b, and VEGFR2 showed a decrease in levels during SDI (95% CI, −3238.7 to −3.2 pg/mL, 1–3 studies, n = 95–418, I2 = 97.59%–99.99%). Levels of these biomarkers were also found to correlate with the severity of the dengue infection, in comparison to healthy controls. Furthermore, the results showed that IL-7, IL-8, IL-10, TGF-b, and VEGFR2 display peak differences between DF and SDI during or before the critical phase (day 4–5) of SDI. Discussion This meta-analysis suggests that IL-7, IL-8, IL-10, TGF-b, and VEGFR2 may be used as potential early laboratory biomarkers in the diagnosis of SDI. This can be used to predict the severity of dengue infection and to monitor the effectiveness of treatment. Nevertheless, methodological and reporting limitations must be overcome in future research to minimize variables that affect the results and to confirm the findings.