Leaf Extract Of Ocimum Gratissimum Research Articles

Acid buffering effects of aqueous leaf extract of Ocimum gratissimum L. in the rabbit stomach

Although the gastroprotective properties of Ocimum gratissimum L. have been mentioned, the exact mechanism is yet to be explored. Since acid output plays a significant role in the pathogenesis of gastric ulceration, the present study was aimed at investigating the effect of leaf extract of Ocimum gratissimum on gastric luminal pH, acid output, parietal cell mass and gastric mucous cell population in rabbits. The model of pyloric ligation for acid secretion and ulcer study was employed. Prior to the 4 h ligation, male New Zealand rabbits were treated orally with 75 mg/kg, 150 mg/kg and 250 mg/kg b.w aqueous leaf extract of Ocimum gratissimum twice daily for three weeks. The antisecretory and antiulcer effect of Ocimum gratissimum was compared with omeprazole (20 mg/kg p.o). Parietal cell mass and gastric mucous cell population were determined in the gastric samples by histometry. Aqueous leaf extract of Ocimum gratissimum caused significant reduction in ulcer formation, gastric secretion volume and acid output in a dose dependent manner (p<0.05). Percentage inhibition was recorded as 29%, 46.2%, 52.9% for ulcer; and 16.2%, 35.9%, 52.1% for acid output upon pretreatment with 75 mg/kg, 150 mg/kg and 250 mg/kg b.w respectively. Parietal cell mass was also reduced while gastric mucous cell population and luminal pH increased accordingly when compared to the control group. Data were comparable with the antisecretory effect of omeprazole. The results indicate that the anti-secretory activity of Ocimum gratissimum may be the anti-ulcer mechanism of this plant.

Establishing a preliminary basis for the use of &lt;i&gt;Ocimum gratissimum&lt;/i&gt; in the traditional management of haemorrhoids

The ethanolic leaf extract of Ocimum gratissimum was tested for anti-inflammatory, analgesic and muscle relaxant properties following reports of its use in the traditional management of haemorrhoids. The isolated rabbit jejunum and phrenic nerve-diaphragm preparations were used to screen for smooth and skeletal muscle relaxant effects respectively. Anti-inflammatory and analgesic activities were evaluated using rat-paw oedema method and hot plate methods respectively. The results show that the crude extract (2.0 x 10-4 – 3.2 x 10-3g/ml) inhibited both the twitch responses to nerve stimulation and the rhythmic contractility of the rabbit jejunum in a graded manner. The extract (100-1000mg/kg) also dose-dependently inhibited egg white-induced increase in rat paw oedema and prolonged the reaction time of mice subjected to thermal stimuli. The study suggests a scientific basis for the use of Ocimum gratissimum in the traditional management of haemorrhoids. Keywords : Ocimum gratissimum, haemorrhoids, anti-inflammatory, analgesic

Ocimum Gratissimum Alleviates Derangements in Serum and Biliary Bilirubin, Cholesterol and Electrolytes in Streptozotocin- Induced Diabetic Rats

Aims: The effects of oral administration of aqueous leaf extract of Ocimum gratissimum (OG) on biliary and serum bilirubin, cholesterol and electrolytes in streptozotocin (STZ)induced diabetic Albino Wistar rats was studied. Methodology: Type 1 Diabetes mellitus was induced in the test groups (DM and DMT) by a single dose of STZ (65 mg/kg, i.p.). The phytoconstituents and median lethal dose of the plant extract was determined before administration. The extract was administered per oral to the DMT group at a dose of 1500 mg/kg body weight daily for 28 days. All the groups were fed normal rat chow and allowed water ad libitum. Biliary secretion was collected and assayed, biliary bilirubin was measured by colorimetric method, Sodium and potassium was determined using a flame photometer and Chloride was determined by end point calorimetric titration. Research Article

Methanolic crude leaf extract of Ocimum gratissimum reverses phenylhydrazine-induced anemia in albino wistar rats

Background: The therapeutic and culinary applications of Ocimum gratissimum leaf have been practiced in Central and West Africa for decades. This study was designed and conducted to investigate the haematinic and haemopoietic activities of phenylhydrazine-induced anaemia in Albino wistar rats. Materials and Methods: Twenty-four (24) Albino wistar rats were grouped into four (A, B, C and D) with six rats per cage. Groups B, C and D served as the test groups, while group A was the control. The test groups were gavaged with graded doses (4, 8 and 12mg/kg body weight respectively) of Ocimum gratissimum methanolic crude leaf extract once daily for 9 days. Two (2) mls of venous blood was collected from the ocular plexus from each animal into tripotassium ethylene diamine tetra-acetic acid anticoagulant bottle. This was used to determine complete blood count using automated haematology autoanalyzer (Sysmex KX-21N). Results: Red blood cell (RBC) mean value recorded a dose and duration-related statistically significant decrease (P < 0.05) in group D on day 3. However, there was statistically significant increase (P < 0.05) in the RBC indices. In addition, total white blood cell (WBC) recorded a marginal increase in the mean values throughout the study period though not statistically significant (P > 0.05). Furthermore, lymphocyte recorded both dose and duration-related statistically significant increase (P < 0.01). Conclusion: From the result of this study, it can be concluded that the methanolic crude leaf extract of Ocimum gratissimum possesses both haemopoetic and haematinic potentials which are dose and duration-related.

Determination of the Antibacterial Effects of Prunus amygdalinus (Almond Leaf) and Ocimum Gratissimum (Basil Leaf) on Selected Bacteria

antimicrobial acts of leaf extracts of Ocimumgratissimum and Prunusamygdalinus were checked on Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi using agar cup plate method. The outcomes demonstrated that the chosen organisms were susceptible to the plant extracts at concentrations of 500mg, 50mg and 5mg respectively with diameter zone of inhibition (DZI) of about 12.00± 2.00, 13.00± 2.00, 11.60±3.40, and 12.30±3.30. Phytochemical screening of the leaf extract of Ocimumgratissimum manifested the existence of alkaloid, phenols, glycosides, saponin, steroids and triterpenes while the leaf extract of Prunusamygadalinus demonstrated the existence of saponin, flavonoid and triterpenes. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assayed reveals MIC of 5mg and MBC of 50mg respectively. Ocimumgratissimum and Prunusamygdalinus extracts may be applied to treat disorder caused by these organisms.

Effect of Methanolic Leaf Extract of Ocimum gratissimum (Linn) Leaves on Sodium Arsenite-Induced Toxicity in Rats

Natural plant products are considered as possible protective agents against arsenite induced toxicity. Effects of methanolic leaf extract of Ocimum gratissimum were investigated in sodium arsenite exposed rats. Animals were randomly divided into four groups of five per group. Group A (control), Group B (sodium arsenite alone), Group C (extract and sodium arsenite) and Group D (extract only). Rats were orally pretreated with 100 mg kg-1 b.wt. extract for 14 days while 2.5 mg kg-1 b.wt. arsenite was administered intraperitoneally on the 14th day and animals were sacrificed after 24 h. Plasma Alanine Amino Transferase (AL T), Alkaline Phosphatase (ALP) and Gamma Glutamyl Transferase (GGT) were evaluated. Hepatic lipid peroxidation as Malondialdehyde (MDA) and reduced Glutathione (GSH) levels were also assessed. Introduction of sodium arsenite in rats triggered significant increases in plasma ALT, ALP and GGT (p<0.05) levels. Significant increase (p<0.05) in hepatic MDA concentration and depletion in GSH level were obtained. The methanolic leaf extract with arsenite modulated the activities of ALT, ALP and GGT to their normal levels. The extract reversed sodium arsenite-induced decrease in hepatic GSH to their normal levels while significant effect on hepatic MDA level was not observed. Group treated with the extract alone showed no adverse effects on the parameters. The properties exhibited by the extract may be due to the presence of certain bioactive compounds in it. The results obtained from this study underpin the importance offurther research to obtain bioactive substance from the leaf of Ocimum gratissimum.

Oral Administration of Aqueous Leaf Extract of Ocimum Gratissimum Ameliorates Polyphagia, Polydipsia and Weight Loss in Streptozotocin-Induced Diabetic Rats

The effects of oral administration of aqueous leaf extract of Ocimum gratissimum (OG) on food, water intake and weight changes in streptozotocin (STZ)-induced diabetic Albino Wistar rats was studied. Eighteen rats were randomly assigned into 3 groups of 6 rats each for control, diabetic (DM) and diabetic-treated (DMT) groups. Diabetes mellitus was induced in the test groups (DM and DMT) by a single dose of STZ (65 mg/kg, i.p.). The extract was administered per oral to the DMT group at a dose of 1500 mg/k body weight daily for 28 days. All the groups were fed normal rat chow and allowed water freely. The fasting blood glucose levels in the DM and DMT groups were higher (P<0.001) than the control group, with the DMT group lower (P<0.01) than the DM group. There was a significant (P<0.05) loss of body weight in the DM group compared to the control (P<0.01) and DMT (P<0.05) groups. There was an increase (P<0.01) in volume of water taken by the test groups compared to the control. The water intake in DMT group was lower (P<0.01) than the DM group. The food intake in the DM group was greater (P<0.001) than the control and DMT groups, with the later higher (P<0.05) than the control group. We therefore conclude that Ocimum gratissimum reduces blood sugar level in STZ-induced diabetic rats and alleviates the cardinal symptoms of diabetes mellitus namely; polydypsia, polyphagia and weight loss.

Effects of aqueous leaf extract of Ocimum gratissimum on oral glucose tolerance test in type-2 model diabetic rats

Preliminary studies have reported hypoglycaemic effects of leaf extracts of Ocimum gratissimum in type-1 diabetic animal models. However, the mechanism of its antihyperglycaemic activity remains unknown. To shed more light on this activity, we decided to investigate the efficacy of the extract in type-2 model diabetic rats, for which few reliable data are currently available. The results from this study show that aqueous extract of O. gratissimum leaf can significantly reduce postprandial hyperglycaemia in type-2 diabetic model rats, but without the risk of hypoglycemia. This property makes it potentially useful in type-2 diabetes human subjects with insulin resistance who are prone to high postprandial glucose surge. Key words: Streptozotocin, hyperglycaemia, neonatal rat, type-2 diabetes, Ocimum gratissimum.

Antiplasmodial potential of medicinal plant extracts from Malaiyur and Javadhu hills of South India

The emergence and spread of Plasmodium falciparum with resistance to chloroquine (CQ), the safest and cheapest anti-malarial drug, coupled with the increasing cost of alternative drugs especially in developing countries have necessitated the urgent need to tap the potential of plants for novel anti-malarials. The present study investigates the anti-malarial activity of the methanolic extracts of 13 medicinal plants from the Malaiyur and Javadhu hills of South India against blood stage CQ-sensitive (3D7) and CQ-resistant (INDO) strains of P. falciparum in culture using the fluorescence-based SYBR Green I assay. Sorbitol-synchronized parasites were incubated under normal culture conditions at 2% hematocrit and 1% parasitemia in the absence or presence of increasing concentrations of plant extracts. CQ and artemisinin were used as positive controls, while 0.4% DMSO was used as the negative control. The cytotoxic effects of extracts on host cells were assessed by functional assay using HeLa cells cultured in RPMI containing 10% fetal bovine serum, 0.21% sodium bicarbonate and 50 μg/mL gentamycin (complete medium). Plant extracts (bark methanol extracts of Annona squamosa (IC(50), 30 μg/mL), leaf extracts of Ocimum gratissimum (IC(50), 32 μg/mL), Ocimum tenuiflorum (IC(50), 31 μg/mL), Solanum torvum (IC(50), 31 μg/mL) and Justicia procumbens (IC(50), 63 μg/mL), showed moderate activity. The leaf extracts of Aristolochia indica (IC(50), 10 μg/mL), Cassia auriculata (IC(50), 14 μg/mL), Chrysanthemum indicum (IC(50), 20 μg/mL) and Dolichos biflorus (IC(50), 20 μg/mL) showed promising activity and low activity was observed in the flower methanol extracts of A. indica , leaf methanol extract of Catharanthus roseus, and Gymnema sylvestre (IC(50), >100 μg/mL). These four extracts exhibited promising IC(50) (μg/mL) of 17, 24, 19 and 24 respectively also against the CQ resistant INDO strain of P. falciparum. The high TC(50) in mammalian cell cytotoxicity assay and the low IC(50) in anti-malarial P. falciparum assay indicates selectivity and good resistance indices in the range of 0.9-1.7 for leaf extracts of A. indica, C. auriculata, C. indicum and D. biflorus suggests that these may serve as anti-malarial agents even in their crude form. These results indicate a possible explanation of the traditional use of some of these medicinal plants against malaria or malaria-like conditions.

The Effects of Aqueous Ocimum gratissimum Leaf Extract on Some Biochemical and Hematological Parameters in Male Mice

The Effects of Aqueous Ocimum gratissimum Leaf Extract on Some Biochemical and Hematological Parameters in Male Mice

Abstract 1888: Ocimum gratissimum: a novel natural inhibitor of Matrix Metalloproteases

Abstract Ocimum sp. (a.k.a. holy basil or tulsi), exhibits chemo-preventive, anti-carcinogenic, free radical scavenging, radio-protective and numerous other pharmacological properties, and has therefore, been one of the most popular herbs used in Asian and European countries for the treatment of various ailments since ancient times. Extract of Ocimum gratissimum (OG) inhibits proliferation, migration, anchorage-independent growth, three-dimensional growth and morphogenesis, and induction of COX-2 protein in breast cancer cells. In addition, OG extracts also reduced tumor size and neoangiogenesis in a MCF10A DCIS.com xenograft model of human DCIS, suggesting that OG leaf extract may be of value as a breast cancer preventive and therapeutic agent. In an effort to identify the biological target of OG activity, we observed that the aqueous extract of OG inhibited the cleavage of galectin-3 in in vitro conditions. Galectin-3 is a carbohydrate-binding tumor-associated protein containing a collagen-alpha like domain, which is cleavable by Matrix-metalloproteases-2 and −9. We questioned whether the inhibition of galectin-3 cleavage by OG is due to the inhibition of enzymatic activity of MMPs, or the interactions between the MMPs and galectin-3. MCF10AT1, MCF10A and MCF10AEIII8 cells were incubated with various concentrations of the extract and the conditioned media were analyzed for galectin-3 cleavage as well as the gelatinolytic activity by gelatin zymography. The results showed an inhibition of galectin-3 cleavage in the treated cells, but no differences in the MMP activities between the treated and the untreated cells were observed in the zymogram. Next, we performed the gelatin zymography on the recombinant MMP-2 and −9 and incubated the gel with the extract. An inhibition of the gelatinolytic activity was observed in the treated gel. A dose dependent decrease in the MMP-2 and −9 activity was also observed when a fluorogenic peptide, MOCAcPLGLA2pr(Dnp)AR-NH2 was used as a substrate. Furthermore, an inhibition of in vivo activities of MMP-2 and MMP-9 was observed using in situ zymography of fresh frozen MCF10ADCIS.com xenografts in nude mice fed on OG extract compared to the water fed mice. A reduced cleavage of galectin-3 in xenografts harvested from the OG fed mice also indicates a reduced MMP activity. Fractionation of the crude extract indicates that the inhibitory activity is specific to the methanol soluble fraction of OG. Further purification of this fraction by is in progress. The results suggest that OG inhibits the enzymatic activity of MMP-2 and −9 and can be developed as a novel non-toxic therapeutic agent preventing the invasion and progression of cancer cells. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1888.

Modulatory Effect of Psidium Guajava Linn and Ocimum Gratissimum Linn on Lipid Profile and Selected Biochemical Indices in Rabbits Fed High Cholesterol Diet

The effect of aqueous leaf extracts of Psidium guajava(PG) and Ocimum gratissimum(OG) on fasting plasma glucose (FPG), total protein (TP), albumin (ALB), globulin (GLB), total cholesterol (TC), triglyceride (TG), HDL-cholesterol (HDL), LDL-cholesterol (LDL) and lactate dehydrogenase (LDH) concentrations in rabbits fed high-cholesterol diet was investigated. Four groups of animals were used (n = 6). Animals in group A were fed normal laboratory pellet and water ad libitum; those in group B were fed the high-cholesterol diet (normal diet + 1% w/w cholesterol + 1% w/w vegetable oil) while those in groups C and D received a daily oral administration of 250 mg/kg body weight of the extract of Psidium guajava and Ocimum gratissimum, respectively, in addition to the high-cholesterol diet for a period of six weeks. Hypercholesterolemia, associated with hyperglycemia was induced significantly in animals in group B compared to normal control group (A) (P&lt;0.01). There were also significant increases in the levels of LDL (P&lt;0.05) and HDL (P&lt;0.01). Treatments with PG and OG reduced the plasma cholesterol level by 15% and 28%, respectively, compared to animals in Group B. PG caused a remarkable increase in HDL (69%) but a decrease in LDL (74%) levels. OG on the other hand reduced the levels of both HDL and LDL by 50% and 26%, respectively, compared to animals in Group B. While the level of HDL in the OG group was similar to that of normal controls, the LDL level was significantly higher (71%). Furthermore, both extracts reduced the associated hyperglycemia significantly (P&lt;0.05). This decrease was more pronounced in PG treated rabbits (PG; 43%, OG; 19%). In addition, OG stimulated a significant increase in the concentrations of LDH and serum protein, particularly albumin. These results show that aqueous extracts of both plants especially PG ameliorated the hypercholesterolemic and associated hyperglycemic effects of high cholesterol diet. However, OG shows possible contraindications and the safety of its ethnomedical usage warrants further investigation.

Effect of aqueous extract of scent leaf (Ocimum gratissimum) on carbon tetrachloride (CCL4) induced liver damage in albino Wister rats.

The effect of aqueous leaf extract of Ocimum gratissimum was investigated in rat models of liver injury induced by carbon tetrachloride (CCl4). Treatment of separate groups of rats with 2.5 ml/kg body weight of 5, 10 and 15% aqueous extracts of O. gratissimum for 3 weeks after establishment of CCl4 induced liver damage, resulted in significantly (p < 0.05) less hepatotoxicity than with CCl4 alone, as measured by serum alkaline phosphatase (ALP), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities. For serum alanine aminotransferase, activity decreased from 68.95 ± 21.38 U/l to 35.77 ± 1.48 U/L, while for aspartate aminotransferase, activity level decreased from 165.65 ± 17.75 to 110.10 ± 3.05 U/l and for alkaline phosphatase, activity level decreased from 364.65 ± 37.75 to 212.74 ± 15.27 U/l. The reduction though not statistically significant (p < 0.05) was dose dependent. Histopathological findings also suggest that treatment with aqueous extracts of O. gratissimum after establishment of CCl4-induced liver damage significantly reduced and even reversed the liver damage in the rats. The results of the study indicate that O. gratissimum might be an effective plant hepatoprotector in the diet of patients with hepatopathies. Key words: Aqueous extract, Ocimum gratissimum, hepatoprotector, hepatotoxicity, carbon tetrachloride.

Anti-diabetic Potential of the Aqueous Leaf Extracts of Ocimum Gratissimum (Labiatae) and Vernonia Amygdalina Del. (Compositae) in Diabetic–Induced Rabbit

The anti-diabetic potential of aqueous extracts of leaves of both Ocimum gratissimum and Vernonia amygdalina were investigated in rabbits. Ten female rabbits were grouped into five groups (1-5) of two rabbits each. Group 1 is the control. Groups (2-5) was alloxan induced diabetic. Group 3 was thentreated with 200mg/kg body wt. Ocimum gratissimum, group 4 was treated with 200mg/kg body wt. Vernonia amygdalina while group 5 was treated with 400mg/kg body wt. of b oth aqueous extracts in ratio 3: 1. The results showed a significant reduction in the plasma glucose in the treated rabbits.

The Effects of Ocimum Gratissimum Leaf Extract on Cardiovascular and Renal Function in Rats

The effects of Ocimum gratissimum leaf, a local food spice and traditional herbal remedy, on cardiovascular and renal function were studied in Sprague-Dawley rats. The rats were administered with crude ethanolic extract of the leaf of Ocimum gratissimum, orally over five weeks. At the end of the period the blood pressure, heart rate, packed cell volume (PCV), creatinine clearance, plasma urea and electrolyte concentrations (Na+ and K+) were measured. Also determined were the urine output, urine flow rate and urinary excretion of electrolytes (Na+ and K+). Some of the rats were sacrificed at the end of 5 weeks and dissected. The kidneys and urinary bladder were excised for studies of cortical histopathology and smooth muscle activity respectively. Age matched rats given normal saline over the same period acted as controls. Results are presented as means ± Standard error of the mean (SEM). Chronic Ocimum gratissimum administration increased systolic and diastolic blood pressure, heart rate and packed cell volume in the rats (P

Synergistic activity of aqueous extracts mixtures of some Nigerian plants against Maruca vitrata and Clavigralla tomentosicollis on field cowpea, Vigna unguiculata (L.) Walp

Field experiments were conducted under rain fed conditions in two seasons to test the effectiveness of seven different plant extract mixtures for management of Maruca vitrata (Fab.) and Clavigralla tomentosicollis Stal on cowpea, Vigna unguiculata (L.) Walp. The application of 10:10% w/w of peels of Citrus sinensis + Gmelina arborea leaf extracts, fruits of Capsicum annum + Eucalyptus citriodora leaf extracts, and peels of C. sinensis + Ocimum gratissimum leaf extracts were effective in reducing the incidences of M. vitrata and C.tomentosicollis on flowers and pods of cowpea, respectively. Grain yield was subsequently increased by 3.2 – 3.5× in plots treated with these extract mixtures compared with the control check. Although, the mixtures of peels of C. sinensis + Azadirachta indica leaf, fruits of C. annum + A. indica leaf, and peels of C. sinensis + Vernonia amygdelina leaf extracts were inferior to the extracts mixtures mentioned above in effecting reasonable control of the test insect pests, they were significantly superior to the control check in the two seasons of study. The mixtures of C. sinensis + G. arborea, C. annum + E. citriodora, and C. sinensis + O. gratissimum extracts could play an important role in crop pest management for small holder farms in tropical countries and none of the extract mixtures had any phytotoxic effect on the sprayed plants.

Antifungal effects of two tropical plant leaf extracts (Ocimum gratissimum and Aframomum melegueta) on postharvest yam (Dioscorea spp.) rot

Effects of leaf extracts of Ocimum gratissimum and Aframomum melegueta on spore germination and mycelial reduction of the most occurring fungal pathogen causing soft rot of yam tuber were investigated. Fungi isolated from rotted yams were Aspergillus niger, A. flavus, Fusarium oxsporium Rhizopus stolonifer, Botryodiplodia theobromae and Penicillium chrysogenum. The leaf extracts with ethanol extraction were most effective followed by cold-water and hot water extraction. The fungicidal activity with Ocimum gratissimum leaf extracts was more effective. In vitro inoculation of fresh yam with A. niger, A. flavus and F. oxsporum at room temperature for 3 months showed typical rot symptoms characteristic of the disease. The significance of these findings is discussed in relation to plant chemical or non-chemical means of disease control on yams in Africa.

Antibacterial activity of the leaf extract of &lt;i&gt;Ocimum gratissimum&lt;/i&gt; (Fam. Labiatae)

The antibacterial activity of the leaf extract of Ocimum gratissimum was evaluated against isolates of E. coli, S, aureus. P. aeruginosa and B. subtilis using agar-diffusion assay. Extraction was achieved using maceration method and the extract further fractionated by column chromatography. The antibacterial properties of both the extract and the column fractions were separately determined against the test isolates. Results of the antibacterial screening revealed that the extract of O. gratissimum exhibited some degree of antibacterial activity against isolates of E. coli and B. subtilis but showed no activity against isolates of S. aureus and P. aeruginosa. The column fractions (F A - F E ), however, showed no antimicrobial activity against the test microorganisms. The probable antimicrobial activity of the plant is likely to be associated with its volatile oil content. Key words: Ocimum gratissimum, antibacterial activity, leaf extract, column fractions. Bio-Research Vol.1(1) 2003: 35-42

Effects of Ocimum gratissimum L essential oil at subinhibitory concentrations on virulent and multidrug-resistant Shigella strains from Lagos, Nigeria.

Ocimum gratissimum leaf extracts have been extensively demonstrated to be effective against the various aetiologic agents of diarrhoea, including Shigellae. However, the mechanism of the shigellocidal action of this plant remains to be understood. This study investigated the effects of O. gratissimum essential oil (EO) at subinhibitory concentrations of 0.75 and 1.0 microg/ml on virulence and multidrug-resistant strains of 22 Shigella isolates from Nigeria. Compared with untreated Shigella strains, O. gratissimum EO caused significant decreases (p<0.01) in extracellular protease activity, o-lipopolysaccharide rhamnose content and incidence of invasiveness mediated as keratoconjunctivitis in guinea pig. The disparity in extracellular protease activity and o-lipopolysacharide rhamnose between the two treatment groups was also found to be significant (p<0.05), suggesting greater anti-virulent effects of O. gratissimum oil at 1.0 microg/ml. Antibiotic susceptibility testing revealed that the EO of O. gratissimum reduced the MICs of antibiotics to which Shigellae showed resistance by 9.8-53.1% and fluoroquinolones by 18.2-45.5%. The results of this study strongly suggest inhibition of extracellular protease and expression of O-LPS rhamnose in Shigellae by O. gratissimum EO. The future use of O. gratissimum- antibiotic combinations as a therapeutic measure against shigellosis is discussed.

Antidiarrhoeal effects of Ocimum gratissimum leaf extract in experimental animals

The aqueous extract of the leaves of Ocimum gratissimum was screened for antidiarrhoeal effects. The extract inhibited castor oil-induced diarrhoea in rats as judged by a decrease in the number of wet faeces in the extract-treated rats. In addition, the extract inhibited the propulsive movement of intestinal contents. On the isolated ileum of guinea-pig, the extract showed no direct action; however, it reduced the responses of the guinea-pig ileum to acetylcholine, nicotine and histamine. Phytochemical tests revealed the main constituents as tannins, steroids, triterpenoid and carbohydrates. These findings suggested that the aqueous extract of the leaves of O. gratissimum might elicit an antidiarrhoeal effect by inhibiting intestinal motility, partly via muscarinic receptor inhibition.