Okey A. Ojiako

Overview of Anti-Diabetic Medicinal Plants: The Nigerian Research Experience

Medicinal plants have been used since ancient times for the treatment and management of diabetic mellitus (DM) in traditional medicine systems of many cultures throughout the world. Recently, the World Health Organization (WHO) recommended the use medicinal plants for the management of DM and further encouraged the expansion of the frontiers of scientific evaluation of the hypoglycemic properties of diverse plant species. Accordingly, the hypoglycemic activity of a vast number of plant products have been evaluated and confirmed in animal models as well as in human beings. In some cases, the bioactive principles of the medical plants have been isolated and identified. In order to harness these natural resources and maximize the socioeconomic benefits derivable from Nigerian medicinal plants efforts should be geared toward research funding and deployment of Research and Development (R & D) policy framework into medicinal plants research endeavours.

A Time-Trend Hypoglycemic Study of Ethanol and Chloroform Extracts of Strophanthus hispidus

Strophanthus hispidus Del., a plant widely distributed throughout the open African savanna, is used by ethnic, tribal people of Africa for various purposes, including the control of diabetes. To determine whether the plant was effective in the treatment of diabetes, a phytochemical screening and detailed study of ethanol and chloroform extracts of the leaf, stem, and root tissues of the plant were used to determine the effects of these extracts on blood glucose concentrations in laboratory animals. The phytochemical screening indicated the presence of alkaloids, flavonoids, saponins, and cardiac and cyanogenic glycosides. Significant concentration-dependent hypoglycemic effects (p < .05) of both the ethanol and chloroform extracts were observed with the 50% extracts being more effective than the 20% extracts. The ethanol leaf extract showed a higher hypoglycemic effect (60.0%) than other extracts at 1 hour after extract administration. The 50% and 20% chloroform root extracts exhibited more prolonged hypoglycemic effects than those of other chloroform and ethanol extracts. The highest hypoglycemic activity was observed at 1.5 hours after of extract administration, with an increase in blood glucose concentrations noted by 2 hours after extract administration. This study concludes that the leaf and root extracts of this plant could be a source of a potent drug for the management of diabetes, especially in the resource-poor rural communities of Nigeria, and gives credence to the alleged folklore use of extracts of the plant in the treatment of diabetes.

Cyanide and aflatoxin loads of processed cassava (Manihot esculenta) tubers (Garri) in Njaba, Imo state, Nigeria

Objectives: The present study sought to investigate the role of palm oil, in conjunction with the duration of fermentation, on cyanide and aflatoxin (AFT) loads of processed cassava tubers (Garri). Materials and Methods: Matured cassava (Manihot esculenta Crantz) tubers were harvested from three different locations (Akunna, Mkporo-Oji and Durungwu) in Njaba Local Government Area, Imo State, Nigeria. The cassava tubers were processed into Garri according to standard schemes with required modifications and measured for cyanide content using titrimetric methods. Samples of Garri for determination of AFT levels were stored for 30 days before the commencement of spectrophotometric analysis. Results: Cyanide content of peeled cassava tubers was within the range of 4.07 ± 0.16-5.20 ± 0.19 mg hydrocyanic acid (HCN) equivalent/100 g wet weight, whereas the various processed cassava tubers was within the range of 1.44 ± 0.34-3.95 ± 0.23 mg HCN equivalents/100 g. For the 48 h fermentation scheme, Garri treated with palm oil exhibited marginal reduction in cyanide contents by 0.96%, 3.52% and 3.69%, whereas 4 h fermentation scheme is in concurrence with palm oil treatment caused 4.42%, 7.47% and 5.15% elimination of cyanide contents compared with corresponding untreated Garri samples (P > 0.05). Levels of AFT of the various Garri samples ranged between 0.26 ± 0.07 and 0.55 ± 0.04 ppb/100 g. There was no significant difference (P > 0.05) in AFT levels among the various samples in relation to their corresponding sources. Conclusion: The present study showed that the 48 h fermentation scheme for Garri production caused significant (P < 0.05) reduction, but did not obliterate the cyanide content of cassava tubers. Conversely, the 48 h fermentation scheme promoted the elevation of AFT levels, but was relatively reduced in Garri samples treated with palm oil.

Blood glucose level and lipid profile of alloxan-induced hyperglycemic rats treated with single and combinatorial herbal formulations.

The current study sought to investigate the capacities of single and combinatorial herbal formulations of leaf extracts of Acanthus montanus, Asystasia gangetica, Emilia coccinea, and Hibiscus rosasinensis to reverse hyperglycemia and dyslipidemia in alloxan-induced diabetic male rats. Phytochemical composition of the herbal extracts, fasting plasma glucose concentration (FPGC), and serum lipid profile (SLP) of the rats were measured by standard methods. The relative abundance of phytochemicals in the four experimental leaf extracts was in the following order: flavonoids > alkaloids > saponins > tannins. Hyperglycemic rats (HyGR) treated with single and combinatorial herbal formulations showed evidence of reduced FPGC compared with the untreated HyGR and were normoglycemic (FPGC < 110.0 mg/dL). Similarly, HyGR treated with single and combinatorial herbal formulations showed evidence of readjustments in their SLPs. Generally, HyGR treated with triple herbal formulations (THfs) exhibited the highest atherogenic index compared with HyGR treated with single herbal formulations (SHfs), double herbal formulations (DHfs), and quadruple herbal formulation (QHf). The display of synergy or antagonism by the composite herbal extracts in ameliorating hyperglycemia and dyslipidemia depended on the type and number of individual herbal extract used in constituting the experimental herbal formulations. Furthermore, the capacities of the herbal formulations (SHfs, DHfs, THfs, and QHf) to exert glycemic control and reverse dyslipidemia did not follow predictable patterns in the animal models.

Plasma vitamins C and E levels inversely correlate with the risk of ischaemic heart diseases in patients from Imo state, Nigeria

Sixty-six Nigerian patients with ischaemic heart diseases age ranging between 50 -75 years were studied. The samples consisted of 42 cases with angina pectoris and 24 cases with myocardial infarction, which were proven to suffer from ischaemic heart disease by the presence of clinical symptoms, exercise electrocardiogram abnormalities and myocardial enzyme measurement. Controls were 36 subjects who did not show any abnormalities in the parameters used. Controls and patients were classified into groups based on the presence or absence of risk factors (smoking, hypertension, diabetes, hyperlipidaemia, obesity and family history). The mean plasma concentrations of vitamins C and E were significantly inversely related to the risks of ischaemic heart disease. Smoking was a compounding factor. These findings suggest that some populations with high incidence of ischaemic heart disease may benefit from eating diets rich in natural antioxidants, particularly vitamins E and C.

The Proximate, Mineral, and Toxicant Compositions of Four Possible Food Security Crops from Southeastern Nigeria

The proximate, nutritional, and antinutritional compositions of the raw, cooked, and roasted samples of four Nigerian indigenous seeds-Sphenostylis stenocarpa, Pentaclethra macrophylla, Mucuna flagellipes, and Citrullus colocynthis-were evaluated. Also estimated were zinc and divalent cation bioavailability of the seeds using millimolar ratios/kg dry weight of [calcium]/[phytate], [phytate]/[zinc], [calcium][phytate]/[Zn], and [phytate]/[total phosphorus]. The results obtained revealed that the seeds of P. macrophylla and C. colocynthis had high protein and lipid levels. All the seeds were also found to have high energy value and low moisture content. Mineral analysis showed the presence of Na, K, Ca, and Mg in appreciable quantities and Zn, I, Fe, and Se in minute quantities. Antinutritional analyses indicated the presence of traces of tannin, oxalate, phytate, saponin, and cyanide in the samples. The various processing techniques had significant (P ≤ .05) effects on the measured parameters. The calculated [Ca][phytate]/[Zn] molar ratios revealed that these seeds had values above the critical level of 0.5 mL/kg, thus indicating reduced bioavailability of zinc. In view of the high nutrient contents, low antinutritional contents after processing, and their superabundance, these seeds could be cheap nutrient sources. The implications of these findings with regards to food security are enormous.

Radical scavenging potentials of single and combinatorial herbal formulations in vitro

Reactive oxygen and nitrogen species (RONS) are involved in deleterious/beneficial biological processes. The present study sought to investigate the capacity of single and combinatorial herbal formulations of Acanthus montanus, Emilia coccinea, Hibiscus rosasinensis, and Asystasia gangetica to act as superoxide radicals (SOR), hydrogen peroxide (HP), nitric oxide radical (NOR), hydroxyl radical (HR), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical antagonists using in vitro models. The herbal extracts were single herbal formulations (SHfs), double herbal formulations (DHfs), triple herbal formulations (THfs), and a quadruple herbal formulation (QHf). The phytochemical composition and radical scavenging capacity index (SCI) of the herbal formulations were measured using standard methods. The flavonoids were the most abundant phytochemicals present in the herbal extracts. The SCI50 defined the concentration (μg/mL) of herbal formulation required to scavenge 50% of the investigated radicals. The SHfs, DHfs, THfs, and QHf SCI50 against the radicals followed the order HR > SOR > DPPH radical > HP > NOR. Although the various herbal formulations exhibited ambivalent antioxidant activities in terms of their radical scavenging capabilities, a broad survey of the results of the present study showed that combinatorial herbal formulations (DHfs, THfs, and QHf) appeared to exhibit lower radical scavenging capacities than those of the SHfs in vitro.

Herbal Medicine: Yesterday, Today and Tomorrow

Herbal medicines involve the integration of several therapeutic experiences and practices of indigenous systems of medicine that may span many previous generations, which often provides valuable guidelines to the selection, preparation and application of herbal formulation for the treatment, control and management of variety of ailments. According to World Health Organization, 60% of the world’s population depends on traditional medicine and 80% of the population in developing countries depends almost entirely on traditional medicine practices and herbal medicines for their primary health care needs. As a result of increasing demand for herbal medicines, there are increasing concerns about the safety, standardization, efficacy, quality, availability and preservation of herbal products by policy-makers, health professionals as well as the general public. Improvement in the quality of herbal medicines could be achieved by deliberate implementation of good agricultural practices (GAPs) at the point of cultivation of medicinal plants and good manufacturing practices (GMPs) during the process of manufacture and packaging of finished herbal products, as well as post-marketing quality assurance surveillance. Additionally, following the current sustained improvements in quality control and regulatory measures in many countries of the world, it is envisaged that in the near future, herbal medicinal practices will be integrated into the conventional medicines.

Evaluation of the Amino Acid Profile and Haemoglobin Polymerization Inhibition Potential of Some Nigerian Legumes

The amino acid profile and the effects of the seed extracts of Sphenostylis sternocarpa , Monodora myristica and Mucuna sloanei were studied based on their ability to inhibit haemoglobin polymerization and improve the Fe 2+ /Fe 3+ ratio of sickle cell erythrocytes. The samples were fractionated into crude aqueous extract (CAE), fat-soluble (FAS), butanol-soluble (BUS) and water-soluble (WAS) fractions. The CAEs of the samples ranked highest in amino acid content in the range of S. sternocarpa (7.12 ± 0.00 g/100g)>M. myristica (6.00 ± 0.15 g/100g)>M. sloanei (3.56 ± 0.21 g/100g). The amino acids identified in appreciable quantities in the seed samples included Phe, Leu, Val, Ile, His, Arg, Tyr, Met, among others. The extracts inhibited polymerization to varying degrees with CAE of both S. sternocarpa and M. myristica , as well as the WAS of M. myristica eliciting significantly (p<0.05) high percent inhibition of polymerization when compared with Phe standard. The extracts improved the Fe 2+ /Fe 3+ ratio of HbSS blood from 1.36% for CAE of M. sloanei to 85.04% for CAE of S. sternocarpa ; and from 11.03% for WAS of S. sternocarpa to 36.08% for WAS of M. sloanei . These legumes could, therefore, have immense nutritional and therapeutic importance in the management of sickle cell disease and other related diseases.

Glycemic Indices/Renal and Hepatic Antioxidant Status of Hyperglycemic Rats Treated with Single and Combinatorial Herbal Formulations

The present study ascertained the comparative capacities of single and combinatorial herbal formulations of Acanthus montanus, Emilia coccinea, Hibiscus rosasinensis and Asystasia gangetica to exert glycemic control and ameliorate oxidative stress in renal and hepatic tissues of alloxan-induced hyperglycemic rats (HyGR) following 30 days treatment. Phytochemical composition of the herbal extracts and fasting plasma glucose concentration (FPGC) of the rats were measured by standard methods. The post mitochondrial supernatant fractions (PMSF) of renal and hepatic tissues homogenates were measured for activity levels of glutathione peroxidase (GPOx), superoxide dismutase (SOD) and catalase (CAT) as well as glutathione (GSH) concentration. Comparatively, flavonoids were the most abundant phytochemical present in the four herbal extracts. FPGC of treated HyGR was within the range of 66.30 ± 0.71 - 133.00 ± 0.63 mg/dL as against the untreated hyperglycemic rat group=368.20 ± 0.72 mg/dL (p<0.05). At the end of the experimental time, treated HyGR liver SOD activities were lower than that of normal group (p<0.05). Liver and kidney GPOx activities of HyGR were 2.36 folds and 3.93 folds lower than the normal rats. Furthermore, liver and kidney CAT activities of the treated HyGR were significantly (p<0.05) lower than the normal rats, whereas liver and kidney GSH/GSSG ratios were significantly (p<0.05) increased when compared with treated HyGR. Combinatorial herbal formulations exerted greater glycemic control than the single herbal formulations and caused a sparing effect on renal and hepatic antioxidants against reactive oxygen species.