Inhibitory Effect of Mammea africana on Alpha-Amylase and Alpha-Glucosidase Enzymes of Rats

Biology, Medicine, & Natural Product Chemistry Volume 11, Number 2, October 2022 | Pages: 175-180 | DOI: 10.14421/biomedich.2022.112.175-180 ISSN 2089-6514 (paper) ISSN 2540-9328 (online) Inhibitory Effect of Mammea africana on Alpha-Amylase and Alpha-Glucosidase Enzymes of Rats Nwakaego Omonigho Ebong1,*, Jude Efiom Okokon1,2, Jesse Idakwoji1 1 Department of Pharmacology and Toxicology, Faculty of Pharmacy, Madonna University, Elele, Nigeria. 2 Department of Pharmacology and Toxicology, Faculty of Pharmacy, University of Uyo, Uyo, Nigeria. Corresponding author* Manuscript received: 10 August, 2022. Revision accepted: 23 August, 2022. Published: 12 September, 2022. Abstract Mammea africana Sabine (Guttiferae), a medicinal plant used traditionally in the treatment of diseases including diabetes was evaluated for effect on alpha-amylase and alpha-glucosidase enzymes in vivo. The stembark extract (30, 60 and 90 mg/kg) of M. africana were investigated in vivo for inhibitory effect on alpha-amylase and alpha-glucosidase enzymes using starch, sucrose and maltose as substrates. Acarbose was used as reference drug. The stembark extract caused significant (p<0.05) reduction in blood glucose levels of treated rats with the various substrates used. The results suggest that the stembark extract of M. africana have the potentials to inhibit alpha-amylase and alpha-glucosidase in rats. Keywords: alpha-amylase; alpha-glucosidase; hypoglycaemia; Mammea africana. Abbreviations: Blood Glucose Level (BGL). INTRODUCTION Mammea africana Sabine (Guttiferae) (syn. Ochrocarpus africana Oliv.) (M. africana) is a large forest tree of 50 to 100 feet high with bark often yellow with pale scales and resinous yellow sap (Hutchison and Daziel, 1958). The plant is widely distributed in tropical Africa. Traditionally, the stem bark of the plant is used by the Ibibios, of the Niger Delta region of Nigeria, in the treatment of malaria related fever, diabetes, microbial infections and mental disorders. The stembark is also traditionally used to treat stomach pains, rheumatism pains, scabies, cough and hypertension (Raponda-Walter and Sillans, 1961; Adjanohoun et al. 1996). The stembark extract has been reported to possess cytotoxic activity, in vitro (Chapuis et al. 1988; Okokon et al. 2012). Ouahouo et al. (2004) reported cytotoxic coumarins with anti-microbial activity against Staphylococcus aureus from the plant stembark. The stembark has been reported to have anti-plasmodial (Okokon et al. 2006), cardioprotective (Okokon and Antia,2007), anti-diabetic, hypolipidaemic (Okokon et al. 2007), vasorelaxant (Dongmo et al. 2007), antihypertensive (Nguelefack-Mbuyo et al. 2008), antiinflammatory, analgesic (Okokon et al. 2009), antioxidant (Nguelefack-Mbuyo et al. 2010), antidiarrheal, anti-ulcer (Okokon et al. 2010), immunomodulatory, anti-lesihmanial (Okokon et al. 2012), depressant and anti-convulsant (Okokon and Davis, 2014) as well as nephroprotective (Okokon and Bawo, 2014) and hepatoprotective (Okokon et al. 2016) activities. The stembark has been reported to have 5,-7dihydroxy-8-(12-methyl-butryl)–4–N-pentylcoumarins (Carpenter et al. 1970, 1971; Crichton and Waterman, 1978), 4-phenyl and 4- alkylcoumarins (Games, 1972), mesuxanthone B (Carpenter et al. 1971). Alkaloids have been reported to be absent in the entire plant parts (Gartlands et al. 1980). We report in this study the effect of leaf extract and fractions of the plant on alphaamylase and alpha-glucosidase of rats. MATERIALS AND METHODS Plants Collection The plant material Mammea africana (stembark) were collected in Anwa forest in Uruan area, Akwa Ibom State, Nigeria in January 2022. The plant was identified and authenticated by Dr. Margaret Bassey, at the Department of Botany and Ecological Studies, University of Uyo, Uyo, Nigeria with voucher number FPHUU 381. Extraction The stembarks were washed and shade-dried for two weeks. The dried plants’ materials were further chopped 176 Biology, Medicine, & Natural Product Chemistry 11 (2), 2022: 175-180 into small pieces and reduced to powder using electric grinder. The powdered material (1.5 kg) was macerated for 72 h in 50% ethanol. This was thereafter filtered and the liquid filtrate was concentrated and evaporated to dryness in vacuo 40˚C using a rotary evaporator (BuchiLab, Switzerland). The extract was stored in a refrigerator at -4˚C, until used for the proposed experiments. Animals Albino wistar rats (120 -135 g) of either sex were used for these experiments. The animals were housed in standard cages and were maintained on a standard pelleted feed (Guinea feed) and water ad libitum. electrode sensor measures the current produced when the enzyme converts glucose to gluconic acid. The resulting current is directly proportional to the amount of glucose in the sample (WHO, 2011). Statistical Analysis Data obtained from this work were analysed statistically using one –way ANOVA followed by Tukey-Kramer multiple comparison test using Instat Graphpad software, (San Diego, USA). Differences between means were considered significant at 5% level of significance i.e. p≤ 0.05. RESULTS AND DISCUSSION In Vivo Alpha-amylase Inhibition Study and Alpha-glucosidase Alpha-amylase Inhibitory Study Thirty-five Wistar rats were divided into 6 groups of 5 rats each. The rats in all groups were fasted for 18 hours and fasting blood glucose concentration was first taken at 0 minutes before administration. Group I, as the normal control, received distilled water (10 mL/kg). Group II rats were orally administered starch at 2 g/kg body weight (orally with distilled water as vehicle) and distilled water (10 mL/kg) simultaneously. Rats in group III were administered starch (2 g/kg) and the standard drug (acarbose) at 100 mg/kg simultaneously. Groups IV, V and VI were administered simultaneously, starch (2 g/kg) and Mammea africana stembark extract at 30, 60 and 90 mg/kg respectively. All administrations were done orally and blood glucose concentration was monitored at 30, 60, 90, 120 and 180 minutes (Gidado et al. 2019). Alpha-glucosidase Inhibitory Study The procedure as described above was used for this study but with sucrose and maltose used as substrates (Gidado et al. 2019). Blood Glucose Determination Drops of blood from tip of rats’ tails were dropped on stripes and glucose concentration was measured using a glucometer according to manufacturer’s specifications (Accu-chek, Indiana). The glucometer works with the following principle; the blood sample is exposed to a membrane covering the reagent pad (strip), which is coated with an enzyme (glucose oxidase, glucose dehydrogenase). The reaction causes a colour change and the intensity of this change is directly proportional to the amount of glucose in the blood sample. Light from a Light Emitting Diode strikes the pad surface and is reflected to a photodiode, which measures the light intensity and converts it to electrical signals. An In Vivo (...truncated)