Mechanisms of gastroprotection of methanol extract of Melastoma malabathricum leaves.
BACKGROUND
Melastoma malabathricum L. (Melastomaceae) is a small shrub with various medicinal uses. The present study was carried out to determine the gastroprotective mechanisms of methanol extract of M. malabathricum leaves (MEMM) in rats.


METHODS
The extract's mechanisms of gastroprotection (50, 250, 500 mg/kg) were studied using the pylorus-ligation in rat model wherein volume, pH, free and total acidity of gastric juice, and gastric wall mucus content were determined. The involvement of endogenous nitric oxide (NO) and sulfhydryl (SH) compounds in the gastroprotective effect of MEMM were also measured. MEMM was subjected to the antioxidant, anti-inflammatory and phytochemical analysis and HPLC profiling.


RESULTS
MEMM contained various phyto-constituents with quercitrin being identified as part of them. MEMM and quercitrin: i) significantly (p < 0.05) reduced the volume and acidity of gastric juice while increasing the pH and gastric wall mucus content.; ii) significantly (p < 0.05) increased the level of SOD, GTP and GTR while significantly (p < 0.05) reduced the level of CAT, MPO and TBARS activities.; iii) exerted gastroprotective activity when assessed using the ethanol-induced gastric ulcer assay, which was reversed by N(G)-nitro-L-arginine methyl esters (L-NAME; an inhibitor of NO synthase) and N-ethylmaleimide (NEM; a sulfhydryl (SH) blocker). MEMM inhibited the lipoxygenase (LOX) and xanthine oxidase (XO) activities with the highest affinity for the former while quercitrin showed high affinity for XO activity.


CONCLUSIONS
MEMM exhibited a gastroprotective activity due partly to the presence of quercitrin, its antioxidant and anti-inflammatory activities, and via the modulation of NO and SH groups.
Halal Product Research Institute, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia. dr_zaz@yahoo.com.|Integrative Pharmacogenomics Institute (iPROMISE), Faculty of Pharmacy, Universiti Teknologi MARA, Shah Alam, Selangor, Malaysia. dr_zaz@yahoo.com.
Zainul Amiruddin
ZA
Zakaria
Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Serdang, Selangor, Malaysia. tavamani85@gmail.com.
Tavamani
T
Balan
Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Serdang, Selangor, Malaysia. ss.mamat@gmail.com.
Siti Syariah
SS
Mamat
Department of Pathology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Serdang, Selangor, Malaysia. hafizah@medic.upm.edu.my.
Norhafizah
N
Mohtarrudin
Integrative Pharmacogenomics Institute (iPROMISE), Faculty of Pharmacy, Universiti Teknologi MARA, Shah Alam, Selangor, Malaysia. tehlaykek@yahoo.com.
Teh Lay
TL
Kek
Integrative Pharmacogenomics Institute (iPROMISE), Faculty of Pharmacy, Universiti Teknologi MARA, Shah Alam, Selangor, Malaysia. zakisalleh.mzs@gmail.com.
Mohd Zaki
MZ
Salleh
D000818:Animals; D005750:Gastric Juice; D008297:Male; D035322:Melastomataceae / Q000737:chemistry*; D000432:Methanol / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry; D020011:Protective Agents / Q000737:chemistry / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013270:Stomach / Q000187:drug effects*
D010936:Plant Extracts; D020011:Protective Agents; D000432:Methanol