Anti-diabetic activity of extract from Persea americana Mill. leaf via the activation of protein kinase B (PKB/Akt) in streptozotocin-induced diabetic rats

Ethnopharmacological relevance

The leaves of Persea americana Mill. (Lauraceae) have been popularly used in the treatment of diabetes in countries in Latin America and Africa.

Aim of the study

To investigate the hypoglycaemic properties and to determine the molecular mechanism by which the hydroalcoholic extract of the leaves of Persea americana reduce blood glucose levels in streptozotocin (STZ)-induced diabetes in rats via the enzymatic pathway of protein kinase B (PKB/Akt).

Methods

The hydroalcoholic extract of the leaves of Persea americana (0.15 and 0.3 g/kg/day), vehicle and metformin (0.5 g/kg/day) were administered orally to STZ-diabetic rats (n = 7/group) for 4 weeks. Changes in body weight, food and water intake, fasting glucose levels and oral glucose tolerance were evaluated. Phosphorylation and the expression of PKB in the liver and soleus muscle were determined by Western blot.

Results

The hydroalcoholic extract of the leaves of Persea americana reduced blood glucose levels and improved the metabolic state of the animals. Additionally, PKB activation was observed in the liver and skeletal muscle of treated rats when compared with untreated rats.

Conclusion

The results indicate that the hydroalcoholic extract of the leaves of Persea americana has anti-diabetic properties and possibly acts to regulate glucose uptake in liver and muscles by way of PKB/Akt activation, restoring the intracellular energy balance.     

In vitro anti-prostate cancer and ex vivo antiangiogenic activity of Vernonia guineensis Benth. (Asteraceae) tuber extracts

Ethnopharmacological relevance

Prostate cancer is a major problem worldwide and affects most men above the age of forty-five. Vernonia guineensis Benth. (Asteraceae) root decoction is used in folk medicine in Cameroon to treat a number of ailments including prostate cancer. The aim of this study was to provide a preliminary validation of the use of Vernonia guineensis Benth. extracts to treat prostate cancer by evaluating the in vitro activity of its crude extracts and isolated molecules on prostate cancer cells lines and effect on angiogenesis which is essential for growth and metastases of prostate cancer.

Materials and methods

Aqueous, dichloromethane and methanol extracts of Vernonia guineensis Benth. tubers were tested for activity against three prostate cancer cell lines (PC-3, DU-145 and AT3B-1). The dichloromethane extract was subjected to bioactivity guided fractionation. Anti-proliferation, clonogenic and antiangiogenic activity of the crude extracts and isolated compound were tested. The WST-1 assay was used for the anti-proliferation activity meanwhile the standard clonogenic test and the rat ring aorta assay were carried out to determine the clonogenic and antiangiogenic activity of tested products respectively.

Results

The aqueous and methanol extracts of Vernonia guineensis Benth. demonstrated weak activity against prostate cancer cell lines in vitro with IC₅₀ > 100 μg/mL. The dichloromethane extract was more potent with IC₅₀ of 56.233 ± 3.630 μg/ml and 67.316 ± 2.452 μg/ml against the DU-145 and PC-3 cell lines respectively. Activity guided fractionation of this extract yielded a Pentaisovalerylsucrose (1) isolated for the first time from a natural source to the best of our knowledge. Compound 1 demonstrated in vitro activity against the human prostate cancer cell lines PC-3 and DU-145 with IC₅₀ of 5.701 ± 0.142 μM and 4.275 ± 0.710 μM, respectively. The IC₅₀ of the compound was 5.763 ± 0.425 μM against AT3B-1, a rat prostate cancer cell line expressing P-glycoprotein which is linked to drug resistance in most metastatic cancers. Compared to compound 1, Paclitaxel and Docetaxel were active against AT3B-1 at 2.641 ± 1.253 μM and 0.613 ± 0.251 μM. Paclitaxel showed IC₅₀ values of 0.004 ± 0.002 μM and 0.003 ± 0.001 μM against DU-145 and PC-3 prostate cancer cell lines respectively. Docetaxel showed IC₅₀ values of 0.002 ± 0.001 μM and 0.004 ± 0.001 μM against DU-145 and PC-3 prostate cancer cell lines respectively.

Conclusion

The in vitro anti-prostate cancer and the antiangiogenic activity of Vernonia guineensis Benth. extracts and isolated compound support the use of the tubers of this plant for the treatment of prostate cancer.     

Apocynum venetum leaf extract, an antihypertensive herb, inhibits rat aortic contraction induced by angiotensin II: A nitric oxide and superoxide connection

Ethnopharmacological relevance

The leaves extract of Apocynum venetum (AVLE), also known as “luobuma”, have long been used in traditional Chinese medicine to treat hypertension and depression in parts of China and it has been shown to possess anti-oxidant and anti-lipid peroxidation effects. AVLE (10 μg/ml) has been reported to have a long-lasting endothelium-dependent relaxant effect and this effect has been proposed to be due to its nitric oxide(NO)-releasing and superoxide anion(SOA)-scavenging properties.

Aim of the study

The present study seeks to evaluate the differential actions of AVLE extract between Ang II- and PE-induced vasoconstriction and the involvement of superoxide anions.

Materials and methods

Single dose of Ang II (100 nM and 1 nM)- or PE (0.1 μM)-induced contraction were assessed in both endothelium-intact and -denuded aortic rings after pre-incubation of AVLE (10 μg/ml) for 15 min. The experiment was repeated in either the presence of NO synthase inhibitor, l-NAME (300 μM) or selective AT₁ receptor inhibitor, losartan (0.1 nM), or superoxide scavenger, tiron (1 mM) or a combination of l-NAME and AVLE. Superoxide production was measured by using enhanced-chemiluminescence assay.

Results

We have demonstrated that AVLE (10 μg/ml) effectively suppressed the Ang II-induced contraction (100 nM and 1 nM) of both endothelium-intact and -denuded rat aortic rings. In endothelium-intact rings, l-NAME, reversed AVLE-induced inhibition of Ang II-contraction. PE-induced contraction was significantly inhibited by AVLE in endothelium-intact rings, but not in endothelium-denuded rings. The inhibition by AVLE of PE-induced contraction was totally abolished in the presence of l-NAME. Ang II-induced SOA production concentration dependently with the optimal effect seen at 100 nM of Ang II, and AVLE (0.3, 1, 10 μg/ml) reduced this effect. SOA production in Ang II-stimulated rings was significantly higher than unstimulated control rings, while PE did not stimulate SOA production at all. SOA formation in the presence of Ang II was also inhibited in the presence of SOD (superoxide scavenger), DPI (NADPH inhibitor) and losartan (specific AT₁ receptor antagonist).

Conclusion

These results collectively suggest that the ability of AVLE in inhibiting Ang II-induced contraction via its SOA scavenging properties and nitric oxide releasing effect may account for its usage as an antihypertensive treatment in traditional folk medicine.     

Antimalarial activities of medicinal plants traditionally used in the villages of Dharmapuri regions of South India

Ethnopharmacological relevance

An ethnopharmacological investigation of medicinal plants traditionally used to treat diseases associated with fevers in Dharmapuri region of South India was undertaken. Twenty four plants were identified and evaluated for their in vitro activity against Plasmodium falciparum and assessed for cytotoxicity against HeLa cell line.

Aim of the study

This antimalarial in vitro study was planned to correlate and validate the traditional usage of medicinal plants against malaria.

Materials and methods

An ethnobotanical survey was made in Dharmapuri region, Tamil Nadu, India to identify plants used in traditional medicine against fevers. Selected plants were extracted with ethyl acetate and methanol and evaluated for antimalarial activity against erythrocytic stages of chloroquine (CQ)-sensitive 3D7 and CQ-resistant INDO strains of Plasmodium falciparum in culture using the fluorescence-based SYBR Green I assay. Cytotoxicity was determined against HeLa cells using MTT assay.

Results

Promising antiplasmodial activity was found in Aegle marmelos [leaf methanol extract (ME) (IC₅₀ = 7 μg/mL] and good activities were found in Lantana camara [leaf ethyl acetate extract (EAE) IC₅₀ = 19 μg/mL], Leucas aspera (flower EAE IC₅₀ = 12.5 μg/mL), Momordica charantia (leaf EAE IC₅₀ = 17.5 μg/mL), Phyllanthus amarus (leaf ME IC₅₀ = 15 μg/mL) and Piper nigrum (seed EAE IC₅₀ = 12.5 μg/mL). The leaf ME of Aegle marmelos which showed the highest activity against Plasmodium falciparum elicited low cytotoxicity (therapeutic index > 13).

Conclusion

These results provide validation for the traditional usage of some medicinal plants against malaria in Dharmapuri region, Tamil Nadu, India.     

Protective effect of hydroalcoholic extract of Mimusops elengi Linn. flowers against middle cerebral artery occlusion induced brain injury in rats

Ethnopharmacological relevance

In the traditional Indian and Thai system of medicine, Mimusops elengi Linn., flower is used as brain tonic and to calm anxiety and panic attacks.

Aim of the study

The present study was designed to investigate the neuroprotective effect of hydroalcoholic extract of Mimusops elengi (ME) against cerebral ischemic reperfusion injury in rats.

Materials and methods

Male rats were pretreated with ME (100 and 200 mg/kg) for seven days and focal cerebral ischemia was induced by middle cerebral artery occlusion (MCAO) method. After 60 min of MCAO and 24 h of reperfusion, a battery of behavioral tests assessed the extent of neurological deficits. Infarct volume and brain edema were measured in TTC stained brain sections and the extent of blood brain barrier (BBB) disruption was observed by Evan's blue extravasation. Oxidative and nitrative stress parameters were estimated in the brain homogenates. Further, simultaneous quantification of five polyphenolic biomarkers were done using HPLC.

Results

Pretreatment with ME at doses of 100 and 200 mg/kg significantly improved the neurobehavioral alterations and reduced the infarct volume, edema and extent of BBB disruption induced by ischemia reperfusion injury. It also prevented the alteration in the antioxidant status and reduced the nitrite levels when compared to ischemic animals. Further, HPLC studies revealed that ME contains five bioactive polyphenolic compounds.

Conclusions

These results clearly indicate the neuroprotective effect of ME against stroke like injury. The observed protective effect might be attributed to the polyphenolic compounds and their antioxidant and anti-inflammatory property.     

Evaluation of the wound healing potential of Wedelia trilobata (L.) leaves

Ethnopharmacological relevance

Wedelia trilobata (L.) Hitchc (Asteraceae) leaves are used in the treatment of wounds by traditional healers. Despite the use of this plant in wound healing, there is a scarcity of scientific data to support its therapeutic application.

Aim of the study

To investigate the wound healing potential of Wedelia trilobata (L.) leaves commonly employed by traditional healers and to clarify its traditional use in a scientific investigation.

Materials and methods

An ethanolic extract of Wedelia trilobata leaves was subjected to column chromatography. Hexane, ethyl acetate (WEA) and chloroform:methanol (50:50) (WCM) fractions were obtained. The fractions were tested using relevant in vitro wound healing assays. Antioxidant activity was measured by the DPPH assay. The fibroblast proliferation, oxidative stress using hydrogen peroxide, an in vitro scratch assay, and increasing collagen content was determined using fibroblast L929. Minimum inhibitory concentrations (MICs) were determined against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa.

Results

WEA (3 μg/mL) promoted fibroblast L929 survivability up to more than 90% before and more than 85% after hydrogen peroxide induced oxidative stress. WEA (3 μg/mL) induced a 70% migration rate in the in vitro scratch assay and the collagen content was increased to 261 μg/mL compared to the control (57.5 μg/mL). WCM exhibited a scavenging activity for DPPH with an IC₅₀ value of 179.5 μg/mL comparable to BHT (139.3 μg/mL). WEA was active against Gram positive bacteria Staphylococcus aureus, Staphylococcus epidermidis with MIC values of 62.5 and 31.25 μg/mL, respectively.

Conclusion

These scientific findings of wound healing activity supports the traditional claims for Wedelia trilobata (L.) leaves. The WEA displayed antibacterial and fibroblast stimulatory activities while WCM exhibited antioxidant to indicate its potential wound healing properties. However further studies to isolate the antibacterial, antioxidant and fibroblast stimulatory compounds that contribute to the wound healing properties of this plant are needed.     

Hancornia speciosa: indications of gastroprotective, healing and anti-Helicobacter pylori actions

Ethnopharmacological relevance

Mangaba (Hancornia speciosa Gomez) is a medicinal plant frequently cited in ethnopharmacological inventories of the central region of Brazil against gastrointestinal disorders such as diarrhoea, ulcer, gastritis and stomachache.

Aim of the study

The hydroalcoholic extract (HE) and infusion (BI) of Hancornia speciosa bark were investigated for their ability to prevent and heal rodent gastric ulcer.

Materials and methods

The preventive and healing action of both preparations of Hancornia speciosa were evaluated in experimental models in rodents that simulated this disease in human gastric mucosa.

Results

BI did not exert gastroprotective effect, in contrast to HE (500 mg/kg, p.o.) that decreased (p < 0.05) the severity of gastric damage induced by HCl/ethanol (52%), indomethacin/bethanechol (51%), stress (52%) or pylorus ligature experiments (54%). HE increased (p < 0.05) the pH and decreased acid output of gastric juice. This extract promoted increase of mucus amount (3.62 mg/wt. tissue vs. 5.81 mg/wt. tissue), healing action (67%) and displayed anti-Helicobacter pylori effect.

Conclusions

The antiulcer action of Hancornia speciosa resulted in increase of gastric mucus formation and antioxidant properties of polymeric proanthocyanidins present in the bark composition of this medicinal plant.     

Effect of Tulbaghia violacea on the blood pressure and heart rate in male spontaneously hypertensive Wistar rats

Ethnopharmacological relevance

Tulbaghia violacea Harv. (Alliaceae) is a small bulbous herb which belongs to the family Alliaceae, most commonly associated with onions and garlic. In South Africa, this herb has been traditionally used in the treatment of various ailments, including fever, colds, asthma, paralysis, hypertension and stomach problems. The aim of this study was to evaluate the effect of methanol leaf extracts (MLE) of Tulbaghia violacea on the blood pressure (BP) and heart rate (HR) in anaesthetized male spontaneously hypertensive rats; and to find out the mechanism(s) by which it acts.

Materials and methods

The MLE of Tulbaghia violacea (5–150 mg/kg), angiotensin I human acetate salt hydrate (ang I, 3.1–100 μg/kg), angiotensin II human (ang II, 3.1–50 μg/kg), phenylephrine hydrochloride (phenylephrine, 0.01–0.16 mg/kg) and dobutamine hydrochloride (dobutamine, 0.2–10.0 μg/kg) were infused intravenously, while the BP and HR were measured via a pressure transducer connecting the femoral artery and the Powerlab.

Results

Tulbaghia violacea significantly (p < 0.01) reduced the systolic, diastolic, and mean arterial BP; and HR dose-dependently. Ang I, ang II, phenylephrine and dobutamine all increased the BP dose-dependently. The hypertensive effect of ang I and the HR-increasing effect of dobutamine were significantly (p < 0.01) decreased by their co-infusion with Tulbaghia violacea (60 mg/kg). However, the co-infusion of ang II or phenylephrine with Tulbaghia violacea (60 mg/kg) did not produce any significant change in BP or HR when compared to the infusion of either agent alone in the same animal.

Conclusions

Tulbaghia violacea reduced BP and HR in the SHR. The reduction in BP may be due to actions of the MLE on the ang I converting enzyme (ACE) and β₁ adrenoceptors.     

Antimicrobial activity of stingless bee (Trigona sp.) propolis used in the folk medicine of Western Maharashtra, India

Ethnopharmacological relevance

Stingless bee (Trigona sp.) propolis is widely used in the folk medicine of Western Maharashtra, India to treat a variety of ailments.

Aim of the study

To determine the chemical composition and evaluate the antimicrobial activity of Indian stingless bee propolis.

Materials and methods

Chemical composition of the ethanolic extract of propolis (EEP) was determined by GC–MS analysis. A range of bacteria including multidrug resistant (MDR) cultures as well as a yeast strain was tested for antimicrobial activity using EEP. MIC, MBC, MFC, Kill curves and post agent effect (PAE) of the EEP were assessed using standard microbiological methods.

Results

GC–MS analysis revealed that propolis contained 24 compounds (9 known and 15 newly reported). Many of these were known bioactive compounds, including antimicrobials. The MICs of EEP were in the range of 1.21–9.75 μg/mL while the MBCs/MFC were between 2.43 and 19.5 μg/mL. The time required to achieve 90% (1 log₁₀) reduction in culture growth ranged between 1.06 and 3.53 h at their respective MIC values. PAE for all the cultures was >24 h.

Conclusion

Indian stingless bee propolis has a complex nature with 24 chemical compounds. It has a potent broad-spectrum antimicrobial activity. The latter finding, in conjunction with other bioactive properties, could provide a scientific basis to its popular use in the Indian folk medicine.     

Immunomodulatory potential of Enicostema axillare (Lam.) A. Raynal, a traditional medicinal plant

Ethnopharmacological relevance

Enicostema axillare (Lam.) A. Raynal., (Gentianaceae) has been used in traditional Indian system of medicine as depurative and for the treatment of psoriasis, intermittent fever and cancer. Ethnobotanical survey conducted in Theni District indicated a high consensus for this plant as blood purifier and to treat dermatopathy and venereal infections. The present study evaluated the immunomodulatory activity of the methanol extract of Enicostema axillare.

Materials and methods

In vivo immunomodulatory activity of Enicostema axillare methanol extract (100 and 200 mg/kg b.w) was evaluated by assessing its effect on the total and differential leukocyte count, organ weight, hemaggultinating antibody titer, plaque forming cells, quantitative hemolysis of SRBC and delayed type hypersensitivity. Sheep red blood cells (SRBC, 5 × 10⁸ cells/0.1 mL) were used to immunize the animals. In vitro immunomodulatory potential of the extract was studied using peritoneal macrophages by evaluating its effects on NBT reduction, NO production and cytokine release.

Results

The animals treated with Enicostema axillare methanol extract showed a significant (P ≤ 0.05) increase in weight of the thymus and spleen. The total leukocyte and lymphocyte count was increased significantly (P < 0.005) by the treatment. There was no significant alteration in neutrophil count. A dose dependent increase in antibody titer value was observed. A decreased response to DTH reaction induced by SRBC was recorded. A potential phagocytic response was seen on treatment with the extracts at 10 and 25 μg/mL. The extract inhibited the release of pro-inflammatory cytokines and production of NO significantly in a dose dependent manner.

Conclusion

These findings suggested that the methanol extract of Enicostema axillare acted on both humoral and cell mediated immune functions and decreased the release of pro-inflammatory cytokines in the peritoneal macrophages.     

In vitro and in vivo immunomodulatory activities of iridoids fraction from Barleria prionitis Linn

Ethnopharmacological relevance

Barleria prionitis Linn. (Family: Acanthaceae), one of the important Ayurvedic medicinal plant in India, has long been used to treat variety of ailments including swellings, gout, arthritic and rheumatic disorders, nervine and skin diseases, and also acts as immunorestorative.

Aim of the study

The present study was aimed to explore in vitro and in vivo immunomodulatory activities of the iridoids fraction i.e. n-butanol fraction of methanol extract from Barleria prionitis aerial parts (IFBp).

Materials and methods

IFBp was studied for in vitro [nitroblue tetrazolium (NBT) test and neutrophils candidacidal assay] and in vivo immunomodulatory activity on cellular and humoral immune responses to the antigenic challenge by sheep red blood cells (SRBCs) and by neutrophil adhesion test, phagocytic activity and cyclophosphamide-induced myelosuppression. The study comprised the preliminary phytochemical screening, HPTLC standardization and maximum tolerable dose determination of IFBp.

Results

IFBp (50, 100 and 200 μg/ml) significantly (P ≤ 0.01) increased the intracellular killing activity of stimulated neutrophils assayed by in vitro NBT reduction test and neutrophils candidacidal assay. Pretreatment of IFBp (100 and 200 mg/kg; p.o.) evoked a significant increase in percent neutrophils and neutrophils adhesion to nylon fibres. Oral administration of IFBp augmented the humoral immune response to SRBCs, evidenced by increase in antibody titres and dose dependently potentiated the delayed-type hypersensitivity reaction induced by SRBCs in mice. IFBp potentiated significantly (P ≤ 0.01) the macrophage phagocytic activity and ameliorated the red blood cells, total white blood cells and platelets count and haemoglobin concentration, and also restored the myelosuppressive effects induced by cyclophosphamide. The content (% w/w; mean ± SD, n = 3) of main iridoids i.e. shanzhiside methyl ester and barlerin was found to be 21.55 ± 2.40 and 10.03 ± 1.69 in IFBp of BP, respectively.

Conclusion

The present investigation reveals that IFBp is a potent immunostimulant, stimulating both the specific and non-specific immune mechanisms.     

Andrographolide inhibits the expression and metabolic activity of cytochrome P450 3A4 in the modified Caco-2 cells

Aim of the study

The aim of this study is to examine the effects of andrographolide on intestinal enzyme cytochrome P450 3A4 (CYP3A4) and predict whether oral administration of andrographolide-containing remedy leads to herb–drug interaction.

Materials and methods

Caco-2 cells are treated with 1α, 25-dihydroxyvitamin D3 for 3 wks to induce the expression of CYP3A4, and then andrographolide (1, 10, 100 μM) is added and treated for 72 h. Upon the further 4-h testosterone (250 μM) or nifedipine (200 μM) treatment, the basolateral medium samples and the Caco-2 monolayers are collected for analyses.

Results

Andrographolide (1, 10, 100 μM) significantly down-regulates the mRNA level and protein level of CYP3A4, and inhibits nifedipine oxidation and testosterone 6β-hydroxylation.

Conclusion

Oral administration of andrographolide likely leads to reduction of the metabolic activity of intestinal CYP3A4, therefore herb preparations containing andrographolide may result to herb–drug interactions in combination therapy.     

Antioxidant and hepatoprotective activity of aqueous extract of Solanum fastigiatum (false "Jurubeba") against paracetamol-induced liver damage in mice

Aim of the study

Solanum fastigiatum is a medicinal plant widely distributed in the south of Brazil and has been used mainly to treat hepatitis, spleen disorders, uterine tumors, irritable bowel syndrome and chronic gastritis. The present research was aimed to evaluate the potential antioxidant and hepatoprotective activity of aqueous extracts of leaves using in vitro and in vivo models to validate the folkloric use of the plant.

Materials and methods

Antioxidant activity was evaluated by different assays, including thiobarbituric acid reactive species (TBARS), total antioxidant, 2,2-diphenlyl-1-picrylhydrazyl (DPPH) radical and metal ion-chelating activities. The hepatoprotective activity of the aqueous extracts was studied on mice liver damage induced by paracetamol (250 mg/kg) by monitoring biochemical parameters.

Results

The extract showed inhibition against TBARS, induced by 10 μM FeSO₄ and 5 μM sodium nitroprusside in rat liver, brain and phospholipid homogenates from egg yolk. The plant exhibited strong antioxidant activity in the DPPH (IC₅₀, 68.96 ± 1.25 μg/ml) assay. The aqueous extract also showed significant hepatoprotective activity that was evident by enzymatic examination and brought back the altered levels of TBARS, non-protein thiol and ascorbic acid to near the normal levels in a dose dependent manner. Acute toxicity studies revealed that the LD₅₀ value of the extract is more than the dose 4 g/kg body weight of mice.

Conclusions

The results indicate that this plant possesses potential antioxidant and hepatoprotective properties and has therapeutic potential for the treatment of liver diseases.     

Hyperpigmentant activity of leaves and flowers extracts of Pyrostegia venusta on murine B16F10 melanoma

Ethnopharmacological relevance

Pyrostegia venusta is a native Brazilian plant which has a variety of uses in traditional folk medicine including the treatment of vitiligo. However, its effectiveness on melanogenesis is not yet elucidated.

Aim of the study

This study aimed to investigate the melanogenic activity of hydroalcoholic extracts from the leaves and flowers of P. venusta on murine B16F10 melanoma cells.

Materials and methods

Different concentrations of the hydroalcoholic extracts of flowers and leaves of P. venusta were evaluated in trials of spontaneous melanin content (4 days), and cell viability by the MTT assay in murine B16F10 cells, and in the mushroom tyrosinase activity in vitro.

Results

Both extracts, leaves (0.1; 0.3; 1 and 3 μg/mL) and flowers (0.03 and 0.1 μg/mL) increased the melanin content in a concentration dependent manner after 4 days of incubation on melanoma cells. Leaves extract promoted enhancement of melanogenesis with maximum effect of 33.3 ± 3% (3 μg/mL), and the flower extract increased in 23.4 ± 3% (0.1 μg/mL). The cell viability test using MTT showed that in the same tested concentrations of both extracts no cell death was detected. Actually, either extract was not able to cause any change in the tyrosinase activity. HPLC analysis of P. venusta extracts found 0.09% and 1.08% of allantoin on leaves and flowers extracts, respectively.

Conclusions

The leaves and flowers extracts of P. venusta stimulates B16F10 melanogenesis at very low concentrations. These findings support the folk medicinal use of P. venusta on the treatment of hypopigmentation diseases, such as vitiligo.     

Hepatoprotective and antioxidant activity of Amaranthus spinosus against CCl4 induced toxicity

Aim

50% ethanolic extract (ASE) of Amaranthus spinosus (whole plant) was evaluated for in vitro antioxidant and hepatoprotective activity.

Methods

The total phenolics and reducing capacity of ASE was determined using standard curve of gallic acid (0–1.0 mg/ml) and butylated hydroxy anisole. In vitro antioxidant activity was determined by DPPH, superoxide, hydroxyl radicals, hydrogen peroxide and nitric oxide scavenging methods. The hepatoprotective activity of ASE was evaluated at 6, 7, 8, 9 and 10 μg/ml concentration against CCl₄ (1%) induced toxicity in freshly isolated rat hepatocytes and HepG2 cells.

Results

ASE was found to contain 336 ± 14.3 mg/g total polyphenolics expressed as gallic acid equivalent while the reducing capacity was 2.26 times of BHA. ASE showed significant antioxidant activity in DPPH assay (IC₅₀ 29 μg/ml), scavenges superoxide (IC₅₀ ∼ 66–70 μg/ml), hydrogen peroxide (IC₅₀ ∼120–125 μg/ml), hydroxyl radicals (IC₅₀ ∼140–145 μg/ml) and nitric oxide (IC₅₀ ∼ 135–140 μg/ml). ASE (6, 7, 8, 9 and 10 μg/ml) was able to normalise the levels of biochemical parameters in isolated rat hepatocytes intoxicated with CCl₄. A dose dependent increase in percentage viability was observed in CCl₄ intoxicated HepG2 cells.

Conclusions

ASE possesses significant hepatoprotective activity which might be due to antioxidant defence factors and phenolics might be the main constituents responsible for activity.     

In vivo study of the anti-inflammatory and antitumor activities of leaves from Plectranthus amboinicus (Lour.) Spreng (Lamiaceae)

Ethnopharmacological relevance

Plectranthus amboinicus (Lour.) Spreng is a medicinal specie often used in Brazil, especially in Northeast Region, for the treatment of several diseases including inflammations and cancer.

Aim of the study

To evaluate the anti-inflammatory and antitumor activities of the hydroalcoholic extract from leaves of P. amboinicus in an attempt to determine whether the medicinal uses are supported by pharmacological effects.

Materials and methods

Anti-inflammatory activity was determined by carrageenan-induced paw edema method. The antitumor effect was evaluated in an in vivo experimental study, using the following tumors: Sarcoma-180 and Erlich ascite carcinoma.

Results

There were statistically significant decreases (p < .05) of edema paw in at the doses of 150, 250 and 350 mg/kg (i.p.) of the hydroalcoholic extract of P. amboinicus. Similarly, the administration of P. amboinicus at the doses of 100, 150, 250 and 350 mg/kg (i.p.) inhibited the growth of sarcoma-180 and Ehrlich ascite carcinoma tumors in mice.

Conclusion

The results suggest that the hydroalcoholic extract of P. amboinicus possesses anti-inflammatory and antitumor activities, supporting the folk use of this medicinal specie.     

Evaluation of mechanism for antihypertensive action of Clerodendrum colebrookianum Walp., used by folklore healers in north-east India

Ethnopharmacological relevance

The present investigation was aimed to justify the pharmacological basis in traditional use of Clerodendrum colebrookianum as antihypertensive agent in north-east India.

Materials and Methods

The aqueous extract (AECc), its aqueous, n-butanol (nBFCc), Ethyl-acetate (EtFCc) and Chloroform fractions of C. colebrookianum leaves were evaluated for antihypertensive potential by using fructose-induced hypertension model in rats and in isolated frog heart. The ex-vivo muscarinic action in isolated rat ileum, in-vitro assay for Rho-kinase (ROCK –II), phosphodiesterase-5 (PDE-5) and angiotension converting enzyme (ACE) were also carried out to establish the mechanism of action of samples. The total phenolic and flavonoied contents in test samples were estimated to establish phyto–pharmacological relationship.

Results

The 100 μg/mL test samples were showed calcium antagonism in rat ileum and at 50 μg/mL and 75 μg/mL doses exhibited ROCK-II and PDE-5 inhibition respectively where, EtFCc was caused maximum 68.62% (ROCK-II) and 52.28% (PDE-5) inhibition, but none of the sample was exhibit effect in ACE at 100 μg/mL. The test samples also showed negative inotropic and chronotropic effect on isolated frog heart and significant (P<0.001) reduction in systolic blood pressure and heart rate in hypertensive rats compared to control. The total phenolic content maximum 80 μg gallic acid equivalents in nBFCc and flavonoids content maximum 69.57 μg Quercetin equivalent in AECc were estimated.

Conclusions

These observations established the traditional claim and thus C. colebrookianum could be a potent antihypertensive agent for use in future. The antihypertensive effect mediated by cholinergic action and following ROCK – II, PDE-5 inhibition of C. colebrookianum.     

Anti-mycobacterial natural products from the Canadian medicinal plant Juniperus communis

Ethnopharmacological relevance

Common juniper, Juniperus communis, is amongst the plants most frequently used by the indigenous peoples of North America for medicinal purposes. The First Nations of the Canadian Maritimes use infusions of juniper primarily as a tonic and for the treatment of tuberculosis. Previous investigations of extracts derived from the aerial parts of J. communis have shown it to possess anti-mycobacterial activity. The aim of the study is to isolate and identify anti-mycobacterial constituents from the aerial parts of J. communis.

Materials and Methods

Methanolic extracts of J. communis needles and branches were subjected to bioassay guided fractionation using the microplate resazurin assay (MRA) to assess inhibitory activity against Mycobacterium tuberculosis strain H37Ra. The anti-mycobacterial constituents were identified by NMR, MS and polarimetry.

Results

The diterpenes isocupressic acid and communic acid and the aryltetralin lignan deoxypodophyllotoxin were isolated from the J. communis extract. Isocupressic acid and communic acid (isolated as an inseparable 3:2 mixture of cis and trans isomers) displayed MICs of 78 μM and 31 μM and IC₅₀s of 46 μM and 15 μM against M. tuberculosis H37Ra respectively. Deoxypodophyllotoxin was less active, with a MIC of 1004 μM and an IC₅₀ of 287 μM.

Conclusions

Isocupressic acid, communic acid and deoxypodophyllotoxin were identified as the principal constituents responsible for the anti-mycobacterial activity of the aerial parts of J. communis. Although further research will be required to evaluate the relative activities of the two communic acid isomers, this work validates an ethnopharmacological use of this plant by Canadian First Nations and Native American communities.