Cholinesterase inhibitory activity and structure elucidation of a new phytol derivative and a new cinnamic acid ester from Pycnanthus angolensis

ABSTRACT The leaves of Pycnanthus angolensis (Welw.) Warb., Myristicaceae, are used as memory enhancer and anti-ageing in Nigerian ethnomedicine. This study aimed at evaluating the cholinesterase inhibitory property as well as isolates the bioactive compounds from the plant. The acetylcholinesterase and butyrylcholinesterase inhibitory potentials of extracts, fractions, and isolated compounds were evaluated by colorimetric and TLC bioautographic assay techniques. The extract inhibited both enzymes with activity increasing with purification, ethyl acetate fraction being most active fraction at 65.66 ± 1.06% and 49.38 ± 1.66% against acetylcholinesterase and butyrylcholinesterase, respectively while the supernatant had 77.44 ± 1.18 inhibition against acetylcholinesterase. Two new bioactive compounds, (2E, 18E)-3,7,11,15,18-pentamethylhenicosa-2,18-dien-1-ol (named eluptol) and [12-(4-hydroxy-3-methyl-oxo-cyclopenta-1,3-dien-1yl)-11-methyl-dodecyl](E)-3-(3,4-dimethylphenyl)prop-2-enoate (named omifoate A) were isolated from the plant with IC50 of 22.26 µg/ml (AChE), 34.61 µg/ml (BuChE) and 6.51 µg/ml (AChE), 9.07 µg/ml (BuChE) respectively. The results showed that the plant has cholinesterase inhibitory activity which might be responsible for its memory enhancing action, thus justifying its inclusion in traditional memory enhancing preparations.

Studies of the antitrypanosomal and toxicological properties of Anogeissus leiocarpus (Dc.) Guill. & Perr. (Combretaceae) and Vitellaria paradoxa C. F. Gaertn (Sapotaceae) in mice / Estudios de las propiedades antitripanosómicas y toxicológicas de Anogeissus leiocarpus (Dc). Guill. & Perr. (Combretaceae) y Vitellaria paradoxa C. F. Gaertn (Sapotaceae) en ratones

African animal trypanosomosis (AAT) is a disease of concern with ravaging effects on the health of both animals and livestock in tropical Africa. This study investigates the anti-trypanosomal activities of Anogeissus leiocarpus (ALE) and Vitelleria paradoxa (VPE) stem bark extracts and also determines the toxicological profile of the active plant, with a view to establishing the anti-trypanosomal potential and safety of the plants. Laboratory mice (19 g – 26 g) and rats (140 g – 165 g) obtained from the Animal house, Faculty of Pharmacy, OAU, Ile-Ife were used for the study. The animals were treated according to the standard set criteria for animal use and care. VPE showed neither trypanocidal nor trypanostatic activities while ALE was found to be trypanostatic at 62.5 and 125 mg/kg body weight. However, the partitioned aqueous fraction of ALE was found to demonstrate comparable anti-trypanocidal effect as Diminal (standard agent). In conclusion, the ethanolic extract of A. leiocarpus possesses antitrypanosomal effect through the relative suppression or delay in parasite establishment in trypanosome-infected mice. The toxicological study of A. leiocarpus stem bark extract revealed that it is relatively safe for use in cattle and other grazing animals.

La tripanosomiasis africana de los animales es una enfermedad de preocupación que causa estragos sobre la salud de los animales y el ganado en África tropical. Este estudio investiga las actividades anti-tripanosomal de Anogeissus leiocarpus (ALE) y Vitelleria paradoxa (VPE) del tallo y extractos de corteza. También determina el perfil toxicológico de la planta activa, con el fin de establecer el potencial anti-tripanosomal y la seguridad de las plantas. Ratones de laboratorio (19 g - 26 g) y ratas (140 g - 165 g) obtenidos del Bioterio de la Facultad de Farmacia de la OUA, se utilizaron para el estudio. Los animales fueron tratados de acuerdo con los criterios estándar establecido para el uso y cuidado de animales. VPE mostró actividades no tripanocidas ni tripanostáticas mientras que en ALE se encontró que era tripanostático a 62,5 y 125 mg/kg de peso corporal. Sin embargo, se encontró que la fracción acuosa de ALE demostró un efecto anti-tripanocida comparable como Diminal (agente estándar). En conclusión, el extracto etanólico de A. leiocarpus posee efecto sobre tripanosomas a través de la supresión relativa o retraso en la creación de parásitos en ratones infectados con tripanosomosis. El estudio toxicológico del extracto de corteza del tallo A. leiocarpus reveló que es relativamente seguro para su uso en el ganado y otros animales de pastoreo.

Acetylcholinesterase and butyrylcholinesterase inhibitory activity of some selected Nigerian medicinal plants / Atividade inibitória da acetilcolinesterase e butirilcolinesterase de algumas plantas medicinais da Nigéria

Plants have been found to be useful as memory enhansers as well as antiaging. Twenty two of such plants from sixteen families were investigated for their acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory activities using the in vitro Ellman's spectrophotometric and in situ bioautographic methods with physostigmine as standard. At least three morphological parts were examined for each of the plants investigated and the test concentration was 42.5 µg/ mL. Some plants were active on both enzymes though with some morphological parts being more active than others. The root bark of Spondias mombin showed the highest activity to the two enzymes; 64.77 percent and 83.94 percent on AChE and BuChE respectively. Other plant parts of the selected plants exhibited some remarkable selectivity in their actions. Those selectively active against AChE were Alchornia laxiflora stem bark (41.12 percent) and root bark, Callophyllum inophyllurn root bark (56.52 percent). The leaves of C. jagus (74.25 percent), Morinda lucida leaves (40.15 percent), Peltophorum pterocarpum leaves and stem bark (49.5 percent and 68.85 percent, respectively), physiostigmine gave 90.31 percent inhibition. Generally higher activities were found against BuChE. Bombax bromoposenze leaves, root bark and stem bark were particularly active. The inhibition was over 80 percent. Other selective plant parts are the leaves Antiaris africana, Cissampelos owarensis aerial parts (78.96 percent), Combretum molle leaves and stem bark (90.42 percent and 88.13 percent, respectively), Dioscorea dumentorum root bark and tuber (over 87 percent), G. kola leaves, Markhamia tomentosa root bark, Pycnanthus angolensis stem bark and Tetrapleura tetraptera leaves. Most of these plants are taken as food or are food ingredients in Nigeria and may account for the low incidence of Alzheimer's disease in the country and may play certain roles in the mediation of the disease.

As plantas podem ser úteis para estimular a memória, bem como serem usadas para combater o envelhecimento. Vinte e duas plantas, de dezesseis famílias, foram investigadas in vitro oara verificar sua atividade inibidora das enzimas acetilcolinesterase (AChE) e butirilcolinesterase (BuChE) pelo método espectrofotométrico de Ellman in situ e métodos de bioautografia utilizando fisostigmina como padrão. Pelo menos três partes morfológicas de cada planta foram analisadas e a concentração de ensaio foi de 42,5 µg/mL. Algumas plantas foram ativas em ambas as enzimas, embora com algumas partes mais ativas que outras. A casca da raiz de Spondias mombin apresentou a maior atividade as duas enzimas, 64,77 por cento para AChE e 83,94 por cento para BuChE. Outras partes das plantas selecionadas apresentaram boa seletividade em suas ações. As plantas seletivamente ativos contra AChE foram as casca do caule e casca da raiz de Alchornia laxiflora (41,12 por cento), e casca da raiz de Callophyllum inophyllurn (56,52 por cento). As folhas de C. jagus (74,25 por cento), folhas de Morinda lucida (40,15 por cento), folhas e casca do caule de Peltophorum pterocarpum (49,5 por cento e 68,85 por cento, respectivamente), physiostigmine inibiu 90,31 por cento. Em geral, atividades melhoras foram apresentadas contra BuChE. Folhas, casca da raiz e casca do caule Bombax bromoposenze foram particularmente ativos. A inibição foi acima de 80 por cento. Outras partes de algumas espécies também foram seletivas, como as partes aéreas de Antiaris africana, Cissampelos owarensis (78,96 por cento), folhas e casca do caule de Combretum molle (90,42 por cento e 88,13 por cento, respectivamente), casca da raiz e de tubérculos de Dioscorea dumentorum (mais de 87 por cento), folhas de G cola, cascas de raiz de Markhamia tomentosa, casca do caule de Pycnanthus angolensis e folhas de Tetrapleura tetraptera. A maioria destas plantas são utilizadas como alimentos ou ingredientes alimentares na Nigéria e podem ser responsáveis pela baixa incidência da doença de Alzheimer no país e desempenhar determinadas funções na mediação da doença.