Acute and sub-acute toxicological assessment of the aqueous seed extract of <i>Persea americana</i> Mill (Lauraceae) in rats

Abstract

The aqueous seed extract of Persea americana Mill (Lauraceae) is used by herbalists in Nigeria for the management of hypertension. As part of our on-going scientific evaluation of the extract, we designed the present study to assess its acute and sub-acute toxicity profiles in rats. Experiments were conducted to determine the oral median lethal dose (LD 50 ) and other gross toxicological manifestations on acute basis. In the sub-acute experiments, the animals were administered 2.5 g/kg (p.o) per day of the extract for 28 consecutive days. Animal weight and fluid intake were recorded during the 28 days period. Terminally, kidneys, hearts, blood/sera were obtained for weight, haematological and biochemical markers of toxicity. Results show that the LD 50 could not be determined after a maximum dose of 10 g/kg. Sub-acute treatment with the extract neither affected whole body weight nor organ-tobody weight ratios but significantly increased the fluid intake (P < 0.0001). Haematological parameters and the levels of ALT, AST, albumin and creatinine were not significantly altered. However, the concentration of total proteins was significantly increased in the treated group. In conclusion, the aqueous seed extract of P. americana is safe on sub-acute basis but extremely high doses may not be advisable. Keywords: Persea americana seed, herbal medicine, safety profile IntroductionThe use of herbal medicines as complements or alternatives to orthodox medicines has been on the increase. The reasons, which have given rise to this trend, include the cheapness, availability and accessibility of these natural medicines. Besides, there has been the erroneous belief that these medicines are free from adverse effects (Larrey, 1994;Ernst, 2005). On the other hand they have been rejected because many of the acclaimed medicinal values have not been scientifically evaluated and their safety profiles uncertain (Ernst, 2005). It is, therefore, pertinent that safety assessments should be conducted on natural products for which certain medicinal uses have been scientifically validated.The fruit of Persea americana Mill of family Lauraceae is eaten in many parts of the world. In recent years, research has focused on various parts of the plants. The fruit in particular has been shown to possess medicinal properties. The edible fruit pulp contains up to 33% oil rich in monounsaturated fatty acids (Ortiz et al., 2004) that are believed to modify the fatty acid contents in cardiac and renal membranes and enhance the absorption of α/β-carotene and lutein (Salazar et al., 2005). The carotenoid content has been reported to play significant role in cancer risk reduction (Lu et al., 2005).Other properties of the oil include wound healing (Nayak et al., 2008) and hepatoprotection (Kawagishi et al., 2001). Proximate analysis has been conducted on the seeds (Olaeta et al., 2007).Other parts of the plant have been reported to possess medicinal properties. The aqueous leaf extract for example has analgesic and anti-inflammatory (Adeyemi et al.,...

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