Field evaluation of G10, a celery (Apium graveolens)-based topical repellent, against mosquitoes (Diptera: Culicidae) in Chiang Mai province, northern Thailand.

The potential of G10, a celery (Apium graveolens)-based topical product, as a repellent against natural mosquito populations was evaluated in comparison to commercial (Insect Block 28) and standard (25% DEET) repellents in Chiang Mai province, northern Thailand. These repellent products afforded encouragingly excellent personal protection against a broad range of mosquito species belonging to various genera, including Aedes, Anopheles, Armigeres, Culex, and Mansonia. No mosquito bite was observed on the volunteers treated with G10 and Insect Block 28 throughout the field study, whereas two species, i.e., six A. barbirostris and two A. subalbatus, came to bite or land on 25% DEET-treated volunteers. Thus, it can be concluded that while G10 and Insect Block 28 exhibited similarly powerful repellent activities with complete (100%) protection, 25% DEET was effective in minimizing bites with 99.68% protection. G10 formula was also studied for physical properties and biological stability after being kept under two conditions; a heating and cooling cycle, and varying temperature and time storage. Most samples of stored G10 not only demonstrated a similarity in appearance and physical properties, but also provided comparable repellency to that of the fresh preparation. These findings encourage commercial development of G10 formula as an alternative to conventional synthetic repellents.

Celery-based topical repellents as a potential natural alternative for personal protection against mosquitoes.

Celery-based products were investigated for chemical composition, skin irritation, and mosquito repellency in comparison to commercial repellents and the standard chemical, N,N-diethyl-3-methylbenzamide (DEET), with a goal to develop a natural alternative to synthetic repellents for protection against mosquitoes. Chemical identification by gas chromatography coupled with mass spectrometry discovered that the major constituents of Apium graveolens hexane extract (AHE) were 3-n-butyl-tetrahydrophthalide (92.48%), followed by 5.10% beta-selinene and 0.68% gamma-selinene. Evaluation of skin irritation in 27 human volunteers revealed no irritant potential from 25% ethanolic AHE solution. Laboratory investigated repellent against female Aedes aegypti mosquitoes demonstrated that G10 formula, the best AHE-developed product, provided remarkable repellency with a median protection time of 4.5 h (4.5-5 h), which was greater than that of ethanolic DEET solution (25% DEET, 3.5 h) and comparable to that of the best commercial repellent, Insect Block 28 (28.5% DEET, 4.5 h). According to significantly promising results, including highly effective repellency and no potential skin irritation or other side effects, the G10 formula is a worthwhile product that has the promise of being developed for commercialized registration. This developed AHE product could be an acceptable and affordable alternative to conventional synthetic chemicals in preventing mosquito bites, and in turn, helping to interrupt mosquito-borne disease transmission.

Aromatic plant-derived essential oil: an alternative larvicide for mosquito control.

Five aromatic plants, Carum carvi (caraway), Apium graveolens (celery), Foeniculum vulgare (fennel), Zanthoxylum limonella (mullilam) and Curcuma zedoaria (zedoary) were selected for investigating larvicidal potential against mosquito vectors. Two laboratory-reared mosquito species, Anopheles dirus, the major malaria vector in Thailand, and Aedes aegypti, the main vector of dengue and dengue hemorrhagic fever in urban areas, were used. All of the volatile oils exerted significant larvicidal activity against the two mosquito species after 24-h exposure. Essential oil from mullilam was the most effective against the larvae of A. aegypti, while A. dirus larvae showed the highest susceptibility to zedoary oil.

Hypotensive effect and toxicology of the extract from Coscinium fenestratum (Gaertn.) Colebr.

The water extract from Coscinium fenestratum (Gaertn.) Colebr. (CF extract) was tested for hypotensive and vasorelaxant effects. Acute and subchronic toxicity as well as motor activity of CF extract were also evaluated. The present study demonstrates that CF extract is effective in reducing blood pressure in anesthetized normotensive rats. This effect is shown to be dose-related and rapid in onset. The extract showed an endothelium-dependent and independent vasorelaxant activity in isolated aortic rings precontracted with phenylephrine (1 microM) and KCl (60 mM). The capacity of L-NAME (100 microM), an inhibitor of nitric oxide synthase, to reduce the vasorelaxant action of the extract indicates the involvement of nitric oxide. In the acute toxicity test, an oral dose of 5000 mg/kg of the CF extract did not produce mortality or significant changes of the general behavior of animals and gross appearance of internal organs of rats. Similarly, in the subchronic toxicity test, an oral dose of 2500 mg/kg/day of the CF extract given to rats for 90 days did not cause any significant change of any of the parameters observed when compared with those of the control animals. Moreover, the CF extract did not produce any effect on the central nervous system when spontaneous motor activity in rats was assessed. However, because some average hematological and blood chemistry values were found to be statistically different, further studies, including chronic toxicity test, should be done to confirm the safety of this plant when it is used over a long period of time.

Anti-gastric ulcer effect of Kaempferia parviflora.

Kaempferia parviflora is a Zingiberaceous plant, which has been reputed for its beneficial medicinal effects. The present study was undertaken to evaluate the Kaempferia parviflora ethanolic extract (KPE) for its anti-gastric ulcer activity by experimental models. Oral administration of the KPE at 30, 60 and 120 mg/kg significantly inhibited gastric ulcer formation induced by indomethacin, HCl/EtOH and water immersion restraint-stress in rats. In pylorus-ligated rats, pretreatment with the KPE had no effect on gastric volume, pH and acidity output. In ethanol-induced ulcerated rats, gastric wall mucus was significantly preserved by the KPE pretreatment at doses of 60 and 120 but not at 30 mg/kg. The findings indicate that the ethanolic extract of Kaempferia parviflora possesses gastroprotective potential which is related partly to preservation of gastric mucus secretion and unrelated to the inhibition of gastric acid secretion.

The anti-gastric ulcer effect of Gynostemma pentaphyllum Makino.

Gynostemma pentaphyllum is an oriental medicinal herb reputed to have broad-spectrum activities. The plant's principal saponin components are structurally similar to those found in ginseng plants and this similarity is assumed to be responsible for the claimed activities. The present study was undertaken to evaluate a G. pentaphyllum butanol fraction (GPB) for its anti-gastric ulcer activity using experimental models. Oral administration of the GPB at 200 and 400 mg/kg body wt. significantly inhibited gastric ulcer formation induced by indomethacin, HCl/EtOH and water-immersion restraint stress in rats. In pylorus-ligated rats, pretreatment with the GPB had no effect on gastric volume, pH or acidity output, thus indicating a lack of anti-secretory effect. In ethanol-induced ulcerated rats, gastric wall mucus and hexosamine content were markedly preserved by GPB pretreatment. The findings indicate that the butanol fraction of G. pentaphyllum possesses gastroprotective potential related to the preservation of gastric mucus synthesis and secretion.

Toxicity of crude rhizome extract of Kaempferia galanga L. (Proh Hom).

The ethanolic rhizome extract of Kaempferia galanga L. (Zingiberaceae) was studied by conventional pharmacological methods including the Hippocratic screening test, and acute and subacute toxicities in rats. The hexane fraction was tested for dermal irritation in rabbits. The ethanolic extract, when tested by the Hippocratic screening test, demonstrated signs that indicated CNS depression such as a decrease in motor activity and respiratory rate, and a loss of screen grip and analgesia. In the acute toxicity test, oral administration of 5 g/kg of Kaempferia galanga produced neither mortality nor significant differences in the body and organ weights between controls and treated animals. Moreover, both gross abnormalities and histopathological changes were not comparatively detectable between all controls and treated animals of both sexes. In subacute toxicity studies, no mortality was observed when varying doses of 25, 50 or 100 mg/kg of ethanolic Kaempferia galanga extract were administered orally per day for a period of 28 days. There were no significant differences in the body and organ weights between controls and treated animals of both sexes. Hematological analysis showed no differences in any of the parameters examined (WBC count, platelet, hematocrit and hemoglobin estimation) in either the control or treated groups of both sexes. However, the differential leukocyte counts showed a slight but significant decrease of lymphocyte count in the 50 and 100 mg/kg male rat groups. In the blood chemistry analysis, no significant change occurred in the blood chemistry parameters, including glucose, creatinine, blood urea nitrogen (BUN), aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (Alk-P), total protein and albumin of both sexes. Pathologically, neither gross abnormalities nor histopathological changes were observed. No sign of irritation was observed during the dermal irritation test of the hexane fraction of Kaempferia galanga.

Anti-inflammatory and analgesic activities of Mallotus spodocarpus Airy shaw.

The chloroform extract from the roots of Mallotus spodocarpus was investigated for anti-inflammatory and analgesic activities in animal models. In acute inflammatory models, the extract significantly inhibited ethyl phenylpropiolate-induced ear edema and carrageenin- and arachidonic acid-induced hind paw edema in rats. In the chronic inflammatory model using the cotton pellet-induced granuloma in rats, the extract exhibited inhibitory activity on the formation of granuloma. The extract also elicited pronounced inhibitory effect on acetic acid-induced writhing response in mice in the analgesic test. The results obtained suggest marked anti-inflammatory and analgesic activity of the extract.

Pharmacological effect and toxicity of alkaloids from Gelsemium elegans Benth.

Gelsemium elegans Benth. (Loganiaceae), a toxic plant indigenous to southeastern Asia, is well known among hilltribes as an effective means for committing suicide. A crude alkaloidal fraction from its leaves was isolated by conventional acid-base extraction. Tests in animals showed that the alkaloids exerted analgesic and anti-inflammatory effects. At a lethal dose, the alkaloids produced violent clonic convulsions that led to respiratory failure. Since the convulsions could be prevented by pentobarbital or diazepam and potentiated by reserpine, it is postulated that the alkaloids act centrally against GABA action.

Acute and subacute toxicities of the saponin mixture isolated from Schefflera leucantha Viguier.

Acute toxicity of the bronchodilator saponin mixture isolated from Schefflera leucantha Viguier leaves was investigated in comparison with the methanol and the water extract of this plant. Oral doses of 5000 mg/kg of the methanol extract, the water extract and the saponin mixture did not produce mortality or significant changes in the general behavior and gross appearance of internal organs of rats. Subacute toxicity of the saponin mixture was evaluated with the dose of 1000 mg/kg, orally for 14 days. An extra group (satellite group) was given saponin mixture and kept for a further 14 days after treatment. All animals did not show signs of toxicity during the experimental period. Liver weights of the saponin-treated and the satellite male groups were higher whereas testis weight were lower than those of the control group which received distilled water. However, the histological examination of various organs revealed that there were no differences between the control and the treated rats. BUN, Cr, AST, ALT and ALP levels increased in saponin-receiving rats. It is possible that the saponin mixture directly impacts on the liver and the kidney functions.

The analgesic, antipyretic and anti-inflammatory activity of Diospyros variegata Kruz.

Pharmacological studies were conducted with the hexane extract of the dry stem of Diospyros variegata Kruz. (Ebenaceae) on experimental animals for evaluating the analgesic, antipyretic and anti-inflammatory activities. In the analgesic test, the hexane extract elicited inhibitory intensity on acetic acid-induced writhing response and on the late phase of formalin test but possessed only a weak effect on the tail-flick response and on the early phase of formalin test. The hexane extract also elicited antipyretic action when tested in yeast-induced hyperthermia in rats. In addition, the hexane extract showed an anti-inflammatory effect when tested in ethyl phenylpropiolate (EPP)- and arachidonic acid (AA)-induced rat ear edema.

Anti-inflammatory and antipyretic properties of Clerodendrum petasites S. Moore.

The methanol extract from Clerodendrum petasites S. Moore (CP extract) was assessed for anti-inflammatory and antipyretic activities on the experimental animal models. It was found that CP extract possessed moderate inhibitory activity on acute phase of inflammation in a dose-related manner as seen in ethyl phenylpropiolate-induced ear edema (ED(50)=2.34 mg/ear) as well as carrageenin-induced hind paw edema (ED(30)=420.41 mg/kg) in rats. However, CP extract did not elicit any inhibitory effect on arachidonic acid-induced hind paw edema in rats. In subchronic inflammatory model, CP extract provoked a significant reduction of transudation but had no effect on proliferative phase when tested in cotton pellet-induced granuloma model. CP extract also reduced the alkaline phosphatase activity in serum of rats in this animal model. Moreover, CP extract possessed an excellent antipyretic effect when tested in yeast-induced hyperthermic rats. It is postulated that the anti-inflammatory and antipyretic effects of CP extract are caused by the inhibition of the prostaglandin synthesis. Anyhow, CP extract did not possess any analgesic activity in acetic acid-induced writhing response in mice. The results obtained show that C. petasites has beneficial properties since it possesses potent antipyretic and moderate anti-inflammatory activities without ulcerogenic effect.

Anti-inflammatory, antipyretic and antinociceptive activities of Tabernaemontana pandacaqui Poir.

Studies on carrageenin-induced rat paw edema, yeast-induced hyperthermia in rat and writhing response induced by acetic acid in mice showed that the alcoholic extract of stems of Tabernaemontana pandacaqui (T. pandacaqui) has significant anti-inflammatory, antipyretic and antinociceptive activities. These activities are due to alkaloidal components since they were also observed when the crude alkaloidal (CA) fraction separated from alcoholic extract was tested in the same models.

Larvicidal, adulticidal and repellent effects of Kaempferia galanga.

Four fractions of Kaempferia galanga (hexane fraction, dichloromethane fraction 1, dichloromethane fraction 2 and methanolic fraction) were tested for larvicidal activity toward fourth instar Culex quinquefasciatus. The hexane fraction was found to exhibit the highest larvicidal effect with the LC50 of 42.33 ppm. Testing for adulticidal activity, the hexane fraction did not show any promising adulticidal effect. However, it caused a knockdown effect which might be useful as a repellent. It was then tested for repellent activity in human volunteers both in laboratory and field studies. In a laboratory study, the hexane fraction possessed repellency against Aedes aegypti (ED50 value of 30.73 microg/cm2), and provided biting protection for 3 hours. In a field study, it could protect against certain mosquitos, ie, Armigeres subalbatus, Anopheles barbirostris, An. aconitus, Mansonia uniformis, Cx. quinquefasciatus, Cx. gelidus, Cx. tritaeniorhynchus and Ae. aegypti. The hexane fraction did not cause dermal irritation when applied on human skin.

Neuropharmacological activities of the crude alkaloidal fraction from stems of Tabernaemontana pandacaqui Poir.

The crude alkaloidal (CA) fraction from the stem of Tabernaemontana pandacaqui Poir. was studied for its pharmacological activity on the central nervous system (CNS) of animals. The CA fraction was found to produce symptoms of CNS depression in conscious rats and mice, viz. reduction in spontaneous motility, potentiation of pentobarbital sleeping time, prolongation of latency of convulsions induced by pentylenetetrazole and antinociception. However, the fraction could not antagonize oxotremorine-induced tremor. The observations suggest that the CA fraction possesses a CNS depressant activity.

Anti-inflammatory activity of the alkaloid bukittinggine from Sapium baccatum.

The anti-inflammatory and related activities of bukittinggine were evaluated in comparison with reference drugs. The results obtained revealed that bukittinggine exhibited a significant inhibitory effect in carrageenin-induced hind paw edema and adjuvant-induced arthritis in rats. Its anti-inflammatory activity in both test models was comparable to that of acetylsalicylic acid. Bukittinggine also showed an inhibitory effect on the late proliferative phase of the inflammatory process in cotton pellet-induced granuloma formation in rats. In carrageenin-induced rat pleurisy, bukittinggine exhibited marked inhibitory activity on exudative formation, accumulation of leukocytes and on PGE2-like activity in the exudate. Furthermore bukittinggine could significantly reduce fever in yeast-induced hyperthermic rats and possessed analgesic activity comparable to that of acetylsalicylic acid when tested in acetic acid-induced writhing response in mice. However, bukittinggine exhibited only a weak effect in the tail-flick test when compared with morphine. It is likely that bukittinggine possesses a mechanism of anti-inflammatory, analgesic and antipyretic action similar to that of acetylsalicylic acid.

Cardiovascular activity of the crude alkaloidal fraction from Tabernaemontana pandacaqui in the rat.

The effects of a crude alkaloidal (CA) fraction from the stem of Tabernaemontana pandacaqui Poir. on the blood pressure and heart rate were investigated in conscious as well as anesthetized rats. The CA fraction exerted a hypotensive activity in both experimental models. In pentobarbital anesthetized rats, an intravenous administration of the CA fraction caused two consecutive hypotensive and bradycardiac responses. In order to investigate the mechanism of the responses, the effect of the CA fraction on the blood pressure and the heart rate was tested in various experimental animals such as pithed rats, reserpinized rats under pentobarbital anesthesia and atropine- or chlorpheniramine-treated rats under pentobarbital anesthesia. The results obtained suggest that the hypotensive and bradycardiac responses of the first phase might involve cholinergic and central mechanisms, whereas those of the second phase involve mechanisms which are mediated by central, biogenic amines, acetylcholine and histamine.

Screening for larvicidal activity of ten carminative plants.

Ten species of plants, reported to possess carminative property, were screened for larvicidal potential against Culex quinquefasciatus by exposing early 4th instar larvae to a series of concentrations of the ethanolic extracts of the plants. Mortality counts were made after 24 hours exposure. Probit analysis using computerized Harvard Programming (Hg1, 2) was employed to determine the LC50, LC95 and LC99 values in order to compare the larvicidal potency of the ten plants. Marked larvicidal effects were seen with Kaempferia galanga, Illicium vernum and Spilanthes acmella having LC50 values of 50.54, 54.11 and 61.43 ppm, respectively.

Anti-inflammatory activity of compound D {(E)-4-(3',4'-dimethoxyphenyl)but-3-en-2-ol} isolated from Zingiber cassumunar Roxb.

Compound D, (E)-4-(3',4'-dimethoxyphenyl)but-3-en-2-ol, is one of many compounds found in the hexane extract of Zingiber cassumunar Roxb. The anti-inflammatory activity of compound D was assessed using various inflammatory models in comparison with aspirin, indomethacin and prednisolone. The results obtained showed that the anti-inflammatory effect of compound D mediated prominently on the acute phase of inflammation. It exerted marked inhibition on carrageenin-induced rat paw edema as well as on the exudate formation, leukocyte accumulation and prostaglandin biosynthesis in carrageenin-induced rat pleurisy. Compound D possessed only slight inhibition on both primary and secondary lesions of adjuvant-induced arthritis and had no effect on cotton pellet-induced granuloma. Compound D elicited analgesic activity when tested on acetic acid-induced writhing response in mice but had weak inhibitory activity on tail flick responding to radiant heat. Compound D possessed marked antipyretic effect when tested on yeast-induced hyperthermia in rats.

Pharmacokinetics, metabolism and toxicity of the plant-derived photoxin alpha-terthienyl.

The plant-derived insecticide, alpha-terthienyl was prepared by synthesis as 3',4'-di[14C]-alpha-terthienyl for pharmacokinetic and metabolism studies. When administered orally to rats at a single dose of 50 mg/kg, excretion of the labelled material was maximal one day after administration and declined to no measurable quantities by day 4. Two metabolites [1,4-di(2'-thienyl)1,4-butadione and 2-2'-bithiophene-5-carboxylic acid] and trace quantities of the parent material were isolated from the urine and chemically identified. These represent the first metabolites of alpha-terthienyl identified. In pilot acute and subacute trials, unlabelled alpha-terthienyl was non-toxic when administered orally to rats as the "ready to use" formulation (0.1% active ingredient). The pure compound had an LD50 of 110 mg/kg when administered intraperitoneally to rats. The results suggest that there is considerable separation with respect to mosquito larvae and non-target mammal sensitivity.