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Nazifi et al., Journal of Herbal Drugs, Vol. 10, No. 1: 11-21, 2019 Journal of Herbal Drug journal homepage: www.jhd.iaushk.ac.ir Memory-enhancing potentials of hydroalcoholic extract of Eragrostis tremula Hochst. exSteud. (Poaceae) in Mice *1 2 1 2 Abdullahi Balarabe Nazifi , Mohammed Garba Magaji , Musa Aliyu , Nuhu Mohammed Danjuma 1Department of Pharmacology and Therapeutics, Bayero University, Kano, Nigeria; *Email: [email protected] 2 Department of Pharmacology and Therapeutics, Ahmadu Bello University, Zaria, Nigeria; ARTICLE INFO ABSTRACT Background & Aim: Cognitive impairment is one of the age-related Type: Original Research mental problems and a typical indicator of neurodegeneration. Eragrostis Topic: Medicinal Plants tremula Hochst. ex Steud. is a commonly used medicinal plant in Nigeria Received January 28th 2020 for memory enhancement. This study, therefore, aimed at evaluating the Accepted April 25th 2020 memory-enhancing potential of aqueous ethanolic extract of E. tremula in mice. Key words: Experimental: Classes of phytochemicals present in the extract were determined using standard protocol while its oral median lethal dose Amnesia (LD50) in mice was estimated. The effect of E. tremula extract (125, 250 Eragrostis tremula and 500 mg/kg) on learning and memory was evaluated in mice using Exploration behavioural paradigms: elevated plus maze (EPM), novel object Learning recognition and Barnes maze. Open field and hole-board tests were also Memory carried out to evaluate locomotion. Results: The phytochemical constituents of E. tremula were alkaloids, cardiac glycosides, flavonoids, tannins, saponins, steroids and triterpenes. Oral LD50 was estimated to be >5000 mg/kg. E. tremula extract significantly (P<0.05) decreased the transfer latency of mice during the retention phase of EPM test. In the novel object recognition test, it significantly (P<0.05) increased the discrimination index. In Barnes maze test, the extract significantly (P<0.05) decreased the mean primary errors during the acquisition trials. It also significantly (P<0.05) decreased the primary latency, primary error and increased the time spent in the target quadrant during the probe trial. E. tremula extract significantly (P<0.05) decreased the immobility time of mice in an open field at 250 mg/kg, while in the hole-board test, it significantly (P<0.05) increased the mean head-dip of mice at 125 mg/kg when compared to the negative control. Recommended applications/industries: The ethanol extract of E. tremula possesses memory enhancing properties which can be utilized in the management of amnesia and cognitive deficit. 1. Introduction Cognitive impairment is thus a distressing comorbid Cognitive function is susceptible to a variety of outcome of neurodegenerative diseases that often pathological state including many neuropsychiatric and negatively impact on daily activities and quality of life neurodegenerative diseases (Bhattacharjee et al., 2015). (Sandry, 2015). Alzheimer's disease is the most 11 Nazifi et al., Journal of Herbal Drugs, Vol. 10, No. 1: 11-21, 2019 common neurodegenerative disorder that shows (Akobundu and Agyakwa, 1998; Poilecot et al., 2007). cognitive deficit (disorientation, impairmentsin Reports by Soladoye et al. (2010) showed that E. learning and memory functions) as the primary tremula is used traditionally in Nigeria to improve symptom (Silva et al., 2014). It is estimated that memory. Traditional medical practitioners from currently 50 million victims of Alzheimer's disease Northern part of Nigeria also utilize the whole plant exist worldwide and that number is expected to grow extract of E. tremula as a “brain cleanser” to treat many up to more than 80 million by 2050 as a result of life central nervous system (CNS) disorders including expectancy increase over the next decades (Thies and learning and memory deficit (Malam Rabiu Salihu, Bleiler, 2013; Patterson et al., 2018). Notwithstanding Personal Communication, 2016). To our knowledge, the extensive research in Alzheimer‟s disease drug reports on the memory enhancing activity of E. tremula development, limited number of approved drugs are are scarce in spite of its well commended efficacy and available for the symptomatic treatment of the disease acceptability in the management of learning and and such drugs are frequently associated with adverse memory deficit. This research therefore, aimed at effects (Anand et al., 2014). Thus, there remains an evaluating the memory-enhancing potential of the insistent need for the development of safer alternatives whole plant extract of E. tremula in mice. to treat cognitive deficits (Cummings et al., 2017; Vyas et al., 2019). 2. Materials and Methods Research on medicinal plants has led to the discovery of bioactive compounds which serve as lead 2.1. Experimental animals compounds for the development of drugs acting on new Swiss Albino mice (20-24 g) of either sex were or known therapeutic targets (Uddin et al., 2018). obtained from the Animal House Facility of the Indeed, there has been a focus on the search for new Department of Pharmacology and Therapeutics, drugs from medicinal plants that will be useful in the Ahmadu Bello University, Zaria. The mice were management of cognitive dysfunction (Tewari et al., housed in standard propylene cages under natural day 2018; Srivastava et al., 2019; Vyas et al., 2019). The and light cycle, and were given free access to standard genus Eragrostiscontains about 350 species which are laboratory rodent feed and water ad libitum. The important medicinal plants widely distributed in experimental protocols were approved by the Ahmadu tropical, subtropical and warm temperate regions Bello University Committee on Animal Use and Care (Peterson and Vega, 2007). Some of the specieshave (Approval number: ABUCAUC/2020/68). been used in ethnomedicine against various disease conditions including learning and memory related 2.2. Reagent, drug and equipment problems (Odugbemi, 2008; Soladoye et al., 2010). Ethanol (Sigma-Aldrich, U.S.A.), Piracetam tablets Eragrostis ferruginea has been reported to possess (Nootropil, UCB Pharma Ltd, U.K.), Digital camcorder important compounds with neuroprotective activities (JVC Everio 32G HDD, Japan), Open field paradigm, against amyloid beta peptide (Na et al., 2010). hole-board and Barnes maze. Isoorientin, isovitexin, and caffeic acid isolated from Eragrostis japonica have also been reported to possess 2.3. Collection, identification and extraction of plant neuroprotective activities (Na et al., 2018). material Eragrostis tremula Hochst. ex Steud. (Family: The whole plant of Eragrostis tremula was collected Poaceae), is a loosely-tufted annual to short-lived in October, 2017 from Batagarawa, Katsina State. It perennial grass that culms 30-100 cm high with was identified and authenticated in the Herbarium attractive trembling panicles (Burkill, 1985). It is Section of Department of Botany, Ahmadu Bello commonly known in English as “love grass” and in University, Zaria, by comparing with existing reference local languages as “Burburwa” (in Hausa), “Ariranor voucher specimen previously deposited in the Agbado-eshin” (in Yoruba), “Dutaleho” (in Fulfulde) herbarium (900729). The whole plant was air-dried and “Berberinoa” (in Nupe). E. tremula is used in under shade with intermittent weighing until constant ethnomedicine as lactation stimulant, aphrodisiac weight was obtained and then pulverized. The (Burkill, 1985), and as antidote to snake bites powdered plant material (1840 g) was extracted with 12 Nazifi et al., Journal of Herbal Drugs, Vol. 10, No. 1: 11-21, 2019 10 liters of 70% v/v aqueous ethanol (70% absolute 2.7. Exteroceptive behavioural studies ethanol and 30% water) by cold maceration with 2.7.1. Elevated plus mazetest occasional shaking for 2 weeks. The mixture was filtered and the filtrate was concentrated using a rotary Elevated plus maze (EPM) serves as an exteroceptive evaporator to obtain a dark brown mass subsequently behavioral model (where in the stimulus existed outside referred to as ethanolic extract of Eragrostis tremula the body) to evaluate learning and memory in mice (EEET). Thereafter, the percentage yield was (Itoh et al., 1990). The test was conducted as described by (Komada et al., 2008). The paradigm consisted of calculated and the extract was stored in a desiccator two open arms (35×5 cm) and two enclosed arms of the until required for further studies. Fresh solution of the same size with 15 cm high wooden walls. The arms are extract was prepared with distilled water for each extended from central platform (5 cm × 5 cm) and study. elevated 60 cm above the floor. An hour after the 2.4. Preliminary phytochemical screening administrations, each mouse was subjected to the EPM test. The EPM was conducted for 2 days. On the first Preliminary phytochemical screening of EEET was day (acquisition test), each animal was placed at the carried out using standard procedures described by end of one open arm, facing away from the central Evans (2009). The extract was screened for the platform. The transfer latency (time taken for the presence or absence of phyto-constituents such as mouse to move from the open to the enclosed arms) alkaloids, flavonoids, cardiac glycosides, tannins, was recorded within 60 sec. A mouse is said to have anthraquinones, saponins, steroids and triterpenes. entered an arm, when it has placed all four paws over 2.5. Acute toxicity study the line separating the area and the center. Following Acute toxicity study as described by Lorke (1983) entry into the arm, each mouse was allowed to explore the apparatus for 20 sec and then returned to the home was employed in the estimation of oral median lethal cage. Twenty-four hours later (on the second day), the dose (LD ) of EEET in mice. The test was in two 50 second trial (retention test) was performed and each phases; in phase one, three groups of mice (n=3) were mouse was observed for 60 sec. After each trial, the administered widely differing doses of the extract (10, maze was wiped with a cotton wool dipped in 70% 100 and 1000 mg/kg, p.o) and observed for signs of ethanol and allowed to dry to remove any olfactory toxicity and mortality for 24 h.