European Bulletin of Drug Research Volume 12, 2004 1 SUBCHRONIC ADMINISTRATION OF NIGERIAN SPECIES OF AQUEOUS EXTRACT OF HIBISCUS SABDARIFFA CALYX IN RATS DID NOT PRODUCE CARDIOTOXICITY. D.C Hussaini, O.E. Orisakwe , D.N Akunyili* A.A. Njan**, D.D. Akumka*, O O. Udemezue # College of Health Sciences, Nnamdi Azikiwe University, Nnewi Campus, Anambra State, Nigeria; *National Agency for Food and Drug Administration and Control (NAFDAC), Lagos, Nigeria; **Department of Pharmacology & Toxicology, National Institute for Pharmaceutical Research and Development, Idu, Abuja, Nigeria; # Department of Anatomy, College of Health Sciences, Abia State University ,Uturu, Abia State, Nigeria. Key words: Hibiscus sabdariffa, cardiotoxicity, absolute weight, relative weight. SUMMARY In a 3-month study, 3 groups of 8-week-old Wis- tar albino rats were dosed 1.15, 2.3, and 4.6 g/kg aqueous extract of Hibiscus sabdariffa (HS) calyx juice. The control group received an equivalent volume of water ad libitum. Food and fluid con- sumption were significantly (p<0.05) reduced. A significant decrease (p<0.05) in the body weight was observed but there was no significant differ- ence in the absolute and relative weights of the heart weights between the control and the HS treated groups. A significant (p<0.05) decrease in serum cholesterol level was seen in the HS treated group. Histological studies revealed morpholog i- cally normal cardiac muscle fibres in all the ani- mals. This study suggests that Nigerian specie of HS extract does not cause cardiotoxicity in rats 1 . INTRODUCTION Red Hibiscus sabdariffa (HS) calyx juice has been reported to have antihypertensive activities (Onyenekwe et al, 1999; Hajj and Hajj, 1999) , and 1Corresponding author : Orish Ebere Orisakwe PhD, Toxicology Unit, Department of Pharmacology, College of Health Sciences, Nnamdi Azikiwe University, Nnewi Campus, P.M.B. 5001, Nnewi, Anambra State, Nigeria.Tel.: +234-803-5510063; Fax: +234 -46-462496; E-mail: eorish@aol.com decreased salt output was reported in urine of he- althy volunteers after consuming HS calyx juice (Kirdpon et al, 1994). Among the phytoconstituents found in HS calyx extract are flavonoids, polysac- charides and organic acids, which may be mainly responsible for its pharmacological activities (Daf- fallah and a-Mustafa, 1996). In recent years, it has been shown that phenolic substances from red wine could inhibit low density lipoprotein (LDL) oxidation in vitro (Frankel et al, 1993a; David,1995; Frankel et al, 1993b). LDL oxidation was inhibited almost entirely by phenolic extracts in wine after a 1000-fold dilution. Frankel et al (1993b) postulated that the active antioxidants in red wine that inhibit LDL oxidation may be fla- vonoids. Flavonoids constitute a very large class of compounds, which contain phenol hydroxyl groups and therefore have antitoxidant activity (David, 1995; Kondo et al, 1994). These compounds are ubiquitous in plants and therefore form part of our normal diet. In support of flavonoids possibly ha- ving a protective effect in vivo are the findings of a Dutch epidemiological study which showed that coronary heart disease in elderly men was inversely correlated with their intake of flavonoids (David, 1995; Hartog et al, 1993).