Acute and 28-Day Repeated-Dose Oral Toxicity Assessment of Abelmoschus moschatus Medik. in Healthy Wistar Rats

Abstract

Abelmoschus moschatus Medik. (family: Malvaceae) has a long history of being used as a folk medicine in Sri Lanka. Despite the therapeutic use of this plant in traditional medicine, leaves of A. moschatus have not been subjected to scientific evaluation of toxicity/adverse effects in vivo. Thus, the present study was aimed to assess the acute and 28-day repeated-dose oral toxic effects of hexane (55 mg/kg), ethyl acetate (75 mg/kg), butanol (60 mg/kg), and aqueous (140 mg/kg) leaf extracts of A. moschatus in Wistar rats. Furthermore, identification of phytochemical constituents and determination of in vitro total antioxidant activity of the selected leaf extracts of A. moschatus were carried out. Repeated-dose oral administration of hexane and aqueous plant extracts produced no significant changes in the hematological profile and in selected biochemical parameters compared to the untreated healthy rats (p > 0.05). The administration of ethyl acetate and butanol extracts resulted in significant changes in some of the hematological parameters (p < 0.05), whereas biochemical parameters were not changed (p > 0.05). No significant changes in the relative organ weight of treated rats were observed (p > 0.05) except in the kidneys of Wistar rats treated with the ethyl acetate extract of A. moschatus (p < 0.05). Normal morphology with no signs of hemorrhages, necrosis, or inflammatory cell infiltrations was observed in the vital organs selected during the assessment of histopathology on H and E-stained tissue sections upon the treatment of selected extracts. Alkaloids were absent in the selected leaf extracts excluding the health risk for harmful alkaloids. The highest total antioxidant activity was reported in the butanol extract. In conclusion, the hexane and aqueous extracts of A. moschatus were completely nontoxic, whereas butanol and ethyl acetate extracts showed statistically significant changes in some hematological parameters and in relative organ weight of kidneys in healthy Wistar rats.

Figure 1

Change in body weight of Wistar rats administered with the hexane, ethyl acetate, butanol, and aqueous extracts of Abelmoschus moschatus during a 28-day repeated-dose oral toxicity study (n = 10/group). Each point represents mean ± SEM. No significant difference was observed in test group rats compared to the normal control (p > 0.05).

Figure 2

Photomicrographs of H and E-stained cardiac tissues of the different groups of experimental rats (×400). Healthy control group (a), vehicle 1: corn oil (b), vehicle 2: PVP (c), groups of animals treated with the hexane (d), ethyl acetate (e), butanol (f), and aqueous (g) extracts of A. moschatus at the equivalent therapeutic dose are shown. Repeated oral administration of the selected plant extracts for 28 consecutive days resulted in no significant adverse effects on the histomorphology of cardiac muscle and connective tissue. No signs of necrosis could be observed.

Figure 3

Photomicrographs of H and E-stained liver tissues of the different groups of experimental rats (×400). Healthy control group (a), vehicle 1: corn oil (b), vehicle 2: PVP (c), groups of animals treated with the hexane (d), ethyl acetate (e), butanol (f), and aqueous (g) extracts of A. moschatus at the equivalent therapeutic dose are shown. Repeated oral administration of the selected plant extracts for 28 consecutive days showed no significant adverse effects on the histomorphology of liver tissues. The cellular features of hepatocytes, sinusoids, and central vein in liver tissues of the experimental groups were similar to those in the untreated control group. The hepatocytes arranged in cords were normal. Early signs of cell injury, necrosis, congestion, or hemorrhage were not observed.

Figure 4

Photomicrographs of H and E-stained sections of the small intestine of the different groups of experimental rats (×400). Healthy control group (a), vehicle 1: corn oil (b), vehicle 2: PVP (c), groups of animals treated with the hexane (d), ethyl acetate (e), butanol (f), and aqueous (g) extracts of A. moschatus at the equivalent therapeutic dose are shown. Repeated oral administration of the selected plant extracts for 28 consecutive days showed no significant adverse effects on the histomorphology of tissues attributable to the treatment with plant extracts.

Figure 5

Photomicrographs of H and E-stained sections of spleen of the different groups of experimental rats (×400). Healthy control group (a), vehicle 1: corn oil (b), vehicle 2: PVP (c), groups of animals treated with the hexane (d), ethyl acetate (e), butanol (f), and aqueous (g) extracts of A. moschatus at the equivalent therapeutic dose are shown. Repeated oral administration of the selected plant extracts for 28 consecutive days showed no significant adverse effects on the histomorphology of spleen tissues attributable to the treatment with plant extracts.

Figure 6

Photomicrographs of H and E-stained sections of kidney tissues of the different groups of experimental rats (×400). Healthy control group (a), vehicle 1: corn oil (b), vehicle 2: PVP (c), groups of animals treated with the hexane (d), ethyl acetate (e), butanol (f), and aqueous (g) extracts of A. moschatus at the equivalent therapeutic dose are shown. Repeated oral administration of the selected plant extracts for 28 consecutive days showed no significant adverse effects on the histomorphology of kidney tissues. Normal morphological architecture was observed with no signs of necrosis or inflammatory cell infiltration. The glomeruli, distal tubules, and proximal tubules appeared normal in all groups with no signs of glomerular congestion or tubular atrophy.

Figure 7

TLC profiles for hexane, ethyl acetate, butanol, and aqueous extracts of Abelmoschus moschatus. (a) TLC fingerprint under the solvent system: dichloromethane : cyclohexane : methanol (1 : 1  : 0.1) for improved separation of the nonpolar extracts (hexane and ethyl acetate). (b) TLC fingerprint under the solvent system: dichloromethane : cyclohexane : methanol : diethylamine (1 : 0.8 : 0.1 : 0.3) for improved separation of the polar extracts (butanol and water).