Antidiarrheal and Hematological Effects of Aqueous and Ethanol Leaf Extracts of Psidium guajava L. in Castor Oil-Induced Diarrhea in Male Wistar Rats

Although Psidium guajava (guava) leaves are traditionally used to manage diarrhoea, comparative evidence on aqueous and ethanol extracts remains limited. This study evaluated their antidiarrhoeal potential and haematological effects in male Wistar rats with castor oil-induced diarrhoea. Thirty-five rats weighing 150–200 g were randomly assigned to seven groups (n = 5): normal control, diarrhoeal control, loperamide control (2 mg/kg), and four treatment groups receiving aqueous or ethanol extracts at 100 or 200 mg/kg. Diarrhoea was induced by oral administration of castor oil (1 mL/kg). After 14 days of treatment, blood samples underwent haematological analysis, and small-intestinal tissues were examined histopathologically. Castor oil administration significantly increased white blood cell counts from 4.96 ± 0.66 to 7.03 ± 2.65 × 10⁹/L and reduced platelet counts from 696.00 ± 344.34 to 522.66 ± 148.04 × 10⁹/L (p < .05), alongside reductions in red blood cell counts and haematocrit. Both extracts significantly reversed these changes in a dose-dependent manner (p < .05). At 200 mg/kg, the ethanol extract produced the greatest increases in red blood cell count and haemoglobin, reaching 8.57 ± 0.52 × 10¹²/L and 12.50 ± 0.52 g/dL, respectively, whereas the aqueous extract produced the highest platelet count (1014.66 ± 187.83 × 10⁹/L). Intestinal histopathology showed near-normal restoration of villi, crypts of Lieberkühn, and goblet cells in the high-dose ethanol group. These findings provide preclinical evidence of haematological improvement and intestinal recovery, supporting further investigation of the antidiarrhoeal and haematoprotective potential of P. guajava leaf extracts, particularly the ethanol extract at 200 mg/kg.