Hypoglycaemic and hypotensive effects of Ficus exasperata vahl. (Moraceae) leaf aqueous extract in rats.

The hypotensive and hypoglycaemic effects of Ficus exasperata (Vahl) (family: Moraceae) leaf aqueous extract (FEE) were investigated in experimental rat models. In this study, spontaneously-hypertensive rats (SHR) (type 1 diabetes), obese Zucker (type 2 diabetes) and Wistar rats were used. Three (A, B and C) groups of rats, each group consisting of 10 rats, were used. Group A Wistar rats received distilled water in quantities equivalent to the volume of streptozotocin (STZ) and FEE administered intraperitoneally to treated rats. Diabetes mellitus was induced in the SHR group B rats by multiple low-dose (MLD) intraperitoneal injections of STZ (40 mg/kg body weight) to induce type 1 diabetes. The animals in group C were the obese Zucker rats with non-insulin-independent diabetes mellitus (NDDM) (type 2 diabetes) on genetic basis. F. exasperata leaf aqueous extract (FEE, 100 mg/kg/day p.o.) was administered orally by orogastric intubation to fasted Groups B and C rats. In groups B and C rats, administration of FEE commenced 4 weeks post STZ injection, and continued for the next 4 consecutive weeks. Group A rats gave normal biochemical and morphological findings. Group B rats exhibited pronounced polyuria, hypoinsulinaemia, hyperlipidaemia and hyperglycaemia. These findings were also observed in group C rats, except that there was hyperinsilinaemia. Histopathological study of the aortic blood vessels showed extensive collagen fiber formation as well as perivascular fibrosis in both groups B and C rats. Four weeks of oral administration of F. exasperata leaf aqueous extract to diabetic groups of rats decreased blood glucose, blood pressure and lipid profiles. Administration of FEE (100 mg/kg p.o.) also restored the microanatomy of the blood vessels to almost normal levels. The findings of this study suggest that F. exasperata leaf aqueous extract possesses hypoglycaemic, hypotensive and hypolipidaemic properties. These findings lend biomedical and pharmacological support to the folkloric, ethnomedical uses of the plant in the management and/or control of diabetes and hypertension among the Yoruba-speaking people of Western Nigeria.

Sclerocarya birrea (A. Rich) Hochst. ['Marula'] (Anacardiaceae): a review of its phytochemistry, pharmacology and toxicology and its ethnomedicinal uses.

A plethora of ethnotherapeutic properties and pharmacological actions have been attributed to Sclerocarya birrea (family: Anacardiaceae). It is one of the most highly valued indigenous trees of southern Africa. Reports in biomedical literature have indicated the presence of medicinally-important chemical constituents in the plant, notably: polyphenols, tannins, coumarins, flavonoids, triterpenoids, phytosterols, and so forth. Pharmacological studies by various groups of investigators have shown that S. birrea possesses antidiarrhoeal, antidiabetic, anti-inflammatory, antimicrobial, antiplasmodial, antihypertensive, anticonvulsant, antinociceptive and antioxidant properties, thus lending pharmacological support to the plant's folkloric, ethnotherapeutic uses in South African traditional medicine. In view of the immense medicinal importance of the plant, this review aimed at compiling all currently available information on S. birrea's chemical constituents, as well as its ethnomedicinal, pharmacological and toxicological properties.

Uterotonic effect of Harpagophytum procumbens DC (Pedaliaceae) secondary root aqueous extract on rat isolated uterine horns.

Some traditional health practitioners of South Africa have claimed that Harpagophytum procumbens DC (family: Pedaliaceae) secondary root is a useful obstetric remedy for induction or acceleration of labour, as well as for expelling retained placentas in pregnant women. In the present study, therefore, we investigated the effect of H. procumbens secondary root aqueous extract (HPE) on longitudinal, tubular uterine horn muscle strips taken from non-pregnant and pregnant, young adult, female rats. HPE (10-800 microg/ml) induced concentration-related and significant (P<0.05) increases in the baseline tone, and caused powerful rhythmic, myogenic contractions of, oestrogen-dominated rat longitudinal uterine horn muscle strips taken from stilboesterol-pretreated, non-pregnant female rats. Relatively low to high concentrations of HPE (10-800 microg/ml) also provoked concentration-dependent and significant (P<0.05-0.001) increases in the baseline tone of, and contracted, longitudinal, tubular uterine horn muscle strips taken from female rats in the early, middle and late stages of pregnancy. Moderate to high concentrations of HPE (200-1,000 microg/ml) always provoked powerful contractions of isolated longitudinal, tubular uterine horn muscle preparations of non-pregnant and pregnant rats. The results of this in vitro study indicate that H. procumbens secondary root aqueous extract possesses spasmogenic, uterotonic action on mammalian uterine muscles. These findings lend pharmacological credence to the suggested folkloric obstetric uses of the plant's secondary root for induction and/or acceleration of labour, as well as for expelling retained placentas in pregnant women.

Bronchorelaxant property of 'African potato' (Hypoxis hemerocallidea corm) aqueous extract in vitro.

This study was undertaken to investigate the bronchorelaxant effect of Hypoxis hemerocallidea corm ('African potato') aqueous extract (APE) on spasmogen-provoked contractions of guinea-pig isolated tracheal smooth muscle preparations. APE (25-400 mg/ml) relaxed spasmogen (histamine-, carbachol- and potassium-)-induced contractions of the isolated tracheal muscle preparations in a concentration-dependent manner. The relaxant effects of APE on spasmogen-evoked contractions of the tracheal muscle preparations were not altered by bath-applied propranolol (0.1-5.0 microg/ml), which markedly inhibited or completely abolished the relaxant effects of isoprenaline (0.1-5.0 microg/ml). Although the precise mechanism of the bronchorelaxant effect of APE could not be established in the present study, it is unlikely that the herb's aqueous extract stimulates the beta(2)-adrenoceptors present on the bronchial smooth muscles to produce its bronchodilatation. The finding that APE significantly relaxed (P<0.05) histamine-, carbachol- and high potassium ion concentration (K(+), 80 mM)-induced contractions of guinea-pig isolated bronchial muscle preparations appears to suggest that the bronchospasmolytic effect of the plant's extract is probably not mediated through a specific receptor, but rather, probably mediated via a non-specific bronchospasmolytic mechanism.

Cardiovascular effects of Ekebergia capensis Sparrm (Meliaceae) ethanolic leaf extract in experimental animal paradigms.

The purpose of this study was to examine the in vivo effects of Ekebergia capensis leaf ethanolic extract (EKE) on the blood pressure of anaesthetised normotensive male Wistar rats and conscious weanling Dahl salt-sensitive (DSS) rats, which develop hypertension as they age. To investigate possible mechanism(s) of the extract's hypotensive effects, the contractile or relaxant responses to EKE in the absence or presence of reference drugs were evaluated in Wistar rat isolated aortic rings precontracted with methoxamine hydrochloride (ME, 10 microM). Acute intravenous administration of EKE elicited hypotensive responses in anaesthetised animals, while sub-chronic treatment with the extract averted the development of high blood pressure in weanling DSS rats. Isometric recordings of methoxamine hydrochloride (ME) pre-contracted, isolated, endothelium-intact and -denuded aortic rings revealed concentration-dependent relaxation responses to EKE (1-160 mg/ml). The potency was significantly less in the endothelium- denuded rings. Inhibitors of endothelium-derived relaxing factor (EDRF), L-NAME, methylene blue and indomethacin significantly reduced EKE-evoked vasorelaxations in endothelium-intact aortic rings. These results indicate that the vasorelaxant effect of EKE was in part mediated via EDRF-dependent or -independent pathways. These observations suggest that the hypotensive effect of EKE was in part mediated via modulation of total peripheral resistance of the vascular smooth muscles.

Spasmolytic effect of Psidium guajava Linn. (Myrtaceae) leaf aqueous extract on rat isolated uterine horns.

Globally, primary dysmenorrhoea is one of the most frequent gynaecological disorders in young women. It is associated with increased uterine tone, and exaggerated contractility of uterine smooth muscles. In many rural African communities, a number of medicinal plants, including Psidium guajava Linn. (family: Myrtaceae), are used traditionally for the management, control and/or treatment of primary dysmenorrhoea. The present study was, therefore, undertaken to examine the spasmolytic effect of Psidium guajava leaf aqueous extract (PGE) on isolated, spontaneously-contracting and oestrogen-dominated, quiescent uterine horns of healthy, young adult, female Wistar rats. Graded, escalated concentrations of PGE (0.5-4.0 mg/ml) produced concentration-dependent and significant inhibitions of the amplitude of spontaneous phasic contractions of the isolated rat uterine horn preparations. In a concentration-related manner, PGE also significantly inhibited or abolished contractions produced by acetylcholine (ACh, 0.5-8.0 microg/ml), oxytocin (0.5-4.0 microU), bradykinin (2.5-10 ng/ml), carbachol (CCh, 0.5-8.0 microg/ml) or potassium chloride (K+, 10-80 mM) in quiescent uterine horn preparations isolated from the oestrogen-dominated rats. The spasmolytic effect of PGE observed in the present study lends pharmacological support to the traditional use of ;guava' leaves in the management, control and/or treatment of primary dysmenorrhoea in some rural African communities.

Antidiarrhoeal activity of Hypoxis hemerocallidea Fisch. & C. A. Mey. (Hypoxidaceae) Corm ('African potato') aqueous extract in rodents.

This study investigated the antidiarrhoeal activity of Hypoxis hemerocallidea corm aqueous extract (APE) on experimentally-induced diarrhoea, gastrointestinal motility, intestinal transit and enteropooling in rodents. H. hemerocallidea corm aqueous extract (APE, 50-400 mg/kg, p.o.) produced dose-dependent and significant (p < 0.05-0.01) protection of rats and mice against castor oil-induced diarrhoea, inhibited intestinal transit and delayed gastric emptying. Like atropine (1 mg/kg, p.o.), APE (50-400 mg/kg, p.o.) produced dose-dependent and significant (p < 0.05-0.01) antimotility effect, and caused dose-related inhibition of castor oil-induced enteropooling in the animals. Like loperamide (10 mg/kg, p.o.), APE (50-400 mg/kg, p.o.) dose-dependently and significantly (p < 0.05-0.01) delayed the onset of castor oil-induced diarrhoea, decreased the frequency of defaecation and reduced the severity of diarrhoea in the rodents. Compared with control animals, APE (50-400 mg/kg, p.o.) dose-dependently and significantly (p < 0.05-0.01) decreased the volume of castor oil-induced intestinal fluid secretion, and reduced the number, weight and wetness of faecal droppings. APE (50-400 mg/mL) also produced concentration-related and significant (p < 0.05-0.01) inhibitions of the spontaneous, pendular contractions of the rabbit isolated duodenum, and attenuated acetylcholine (ACh, 0.1-5.0 microg/mL)-induced contractions of the guinea-pig isolated ileum. Although the precise mechanism of the antidiarrhoeal activity of APE could not be established, the results of this study indicate that APE possesses antidiarrhoeal activity. This finding supports the use of 'African potato' as a natural supplementary remedy for the treatment, management and/or control of diarrhoea in some rural communities of southern Africa.

Hypoglycaemic effect of mollic acid glucoside, a 1alpha-hydroxycycloartenoid saponin extractive from Combretum molle R. Br. ex G. Don (Combretaceae) leaf, in rodents.

In this study, we investigated the hypoglycaemic and antidiabetic properties of mollic acid glucoside (MAG), a 1alpha-hydroxycycloartenoid extractive from Combretum molle leaf, in rodents. Stepwise, escalated doses of MAG (5-80 mg/kg p.o.) produced dose-dependent and significant (P < 0.05-0.01) hypoglycaemic and antidiabetic effects in normal (normoglycaemic) and streptozotocin-treated diabetic rats. Experimental evidence obtained from this laboratory animal study indicates that MAG, an extractive from C. molle leaf, possesses hypoglycaemic and antidiabetic properties. These findings lend pharmacological credence to the folkloric, ethnomedical uses of the plant's leaf in the management and/or control of diabetes mellitus in some rural communities of southern Africa.

'African potato' (Hypoxis hemerocallidea corm): a plant-medicine for modern and 21st century diseases of mankind? - a review.

The traditional uses, therapeutic attributes, phytochemical and pharmacological profiles of 'African potato' (Hypoxis hemerocallidea corm) extracts have been reviewed. Available biomedical evidence suggests that 'African potato' is a potential plant-medicine for some modern and 21st century diseases of mankind. Thus far, biomedical evidence has revealed that 'African potato' extracts possess antiinflammatory, antineoplastic, antioxidant, antidiabetic and antiinfective properties in vivo and in vitro. However, more laboratory and clinical studies are required to clarify these observations, and to isolate, purify and characterize the active chemical constituents responsible for the herb's pharmaco-therapeutic effects.

Cardiovascular effects of Helichrysum ceres S Moore [Asteraceae] ethanolic leaf extract in some experimental animal paradigms.

The aim of this study was to examine some in vivo and in vitro cardiovascular effects of Helichrysum ceres leaf ethanolic extract (HCE) in experimental animal paradigms. The acute effects of HCE on blood pressure were studied in anaesthetised normotensive male Wistar rats challenged with intravenous hypotonic saline infusion after a 3.5-hour equilibration for four hours of one-hour control, 1.5-hour treatment and 1.5-hour recovery periods. HCE was added to the infusate during the treatment period. Sub-chronic hypotensive effects of HCE were examined in weanling Dahl saltsensitive (DSS) genetically hypertensive rats, which progressively develop hypertension with age, treated with HCE (80 mg/kg) every third consecutive day for seven weeks. Isolated atrial muscle strips, portal veins and descending thoracic aortic rings of healthy normotensive Wistar rats were used to investigate the vascular effects of HCE. Acute HCE administration caused a significant (p < 0.05) fall in blood pressure in the normotensive anaesthetised Wistar rats. DSS hypertensive rats treated with HCE displayed low arterial blood pressure and heart rate values from weeks five to seven. HCE produced concentrationdependent negative inotropic and chronotropic effects on rat isolated electrically driven left, and spontaneously beating right atrial muscle preparations, respectively. HCE also evoked concentration-dependent relaxation responses of endothelium-intact aortic rings and portal veins isolated from healthy normotensive Wistar rats. The vasorelaxant effects of HCE in intact aortic rings were significantly reduced, but not completely abolished by adding endothelial- derived factor (EDRF) inhibitor, L-NAME, suggesting that the vasorelaxant effect of the extract is mediated via EDRF-dependent and independent mechanisms. The results of the study suggest that the hypotensive action of HCE is elicited, in part, directly by decreasing myocardial contractile performance and total peripheral vascular resistance due to its negative inotropic and chronotropic effects on rat isolated atrial muscle strips; and vasorelaxant effects on isolated vascular smooth muscles. The observed cardiovascular effects of HCE partly support the basis for its use in the management of high blood pressure in folkloric medicine.

Anticonvulsant effect of Rhus chirindensis (Baker F.) (Anacardiaceae) stem-bark aqueous extract in mice.

Extracts of Rhus chirindensis stem-bark are used extensively in South African traditional medicines for the treatment, management and/or control of an array of human ailments, including childhood convulsions and epilepsy. In this study, we investigated the anticonvulsant activity of the plant's stem-bark aqueous extract (RCE, 50-800 mg/kg i.p.) against pentylenetetrazole (PTZ)-, picrotoxin (PCT)- and bicuculline (BCL)-induced seizures in mice. Phenobarbitone and diazepam were used as reference anticonvulsant drugs for comparison. Single intraperitoneal injections of PTZ (90 mg/kg), PCT(10 mg/kg) or BCL (30 mg/kg) produced tonic-clonic seizures. Like the standard antiseizure drugs used, Rhus chirindensis stem-bark aqueous extract (RCE, 100-800 mg/kg i.p.) significantly delayed (p<0.05-0.001) the onset of, and antagonized pentylenetetrazole-induced seizures. The plant's stem-bark aqueous extract (RCE, 100-800 mg/kg i.p.) also profoundly antagonized picrotoxin-induced seizures, but only weakly antagonized bicuculline-induced seizures. Although the data obtained in the present study do not provide conclusive evidence, it would appear that RCE produces its antiseizure effect by enhancing GABAergic neurotransmission and/or action in the brain. The results of this laboratory animal study indicate that RCE possesses anticonvulsant activity in the mammalian experimental model used, and thus suggest that the plant may be used as a natural supplementary remedy in the management, control and/or treatment of childhood convulsions and epilepsy. In conclusion, the findings of this study lend pharmacological credence to the suggested folkloric, ethnomedical uses of Rhus chirindensis in the management of childhood convulsions and epilepsy in some rural communities of South Africa.

Protective effects of Annona muricata Linn. (Annonaceae) leaf aqueous extract on serum lipid profiles and oxidative stress in hepatocytes of streptozotocin-treated diabetic rats.

Extracts from various morphological parts of Annona muricata Linn. (Annonaceae) are widely used medicinally in many parts of the world for the management, control and/or treatment of a plethora of human ailments, including diabetes mellitus (DM). The present study was undertaken to investigate the possible protective effects of A. muricata leaf aqueous extract (AME) in rat experimental paradigms of DM. The animals used were broadly divided into four (A, B, C and D) experimental groups. Group A rats served as 'control' animals and received distilled water in quantities equivalent to the administered volumes of AME and reference drugs' solutions intraperitoneally. Diabetes mellitus was induced in Groups B and C rats by intraperitoneal injections of streptozotocin (STZ, 70 mg kg(-1)). Group C rats were additionally treated with AME (100 mg kg(-1) day(-1), p.o.) as from day 3 post STZ injection, for four consecutive weeks. Group D rats received AME (100 mg kg(-1) day(-1) p.o.) only for four weeks. Post-euthanization, hepatic tissues were excised and processed biochemically for antioxidant enzymes and lipid profiles, such as catalase (CAT), reactive oxygen species (ROS), glutathione (GSH), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), thiobarbituric acid reactive substances (TBARS), triglycerides (TG), total cholesterol (TC), high density lipoprotein (HDL) and low density lipoprotein (LDL), respectively. Treatment of Groups B and C rats with STZ (70 mg kg(-1) i. p.) resulted in hyperglycaemia, hypoinsulinaemia, and increased TBARS, ROS, TC, TG and LDL levels. STZ treatment also significantly decreased (p<0.05) CAT, GSH, SOD, GSH-Px activities, and HDL levels. AME-treated Groups C and D rats showed significant decrease (p<0.05) in elevated blood glucose, ROS, TBARS, TC, TG and LDL. Furthermore, AME treatment significantly increased (p<0.05) antioxidant enzymes' activities, as well as serum insulin levels. The findings of this laboratory animal study suggest that A. muricata extract has a protective, beneficial effect on hepatic tissues subjected to STZ-induced oxidative stress, possibly by decreasing lipid peroxidation and indirectly enhancing production of insulin and endogenous antioxidants.

Anticonvulsant activity of Hypoxis hemerocallidea Fisch. & C. A. Mey. (Hypoxidaceae) corm ('African potato') aqueous extract in mice.

Extracts of Hypoxis hemerocallidea Fisch. & C. A. Mey. (Hypoxidaceae) corm (popularly known as 'African potato') are extensively used in South African traditional medicines for the treatment, management and/or control of an array of human ailments, including childhood convulsions and epilepsy. This study examined the anticonvulsant activity of the plant's corm aqueous extract (APE, 50-800 mg/kg i.p.) against pentylenetetrazole (PTZ)-, picrotoxin (PCT)- and bicuculline (BCL)-induced seizures in mice. Phenobarbitone and diazepam were used as reference anticonvulsant drugs for comparison. Like the reference antiseizure drugs used, Hypoxis hemerocallidea corm aqueous extract (APE, 100-800 mg/kg i.p.) significantly delayed (p < 0.05-0.001) the onset of, and antagonized, pentylenetetrazole (PTZ)-induced seizures. The plant's corm aqueous extract (APE, 100-800 mg/kg i.p.) also profoundly antagonized picrotoxin (PCT)-induced seizures, but only weakly antagonized bicuculline (BCL)-induced seizures. Although the data obtained in the present study do not provide conclusive evidence, it would appear that 'African potato' aqueous extract (APE) produces its antiseizure effect by enhancing GABAergic neurotransmission and/or action in the brain. The results of this laboratory animal study indicate that APE possesses anticonvulsant activity in the mammalian experimental model used and, therefore, tend to suggest that the herb may be used as a natural supplementary remedy in the management, control and/or treatment of childhood convulsions and epilepsy. In conclusion, the findings of this study indicate that Hypoxis hemerocallidea corm aqueous extract possesses anticonvulsant activity, and thus lend pharmacological credence to the suggested folkloric, anecdotal ethnomedical uses of the herb in the management of childhood convulsions and epilepsy in some rural communities of South Africa.

Analgesic and antiinflammatory effects of mollic acid glucoside, a 1 alpha-hydroxycycloartenoid saponin extractive from Combretum molle R. Br. ex G. Don (Combretaceae) leaf.

The analgesic and antiinflammatory properties of mollic acid glucoside (MAG), a 1 alpha-hydroxycycloartenoid extract from Combretum molle leaf, have been investigated in mice and rats. The effects of graded doses of mollic acid glucoside (MAG, 5-80 mg/kg i.p.) were examined against thermally- and chemically-induced nociceptive pain in mice. Furthermore, the effects of graded doses of the plant extract (MAG, 5-80 mg/kg p.o.) were also investigated on rat paw oedema induced by subplantar injections of fresh egg albumin (0.5 mg/kg). Morphine (MPN, 10 mg/kg i.p.) and diclofenac (DIC, 100 mg/kg i.p.) were used as reference analgesic and antiinflammatory agents for comparison, respectively. Like DIC (100 mg/kg i.p.) and MPN (10 mg/kg i.p.), MAG (5-80 mg/kg i.p.) produced dose-dependent, significant (p < 0.05-0.001) analgesic effects against thermally and chemically induced nociceptive pain in mice. The extractive (MAG, 5-80 mg/kg i.p.) also significantly reduced (p < 0.05-0.001) rat paw oedema induced by subplantar injections of fresh egg albumin in a dose-related fashion. However, the extract (MAG, 5-80 mg/kg i.p.) was found to be less potent than diclofenac (DIC) as an analgesic or antiinflammatory agent. Experimental evidence obtained from this laboratory animal study indicates that the Combretum molle leaf extractive (MAG) possesses analgesic and antiinflammatory properties, and thus lend pharmacological credence to the folkloric, ethnomedical uses of the plant's leaf in the management, control and/or treatment of painful, arthritic and other inflammatory conditions in some rural communities of southern Africa.

Anticonvulsant property of Sutherlandia frutescens R. BR. (variety Incana E. MEY.) [Fabaceae] shoot aqueous extract.

Aerial parts of Sutherlandia frutescens R. BR. [family: Fabaceae] are extensively used in South African traditional medicines for the treatment, management and/or control of an array of human ailments, including childhood convulsions and epilepsy. In this study, we examined the anticonvulsant property of the plant's shoot aqueous extract (SFE, 25-400 mg/kg i.p.) against pentylenetetrazole (PTZ)-, picrotoxin (PCT)- and bicuculline (BCL)-induced seizures in mice. Phenobarbitone and diazepam were used as reference anticonvulsant drugs for comparison. Like the reference antiseizure drugs used, S. frurescens shoot aqueous extract (SFE, 50-400 mg/kg i.p.) significantly delayed (p<0.05-0.001) the onset of, and antagonized, pentylenetetrazole (PTZ)-induced seizures. The plant's shoot aqueous extract (SFE, 50-400 mg/kg i.p.) also profoundly antagonized picrotoxin (PCT)-induced seizures, but only weakly antagonized bicuculline (BCL)-induced seizures. Although the data obtained in the present study do not provide conclusive evidence, it appears that S. frurescens shoot aqueous extract (SFE) produces its antiseizure effect directly by acting like GABA, or indirectly by enhancing GABAergic neurotransmission and/or action in the brain. The results of this laboratory animal study suggest that the herb may be used as a natural supplementary remedy in the management, control and/or treatment of childhood convulsions and epilepsy. In conclusion, the findings of this study indicate that S. frurescens shoot aqueous extract possesses anticonvulsant activity, and thus lend pharmacological credence to the suggested folkloric, ethnomedical uses of the herb in the management or treatment of childhood convulsions and epilepsy in some rural communities of South Africa.

Antidiarrhoeal activity of Psidium guajava Linn. (Myrtaceae) leaf aqueous extract in rodents.

The leaf of Psidium guajava Linn. (family: Myrtaceae) is used traditionally in African folk medicine to manage, control and/or treat a plethora of human ailments, including diarrhoea. In this study, we examined the antidiarrhoeal activity of Psidium guajava leaf aqueous extract (PGE) on experimentally-induced diarrhoea in rodents. PGE (50-400 mg/kg p.o.) produced dose-dependent and significant (P<0.05-0.01) protection of rats and mice against castor oil-induced diarrhoea, inhibited intestinal transit, and delayed gastric emptying. Like atropine (1 mg/kg, p.o.), PGE produced dose-dependent and significant (P<0.05-0.01) antimotility effect, and caused dose-related inhibition of castor oil-induced enteropooling in the animals. Like loperamide (10 mg/kg, p.o.), PGE dose-dependently and significantly (P<0.05-0.01) delayed the onset of castor oil-induced diarrhoea, decreased the frequency of defaecation, and reduced the severity of diarrhoea in the rodents. Compared with control animals, PGE dose-dependently and significantly (P<0.05-0.01) decreased the volume of castor oil-induced intestinal fluid secretion, and reduced the number, weight and wetness of faecal droppings. PGE also produced concentration-related and significant (P<0.05-0.01) inhibitions of the spontaneous, rhythmic, pendular contractions of the rabbit isolated duodenum. The findings of this study indicate that PGE possesses antidiarrhoeal activity, and thus lend pharmacological credence to the suggested folkloric use of the plant as a natural remedy for the treatment, management and/or control of diarrhoea in some rural communities of southern Africa.

Biphasic effect of Psidium guajava Linn. (Myrtaceae) leaf aqueous extract on rat isolated vascular smooth muscles.

In this study, we examined the effects of Psidium guajava Linn. leaf aqueous extract (PGE) on isolated, spontaneously-contracting portal veins, as well as on endothelium-intact and endothelium-denuded descending thoracic aortic ring preparations of healthy, normotensive rats. Graded concentrations of PGE (0.25-4.0 mg/ml) caused concentration-dependent, initial brief but significant (P<0.05) rises of the basal tones and amplitudes of pendular, rhythmic contractions, followed by secondary pronounced, longer-lasting and significant (P<0.05-0.001) inhibitions of contractile amplitudes of the isolated portal veins. Relatively low concentrations of PGE (<1.0 mg/ml) always contracted freshly-mounted, naïve, endothelium-intact aortic ring preparations. However, relatively high concentrations of PGE (1.0-4.0 mg/ml) always produced initial brief contractions/augmentations of noradrenaline (NA, 10(-7)M)-induced contractions of endothelium-intact and endothelium-denuded aortic ring preparations, followed by secondary, pronounced relaxations of the aortic ring muscles. Moreover, relatively high concentrations of PGE (1.0-4.0 mg/kg) always relaxed NA-induced contractions of the aortic ring preparations in a concentration-related manner. The arterial-relaxing effects of PGE were more pronounced in endothelium-intact aortic rings than in endothelium-denuded aortic ring preparations. The relaxant effects of PGE on endothelium-intact aortic rings were only partially inhibited by N(G)-nitro-L-arginine methyl ester (L-NAME, 100 microM), a nitric oxide synthase inhibitor, suggesting that the vasorelaxant effect of PGE on aortic rings is probably mediated via both endothelium-derived relaxing factor (EDRF)-dependent and EDRF-independent mechanisms. Taken together, the findings of this study indicate that PGE possesses a biphasic effect on rat isolated vascular smooth muscles.

Uterolytic effect of Hypoxis hemerocallidea Fisch. & C.A. Mey. (Hypoxidaceae) corm [;African Potato'] aqueous extract.

Extracts of Hypoxis hemerocallidea corm (African potato) are commonly used by some traditional health practitioners in KwaZulu-Natal Province of South Africa as natural antenatal remedy to prevent threatening or premature abortion and miscarriage, and to ensure successful confinement. In this study, we investigated the uterolytic activity of H. hemerocallidea corm aqueous extract on spontaneous, rhythmic contractions of uterine horns taken from pregnant rats and guinea-pigs, as well as on spasmogen-provoked contractions of stilboesterol-primed, oestrogen-dominated, non-pregnant rat and guinea-pig isolated uterine horns. Relatively low to high concentrations of H. hemerocallidea corm aqueous extract (APE, 25-400 mg/ml) inhibited the amplitude of the spontaneous, rhythmic contractions of, and relaxed, uterine horns isolated from pregnant rats and guinea-pigs in a concentration-related manner. Furthermore, relatively low to high concentrations of APE (25-400 mg/ml) relaxed basal tones of uterine horns taken from non-pregnant, oestrogen-dominated rats and guinea-pigs in a concentration-dependent manner. The same moderately low to high concentrations of APE (25-400 mg/ml) inhibited acetylcholine-, oxytocin-, bradykinin-, and potassium chloride (K(+))-induced contractions of oestrogen-dominated rat and guinea-pig isolated uterine horns in a concentration-related manner. Although the mechanism of uterolytic action of APE could not be established, the results of the present study lend pharmacological credence to the folkloric, ethnomedical uses of APE as a natural antenatal remedy for threatening or premature abortion, and suggest that the uterolytic action of the corm's extract is unlikely to be mediated via beta(2)-adrenoceptor stimulation, but probably mediated through a non-specific spasmolytic mechanism.

Analgesic, anti-inflammatory and hypoglycaemic effects of Rhus chirindensis (Baker F.) [Anacardiaceae] stem-bark aqueous extract in mice and rats.

In an attempt to scientifically evaluate some of the anecdotal, folkloric, ethnomedical uses of Rhus chirindensis Baker F. ('red currant'), the present study was undertaken to investigate the analgesic, anti-inflammatory and hypoglycaemic effects of the plant's stem-bark aqueous extract (RCE) in mice and rats. The analgesic effect of RCE was evaluated by 'hot-plate' and 'acetic acid' analgesic test methods in mice; while its anti-inflammatory and hypoglycaemic effects were investigated in rats, using fresh egg albumin-induced pedal oedema, and streptozotocin (STZ)-induced diabetes mellitus animal models. Morphine (MPN, 10 mg/kg), diclofenac (DIC, 100 mg/kg) and chlorpropamide (250 mg/kg) were used as reference drugs for comparison. RCE (50-800 mg/kg i.p.) produced dose-dependent, significant (P<0.05-0.001) analgesic effects against thermally- and chemically-induced nociceptive pain in mice. The plant's extract (RCE, 50-800 mg/kg p.o.) also significantly (P<0.05-0.001) inhibited fresh egg albumin-induced acute inflammation, and caused dose-related, significant (P<0.05-0.001) hypoglycaemia in normal (normoglycaemic) and diabetic (hyperglycaemic) rats. The flavonoids, triterpenoids and other chemical compounds present in RCE are speculated to account for the observed pharmacological effects of the plant's extract in the experimental animal paradigms used. The findings of this experimental animal study indicate that Rhus chirindensis stem-bark aqueous extract possesses analgesic, anti-inflammatory and hypoglycaemic properties; and thus lend pharmacological credence to the anecdotal, folkloric, ethnomedical uses of the plant in the treatment and/or management of painful, arthritic, inflammatory conditions, as well as in the management and/or control of type 2 diabetes mellitus in some rural communities of South Africa.