Effects of Syzygium cordatum (Hochst.) [Myrtaceae] leaf extract on plasma glucose and hepatic glycogen in streptozotocin-induced diabetic rats.
The present study investigates the hypoglycaemic effect of Syzygium cordatum (Hochst.) [Myrtaceae] leaf extract in non-diabetic and streptozotocin (STZ)-induced diabetic rats. Oral glucose tolerance tests (OGGT) were conducted in non-diabetic and STZ-diabetic rats using orally administered glucose (1.4 g 100 g(-1) body weight) followed by either the leaf extract (6 mg 100 g(-1) body weight) or subcutaneous (sc) injection of metformin (50 mg 100 g(-1)). Weekly plasma glucose and terminal hepatic glycogen concentrations were recorded in control STZ-diabetic rats and diabetic rats orally treated with the leaf extract once every third day for 4 weeks. Administration of the leaf extract decreased plasma glucose from 7.7+/-0.9 mmol l(-1) to 3.7+/-0.6 mmol l(-1) (n = 6), and 21.1+/-2.2 mmol l(-1) to 12.5+/-1.8 mmol l(-1) (n = 7) by 2 1/2 h in non-diabetic and STZ-diabetic rats, respectively. OGTT data in metformin-treated rats were similar at the corresponding time in all groups, except for significant blood glucose reduction by the drug in non-diabetic rats between 1 and 1 1/2 h after treatment. Oral administration of the extract did not affect plasma glucose concentration in STZ-diabetic rats after 4 weeks, although it significantly increased hepatic glycogen content by comparison with untreated STZ-diabetic rats (28+/-5 mg 100 g(-1) body weight, n = 7, versus 16+/-3 mg 100 g(-1) body weight, n = 6). We conclude that Syzygium cordatum leaf extract contains compounds that could be effective in mild diabetes mellitus or in cases of glucose tolerance impairment. The possible mechanism(s) involved in the short-term hypoglycaemic effect of the extract could not be established by the current study.
Musabayane
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Department of Human Physiology and Physiological Chemistry, School of Medical Sciences, University of KwaZulu-Natal, Westville Campus, Private Bag X54001, Durban 4000, South Africa. musabayanec@ukzn.ac.za
Mahlalela
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Shode
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FO
Ojewole
J A O
JA
D000818:Animals; D001786:Blood Glucose / Q000187:drug effects* / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy* / Q000378:metabolism; D008112:Liver Glycogen / Q000378:metabolism*; D008297:Male; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology / Q000627:therapeutic use; D018515:Plant Leaves; D051381:Rats; D017208:Rats, Wistar; D027842:Syzygium
D001786:Blood Glucose; D008112:Liver Glycogen; D010936:Plant Extracts