Abidemi J. Akindele

Anticonvulsant, anxiolytic and sedative activities of the aqueous root extract of Securidaca longepedunculata Fresen.

AIM OF THE STUDY The objective of this study is to investigate the anticonvulsant, anxiolytic and sedative activities of the aqueous root extract of Securidaca longepedunculata. MATERIALS AND METHODS The anticonvulsant effect of the aqueous root extract (100, 200 and 400 mg/kg) was evaluated in mice using the strychnine- and picrotoxin-induced seizure models. Its anxiolytic activity was evaluated using the elevated plus maze (EPM) and the Y maze (YM) methods (Hogg, 1996; Yemitan and Adeyemi, 2003) while the hexobarbitone induced sleep and the hole board models were used to evaluate the sedative and exploratory activities in mice respectively. The acute toxicity studies and phytochemical analysis of the extract were also carried out. RESULTS The extract (100-400 mg/kg) produced a significant (P<0.01) dose dependent increase in onset of convulsion compared to the control for strychnine- and picrotoxin-induced seizures. It also produced a significant (P<0.01) dose dependent prolongation of the cumulative time spent in the open arms of the elevated plus maze and Y maze compared with the control. The extract (100-400 mg/kg) produced significant (P<0.01) reduction in the time of onset of sleep induced by hexobarbitone. The prolongation of hexobarbitone sleeping time by the extract (200 mg/kg) was comparable to that produced by diazepam (3 mg/kg). At doses of 100-400 mg/kg, the extract produced a dose dependent decrease in exploratory activity of the mice. The reduction in exploratory activity produced by the extract (400 mg/kg) was greater than that of chlorpromazine (1 mg/kg). The results obtained from the experiments indicate that the extract has central nervous system depressant and anxiolytic activities. The LD(50) obtained for the acute toxicity studies using both oral and intraperitoneal routes of administration were 1.74 g/kg and 19.95 mg/kg respectively. CONCLUSION These findings justify the use of Securidaca longepedunculata in traditional medicine for the management of convulsion and psychosis.

Evaluation of the antidiarrhoeal effect of Sanseviera liberica Gerome & Labroy (Agavaceae) root extract

ETHNOPHARMACOLOGICAL RELEVANCE The aqueous root extract of Sansevieraliberica (Agavaceae), SL, is used in Traditional African Medicine (TAM) for the treatment of diarrhoea. However, the scientific basis for this usage has not been established. AIM OF THE STUDY To evaluate the antidiarrhoeal activity of SL using various pharmacological models. MATERIALS AND METHODS The intestinal transit, castor oil induced diarrhoea, enteropooling, and gastric emptying methods were used in this study. RESULTS SL (25-400 mg/kg, p.o.) produced significant (P < 0.05) dose dependent reduction in propulsive movement in both the normal and castor oil induced intestinal transit tests in mice. Peak effect was elicited at 200 mg/kg but this effect was lower than that produced by morphine (10 mg/kg, s.c.). The effect of SL on castor oil induced intestinal transit was antagonized by isosorbide dinitrate, IDN (150 mg/kg, p.o.) but not by yohimbine (1 mg/kg, s.c.). In the castor oil induced diarrhoea test, SL significantly delayed the onset and decreased the frequency and severity of diarrhoea. The effect at 200 mg/kg was comparable to that of morphine and was reversed by IDN. SL at the dose of 200 mg/kg significantly reduced the volume of intestinal secretion induced by castor oil but produced no effect on gastric emptying. The extract was practically nontoxic administered p.o. The LD(50) was 631 mg/kg given i.p. Phytochemical analysis revealed the presence of oils, reducing sugars, alkaloids, saponins, anthraquinones, and tannins in the extract. CONCLUSION The results obtained in this study suggest that the aqueous root extract of Sanseviera liberica possesses antidiarrhoeal property due to inhibition of gastrointestinal propulsion and fluid secretion, possibly mediated through inhibition of the nitric oxide pathway. This justifies the use of the plant extract in TAM for the treatment of diarrhoea.

Analgesic and anti-inflammatory activities of Cnestis ferruginea Vahl ex DC (Connaraceae) methanolic root extract

ETHNOPHARMACOLOGICAL RELEVANCE Cnestis ferruginea Vahl ex DC (Connaraceae) is a shrub widely used in traditional African Medicine (TAM) for the treatment of various painful and inflammatory conditions. AIM OF THE STUDY The objective of this study was to investigate the analgesic and anti-inflammatory properties of the methanolic root extract of Cnestis ferruginea. MATERIALS AND METHODS Analgesic activity was evaluated using the acetic acid-induced writhing, formalin, tail clip, and hot plate tests in mice. The carrageenan- and egg albumin-induced rat paw oedema, formaldehyde-induced arthritis inflammation, and xylene-induced ear oedema tests were used to investigate the anti-inflammatory actions of Cnestis ferruginea. RESULTS The methanolic root extract of Cnestis ferruginea (100, 200, and 400mg/kg; p.o.) produced significant (P<0.05) dose-dependent inhibition of pain response elicited by acetic acid and formalin while also increasing the nociceptive reaction latency in the tail clip and hot plate tests. In respect of anti-inflammatory activity, Cnestis ferruginea caused significant (P<0.05) dose-dependent inhibition of oedema development in the carrageenan, egg albumin, formaldehyde, and xylene-induced inflammation tests. The effects of the extract in the various models were generally comparable to those of the standard drugs used. CONCLUSION The findings in this study suggest that the methanolic root extract of Cnestis ferruginea possesses analgesic and anti-inflammatory activities possibly mediated through peripheral and central mechanisms involving inhibition of release and/or actions of vasoactive substances (histamine, serotonin and kinins) and prostaglandins. The results justify the use of the extract in TAM for the treatment of painful and inflammatory conditions.

Polychlorinated biphenyls (PCBs) in Africa: a review of environmental levels

Several studies have shown an increase in PCB sources in Africa due to leakage and wrongly disposed transformers, continuing import of e-waste from countries of the North, shipwreck, and biomass burning. Techniques used in the recycling of waste such as melting and open burning to recover precious metals make PCBs contained in waste and other semivolatile organic substances prone to volatilization, which has resulted in an increase of PCB levels in air, blood, breast milk, and fish in several regions of Africa. Consequences for workers performing these activities without adequate measures of protection could result in adverse human health effects. Recent biodegradation studies in Africa have revealed the existence of exotic bacterial strains exhibiting unique and unusual PCB metabolic capability in terms of array of congeners that can serve as carbon source and diversity of congeners attacked, marking considerable progress in the development of effective bioremediation strategies for PCB-contaminated matrices such as sediments and soils in tropical regions. Action must be taken to find and deal with the major African sources of these pollutants. The precise sources of the PCB plume should be pinned down and used to complete the pollutant inventories of African countries. These nations must then be helped to safely dispose of the potentially dangerous chemicals.

Hepatoprotective and in vivo antioxidant effects of Byrsocarpus coccineus Schum. and Thonn. (Connaraceae)

ETHNOPHARMACOLOGICAL RELEVANCE The leaf decoction of Byrsocarpus coccineus (Connaraceae) is drunk for the treatment of jaundice in West African traditional medicine. AIM OF THE STUDY To investigate the hepatoprotective and in vivo antioxidant effects of Byrsocarpus coccineus in carbon tetrachloride (CCl(4))-induced hepatotoxicity in rats. MATERIALS AND METHODS Group allotment in this study included vehicle, CCl(4), Byrsocarpus coccineus 1000 mg/kg alone, Byrsocarpus coccineus 200, 400, and 1000 mg/kg+CCl(4) and Livolin((R)) 20mg/kg+CCl(4), and treatment was carried out accordingly. On the 7th day, rats were sacrificed and blood was withdrawn by cardiac puncture. The levels and activities of serum biochemical parameters and antioxidant enzymes were then assayed using standard procedures. RESULTS CCl(4) significantly (P<0.05) increased the levels of ALT and AST and reduced total protein. In CCl(4) treated animals, Byrsocarpus coccineus (200, 400, and 1000 mg/kg) dose-dependently and significantly decreased ALT, AST and ALP levels with peak effect produced at the highest dose. Conversely, Byrsocarpus coccineus produced significant increases in albumin and total protein levels. The standard drug produced significant effects in respect of ALT (downward arrow), albumin (upward arrow), and total protein (upward arrow). CCl(4) also produced significant (P<0.05) reductions in the activity of catalase, SOD, peroxidase and GSH, and conversely increased MDA level. Byrsocarpus coccineus produced significant and dose-dependent reversal of CCl(4)-diminished activity of the antioxidant enzymes and reduced CCl(4)-elevated level of MDA. The standard drug also significantly increased CCl(4)-diminished antioxidant enzymes activity and reduced CCl(4)-elevated MDA level. In general, the effects of the standard drug were comparable and not significantly different from those of Byrsocarpus coccineus. CONCLUSION The results obtained in this study suggest that the aqueous leaf extract of Byrsocarpus coccineus possesses hepatoprotective and in vivo antioxidant effects. This finding justifies the use of this preparation in West African traditional medicine for the treatment of liver disease.

Antidiarrhoeal activity of the ethyl acetate extract of Baphia nitida (Papilionaceae)

In our search for plants useful in the treatment of diarrhoea, we investigated the ethyl acetate extract of Baphia nitida (BN) using intestinal transit, enteropooling and gastric emptying tests in mice and rats. In the castor oil intestinal transit test, BN produced a significant (P<0.05) dose dependent decrease in propulsion with peristaltic index (PI) values of 56.85+/-6.76, 36.84+/-3.04 and 31.98+/-2.60%, respectively at doses of 100, 200 and 400mg/kg vs. 89.33+/-6.28% for control. The effect at 400mg/kg was significantly lower than that of morphine, 10mg/kg, s.c. (20.29+/-3.78%), and was antagonized by isosorbide dinitrate, IDN (150mg/kg, p.o.) but not by yohimbine (1mg/kg, s.c.). This effect was not potentiated by atropine (1mg/kg, s.c.). In the castor oil-induced diarrhoea test, BN produced a significant increase in onset of diarrhoea (103.40+/-8.74, 138.80+/-17.04 and 174.8+/-29.04min, 100 to 400mg/kg, vs. 47.60+/-8.76min for control and 226.10+/-12.57min for morphine). The severity of diarrhoea (diarrhoea score) was dose dependently reduced (19.00+/-2.26, 17.04+/-1.89, 15.00+/-2.05, 100 to 400mg/kg, vs. 31.40+/-2.11 for control and 7.7+/-2.2 for morphine). This effect was not antagonized by IDN or yohimbine. The effect on severity was, however, potentiated by atropine. BN also reduced the number and weight of wet stools but did not have any significant effect on intestinal fluid accumulation and gastric emptying. Results obtained suggest that the ethyl acetate extract of Baphia nitida is endowed with antidiarrhoeal activity possibly mediated by interference with the l-arginine nitric oxide pathway and synergistic with antagonistic action on muscarinic receptors.

Hepatoprotective and in vivo antioxidant activities of the hydroethanolic leaf extract of Mucuna pruriens (Fabaceae) in antitubercular drugs and alcohol models

AIM Hepatotoxicity is a significantly increasing health problem worldwide, and the extent of the problem has stimulated interest in the search for hepatotherapeutic agents from plants. This study investigated the hepatoprotective and in vivo antioxidant activities of the hydroethanolic extract of Mucuna pruriens leaves in antitubercular and alcohol-induced hepatotoxicity assays in rats. METHOD In each of the models used, seven groups were allotted. The different groups received normal saline (10 mL·kg(-1), p.o.); hepatotoxicant (isoniazid-rifampicin, INH-RIF, 100 mg·kg(-1), i.p. or 20% ethanol 5 g·kg(-1), p.o.) and normal saline (10 mL·kg(-1), p.o.); hepatotoxicant and extract at doses of 100, 200, and 400 mg·kg(-1) p.o.; hepatotoxicant and silymarin 50 mg·kg(-1) p.o.; and extract at 400 mg·kg(-1) p.o. On the 21(st) day of treatment, blood was collected for assessment of serum biochemical parameters and harvested liver samples were assessed for antioxidants. RESULTS The hepatotoxicants significantly (P < 0.05-0.001) increased the levels of alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), bilirubin, and malondialdehyde (MDA); and reduced the levels of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and reduced glutathione GSH compared to control. M. pruriens significantly reversed (P < 0.05-0.001) the elevation in the level of ALT, AST, ALP, and bilirubin caused by the hepatotoxicants. The extract (200 and 400 mg·kg(-1)) significantly reversed (P < 0.05) the diminution in the level of in vivo antioxidants and increased the level of MDA produced by INH-RIF. M. pruriens (100-400 mg·kg(-1)) elicited significant reduction (P < 0.001) in the level of MDA compared to the alcohol group. Silymarin also reversed the deleterious effects of the hepatotoxicants. CONCLUSION The hydroethanolic extract of Mucuna pruriens leaves possesses hepatoprotective activity with enhancement of in vivo antioxidants as a possible mechanism of action.

Hypoglycemic, antilipidemic and antioxidant effects of valproic acid in alloxan-induced diabetic rats

This study was designed to investigate the hypoglycemic, antilipidemic and antioxidant effects of valproic acid (VA) in alloxan-induced diabetic rats. VA (100, 300 and 600mg/kg p.o.) and insulin (17IU/kg s.c.) were administered once daily for 21 days. Fasting blood glucose level was determined at 7 days interval. On day 21, blood samples were collected for assay of serum biochemical parameters (total protein, creatinine, urea, alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), triglycerides (TG), total cholesterol (TC), high density lipoprotein (HDL), and low density lipoprotein (LDL)). Kidneys and livers were harvested for antioxidant indices and histopathological examination. In diabetic rats, VA produced a dose and day-dependent reduction in glucose level. Peak effect (52.79% reduction; P<0.001) was produced at the dose of 600mg/kg on day 21. In normoglycemic rats, VA (600mg/kg) caused significant reduction (P<0.05) in blood glucose level on days 1 and 21 with 16.38% and 15.63% reductions respectively. In diabetic rats, VA significantly reduced the level of catalase (CAT) and malondialdehyde (MDA) in the kidney, and increased the level of superoxide dismutase, CAT and glutathione peroxidase with reduction in MDA in the liver compared to diabetic control, especially at the dose of 600mg/kg. VA (600mg/kg) generally increased the level of HDL and reduced the levels of TG, LDL, TC, AST, ALT, ALP, bilirubin, creatinine and urea compared with diabetic control. The findings in this study suggest that VA possess beneficial antidiabetic effects.

A 90 day chronic toxicity study of Nigerian herbal preparation DAS-77 in rats

BackgroundThe herbal preparation DAS-77, used for the treatment of various ailments in Nigeria, contains the milled bark of Mangifera indica L. and root of Carica papaya L. Toxicological assessment of the preparation was carried out in this study.MethodsIn the acute toxicity study, DAS-77 was administered to mice p.o. up to 20 g/kg in divided doses and i.p. at 250–3000 mg/kg. Mortality within 24 h was recorded. In the chronic toxicity study, rats were treated p.o. for 90 days at doses of 80, 400 (therapeutic dose, TD) and 2000 mg/kg. By 90 days, animals were sacrificed and blood samples collected for hematological and biochemical analysis. Organs were harvested for weight determination, antioxidants and histopathological assessments.ResultsDAS-77 did not produce any lethality administered p.o. up to 20 g/kg in divided doses but the i.p. LD50 was 1122.0 mg/kg. At TD, DAS-77 produced significant (p < 0.05) reductions in body weight, food intake and K+, and increases in ovary weight, neutrophils and HDL, which were reversible. Histopathological presentations were generally normal. Effects at the other doses were comparable to those at TD except for reversible increases in antioxidants in the liver, kidney and testes, and sperm abnormality, and reductions in liver enzymes, sperm motility and count.ConclusionsFindings in this study revealed that DAS-77 is relatively safe with the potential for enhancing in vivo antioxidant activity. However, possibly reversible side-effects include electrolyte imbalance and sterility in males.

Dose and time-dependent sub-chronic toxicity study of hydroethanolic leaf extract of Flabellaria paniculata Cav. (Malpighiaceae) in rodents

Flabellaria paniculata Cav. (Malpighiaceae) is a climbing shrub, the preparations of which are used in the treatment of wounds and ulcers in Nigeria and Ghana. This study investigated the sub-chronic toxicity profile of the hydroethanolic leaf extract of F. paniculata (HLE-FP). HLE-FP was administered p.o. (20, 100, and 500 mg/kg) for 30 and 60 days to different groups of rats. Control animals received 10 ml/kg distilled water. In the group of animals for reversibility study, HLE-FP administration ceased on the 60th day and animals were monitored for a further 15 days. Results showed that oral treatment with HLE-FP for 30 days caused significant (p < 0.05) reductions in weight gain pattern compared to control. These changes were sustained with 60 days treatment. However, no significant (p > 0.05) differences in relative organ weights between control and treatment groups were observed. HLE-FP-treated rats showed significant (p < 0.05) increases in Hb, PCV and RBC on day 30 and significant (p < 0.05) increases in MCV and MCH indices on day 60 compared to control. There were significant (p < 0.05) elevations in serum K+, urea and creatinine compared to control. The liver function tests showed slight but non-significant alterations in relevant parameters when compared to control. Biochemical findings were supported by histopathological observations of vital organs including the kidney and liver. Toxicities observed in respect of kidney function were irreversible at 15 days of stoppage of treatment. In the acute toxicity study, HLE-FP given p.o. caused no lethality at 5000 mg/kg but behavioral manifestations like restlessness, generalized body tremor, feed, and water refusal were observed. The i.p. LD50 was estimated to be 2951.2 mg/kg. Findings in this study showed that HLE-FP is relatively non-toxic on acute exposure and generally safe on sub-chronic administration, but could be deleterious on the kidneys on prolonged oral exposure at a high dose. Thus, caution should be exercised with its long-term usage.