Omotayo et al Pan African Journal of Life Sciences (2019): 3: 151-156 DOI: 10.36108/pajols/9102/30(0160)

www.pajols.org Online ISSN:2672-5924 RESEARCH Open Access Toxicity and Sedative Effect of Africana Ethanolic Leaf Extract

Ahmed I. Omotayo1*, Qudus A. Ojomo2, Subair Hassan2, Mutolib Olatunbosun3, Monsurat Fakayode 4

1Vector Biology and Control Unit, Department of Zoology, University of Ilorin, Ilorin, Nigeria. 2Department of Pharmacy, Obafemi Awolowo University, Ile-Ife, Nigeria. 3Department of Biochemistry, Federal University of Technology, Minna, Nigeria. 4Departement of Science Education, University of Lagos, Lagos, Nigeria.

*Correspondence should be addressed to Omotayo I. Ahmed: [email protected]

Received 10 September 2019; Revised 15 October 2019; Accepted 31 October 2019

© 2019 Omotayo et al. Licensee Pan African Journal of Life Sciences. This is an Open Access article distributed un- der the terms of the Creative commons Attribution License (https://creativecommons.org/licenses/BY/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Background: Traditional have been good sources of alternatives for conventional drugs in recent years. The search for alternatives for conventional drugs becomes imperative most espe- cially because of their high cost demand and side effects. The search for alternatives from traditional me- dicinal plants sources has been fruitful for many ailments and this has led to intense research on the po- tentials of many other plants that are used traditionally in different part of the world. This study assessed the sedative potentials of ethanol extract of Voacanga africana leaf (VAEE) as well as its toxicity. Methods: Toxicity of the Voacanga africana leaf was examined using Lorke’s method while its sedative activity was evaluated using phenobarbitone and ketamine-induced sleeping time models in mice. The doses used in this study were 50, 100, 200, 400 and 800 mg/kg, administered intra- peritoneal.

Results: Results revealed that the LD 50 of VAEE was greater than 5 g/kg. Using phenobarbitone- induced sedation, the sleep latency was found to be dose dependent and significantly decreased at higher dose when compared with normal saline while the total sleeping time was found to be significantly in- creased (p<0.05) as dosage increases. Conclusion: The increase in total sleeping time using the two models showed that VAEE possesses marked sedative ability and can serve as a good alternative to conventional sedatives.

Keywords: Voacanga africana, Traditional medicine, Sedation, Phenobarbitone, Ketamine

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1.0 INTRODUCTION treatment of a wide range of diseases [12]. Leaves and roots decoction are known for their antinociceptive Traditional medicine using different parts have

been one of the mainstays of disease treatment in Africa. activity [9], antioxidant and anti-inflammatory It is the sole medical system for healthcare before the properties [13], antiulcer properties[10], usefulness in advent of conventional medicine [1]. Evidence based treatment of anaemia and other blood disorders [14] as well as in the treatment of malaria, diarrhea, infant traditional medicine has shown that some of these herbs convulsion, and heart arches [10]. According to Hussain are potent in alleviating many bad health conditions [2]. et al [8], the medicinal properties of V. Africana is Traditional medicine has received due attention in recent attributed to more than 100 phytochemicals (indole time due to its accessibility, economic viability, strong alkaloids, ibogain, tabernanthin, ibogamine, vincanol, pharmacological potential and lesser side effects as vincamone etc.) found in different parts of the plant. compared to conventional ones [3]. Traditional medcine Considering the various reports on the medicinal use of involves the extraction of different medicinal substances called phytochemicals found in different plant parts. V. Africana, coupled with the fact that the sedative and These plant extracts usually contain spectrum of anxiolytic properties are not yet well documented, this phytochemicals ranging from flavonoids to alkaloids, and research seeks to study the sedative activity of ethanolic extract of V. Africana leaf as well of its toxicity. terpenoids to anthraquinones [4]. In the development of new chemotherapeutic agents, medicinal plants are 2.0 METHODOLOGY considered important in identifying potential useful 2.1 Study Location chemical structures [5, 6]. Often times, the extracts are taken in the form of a concoction combining more than This study was conducted between October 2017 and one plants, however, there are cases involving use of April 2018 at the Department of Pharmacology, Faculty extract from single plant for the treatment of specific of Pharmacy, Obafemi Awolowo University (OAU), Ile- ailments. This aspect of traditional medicine has really Ife, Osun State, South-West, Nigeria. aided conventional medicine as results of phytochemical 2.2 Plant Collection and Identification screening of extracts found in concoctions that have Fresh leaves were collected in November 2017 from a formed the basis for the development of new drugs [7], wild V. africana growing near the University Health thereby opening new area of research in pharmacology. Centre, Obafemi Awolowo University (OAU), Ile-Ife, Medicinal plants have long been exploited as sedatives South-West, Nigeria. Leaf samples were identified and [15]. Sedatives are substances used in treating sleeping authenticated by an expert botanist, after which they disorders. These conventional sedating drugs used in were deposited at the Pharmacognosy herbarium (FPI addressing sleeping disorders are known with some side 2134) of the same institution for research and reference effects, tolerance and addiction issues and these have purposes. made imminent the search for alternatives [16]. 2.3 Extract Preparation One of the very good plant used in tropical Africa for traditional medicine is Voacanga Africana. This plant is a Fresh leaves of V. africana were oven-dried and coarsely tropical rain forest shrub also found in the Guinea powdered. 800g of the powdered leaf was used in the Savannah woodland belt [4]. It is cosmopolitan in all extraction process. Extraction was carried out in cycles in parts of West Africa [8, 9] and other countries such as which 200 g of the powdered leaf was extracted using Tanzania and Congo [10]. A mature V. africana crop is 200 ml of 50% v/v ethanol at a temperature of 70oC in not more than 10 m tall. It has lowly branched stem with soxhlet apparatus, and each cycle lasted for 48 hours. smooth grayish white bark. Leaves are simple, petiolate The mixture obtained was pooled and filtered using and decussately arranged. The flowers are pedicellate, Whatman Filter paper number 1 and the solvent from the mildly scented, corolla lobed with overlapping filtrate was removed by air-evaporator under reduced aestivation. The ovary is superior and bicarpellary. V. pressure and low temperature. The V. africana ethanolic africana fruits are globose berry with brownish–white extract (VAEE) was then stored at 4oC pending use. blotches having dark, bean–shaped seeds with 2.4 Experimental Animals denticulate ornamentation [11]. Eighty-three Swiss albino male mice (Mus musculus), 3 – Various parts V. africana plant has been used for 4 weeks old weighing between 18g and 25g were obtained treatment of many diseases. Its bark is used in the from the animal house, Department of Pharmacology,

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Faculty of Pharmacy, Obafemi Awolowo University, Ile VAEE. Ketamine (100 mg/kg, i.p) was administered 30 Ife. Animals were maintained under standard environ- minutes after the administration of test drugs. Sleep la- mental conditions (28 ± 10C, 70 – 80 % humidity, 12 tency and total sleeping time was calculated as described hour light/dark cycle) at the Drug, Research and Produc- for phenobarbitone-induced sedation. tion Unit laboratory, OAU, Ile Ife. The animals were fed 2.8 Statistical Analysis with standard rodent diet (Livestock Feed Plc, Lagos, Nigeria) and water ad libitum. The mice were acclama- GraphPad prism, version 7.04 (UK) was used for the tized for fourteen days before the commencement of the analysis. Data were analysed using one-way analysis of experiment. The cages were cleaned once a week with five variance (ANOVA), followed by Dunnett’s multiple com- mice (n=5) per cage. All procedures were approved by the parison test between the treated groups and controls. The committee on animal use and care of the Obafemi results obtained were expressed as Mean ± SEM. The Awolowo University, Ile-Ife, Nigeria and conducted in level of significance was set at 95% confidence interval accordance with internationally accepted principles for for all treatment. laboratory animal use and care [17].

2.5 Determination of LD50 3.0 RESULTS

The acute toxicity profile of the ethanol leaf extract of V. 3.1 LD50 Determination africana was determined using the method described by Results of acute toxicity study (Table 1) showed that Lorke [18]. Three mice each were orally fed with 10, 100, ethanol extract of V. africana leaf via the oral route was 1000mg/kg of body weight of VAEE and a mice each was not toxic. The value of the LD50 was ≥5000 mg/kg body fed with 1600, 2900 and 5000mg/kg of body weight weight. No mortality was recorded at the highest dose VAEE. Mortality was then recorded after 24 hours in (5000 mg/kg body weight) tested. each group. Table 1: Summary of Acute Toxicity Test of Ethanolic 2.6 Effects of the Extracts on Phenobarbitone- Extract of V. africana Leaf in Mice. Induced Sleeping Time Dose (mg/kg, orally) Mortality after 24 Healthy albino mice (35) weighing between 18 and 25 g were fasted for 24 hours before the experiment. They 10 0/3 were randomly assigned into seven groups (n=5) per 100 0/3 group. Group I was administered with normal saline (NS) (10 ml/kg, i.p), group II was treated with standard drug 1000 0/3 diazepam (DZM) (1 mg/kg, i.p), group III, IV, V, VI and 1600 0/1 VII were treated the extract VAEE 50, 100, 200, 400 and 2900 0/1 800 mg/kg, i.p respectively. After 30 minutes of admin- istration of extracts, Phenobarbitone sodium (40 mg/kg, 5000 0/1 i.p) was administered 30minutes after pretreatment. The sleep latency is defined as the time in minutes after treat- 3.2 Effect of Ethanol Extract of Voacanga ment with phenobarbitone that the animal presents with africana Leaf on Phenobarbitone-induced loss of righting reflex whilst the time in minutes between Sedation loss and regain of righting reflexes was taken as a index Results as shown in Table 2 revealed that diazepam and of hypnosis or sleeping time [19]. VAEE of 200, 400 and 800 mg/kg caused a dose- 2.7 Effects of the Extracts on Ketamine-Induced dependent significant reduction (p<0.05) in sleep latency Sleeping Time (SL) induced by phenobarbitone (40 mg/kg) when Thirty-five mice weighing between 18 and 25 g were ran- compared with normal saline control (10 ml/kg) but was domly allotted into seven groups. Group I was adminis- higher than the lower doses; 50 and 100 mg/kg body tered with 10 ml/kg normal saline (i.p). Group II was in- weight. Also, VAEE caused a significant increase jected with 1 mg/kg (i.p) of diazepam (standard reference (p<0.05) in the total sleeping time (TST) induced by drug). Groups III - VII were injected with various doses phenobarbitone (40 mg/kg) when compared with normal (50, 100, 200, 400 and 800 mg/kg, i.p respectively) of saline (10 ml/kg) only at 200, 400 and 800 mg/kg.

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3.3 Effects of Ethanol Extract of Voacanga 4.0 DISCUSSION africana leaf on ketamine-induced sedation Folklore medicine has evidence of effectiveness of herbs

VAEE of 100, 200, 400 and 800 mg/caused a dose- in treating various sleeping disorders [20]. dependent significant increase (p<0.05) in sleep latency Conventionally, these disorders are also managed by induced by ketamine (100 mg/kg) compared to normal modern medicinal drugs. Sleeping disorder is one of the saline (10 ml/kg) . VAEE of 50, 100, 200, 400, and 800 common disorders and it is conventionally managed by mg/ caused a dose-dependent significant increase drugs containing sedative substances. The use of these (p<0.05) in the total sleeping time (TST) induced by conventional sedating drugs is accompanied with ketamine (100 mg/kg) compared to normal saline (10 negative feedbacks ranging from addiction to other side ml/kg), however, the TST for VAEE 50 and 100 mg/kg effects of the drugs. With growing concerns about the were significantly lower (p<0.05) when compared to side effects of conventional sedative drugs, assessment of diazepam while other tested doses were higher with only sedative potential of various extracts from different herbs VAEE of 800 mg/kg body weight significantly higher become imminent. In a bid to finding alternatives to (p<0.05) than the rest treatments (Table 3). current conventional drugs, this study assessed the toxic impact and sedative potentials of ethanol extract of V.

africana leaf using ketamine- and phenobarbitone- Table 2: Effect of Ethanol Extract Voacanga africana of Leaf (VAEE) on Phenobarbitone-Induced Sedation. induced sedation models. According to Lorke’s model [18], the LD50 is an index of acute toxicity and it is Treatment Dose Sleep La- Sleeping considered to be of little or no practical importance at groups (mg/kg) tency Time (Min) (n=5) (Min) values above 5.0g/kg. The result from the toxicity study Normal Sa- 10 20.8±0.33 132 ±1.72 shows that no mortality was recorded at 5000 mg/kg, therefore, the LD50 values of VAEE is >5 g/kg. Hence, as Diazepam 1 14.8±0.87 424± 9.21 described in Lorke’s classification, the ethanol extract of Group III 50 24.8±0.66 97± 2.17* V. africana leaf is non-toxic. The non-toxic nature of Group IV 100 21.6± 2.81 121.6±2.66 VAEE may account for the widespread and continuous Group V 200 15.2±0.77* 403.2±6.81* use of the plant leaf as a safe herbal agent in traditional medicine in Africa. Group VI 400 10.6 ± 1.04* 446.6±10.1* The sedative-hypnotic action of phenobarbitone and Group VII 800 10.4 ± 0.46* 485.5±12.46* other barbiturates is due to their interaction on the *= p<0.05. Results for sleep latency and sleeping time are expressed in GABAA receptors which enhances GABAA transmission mean±S.E.M. (n=5) [21]. The binding site is distinct from that of benzodiazepines. Barbiturates potentiate GABA action on Table 3: Effects Of Ethanol Extract of Voacanga chloride entry into the neuron by prolonging the duration africana (VAEE) Leaf on Ketamine-Induced Sedation. of the chloride-channel openings [22]. In addition, Treatment Dose Sleep Latency Sleeping barbiturates can block excitatory glutamate receptors. groups (n=5) (mg/ (Min) Time VAEE was observed to shorten the onset of sleep in kg) (Min) phenobarbitone-induced sedation at doses of 100, 200. Normal Saline 10 4.0 ± 0.4 56.4±2.58 400 and 800 mg/kg except at 50 mg/kg, which might be (ml/kg) due to its low dose compared to the other doses. At all the Diazepam 1 4.4 ± 0.2 125.8±0.77 doses, VAEE also prolong the duration of sleep when Group III 50 1.17±0.52* 77.4±1.37* using phenobarbitone-induced sedation model. This was Group IV 100 5.8± 0.34* 96.0±1.06* similar to the findings of Fujimori [23] and Garige et al. Group V 200 6.2 ± 0.52* 127.0±1.20* [24] who proposed that the enhancement of the barbital hypnosis is a good index of central nervous system (CNS) Group VI 400 6.3 ± 0.22* 129±2.21* depressant activity. It is known that substances Group VII 800 5.4 ± 0.22* 142±0.40* possessing CNS depressant activity either decrease the time for the onset of sleep or prolong the duration of *= p<0.05. Results for sleep latency and sleeping time are expressed in sleep or both. The result of phenobarbitone-induced mean±S.E.M. (n=5) sedation for VAEE revealed that VAEE possesses strong

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sedative ability as it decreased onset of sleep in mice and africana. They possess very strong prospects of being would allow users sleep easily as well as prolong the the most probable short term sustainable solution to duration of the sleep. sleep disorders if they are fully exploited as sources of Ketamine-induced sedation is one of the models used new sedative agents. extensively in screening of sedatives and anaesthethics In conclusion, the present study indicated that ethanolic [25]. The model exploits both the uncompetitive extract of Voacanga africana (VAEE) is non-toxic as no antagonistic ability of ketamine to N-methyl-D-aspartate mortality was recorded as at 5g/kg. Using the (NMDA) type of excitatory receptor system [26, 27] and Phenobarbitone-induced model, VAEE decreased onset the sedative effect of ketamine by gamma-amino butyric of sleep and increased the sleeping time, thereby acid-A (GABAA) receptor potentiation [21]. In this study, suggesting that the plant possesses sedative potentials. In 50, 100, 200, 400 and 800 mg/kg of VAEE was used to slight contrast to the activities of VAEE using the potentiate ketamine-induced sedation in mice in a dose- Phenobarbitone-induced model, VAEE increased both dependent manner. Onset of sleep (sleep latency) was onset of sleep and sleeping time when assessed using the significantly (p<0.05) decreased at 50 mg/kg and ketamine-induced model. While elongation of sleeping increases at higher doses of 100, 200, 400 and 800 mg/ time in both models suggests the plant possesses sedative kg, this suggested that VAEE may have an excitatory potentials, the contrast in the onset of sleep in both effect at higher doses. This effect may be explained with models needs to be further research on. Also, further an understanding of the underlying principle through studies are needed to characterise the active compound which VAEE potentiate ketamine-induced sleep, as it may (s)/metabolites responsible for its pharmacological be due to the blockade of the NMDA receptor or rather activities and also examine the underlying mechanisms the modulation of the GABAA receptor. This calls for for its sedative effects. concern as this may subject the plant to abuse and undermine its role as a sedative in some patients. Hence, the plant should be administered with caution at bedtime Acknowledgements as it can interfere with the sleep pattern of the patient. The authors acknowledge the support of Mr I. I EdiHowever, VAEE increased the time of sleep Ogunlowo for the identification of leaf samples and Miss significantly at all tested doses when compared with Saheedat Tobiloba Adetayo for her assistance in normal saline but it effects when compared with the reviewing the manuscript. standard drugs used in this study (Diazepam) was Conflict of interest significantly lower at 50 and 100 mg/kg and significantly The authors declare that they have no conflicts of higher at 800 mg/kg. At 200 and 400 mg/kg, the impact interest. of VAEE on sleeping time was in same range as that of Diazepam. Therefore, the effectiveness of VAEE in Authors Contribution increasing sleeping time at higher doses when compared OIA conceived and designed the study,performed with the standard drugs established it sedative potentials. analysis,drafted and revised the manuscript.OAQ The sleep latency and duration of sleep in ketamine- conceived and designed the study Performed data induced sedation was observed to be shorter than that of collection and contributed to data analysis tools.HS phenobarbitone-induced sedation. This could be due to contributed to study design and data analysis tools. OM the fact that phenobarbitone is one of the longest-acting contributed to data collection and writting of the barbiturates (half-life of two to seven days) unlike manuscript.FM contributed to data collection and data ketamine whose duration of action is 30 minutes to 2 analysis tools.All authors approved the final manuscript. hours [28]. The increase in the incidence of addiction and other References unwanted side effects such as drowsiness, drug 1. Okoli RI, Aigbe O, Ohaju-Obodo JO, Mensah JK. Medicinal “hangover” and confusion when conventional sedatives herbs used for managing some common ailments among such as benzodiazepines and barbiturates are Esan people of Edo State, Nigeria. Pakistan Journal of Nu- trition. 2007; 6(5): 490–496. administered to patients calls for the development of better alternatives. A good source of these alternatives 2. Ugwah-Oguejiofor CJ, Eze UA, Bello SO, Etuk EU, Ameh GI, Ugwah OM. Anticonvulsant and sedative activities of can be found in traditional medicinal plants such as V. aqueous leave extract of Leucas martinicensis (Jacq.) R.

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Omotayo et al Pan African Journal of Life Sciences (2019): 3: 151-156

Br. Nigerian Journal of Basic and Applied Sciences. Medicines. 2005; 2(3): 222–232. 2015; 23(2): 87–91. 16. Uddin M, Ali Reza ASM, Abdullah-Al-Mamun M, Kabir 3. Chew Al, Jessica JJA, Sasidharan S. Antioxidant and anti- MS, Nasrin M, Akhter S, Arman M, Islam S, Rahman M. bacterial activity of different parts of Leucas aspera. Asian Antinociceptive and anxiolytic and sedative effects of meth- Pacific Journal of Tropical Biomedicine. 2012; 2(3): 176 – anol extract of Anisomeles indica: an experimental assess- 180. ment in mice and computer aided models. Frontiers in Pharmacology. 2018; 9: 246. 4. Duru CM, Onyedineke NE. In vitro antimicrobial assay and phytochemical analysis of ethanolic extracts of Voacanga 17. National Research Council. Guide for the Care and Use of africana seeds. Journal of American Science. 2010; 6(6): Laboratory Animals. 1985; Publication no 85-23. National 119–122. Academy of Sciences, Washington DC, USA 5. Tona L, Kambu K, Ngimbi N, Cimanga K, Vlietinck AJ. 18. Lorke D. A new approach to practical acute toxicity test- Antiamoebic and phytochemical screening of some Congo- ing. Archives of Toxicology. 1983; 54(4): 275–287. lese medicinal plants. Journal of Ethnopharmacology. 19. Olayiwola G, Ukponmwan O, Olawode D. Sedative and 1998; 61(1): 57–65. anxiolytic effects of the extracts of the leaves of Stachytar- 6. Prasad AK, Kumar V, Arya P, Kumar S, Dabur R, Singh N, pheta cayennensis in mice. African Journal of Traditional, Chhillar AK, Sharma GL, Ghosh B, Wengel J, Olsen CE. Complementary and Alternative Medicines. 2013; 10(6): Investigations toward new lead compounds from medici- 568–579.DOI: http://dx.doi.org/10.4314/ajtcam.v10i6.32 nally important plants. Pure and Applied Chemistry; 20. Khan IN, Sarker MMI, Ajrin M. Sedative and anxiolytic 2005; 77(1): 25–40. effects of ethanolic extract of Calotropis gigantea 7. Olorunnisola OS, Bradley G, Afolayan AJ. Chemical com- (Asclepiadaceae) leaves. Asian Pac. J. Trop. Biomed. 2014; position, antioxidant activity and toxicity evaluation of 4(1): S400-S404. DOI: 10.12980/APJTB.4.2014C1147 essential oil of Tulbaghia violacea Harv. Journal of Medici- 21. Henschel O, Gipson KE, Bordey A. GABAA receptors, anes- nal Plants Research. 2012; 6(12): 2340–2347. thetics and anticonvulsants in brain development. CNS and 8. Hussain H, Hussain J, Al-Harrasi A, Green Ir. Chemistry Neurological Disorders-Drug Targets. 2008; 7(2): 211–224. and biology of the genus Voacanga. Pharmaceutical Biolo- 22. Macdonald RL, Olsen RW. GABAA receptor chan- gy. 2012; 50(9): 1183–1193 DOI: nels. Annual Review of Neuroscience. 1994; 17(1): 569– 10.3109/13880209.2012.658478 602. 9. Igbe I, Edike T. In vivo antinociceptive activity of the aque- 23. Fujimori H. Potentiation of barbital hypnosis as an evalua- ous leaf extract of Voacanga africana Stapf () tion method for central nervous system depres- in mice. Journal of Science and Practice of Pharmacy. sants. Psychopharmacologia. 1965; 7(5): 374–378. 2015; 2(1): 51–54. 24. Garige BSR, Keshetti S, Vattikuti UMR. CNS Depressant 10. Tan PV, Penlap VB, Nyasse B, Nguemo JD. Anti-ulcer ac- effects and muscle relaxant activity of Galphimia glauca tions of the bark methanol extract of Voacanga africana in leaf methanol extract. International Journal of PharmTech different experimental ulcer models in rats. Journal of Eth- Research. 2016; 9(6): 230–240.DOI: 10.4103/0974- nopharmacology. 2000; 73(3): 423–428 8490.188878 11. Iwu, MM. Handbook of African medicinal plants. CRC 25. Tose R, Kushikata T, Yoshida H, Kudo M, Furukawa K, Press Inc. Florida. 1993; Pp257 Ueno S, Hirota K. Orexin A decreases ketamine-induced 12. Adolfina RKH, Rodolfo J, Daniel K, Hanson A, Juliana A, anesthesia time in the rat: the relevance to brain noradren- James ES. Voacanga africana: Chemistry, Quality and ergic neuronal activity. Anesthesia and Analgesia. Pharmacological activity. African Natural Plant Products: 2009; 108(2): 491–495. New Discoveries and Challenges in Chemistry and Quality. 26. Anis NA, Berry SC, Burton NR, Lodge D. The dissociative 2009; Chapter 20, pp363-380. DOI: 10.1021/bk-2009- anaesthetics, ketamine and phencyclidine, selectively re- 1021.ch020 duce excitation of central mammalian neurons by N‐ 13. Ayoola GA, Folawewo AD, Adesegun SA, Abioro OO, methyl‐aspartate. British Journal of Pharmacology. Adepoju-Bello AA. Coker HAB. Phytochemical and antioxi- 1983; 79(2): 565–575. dant screening of some plants of Apocynaceae from South 27. Iadarola ND, Mark JN, Erica MR, Jennifer LV, Elizabeth West Nigeria. African Journal of Plant Science. 2008; 2 DB, Nancy BL, Allison CN, Rodrigo MV, Carlos AZ. Keta- (10): 124–128. mine and other N-methyl-D-aspartate receptor antagonists 14. Omodamiro OD, Nwankwo CI. The effect of Voacanga afri- in the treatment of depression: a perspective review. Ther. cana leaves extract on serum lipid profile and haematologi- Adv. Chronic Dis. 2015; 6(3): 97–114. DOI: cal parameters on albino wistar rats. European Journal of 10.1177/2040622315579059 Experimental Biology. 2013; 3(3): 140–148. 28. Quibell R, Prommer EE, Mihalyo M, Twycross R, Wilcock 15. Akanmu MA, Olayiwola G, Ukponmwan OE, Honda K. A. Ketamine. Journal of Pain Symptom Management. 2011; Acute toxicity and sleep-wake EEG analysis of Stach- 41(3): 640 – 649. tarpheta cayennensis (Verbenaceae) in rodents. African

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