Mechanism(s) of action involved in the gastroprotective activity of Muntingia calabura

Ethnopharmacological relevance: Muntingia calabura L. (Muntingiaceae) is locally known as kerukup siam. Its leaves, flowers, barks and roots have been used traditionally in East Asia and South America to treat various diseases including ulcer-related diseases. The present study aimed to investigate the mechanism(s) of gastroprotective effect of methanol extract of Muntingia calabura leaves (MEMC) using the pylorus ligation induced gastric ulceration in rats. Materials and methods: Five groups of rats (n=6) were administered orally once daily for 7 days with 8% Tween 80 (negative control), 100 mg/kg ranitidine (positive control), or MEMC (100, 250 or 500 mg/kg), followed by the ulcer induction via ligation of the pyloric part of the rat’s stomach. This was followed by the macroscopic analysis of the stomach, evaluation of gastric content parameters, and quantification of mucus content. The antioxidant (measured using the superoxide anion and 2,2-diphenyl-1-picrylhydrazyl (DPPH)-radical scavenging, oxygen radical absorbance capacity (ORAC) and total phenolic content (TPC) assays), anti-inflammatory (evaluated using the in vitro lipoxygenase and xanthine oxidase assays), phytoconstituents and HPLC analysis of MEMC were also carried out. Results: The MEMC significantly (p<0.05) reduced gastric lesion in this model. Furthermore, the extract also significantly (p<0.01) reduced the volume of gastric content whereas the total acidity was significantly (p<0.05) reduced in the doses of 100 and 500 mg/kg MEMC. Moreover, the mucus content increased significantly (p<0.01) in MEMC-treated rats. The extract also showed high antioxidant and anti-inflammatory activities in all assays tested, and demonstrated the presence of high tannins and saponins followed by flavonoids. Conclusion: The MEMC exerted gastroprotective effect via several mechanisms including the anti-secretory, antioxidant and anti-inflammatory activities. These activities could be attributed to the presence of tannins, saponins and flavonoids (e.g. rutin, quercitrin, fisetin and dihydroquercetin)

Antiulcer activity of Muntingia calabura leaves involves the modulation of endogenous nitric oxide and nonprotein sulfhydryl compounds

Context: Muntingia calabura L. (Muntingiaceae) is a native plant species of the American continent and is widely cultivated in warm areas in Asia, including Malaysia. The plant is traditionally used to relieve pain from gastric ulcers. Objective: This study was designed to determine the antiulcer activity of a methanol extract of M. calabura leaves (MEMC) and the possible mechanisms of action involved. Materials and methods: An acute toxicity study was conducted using a single oral dose of 2000 mg/kg MEMC. The antiulcer activity of MEMC was evaluated in absolute ethanol- and indomethacin-induced gastric ulcer rat models. MEMC was administered orally (dose range 25–500 mg/kg) to rats fasted for 24 h. The animals were pretreated with NG-nitro-l-arginine methyl esters (l-NAME) or N-ethylmaleimide (NEM) prior to MEMC treatment to assess the possible involvement of endogenous nitric oxide (NO) and nonprotein sulfhydryl (NP-SH) compounds in the gastroprotective effect of MEMC. Results: As the administered dose did not cause toxicity in the rats, the oral median lethal dose (LD50) of MEMC was >2000 mg/kg in rats. MEMC exerted significant (p < 0.001) gastroprotective activity in the ethanol- and indomethacin-induced ulcer models dose-dependently. Histological evaluation supported the observed antiulcer activity of MEMC. l-NAME and NEM pretreatment significantly (p < 0.05) reversed and abolished the gastroprotective effect of MEMC, respectively. Discussion and conclusion: The results obtained indicate that MEMC has significant antiulcer activity that might involve the participation of endogenous NO and NP-SH compounds. These findings provide new pharmacological information regarding the potential use of M. calabura

Metabolic alteration in obese diabetes rats upon treatment with Centella asiatica extract

Ethnopharmacological relevance: ‘Pegaga’ is a traditional Malay remedy for a wide range of complaints. Among the 'pegaga’, Centella asiatica has been used as a remedy for diabetes mellitus. Thus, we decided to validate this claim by evaluating the in vivo antidiabetic property of C. asiatica (CA) on T2DM rat model using the holistic 1H NMR-based metabolomics approach. Method: In this study, an obese diabetic (mimic of T2DM condition) animal model was developed using Sprague–Dawley rats fed with a high-fat diet and induced into diabetic condition by the treatment of a low dose of streptozotocin (STZ). The effect of C. asiatica extract on the experimental animals was followed based on the changes observed in the urinary and serum metabolites, measured by 1H NMR of urine and blood samples collected over the test period. Results: A long-term treatment of obese diabetic rats with CA extract could reverse the glucose and lipid levels, as well as the tricarboxylic acid cycle and amino acid metabolic disorders, back towards normal states. Biochemical analysis also showed an increase of insulin production in diabetic rats upon treatment of CA extract. Conclusion: This study has provided evidence that clearly supported the traditional use of CA as a remedy for diabetes. NMR-based metabolomics was successfully applied to show that CA produced both anti-hyperglycemic and anti-hyperlipidemic effects on a rat model. In addition to increasing the insulin secretion, the CA extract also ameliorates the metabolic pathways affected in the induced diabectic rats. This study further revealed the potential usage of CA extract in managing diabetes mellitus and the results of this work may contribute towards the further understanding of the underlying molecular mechanism of this herbal remedy

Bioassay-guided identification of an anti-inflammatory prenylated acylphloroglucinol from Melicope ptelefolia and molecular insights into its interaction with 5-lipoxygenase.

A bioassay-guided investigation of Melicope ptelefolia Champ ex Benth (Rutaceae) resulted in the identification of an acyphloroglucinol, 2,4,6-trihydroxy-3-geranylacetophenone or tHGA, as the active principle inhibiting soybean 15-LOX. The anti-inflammatory action was also demonstrated on human leukocytes, where the compound showed prominent inhibitory activity against human PBML 5-LOX, with an IC 50 value of 0.42 μM, very close to the effect produced by the commonly used standard, NDGA. The compound concentration-dependently inhibited 5-LOX product synthesis, specifically inhibiting cysteinyl leukotriene LTC4 with an IC 50 value of 1.80 μM, and showed no cell toxicity effects. The anti-inflammatory action does not seem to proceed via redox or metal chelating mechanism since the compound tested negative for these bioactivities. Further tests on cyclooxygenases indicated that the compound acts via a dual LOX/COX inhibitory mechanism, with greater selectivity for 5-LOX and COX-2 (IC 50 value of 0.40 μM). The molecular features that govern the 5-LOX inhibitory activity was thus explored using in silico docking experiments. The residues Ile 553 and Hie 252 were the most important residues in the interaction, each contributing significant energy values of 13.45 (electrostatic) and 5.40 kcal/mol (electrostatic and Van der Waals), respectively. The hydroxyl group of the phloroglucinol core of the compound forms a 2.56 Å hydrogen bond with the side chain of the carboxylate group of Ile 553. Both Ile 553 and Hie 252 are crucial amino acid residues which chelate with the metal ion in the active site. Distorting the geometry of these ligands could be the reason for the inhibition activity shown by tHGA. The molecular simulation studies supported the bioassay results and served as a good model for understanding the way tHGA binds in the active site of human 5-LOX enzyme

Leukotriene inhibitor and method for producing the same

The present invention relates to a compound for inhibiting cysteinyl leukotrienes (CysLT) which is the most potent bronchoconstrictors. The present invention further relates to methods for producing the compound either from natural product or chemical synthesis. The compound from the present invention is potent for preventing or treating inflammatory disorders such as psoriasis, asthma, rheumatoid arthritis, inflammatory bowel diseases and ischemic renal failure