Antisickling activities of selected Nigerian medicinal plants.
The study investigated and screened some plants used in ethnomedicine for the management of sickle cell disease (SCD). It further ranked and selected the plants with good antisickling activity and investigated their possible mechanism of action as well as rank andof selected Nigerian medicinal plants. This was with a view to providing scientific information on the antisickling activities of the plants. Ethno-medical survey was carried out in Ondo Local Government area of Ondo State with the aid of a structured questionnaire administered among traditional health practitioners. The plants were identified, collected, authenticated, processed and extracted separately with 70%v/v ethanol in water. The anti-sickling activities of the extracts were assessed usingin vitro inhibitory and reversal antisickling assay techniques with parahydroxybenzoic acid (PHBA) and normal saline as controls. The extracts with good activities were further evaluated for acute toxicity study via oral route usingLorke’s method followed by assessment of their effects on certainheamatological parameters (packed cell volume (PCV), red blood cell count (RBC) and haemoglobin concentration (Hb)) in Wistar rats. These were carried out over a period of 21 days using an automated haematological analyser with normal saline as negative control. The data were expressed as mean±standard error of the mean (SEM). The level of significance was set at p<0.05. The results were analysed using one–way ANOVA and Dunnet for post hoc testing. The results of the ethno-medicinal survey carried out showed that a large number of Nigerian plants are used traditionally in the management of SCD. Eleven plants out of the twenty- three that were most cited were screened for the antisickling activity.The aqueous extracts of the plants were observed to have better activities than the 70% ethanolic extracts of the same plants. The extracts with inhibitory and reversal activities in percentage areCarica papaya (89.65 ± 0.73, 73.00 ± 0.87), Parquetinanigrescence(82.50±0.21, 61.20±0.67),Alchornealaxiflora(78.20±0.14,69.45±0.67), Croton zambescius(74.45 ± 0.61, 70.35 ± 0.64),Morindalucida(72.20±0.77,67.30±0.54), and Mangiferaindica (62.50±0.49, 58.40±0.65). The lethal dose (LD50) of Parquetinanigrescence and Alchornealaxiflorawere found to be greater than 5000mg/kg. The effects of extracts of P. nigrescence on haematological parameters on day 7 are as follows: Packed cell volume (%) on day 7; 40.40±0.93, 42.40±0.40 and 41.40±0.45 at 250,500 and 1000mg/kg respectively, with normal saline being 36.80 ±0.58. Red blood cell count observed with P. nigrescense at day 7 was 4.34x106±0.07, 4.70x106±0.06 and 4.48x10±0.17at 250, 500 and 1000mg/kg respectively while 4.04 x 106 ± 0.07 was observed with the control. The haemoglobin concentration (g/dl) at day 7 with normal saline was 12.16±0.15, whileP. nigrescensegave 13.30± 0.19, 13.98 ± 0.10, 13.86±0.29 at 250, 500and 1000mg/kg respectively. A. laxifloraon day 7 gave a PCV (%) of 47.80± 0.92, 46.20±1.28 and 49.00±1.58 at 250, 500 and 1000mg/kg respectively; Red blood cell count of 5.30x106±0.13, 5.36x106±0.15 and 5.38x106±0.17 at 250, 500mg and 1000 mg/kg respectively; haemoglobin concentration (g/dl) of 15.92±0.35, 15.94±0.56 and 16.16±0.49 at 250, 500 and 1000mg/kg respectively. Their effects on haematinic parameters were observed not to be dose dependent. The study concluded that the aqueous extracts of the screened plants had higher antisickling activities than their ethanolic extracts.