Anti-diabetic activities of Chromolaena odorata methanol root extract and its attenuation effect on diabetic induced hepatorenal impairments in rats

Diabetes mellitus (DM) is a diverse and complex metabolic disorder that occurs due to the disturbances in fat, proteins and carbohydrate metabolism in response to insulin deficiency or insensitivity [1]. The world health organization estimated a total 150 million people on global basis suffer from diabetes and this likely tends to increase to 300 million before 2025. It was also documented that 8.5% of adult’s population in 2014 are diabetes, and about 1.6 million diabetes associated deaths occur in 2016 [2]. The dilemma of diabetes complications also take a great burdened on global expenditure. In 2015, 12% of the global health expenditure was spent on diabetes [3]. About 376 billion USD in form of diets, medicines, research, training etc. was spent on diabetes mellitus and this global expenditure is expected to reach 490 billion USD in 2030 [4]. The current drug therapies including biguanides, α-glucosidase inhibitors, sulfonylureas and glinides are synthetic and are besieged with limitations in terms of cost, safety and efficacy [8].

Natural products are rich sources of medicinal/therapeutic agents and have been use since centuries for management or treatment of diseases and maintenance of good health. Decades of scientific research has also validated the medicinal claim of these natural products against several diseases [5‐8]. It is therefore reasonable to extend our search for better alternative anti-diabetics from natural products that are commonly used in traditional medicine,

Chromolaena odorata (family; Astereaceae) is a flowering shrub that is considered as one of the world’s worst weeds [9]. Chromolaena odorata parts have been used in African folk medicine for varieties of ailments including dysentery, malaria, toothache, diarrhoea, fever, skin diseases and diabetes [10‐12]. Chromolaena odorata has also been reported for several pharmacological properties including antimalerial, anthelmintic, analgesic, anti- antipyretic, inflammatory, antispasmodic, antigonorrheal, antioxidant, insecticidal, antimycobacterial, fungicidal, diuretic, wound healing, blood coagulation and antibacterial [13‐15]. The leaves have also been reported for anti-diabetic properties [9]. However, no known anti-diabetic activity of the whole root extract has either been done in vivo or in vitro. Hence, this study investigated the anti-diabetic properties of the methanol root extract of Chromolaena odorata and its effect on biochemical parameters in alloxan induced diabetic rats.

Alpha-amylase is an important enzyme that hydrolyzes dietary starch during carbohydrate metabolism. In the present study, the potent inhibitory effects of Chromolaena odorata methanol root extract on α-amylase activity is an indication that this plant would be beneficial in keeping the blood glucose level low by delaying the digestion of carbohydrate and thus reduce the concentration of postprandial plasma glucose. This inhibitory activity of the extract could be attributed to the presence of antioxidants phytochemicals including; flavonoids, tannins and saponins which have been reported to inhibit α-amylase activity and preserve the β-cell integrity thus protect against the development of insulin resistance type 2 diabetics [33].

Bamisaye et al. [9] reported that Chromolaena odorata has several medicinal properties due to the presence of high amount of flavonoids and tannins in the plant. Previous study by Phan et al. [11] also reported that Chromolaena odorata contains high amount of phenolic compounds that protect against oxidative damage.

Formation of glycated end products (glucose-hemoglobin complex) serves as a source of free radicals which inturn results in oxidative stress that complicate diabetes mellitus. In this study, methanol root extract of Chromolaena odorata caused appreciable inhibition of glycated hemoglobin formation with an IC₅₀ value of 679.1 μg/ml. This is an indication that the extract could be useful in prevention of diabetes induce oxidative stress. This inhibitory effect of the extract could be credited to the presence of some non-phenolic metabolites that acted as enzyme inhibitors, exhibiting an additive or synergistic effect with the phenolics present in the sample [34]. The ability of the extract to enhance glucose transport (Table 3) could be attributed to the presence of tannin and saponin which have been reported to enhance transportation and expression of GLUT 4 respectively [35].

A preliminary toxicity study of the extract showed that in single dose the plant extract had no adverse effect up to concentration of 5000 mg/kgb.wt. This corroborated the report by Ogbonna et al., [36] that C. odorata showed no toxicity effect on mice up to 5000 mg/kg b.wt. The significant (p < 0.05) blood glucose lowering effect of Chromolaena odorata methanol root extract may be attributed to the presence of phenols, flavonoids, alkaloids, tannins, and saponins that have been associated with hypoglycemic activity [37, 38]. Leaves of C. odorata were also reported by Ijioma et al., [39], to be hypoglycemic. During diabetic conditions, insulin deficiency prevents the body from the utilization of glucose for energy source. Thus the body switched to the stored fats and muscle proteins, leading to the reduction in overall body weight as observed in untreated groups. The anti-diabetic activity of Chromolaena odorata methanol root extract is also supported by the significant weight gain of the treated animals in comparison with the untreated animals. This shows the improvement in metabolic activity of the treated animals.

Hepatic impairment is one of the complications of diabetes mellitus and its evident by elevation of serum transaminase and alkaline phosphatases activities. Therefore, evaluation of serum enzymes biomarker will provide reliable indicator of functional integrity of the liver as well as treatment outcome [40‐42] in diabetic condition. In the present study, the elevated levels of serum aspartate aminotransferase and alkaline phosphatase activities in diabetic untreated rats is an indication of plasma membrane and hepatic impairment, these will adversely hampered amino acid and carbohydrates metabolism and thus effect ATP production [43]. The observation with ALT activities is an indication that diabetes selectively effect transaminases activities since only AST activity was altered and not ALT [44]. Administration of methanol roots extract of C. odorata and standard drug caused a significant restoration of the plasma membrane and liver functional integrity as evident by decrease ALP and AST activities.

The total proteins, albumin and bilirubins play major roles in assessing the integrity of kidney and liver [45]. The observed increases in the total proteins concentrations in diabetic untreated rats could be attributed to the elevation of various acute phase proteins, globulins and fibrinogen in diabetes mellitus [46]. In concordances with this finding, Ladei et al., [47] reported increased plasma levels of acute phase proteins in type 1 and type 2 diabetes adult patients. The increase in total proteins reported in this study could lead to dehydration which is injurious to cellular homeostasis. This will harmfully compromised the normal metabolic activities of the liver and consequently the health of the animals [48]. The significant decreases in albumin concentration in diabetic untreated rats could be attributed to fact that albumin are involve in glycation (Hemangi & Bhonlet [49]. It was observed that methanol extract of Chromolaena odorata root enhance adequate glucose regulation thereby reducing glycated albumin which is responsible for the higher level of albumin concentration in the diabetic treated group. This finding is supported by the significant inhibitory activity of the extract against heamoglobin glycosylation as reported above (Table 3).

Bilirubin is an endogenous anion product of hemoglobin degradation of the red blood cell. The low level of direct and total bilirubin in diabetic untreated control, this is an indication of impair liver function as reported by Libor, [50]. The improvement in the concentrations of direct and total bilirubin in rats treated with C. odorata (300 and 600 mg/kg bw is an indication of increase glucose mobilization into cells leading to more efficient glucose utilization [51].

Plasma electrolytes, creatinine and urea concentrations are useful clinical indicators of renal integrity [18]. Creatinine is a waste product of muscle metabolism while urea is a byproduct of protein metabolism. During renal impairment, the excretion of these metabolites by the kidney is altered and thus accumulates in the plasma [45]. The observed significant increase in serum urea and creatinine concentrations in diabetic rats is an indication of renal impairment. The diseases condition must have either altered the metabolism of creatinine leading to increased synthesis or decrease tubular excretion [52]. These findings corroborated with the studies by Aldler et al. [53] and Judykay et al., [54] which showed that raised plasma urea levels in diabetic patients may indicate a pre-renal problem. Furthermore, the significant alterations in the concentrations of sodium, chloride and bicarbonate suggest that the integrity of renal tubules as regards to the excreation and maintenances of normal levels of these electrolytes in the system of the animal have been compromised [18]. Unfortunately, treatment with Chromolaena odorata resulted does not bring about any significant (p > 0.05) attenuation in the concentrations of urea, creatinine and electrolytes, hence the functional integrity of kidney cannot be preserved by treatment with Chromolaena odorata in diabetic rats.

Chromolaena odorata root extracts exhibited anti-diabetic properties both in vitro and in vivo models. The extract exhibited protective effect against diabetic induces hepatic impairment. However, the functional integrity of kidney cannot be preserved by treatment with Chromolaena odorata in diabetic rats.