Acute Toxicity and Vascular Properties of Seed of Parkia Biglobosa (JACQ) R. Br Gift (Mimosaceae) on Rat Aorta

The authors report here the results of study on Parkia biglobosa seeds used in Burkina Faso for arterial hypertension treatment. Investigations were done on acute toxicity and vascular properties of fermented and roasted seeds. Acute toxicity test using mice, revealed by the intraperitoneal route a lethal dose 50 (LD₅₀) of 1800 mg/kg and 1600 mg/kg of body weight for aqueous extract from roasted and fermented seeds respectively. According to the scale of Hodge and Sterner and that of the World Health Organization, such drugs would be classified lightly toxic. Oral administration (up to 3000 mg/kg) did not induce any death of animal. For the vascular properties, the effects of these products were tested on the aorta isolated from rats. The cumulative administration of extract from roasted and fermented seeds (0.1–10 mg/mL) in an organ bath induced a concentration-dependent relaxation of the aorta pre contracted by phenylephrine, with or without functional endothelium. The extracts (10 mg/mL) inhibited for 100% the contraction induced by phenylephrine. The EC₅₀ values in presence and absence of endothelium were respectively of 5.37 ± 0.12 and 4.19 ± 1.02 mg/mL for fermented seeds; for roasted seeds these values were respectively, 5.39 ± 1.12 and 5.93 ± 0.95 mg/mL. Nevertheless, low concentration of roasted seeds (1–4 mg/mL) induced endothelium-dependent relaxation and this effect was inhibited by indomethacin (10⁻⁵M), and not by L-NAME (310⁻⁴M). These experimental results revealed a vasorelaxant effect of P. biglobosa seeds. P. biglobosa seems to act directly on the smooth muscle and via endothelium involving the generation of vasodilatating prostaglandins. This vasodilator effect would be in favor of an anti hypertensive property of P. biglobosa seeds.     

Antioxidant Activities In Vitro and Hepatoprotective Effects of Nelumbo Nucifera Leaves In Vivo

Background

Herbal medicines played a major role in the treatment of hepatic disorders, and a number of medicinal plants and their compounds were widely used for the treatment of these disorders, and oxidant stress injury was one of the mechanism of liver injury.

Materials and Methods

Antioxidant activity of Nelumbo nucifera leaves (NU) extracts was assayed by the methods of scavenging 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azino-bis (3-ethylbenzo-thiazoline-6-sulfonicacid) (ABTS) radical and ferric reducing antioxidant power (FRAP) in vitro. By intraperitoneal injection carbon tetrachloride (CCl₄) to establish acute liver injury model in mice, the levels of Glutamic-pyruvic transaminase (GPT), glutamic-oxaloacetic transaminase (GOT), superoxide dismutase (SOD) and the content of and maleicdialdehyde (MDA) were detected to evaluate hepatoprotective effect of NU using corresponding test kit.

Results

EtOAC (NUEA) and n-BuOH extracts (NUBU) of N. nucifera leaves had good scavenging DPPH and ABTS radical activity and ferric reducing antioxidant power in vitro. DPPH radical scavenging activity and ferric reducing antioxidant power of NUEA (IC₅₀= 6.68±0.29 µg/mL, RACT₅₀=1749.82±67.03 µmol/g) and NUBU (IC₅₀= 4.61±0.01 µg/mL, RACT₅₀=1995.27±135.71 µmol/g ) were higher than that of BHT (IC₅₀=8.76±0.20 µg/mL, RACT₅₀=1581.68±97.41 µmol/g) and Dangfeiliganning (IC₅₀=28.06±0.17 µg/mL, RACT₅₀=1028.55±3.28 µmol/g). ABTS radical scavenging activity of NUEA (IC₅₀= 5.32±0.12 µg/mL) and NUBU (IC₅₀= 8.16±0.27 µg/mL) were higher than that of Dangfeiliganning (IC₅₀= 9.76±0.16 µg/mL). Thus, hepatoprotective effect of NUEA and NUBU was evaluated on CCl₄-induced acute liver injury mice. The results showed that the levels of GOT and GPT in each treatment group significantly decreased (p<0.001 and p<0.01, p<0.05, respectively) except for the group of NUEA (130.8 mg/kg) (p>0.05). The contents of malondialdehyde (MDA) in liver in groups of NUEA (523 mg/kg), NUBU (840.5 and 420.5 mg/kg, repectively) had significant decrease (p<0.001 and p<0.05, respectively), and the level of SOD in liver for each treatment group could significantly decrease (p<0.001, p<0.05, respectively).

Conclusion

NUEA and NUBU had significantly hepatoprotective effect for Calcium tetrachloride CCl₄-induced liver injury, which might be attributable to its antioxidant activity.     

Anti-Inflammatory,Cytotoxic and Antioxidant Effects of Methanolic Extracts of Drypetes Sepiaria (Euphorbiaceae)

The aim of this study was to investigate in vitro antioxidant, anti-inflammatory and cytotoxic activities of the petroleum ether, ethyl acetate, methanol and aqueous extracts obtained from leaves of Drypetes sepiaria (Euphorbiaceae). Total phenolic and flavonoid contents of these crude extracts were determined as gallic acid and quercetin equivalents, respectively. In in vitro antioxidant method, methanol extract exhibited higher free radical scavenging activity compared to standard compound, ascorbic acid with IC₅₀ of 95.43µg/ml (DPPH) and 67.05µg/ml (ABTS). Methanol extract was able to inhibit inflammation by in vitro about 85–90% (HRBC stabilization method) and in vivo about 40–45% (Paw oedema method) anti-inflammatory assays compared to standard produced 50.04% at 6h period. In cytotoxicity assay (MTT assay) methanolic extract exhibited IC₅₀ of 10µg/ml. In apoptosis (flow cytometric assay), the control group showed normal caspase 3 activity in the SiHa cells which was 0.24%, and increased up to 40% after treatment.     

In vitro anti-inflammatory,cytotoxic and antioxidant activities of boesenbergin A,a chalcone isolated from Boesenbergia rotunda (L.) (fingerroot)

The current in vitro study was designed to investigate the anti-inflammatory, cytotoxic and antioxidant activities of boesenbergin A (BA), a chalcone derivative of known structure isolated from Boesenbergia rotunda. Human hepatocellular carcinoma (HepG2), colon adenocarcinoma (HT-29), non-small cell lung cancer (A549), prostate adenocarcinoma (PC3), and normal hepatic cells (WRL-68) were used to evaluate the cytotoxicity of BA using the MTT assay. The antioxidant activity of BA was assessed by the ORAC assay and compared to quercetin as a standard reference antioxidant. ORAC results are reported as the equivalent concentration of Trolox that produces the same level of antioxidant activity as the sample tested at 20 µg/mL. The toxic effect of BA on different cell types, reported as IC₅₀, yielded 20.22 ± 3.15, 10.69 ± 2.64, 20.31 ± 1.34, 94.10 ± 1.19, and 9.324 ± 0.24 µg/mL for A549, PC3, HepG2, HT-29, and WRL-68, respectively. BA displayed considerable antioxidant activity, when the results of ORAC assay were reported as Trolox equivalents. BA (20 µg/mL) and quercetin (5 µg/mL) were equivalent to a Trolox concentration of 11.91 ± 0.23 and 160.32 ± 2.75 µM, respectively. Moreover, the anti-inflammatory activity of BA was significant at 12.5 to 50 µg/mL and without any significant cytotoxicity for the murine macrophage cell line RAW 264.7 at 50 µg/mL. The significant biological activities observed in this study indicated that BA may be one of the agents responsible for the reported biological activities of B. rotunda crude extract.     

Flavonoids from Sudanese Albizia Zygia (Leguminosae,Subfamily Mimo Soideae), A Plant with Antimalarial Potency

Three flavonoids were isolated for the first time from the Sudanese medicinal plants Albizia zygia. Compounds 1–3 were identified by interpretation of ESI mass data, ¹H, ¹³C and 2D NMR as well as by comparison with published data as 4′,7-dihydroxyflavanone (1) 3′,4′,7-trihydroxyflavone (2), 3-O-methylfisetin (3′,4′,7-trihydroxy-3-methoxyflavone, 3). All flavonoids were tested against Plasmodium falciparum, and only compound 2 showed high antimalarial activity (IC₅₀ 0.078 µg/ml).     

Effect of Allium Cepa and Allium Sativum on Some Immunological Cells in Rats

Extracts of some spices have been reported to play a contributory role in enhancing immune function. We evaluated and compared the effect(s) of single and combined oral administration of fresh aqueous onion (Allium cepa) and garlic (Allium sativum) extracts at different concentrations on some immunological determinants in rats. CD₄ cells of the rats were estimated using Partec flow cytometric technique, while total and differential white blood cell (WBC) counts were estimated using the Sysmsex® automated haematology analyzing technique. Our findings revealed that, CD4 and total WBC counts were significantly increased (P≤0.05) in a dose-dependent manner in both onion (250mg/Kg/d: 349±11cell/ul and 2.75±0.15X10³cell/l; 500mg/Kg/d: 389±10cells/µl and 3.05±0.05 X10³cell/l; 750mg/Kg/d: 600±11cell/µl and 3.25±0.05X10³cells/l) and garlic (250mg/Kg/d: 410±10cell/ul and 2.85±0.15X10³cell/l; 500mg/Kg/d: 494±32cells/µl and 3.30±0.10 X10³cell/l; 750mg/Kg/d: 684±11cell/µl and 3.55±0.05X10³cells/l) treated rats when compared to the zero control (200±11cells/µl and 1.55±0.05X10³cells/l, respectively). Extract of garlic at 750mg/Kg/d had significantly increased the CD4 cells and total white cell count when compared to other concentrations (P≤0.05). However, no significant effect was observed on these parameters when extracts were combined (250mg/Kg/d: 252±21cell/µl and 1.80±0.10X10³cells/l; 500mg/Kg/d: 315±21cells/ul and 2.10±0.10X10³cells/l; 750mg/Kg/d: 368±10cells/µl and 2.35±0.05X10³cells/l, respectively), the differential WBC count showed a significant increase in the proportion of cell types (lymphocytes, neutophils and monocytes) (P≤0.05). The results from this study revealed the immune boosting capabilities of Allium cepa and Allium sativum, but underscored their synergistic activities.     

Study on In Vitro Anti-Tumor Activity of Bidens Bipinnata L. Extract

We studied the in vitro anti-tumor activity of Bidens Bipinnata L. extract. MTT assay was used to investigate the inhibitory effect of different concentrations of the extracts on human hepatocellular carcinoma (HepG2) cell lines and human cervical carcinoma (Hela) cell lines, and the IC₅₀ values were calculated. The Bidens Bipinnata L. extract had different degrees of inhibitory effects on these two cells, and when exposure time was 48 h, the inhibition rate reached its peak, with IC₅₀ values of 14.80 µg/mL and 13.50 µg/mL respectively. The Bidens Bipinnata L. extract had a good inhibitory effect on human HepG2 cell lines and Hela cell lines, and thus has certain development prospects.     

In Vitro Activity of Tigecycline Against Orientia tsutsugamushi

Scrub typhus is a zoonosis caused by Orientia tsutsugamushi (O. tsutsugamushi) occurring mainly in autumn in Korea. The need of new antibiotics has arisen with a report on strains resistant to antibiotics and chronic infection. This study aims to identify susceptibility of tigecycline in-vitro as a new therapeutic option for O. tsutsugamushi. Antibacterial activity of tigecycline against the O. tsutsugamushi was compared with doxycycline using flow cytometry assay. The inhibitory concentration 50 (IC₅₀) was 3.59×10^-3 µg/mL in doxycycline-treated group. Whereas in 0.71×10^-3 µg/mL tigecycline-treated group. These findings indicate that tigecycline may be a therapeutic option for the treatment of scrub typhus.     

Essential oil of Lippia alba and its main constituent citral block the excitability of rat sciatic nerves

Lippia alba is empirically used for infusions, teas, macerates, and hydroalcoholic extracts because of its antispasmodic, analgesic, sedative, and anxiolytic effects. Citral is a mixture of trans-geranial and cis-neral and is the main constituent of L. alba essential oil and possesses analgesic, anxiolytic, anticonvulsant, and sedative effects. The present study evaluated the effects of the essential oil of L. alba (EOLa) and citral on compound action potentials (CAPs) in Wistar rat sciatic nerves. Both drugs inhibited CAP in a concentration-dependent manner. The calculated half-maximal inhibitory concentrations (IC₅₀) of peak-to-peak amplitude were 53.2 µg/mL and 35.00 µg/mL (or 230 µM) for EOLa and citral, respectively. Peak-to-peak amplitude of the CAP was significantly reduced by 30 µg/mL EOLa and 10 µg/mL citral. EOLa and citral (at 60 and 30 µg/mL, values close to their respective IC₅₀ for CAP blockade) significantly increased chronaxy and rheobase. The conduction velocity of the first and second CAP components was statistically reduced to ∼86% of control with 10 µg/mL EOLa and ∼90% of control with 3 µg/mL citral. This study showed that EOLa inhibited nerve excitability and this effect can be explained by the presence of citral in its composition. Both EOLa and citral showed inhibitory actions at lower concentrations compared with other essential oils and constituents with local anesthetic activity. In conclusion, these data demonstrate that EOLa and citral are promising agents in the development of new drugs with local anesthetic activity.     

Acute Effects of Aqueous Leaf Extract of Aspilia Africana C.D. Adams on Some Haematological Parameters in Rats

Several medicinal plants have been documented for their haematological effects either at low or high concentration but very little is known about Aspilia africana. The aim of the study was to investigate the acute effects of aqueous leaf extract of Aspilia africana at different concentrations on some haematological parameters in rats. Following 14 days of oral administration of aqueous extract of A. africana, Haematocrit (HCT), Haemoglobin concentration (HB), Mean Cell Haemoglobin Concentration (MCHC), Red Blood Cell Count (RBC Count), Total White Blood Cell Count (Total WBC Count), Absolute Neutrophils count (NEUT#), Absolute Lymphocytes count (LYM#), Absolute Eosinophils Count (EOSIN#) and Absolute Monocytes (MONO#) were evaluated in twenty (20) male Wistar albino rats. The rats weighed 174±20g, and were randomly assigned into 4 groups viz: Group 1, Control; Group 2, 250mg/Kg/d aqueous extract; Group 3, 500mg/Kg/d aqueous extract; and Group 4, 750mg/Kg/d aqueous extract. HCT, HB, MCHC, RBC Count, Total WBC Count, NEUT#, LYM#, EOSIN# and MONO# were significantly increased (P<0.001) in 500mg/Kg/d of A. africana extract (61.13±1.65%, 13.5±1.29g/dl, 23.33±0.0.02g/dl, 3.68±0.02 X 10¹²Cells/l, 2.33±0.02 X 10⁹Cells/l, 1.32±0.04 X 10⁹Cells/l, 1.43±0.05 X 10⁹Cells/l, 0.47±0.02 X 10⁹Cells/l and 0.47±0.04 X 10⁹Cells/l, respectively) when compared to the Control (51.13±0.85%, 9.56±0.43g/dl, 19.22±0.19g/dl, 2.69±0.01 X 10¹²Cells/l, 1.79±0.01 X 10⁹Cells/l, 0.80±0.00 X 10⁹Cells/l, 0.83±0.00 X 10⁹Cells/l, 0.18±0.00 X 10⁹Cells/l and 0.24±0.00 X 10⁹Cells/l, respectively) which received no extract at all. The 500mg/Kg of A. africana extract proved to be the most effective, while the 750mg/Kg proved to be the least effective in comparison with the control. The results of this study further strengthened the earlier works on the medicinal benefits of Aspilia africana and its virtue as a good pharmacological source of haematopoiesis.     

Spasmolytic Effects of Aqueous Extract of Mixture From Aframomumum Melegueta (K Schum) — Citrus Aurantifolia (Christm and Panzer) on Isolated Trachea From Rat

The spasmolytic properties of the aqueous extract of Aframomum melegueta (K Schum) and Citrus aurantifolia (Christm and Panzer) (AMCA) mixture were tested on isolated rat trachea. Inhibition of the contraction was observed the in presence of the AMCA (EC ₅₀ = 1.80 ± 0.48 mg/mL) after a pre contraction of the trachea by acetylcholine (10⁻⁵ M). With propranolol (10⁻⁶ M), the spasmolytic activity of the mixture was inhibited and the concentration-response curve shifted to the right. The EC₅₀ value was then 2.60 ± 0.41 mg/mL. AMCA also inhibited contraction induced by KCl (4.10⁻² M) with EC₅₀ value = 1.86 ± 0.65 mg/mL. These results clearly show the relaxing effect of the aqueous extract on the isolated rat trachea. This effect involved some β-adrenergic receptor inhibition.     

Participation of the NO/cGMP/K+ATP pathway in the antinociception induced by Walker tumor bearing in rats

Implantation of Walker 256 tumor decreases acute systemic inflammation in rats. Inflammatory hyperalgesia is one of the most important events of acute inflammation. The L-arginine/NO/cGMP/K⁺ATP pathway has been proposed as the mechanism of peripheral antinociception mediated by several drugs and physical exercise. The objective of this study was to investigate a possible involvement of the NO/cGMP/K⁺ATP pathway in antinociception induced in Walker 256 tumor-bearing male Wistar rats (180-220 g). The groups consisted of 5-6 animals. Mechanical inflammatory hypernociception was evaluated using an electronic version of the von Frey test. Walker tumor (4th and 7th day post-implantation) reduced prostaglandin E₂- (PGE₂, 400 ng/paw; 50 µL; intraplantar injection) and carrageenan-induced hypernociception (500 µg/paw; 100 µL; intraplantar injection). Walker tumor-induced analgesia was reversed (99.3% for carrageenan and 77.2% for PGE₂) by a selective inhibitor of nitric oxide synthase (L-NAME; 90 mg/kg, ip) and L-arginine (200 mg/kg, ip), which prevented (80% for carrageenan and 65% for PGE₂) the effect of L-NAME. Treatment with the soluble guanylyl cyclase inhibitor ODQ (100% for carrageenan and 95% for PGE₂; 8 µg/paw) and the ATP-sensitive K⁺ channel (KATP) blocker glibenclamide (87.5% for carrageenan and 100% for PGE₂; 160 µg/paw) reversed the antinociceptive effect of tumor bearing in a statistically significant manner (P < 0.05). The present study confirmed an intrinsic peripheral antinociceptive effect of Walker tumor bearing in rats. This antinociceptive effect seemed to be mediated by activation of the NO/cGMP pathway followed by the opening of KATP channels.     

In Vitro Inhibitory Activities of the Extract of Hibiscus Sabdariffa L. (Family Malvaceae) on Selected Cytochrome P450 Isoforms

Literature is scanty on the interaction potential of Hibiscus sabdariffa L., plant extract with other drugs and the affected targets. This study was conducted to investigate the cytochrome P450 (CYP) isoforms that are inhibited by the extract of Hibiscus sabdariffa L. in vitro. The inhibition towards the major drug metabolizing CYP isoforms by the plant extract were estimated in human liver microsomal incubations, by monitoring the CYP-specific model reactions through previously validated N-in-one assay method. The ethanolic extract of Hibiscus sabdariffa showed inhibitory activities against nine selected CYP isoforms: CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A4. The concentrations of the extract which produced 50% inhibition of the CYP isoforms ranged from 306 µg/ml to 1660 µg/ml, and the degree of inhibition based on the IC₅₀ values for each CYP isoform was in the following order: CYP1A2 > CYP2C8 > CYP2D6 > CYP2B6 > CYP2E1 > CYP2C19 > CYP3A4 >> CYP2C9 >> CYP2A6. Ethanolic extract of Hibiscus sabdariffa caused inhibition of CYP isoforms in vitro. These observed inhibitions may not cause clinically significant herb-drug interactions; however, caution may need to be taken in co-administering the water extract of Hibiscus sabdariffa with other drugs until clinical studies are available to further clarify these findings.     

Evaluation of Three Medicinal Plant Extracts Against Plasmodium Falciparum and Selected Microganisms

Background

A great revival of scientific interests in drug discovery has been witnessed in recent years from medicinal plants for health maintenance. The aim of this work was to investigate three Nigerian medicinal plants collected in Nigeria for their in vitro antiplasmodial and antimicrobial activities.

Materials and Methods

Extracts obtained from parts of Persea americana, Jatropha podagrica and Picralima nitida and their fractions were evaluated for in vitro antiprotozoal and antimicrobial activity.

Result

The methanol extract of P. nitida demonstrated activity against chloroquine-sensitive and chloroquine-resistant P. falciparum clones with IC₅₀ values of 6.3 and 6.0 µg/mL, respectively. Methanol and chloroform extracts of P. americana seed showed antifungal activity against Cryptococcus neoformans IC₅₀ less than 8 and 8.211 µg/mL respectively. Finally, the petroleum ether extract of P. americana had activity against methicillin-resistant Staphylococcus aureus (MRSA) with an IC₅₀ value of 8.7 µg/mL.

Conclusion

The study revealed the antibacterial and antiplasmodial activities of the plants extracts at the tested concentrations.     

Antioxidant Activity In Vitro and Hepatoprotective Effect of Phlomis Maximowiczii In Vivo

Background

A number of medicinal plants and there compounds played a major role in the treatment of hepatic disorders. They were widely used for the treatment of these disorders, and oxidant stress injury was one of the liver injury mechanisms. The present study evaluated the antioxidant activity and the hepatoprotective effect of each extracts of Phlomis maximowiczii.

Materials and Methods

The antioxidant activity was assayed by the methods of ABTS, FRAP and DPPH in vitro. Hepatoprotective effect of P. maximowiczii extracts was examined using carbon tetrachloride-induced acute liver injury in mice.

Results

P. maximowiczii n-butanol (PMBU) extract, ABTS (IC₅₀=18.96 µg/mL), DPPH (IC₅₀=25.15 µg/mL), and FRAP (RACT₅₀=2775.6±144.18 µmol/g), showed higher scavenging capacity than that of P. maximowiczii ethyl acetate (PMEA). The n-butanol extract could significantly reduce the level of GPT, GOT and MDA (P<0.05, P<0.001 and P<0.001, respectively) and increase the level of SOD (P<0.001), respectively.

Conclusion

The antioxidant activity of n-butanol extract in vitro was related with the level of MDA and SOD in vivo, and hepatoprotective effect of n-butanol extract also had relationship with its antioxidant activity in vivo.     

Evaluation of the Antioxidant Activity of Root Extract of Pepper Fruit (Dennetia Tripetala), and It's Potential for the Inhibition of Lipid Peroxidation

Background

The antioxidant properties of ethanolic root extract of pepper fruit (Donnetia tripetala), and its effect on lipid peroxidation of some fresh beef tissues during frozen storage were investigated.

Materials and Methods

The antioxidant parameters were assessed using standard methods, while malondialdehyde levels of different fresh beef tissue sections treated with the extract prior to freezing, were estimated in a colorimetric reaction with thiobarbituric acid.

Results

The H₂O₂-scavenging ability of the extract was similar to that of ascorbic acid, with a maximum scavenging power of 55.61 ±4.98%, and an IC₅₀ value of 86µg/ml. The extract exhibited a concentration-dependent ferric ion-reducing power, although this was significantly lower relative to that of the ascorbic acid (p < 0.05). The total phenolic content was 212.5 ± 0.002 mg/g, while the nitric oxide-scavenging ability was 64.33 ± 0.2% after 150 min. The capacity of the extract to inhibit lipid peroxidation in frozen heart muscle slices was significantly higher than that of vitamin C (p < 0 .05), but comparable to vitamins C and E in frozen testes and kidney slices.

Conclusion

These results suggest that the root extract of D. tripetala is rich in antioxidants which can be applied to meat preservation during refrigerated storage.     

Lactogenic Activity of Rats Stimulated by Gunnera Perpensa L. (Gunneraceae) from South Africa

Gunnera perpensa L. (Gunneraceae) is a medicinal plant used by Zulu traditional healers to stimulate milk production. The effect of an aqueous extract of the rhizome of the plant on milk production in rats was investigated. Female lactating rats that received oral doses of the extract of G.perpensa significantly (p<0.05) produced more milk than controls. The plant extract did not however, significantly influence the levels of prolactin, growth hormone, progesterone, cortisol, ALT, AST and albumin in the blood. The mammary glands of rats treated with the extract showed lobuloalveolar development. The extract (0.8 µg/ml) was also found to stimulate the contraction of the uterus and inhibit (23%) acetylcholinesterase activity. The cytotoxicity of the extract (LC₅₀) to two human cell lines (HEK293 and HepG2) was 279.43 µg/ml and 222.33µg/ml, respectively. It is inferred that the plant extract exerts its activity on milk production and secretion by stimulating lobuloalveolar cell development and the contraction of myoepithelial cells in the alveoli. It is concluded that Gunnera perpensa contains constituents with lactogenic activity that apparently contribute to its effectiveness in folk medicine.     

Martentoxin,a large-conductance Ca2+-activated K+ channel inhibitor,attenuated TNF-α-induced nitric oxide release by human umbilical vein endothelial cells

Martentoxin, a 4,046 Da polypeptide toxin purified from the venom of the scorpion Buthus martensii Karsch, has been demonstrated to block large-conductance Ca²⁺-activated K⁺ (BK_Ca) channels; however, its biological roles are still largely unknown. In the present study, we investigated the pharmacological effects of martentoxin on regulating the production of nitric oxide induced by TNF-α in human umbilical vein endothelial cells (HUVECs). We found that, 1, 10 and 100 µmol/L martentoxin decreased nitric oxide production by HUVECs exposed to 10 ng/mL TNF for 6, 12 and 24 hours. We further demonstrated that martentoxin inhibited the activity of iNOS and retarded the down-regulation of eNOS mRNA induced by TNF-α. Therefore, martentoxin could be a potential therapeutic agent for vascular diseases.     

The Antiplasmodial Agents of the Stem Bark of Entandrophragma Angolense (Meliaceae)

In the search of active principles from the stem bark of Entandrophragma angolense, we submitted the compounds isolated from the dichloromethane - methanol (1:1) extract of the stem bark to antimalarial test against chloroquine resistant strain W2 of Plasmodium falciparum malaria parasite. Only 7α-obacunyl acetate and a cycloartane derivative exhibited a good activity, with IC₅₀s of 2 and 5.4 µg/ml respectively. Other compounds were moderately active.     

Effect of glucagon on insulin secretion through cAMP signaling pathway in MIN6 cells

Objective: To explore the direct regulation effects and mechanisms of glucagon in insulin secretion of MIN6 cells that in the kind of the islet β cells. Methods ICUE3 and PCDNA3.1 plasmid were transfected to the MIN6 cells by electroporation transfection, and then treated with different concentrations of glucagon (Glg) and glucose (Glu). Biosensor technology that based on the fluorescence resonance energy transfer (FRET) was used to monitor the change of cAMP quantitatively and real-time. The level of cAMP and insulin were measured by the enzyme-linked immunosorbent assay (ELISA). Results: The receptor of Glg was mainly located on the cell membrane in MIN6 cells. Compared with the 0 ng/L Glg group in the Glu-free state, the average value of CFP/YFP increased 4% ± 0.02 in the 500 ng/L Glg group, and the value in the 1000 ng/L Glg group increased 6% ± 0.03 (P > 0.05). While in the high-Glu (16.7 mmol/L) state, the value increased 11% ± 0.02 in the 500 ng/L Glg group, and increased 23% ± 0.06 in the 1000 ng/L Glg group when compared with the 0 ng/L Glg group(P < 0.01). The levels of the cAMP of 1000 ng/L and 500 ng/L Glg group were higher than those of the 100 ng/L and 0 ng/L Glg group in the condition of Glu-free (81.27±6.29, 76.73±2.10,39.45±2.83, 40.36±4.20; P < 0.01). The levels of the cAMP of 1000 ng/L, 500 ng/L and 100 ng/L Glg group were higher than those of the 0 ng/L Glg group, at the meanwhile, the levels of the cAMP of 1000 ng/L and 500 ng/L Glg group were also higher than 100 ng/L Glg group in the condition of low-Glu (2.8 mmol/L) (92.91±7.35, 90.36±3.15, 65.82±10.49, 46.73±1.05; P < 0.01). And this trend in the condition of high-Glu was almost to the low-Glu (106.75±7.26, 94.18±2.99, 83.09±1.16, 55.60±5.51, P < 0.01). The levels of the insulin of 1000 ng/L, 500 ng/L and 100 ng/L Glg group were higher than those of the 0 ng/L Glg group. While 1000 ng/L Glg group was higher than that of the 500 ng/L and 100 ng/L Glg group in the condition of Glu-free (1844.02±200.93, 1387.94±483.12, 1251.817±60.30, 787.33±81.72; P < 0.01). The levels of the insulin of 1000 ng/L and 500 ng/L Glg group were higher than those of the 100 ng/L and 0 ng/L Glg group, and the 1000 ng/L and was also higher than 500 ng/L Glg group in the condition of low-Glu (1552.31±81.20, 1285.62±131.67, 1020.85±42.60, 762.89±26.94, P < 0.01). And this trend in the condition of high-Glu was almost to the low-Glu (1898.337±169.03, 1399.30±148.66, 1061.735±9.13, 972.89±22.19; P < 0.01). The levels of cAMP and insulin secretion of MIN6 cells had a positive correlation in different Glu conditions (r² = 0.559, P < 0.01). Conclusion: Glg may stimulate insulin secretion by increasing cAMP levels in the way of concentration gradient within the islet β cell lines--MIN6 cells. And the increasing trend was Glu dependent.