Repellent properties of celery, Apium graveolens L., compared with commercial repellents, against mosquitoes under laboratory and field conditions

[Repellent Activity of Vanillin Derivatives and Monoterpenes to Olive Weevil]

Olive weevils, Pimelocerus (Dyscerus) perforatus Roelofs, utilize olive trees as a host plant. The adult female uses an elongated snout to puncture the trunk and lay one egg a day, resulting in dozens of eggs over its lifetime. The hatched larvae grow by eating the olive trunk. When olive trees die due to feeding damage, olive productivity is seriously impaired. Since there is no effective pesticide for olive weevils so far, the authors aimed to develop a repellent for adult olive weevils from the viewpoint of integrated pest management. We prepared a measurable apparatus for the repellent action against olive weevils and screened chemical substances by using the apparatus. When the repellent activity was measured using vanillin and its derivatives, a clear repellent effect could be confirmed for two types of vanillin derivatives, such as o-vanillin, and 2-hydroxy-4-methoxybenzaldehyde. In addition, when the repellent activity against olive weevils was measured using monoterpenes, four types of acyclic monoterpenes, geraniol, β-citronellol, citral, and linalool, and three types of monocyclic monoterpenes, (-)-limonene, (+)-limonene, and (-)-menthol, and a bicyclic monoterpene, (1R)-(+)-α-pinene, were found to have dose-dependent repellent activity with statistical significance. In the future, it is expected that the formulation for applying the repellent substances to olive trees and the study of their practicality in olive fields will progress.

Mosquito Repellents: Efficacy Tests of Commercial Skin-Applied Products in China

As a prevention tool for mosquito-borne diseases, mosquito repellents have received substantial attention. To make a convincing recommendation for repellent products to Chinese consumers, we compared the protection time (landing time and probing time) of the 26 best-selling commercial repellents in the Chinese market in a controlled laboratory environment. The data were analyzed by one-way ANOVA. Meanwhile, prices and favorable rates of repellents are also taken into consideration. In our study, N, N-diethyl-m-toluamide (DEET)-based products provided the longest protection time (0.5–3.88 h landing time and/or 1–5.63 h probing time) and lower prices (13.9–21.9 yuan) than other components (ethyl butylacetylaminopropionate (IR3535), picaridin, and botanical. Among the 26 selected products, only 17 repellents showed repellency, and the best repellent was Green Jungle (15% DEET), with a mean (±SD) landing and/or probing time of 3.88 ± 1.65 h and/or 5.63 ± 0.36 h. For botanicals, only ICE King, OMNIbaby, and Ren He showed a little repellency. Autan (20% picaridin) performed best in the picaridin group. Run Ben (7% IR3535) stood out from the IR3535 group. In conclusion, DEET repellent is highly recommended to consumers. The combination of botanicals and synthesized chemicals is a new prospect for eco-friendly repellents.

Culex vishnui (Diptera: Culicidae): An Overlooked Vector of Arboviruses in South-East Asia

Culex vishnui Theobald, 1901, a main vector of Japanese encephalitis virus (JEV), is widely distributed in the Oriental region where it often accounts for a great part of the culicid fauna. This species also has been found naturally infected with at least 13 other arboviruses of medical and veterinary importance. Females blood feed predominantly upon pigs and birds, but may readily bite cattle and humans. Because of its abundance, medical importance, and presence throughout ecological gradients among urban, peri-urban, and rural areas, Cx. vishnui potentially may serve as a bridge vector transmitting viruses from natural and wild hosts to humans. Being zoo- and anthropophagic, omnipresent in the Oriental region, and presenting strong resistance to many insecticide families, this overlooked mosquito species may pose a serious health risk in one of the most densely populated regions of the world.

Larvicidal Activity and Phytochemical Profiling of Sweet Basil (Ocimum basilicum L.) Leaf Extract against Asian Tiger Mosquito (Aedes albopictus)

Applying larvicides to interrupt a mosquito’s life cycle is an important strategy for vector control. This study was conducted to evaluate the larvicidal properties of the hexane extract of sweet basil (Ocimum basilicum L.; family Lamiaceae) leaves against the wild strain of Asian tiger mosquito, Aedes albopictus (Skuse). Third instar larvae (20 larvae/replicate, n = 3) were exposed to different concentrations of the extract (6.25–200 µg/mL), and the mortality rate was recorded. Probit analysis showed that the median lethal concentration and 95% lethal concentration of the extract were 16.0 (10.9–22.1) and 53.0 (34.6–136.8) µg/mL, respectively, after 24 h exposure. Only the fractions F3, F4, and F5 from the column chromatography displayed high mortality rates of 91.7–100% at 25.0 µg/mL after 24 h exposure. Subsequent column chromatography from the pooled fraction yielded two active subfractions, H-F345-S2 and H-F345-S3, with mortality rates of 100% and 98.3 ± 2.9%, respectively, at 12.5 µg/mL. Gas chromatography–mass spectrometry analysis unveiled that methyl chavicol, 2-(2-butoxyethoxy)ethanol, cedrelanol, methyl eugenol, 2,4,di-tert-butylphenol, and phytol were the major components in both subfractions with some of them being reported as larvicidal compounds. The results suggest that sweet basil has substantial larvicidal activity against Ae. albopictus mosquito and is a potential source of naturally derived larvicide.

Efficacy and safety of repellents marketed in Brazil against bites from Aedes aegypti and Aedes albopictus: A systematic review

BACKGROUND

Dengue, Zika and Chikungunya viruses represent a serious public health problem. No evidence is available on the efficacy of repellents commercially available in Brazil. This systematic review assessed the efficacy and safety of products containing repellents commercially available in Brazil for protection against bites from Aedes aegypti and Aedes albopictus.

METHODS

We performed a systematic review using the CENTRAL, MEDLINE, EMBASE, CINAHL, Web of Science, AMED, LILACS and Scopus databases. Randomized clinical trials and non-randomized clinical trials comparing topical repellent products registered with the Brazilian Health Surveillance Agency were included. Main outcomes of interest investigated were adverse effects, percentage repellency and protection time against bites. Pairs of reviewers selected the studies, extracted the data and evaluated the risk of bias.

RESULTS

Sixteen studies were included. No adverse effects were reported by the studies. Against Ae. aegypti: protection time using DEET (10% and 20%-spray) was similar to IR3535 (10% and 20%-spray) and longer than citronella (5%-spray). DEET (25%-solution) had longer protection time than eucalyptus (25%-solution), while DEET (20%-lotion) had longer protection time than citronella (10%-lotion). There was no difference in protection time between herbal repellents. DEET (7% and 15%- spray) had higher percentage repellency compared to both icaridin (7%-spray) and IR3535 (20%-spray). Against Ae. albopictus: DEET (15%-spray) had a similar protection time to icaridin (20%-spray), but longer than citronella (10%-spray).

CONCLUSION

DEET proved more effective than the other synthetic and natural repellents marketed in Brazil for protecting against bites from the mosquito species investigated. All repellents studied exhibited satisfactory safety profile.

Repellency of Veratraldehyde (3,4-Dimethoxy Benzaldehyde) against Mosquito Females and Tick Nymphs

Arthropod-borne infectious diseases cause many deaths and a major economic burden worldwide. Repellents play an important role in protecting people from infectious biting arthropods. The repellency of veratraldehyde, a known food additive, and the WJ-1041 formulation containing 10% veratraldehyde was tested against Aedes albopictus and Culex pipiens pallens females and Haemaphysalis longicornis nymphs using arm-in-cage, indoor or filter paper tests. Veratraldehyde exhibited repellency similar to or lower than that of n,n-diethyl-meta-toluamide (DEET) against A. albopictus, but in H. longicornis, the activity of veratraldehyde was better than that of DEET. The repellency of the 10% veratraldehyde solution was comparable to that of 20% DEET against the two mosquitoes. When comparing repellency between the WJ-1041 formulation (10% veratraldehyde) and 10% DEET against C. pipiens pallens, A. Albopictus and H. longicornis, the two showed similar repellency and complete protection time (CPT) values. However, there was a small difference depending on the tested insects. The absorption of veratraldehyde via skin was minimal, if at all. The pharmacokinetic parameters (Cmax and Tmax) of veratraldehyde in blood samples of rats were not different from those of the control group. Based on these results, veratraldehyde has high potential to be commercialized as a repellent agent against infectious disease-borne pests in the near future.

Cytotoxic, antioxidant, and antimicrobial activities of Celery (Apium graveolens L.)

Celery (Apium graveolens Linn, Family: Apiaceae) is a common edible herb used as a spice in the traditional medicine of several nations since time immemorial. The whole plant is extensively used in cooking as soups and salads. A. graveolens has various pharmacological properties such as anticancer, anti-obesity, anti-hepatotoxic, and antihypertensive agents. Hence, it is of interest to document the in vitro cytotoxic, antioxidant, and antimicrobial activity of A. graveolens. The plants were collected in the local market, shade dried, and different parts of the plants were extracted with 70% ethanol using a cold maceration process. Antioxidant tests were performed based on the various radical scavenging methods. Antimicrobial activity and MIC were completed using the respective cup-plate and two-fold serial dilution method. In vitro cytotoxic studies were achieved by the MTT; Sulphorhodamine B assayed total cell protein content. DLA and ESC cells determined the short-term toxicity. The leaf extract exhibited significant antioxidant properties against NO, DPPH, ABTS, LPO, and HPO methods. Thus, potential inhibition against Gram-positive, Gram-negative, and fungal strains within the MIC ranges of 250-500 µg/ml was observed. All the extracts of the plant presented in the study revealed greater cytotoxicity effects against five respective cancer cell lines, L6, Vero, BRL 3A, A-549, L929, and L-929 with the ranging of 443-168.5 µg/ml. Thus, we show that A. graveolens possess a potential cytotoxic, antioxidant, and antimicrobial activity.

Efficacy and safety of ethanolic Curcuma longa extract as a treatment for sand tampan ticks in a rabbit model

Background and Aim:

The soft tick Ornithodoros savignyi is distributed throughout Africa, including Egypt. It primarily attacks camels, cattle, donkeys, and cows; and rarely affects humans. This study evaluated the acaricidal efficacy of ethanolic Curcuma longa extract (Turmeric) on the second nymphs of O. savignyi and then investigated the safety of this herb in rabbits.

Materials and Methods:

The nymphs were immersed in 10, 5, 2.5, 1.25, and 0.625 mg/ml ethanolic C. longa extract. An additional group was immersed in ethanol as a control. On the 1^st, 7^th, and 15^th-day post-treatment, the mortality percentages, LC₅₀, and LC₉₅ were calculated. The ticks exposed to 10mg/ml ethanol C. longa extract were investigated by scanning electron microscopy (SEM). Three male New Zealand White rabbits were orally administered 2ml (two doses) of 10mg/ml ethanolic C. longa extract, and another three rabbits were orally given two doses of 2ml of absolute ethanol as a negative control. Histopathological examination of the kidney and liver hematology and the kidney and liver function was performed. Chemical analysis of the extract was determined by gas chromatography-mass spectrometry (GC-MS).

Results:

The LC₅₀ and LC₉₅ were 1.31 and 15.07, 1.07 and 8.56, and 0.81 and 6.97mg/ml on the 1^st, 7^th, and 15^thday, respectively. SEM revealed that mamillae and spots on the surfaces of the treated ticks were not discriminating except for some clefts on the surfaces. The histological examination, blood profile, and biochemical analyses revealed no significant differences between the treated and untreated rabbits (p>0.05). GC/MS analysis revealed 50 compounds, and curcumene and tumerone were found to be the major constituents of this ethanolic extract.

Conclusion:

The ethanolic C. longa extract produced a strong acaricidal effect on the second nymph of O. savignyi, and it was safe to use in rabbits.

Effectiveness of plant-based repellents against different Anopheles species: a systematic review

Plant-based repellents have been applied for generations in traditional practice as a personal protection approach against different species of Anopheles. Knowledge of traditional repellent plants is a significant resource for the development of new natural products as an alternative to chemical repellents. Many studies have reported evidence of repellant activities of plant extracts or essential oils against malaria vectors worldwide. This systematic review aimed to assess the effectiveness of plant-based repellents against Anopheles mosquitoes. All eligible studies on the repellency effects of plants against Anopheles mosquitoes published up to July 2018 were systematically searched through PubMed/Medline, Scopus and Google scholar databases. Outcomes measures were percentage repellency and protection time. A total of 62 trials met the inclusion criteria. The highest repellency effect was identified from Ligusticum sinense extract, followed by citronella, pine, Dalbergia sissoo, peppermint and Rhizophora mucronata oils with complete protection time ranging from 9.1 to 11.5 h. Furthermore, essential oils from plants such as lavender, camphor, catnip, geranium, jasmine, broad-leaved eucalyptus, lemongrass, lemon-scented eucalyptus, amyris, narrow-leaved eucalyptus, carotin, cedarwood, chamomile, cinnamon oil, juniper, cajeput, soya bean, rosemary, niaouli, olive, tagetes, violet, sandalwood, litsea, galbanum, and Curcuma longa also showed good repellency with 8 h complete repellency against different species of Anopheles. Essential oils and extracts of some plants could be formulated for the development of eco-friendly repellents against Anopheles species. Plant oils may serve as suitable alternatives to synthetic repellents in the future as they are relatively safe, inexpensive, and are readily available in many parts of the world.

Identification of novel bioinspired synthetic mosquito repellents by combined ligand-based screening and OBP-structure-based molecular docking

In this work we report a fast and efficient virtual screening protocol for discovery of novel bioinspired synthetic mosquito repellents with lower volatility and, in all likelihood, increased protection time as compared with their plant-derived parental compounds. Our screening protocol comprises two filtering steps. The first filter is based on the shape and chemical similarity to known plant-derived repellents, whereas the second filter is based on the predicted similarity of the ligand's binding mode to the Anopheles gambiae odorant binding protein (AgamOBP1) relative to that of DEET and Icaridin to the same OBP. Using this protocol, a chemical library containing 42,755 synthetic molecules was screened in silico and sixteen selected compounds were tested for their affinity to AgamOBP1 in vitro and repellence against A. gambiae female mosquitoes using a warm-body repellent assay. One of them showed DEET-like repellence (91%) but with significantly lower volatility (2.84 × 10^-6 mmHg) than either DEET (1.35 × 10^-3 mmHg) or its parental cuminic acid (3.08 × 10^-3 mmHg), and four other compounds were found to exhibit repellent indices between 69 and 79%. Overall, a correlation was not evident between repellence and OBP-binding strength. In contrast, a correlation between binding mode and repellence was found.

The medicinal plants of Myanmar

A comprehensive compilation is provided of the medicinal plants of the Southeast Asian country of Myanmar (formerly Burma). This contribution, containing 123 families, 367 genera, and 472 species, was compiled from earlier treatments, monographs, books, and pamphlets, with some medicinal uses and preparations translated from Burmese to English. The entry for each species includes the Latin binomial, author(s), common Myanmar and English names, range, medicinal uses and preparations, and additional notes. Of the 472 species, 63 or 13% of them have been assessed for conservation status and are listed in the IUCN Red List of Threatened Species (IUCN 2017). Two species are listed as Extinct in the Wild, four as Threatened (two Endangered, two Vulnerable), two as Near Threatened, 48 Least Concerned, and seven Data Deficient. Botanic gardens worldwide hold 444 species (94%) within their living collections, while 28 species (6%) are not found any botanic garden. Preserving the traditional knowledge of Myanmar healers contributes to Target 13 of the Global Strategy for Plant Conservation.

Repellency of zerumbone identified in Cyperus rotundus rhizome and other constituents to Blattella germanica

The compounds 1,8-cineole and zerumbone (ZER) from the Cyperus rotundus rhizome along with another 11 previously identified rhizome essential oil constituents and α-humulene, which lacks the only carbonyl group present in ZER, as well as binary mixtures of ZER and seven active compounds were tested for repellency to male B. germanica. The results were compared to N,N-diethyl-3-methylbenzamide (deet). In filter-paper choice tests, ZER was the most repellent compound, and α-humulene was ineffective, which indicates that the α,β-unsaturated carbonyl group of ZER is a prerequisite component for repellency. At 81.5 μg cm⁻², enhanced repellency was produced by binary mixtures of ZER and 1,8-cineole, (+)-dihydrocarvone or (R)-(+)-limonene (70:30, 50:50 and 30:70 ratios by weight). These mixtures were very effective against male B. germanica within 24 h and were more repellent than a single compound or deet alone. The optimum ZER content was determined to be more than 50%. In Ebeling choice box tests at 652.4 μg cm⁻², these compounds and deet resulted in complete repellency to intact male B. germanica, while they exhibited 35–47% repellency to antennectomized male one. Mixtures formulated from the active constituents of the C. rotundus rhizome could be useful as potential repellents for controlling B. germanica.

Impact of drying and micronization on the physicochemical properties and antioxidant activities of celery stalk

BACKGROUND

The influence of convective drying and ball-mill treatment of celery stalk on particle size distribution, physicochemical properties, bioactive compounds and antioxidant activities were analyzed in this study.

RESULTS

Ball-milling of celery stalk dried at temperatures of 50, 75 and 100 °C resulted in decreased average particle sizes of 48.8, 10.5 and 7.2 µm, respectively. Bulk density was increased with reduced particle size. Darker (L*) and reddish (a*) powders were formed at higher temperatures, while ball-milling increased greenness (-a*) of powders dried at 50 and 75 °C. Total content of phenol compounds increased with increasing temperature. 2,2-Diphenyl-1-picrylhydrazyl radical scavenging activity and reducing power were affected by ball-milling for 24 h and drying at elevated temperatures. Iron chelating ability was unaffected by increasing temperature or reduced particle size.

CONCLUSION

Increasing drying temperatures not only decreased the average particle size of powders, but also increasingly reduced particle size after ball-milling. Micronization of celery stalk dried at the highest temperature had the best antioxidant activities. Drying and ball-milling were not highly deleterious to the major phenolic structures. © 2017 Society of Chemical Industry.

An Updated Phytopharmacological Review on Medicinal Plant of Arab Region: Apium graveolens Linn

Apium graveolens Linn. (Karafs) is used in traditional medicine for the treatment of the various ailments. There is a need to explore and authenticate the pharmacological profile and medicinal importance of the Karafs. In this paper, the literature and the published work on Apium were collected using online resources “Google scholar”, “Web of science”, “Scopus” and “PubMed”. Each of the pharmacological activity was searched individually using the keywords “Apium/Karafs/Apium graveolens + individual pharmacological activity”. We documented the most cited and most recent literatures. The current findings illuminate the importance Karafs in the traditional medicine and their impact in treating various diseases. This review strongly supports the fact that the Apium has emerged as a good source of medicine in treating various diseases. There is also a need to isolate the bioactive phytochemicals present in this plant.

EPA-Registered Repellents for Mosquitoes Transmitting Emerging Viral Disease

In many parts of the United States, mosquitoes were previously nuisance pests. However, they now represent a potential threat in the spread of viral diseases. The Aedes aegypti, Aedes albopictus, and Culex species mosquitoes are endemic to the United States and together may transmit a variety of viral diseases of growing concern, including West Nile virus, chikungunya, dengue fever, and Zika virus. The Centers for Disease Control and Prevention and the Environmental Protection Agency (EPA) recommend N,N-diethyl-meta-toluamide (DEET) as a first-line mosquito repellent, but for patients refusing to use DEET or other conventional repellents, guidance is limited to any EPA-registered product. Therefore, we conducted a systematic review of the literature to identify which EPA-registered personal mosquito repellent provides the best protection from A. aegypti, A. albopictus, and Culex spp. mosquitoes. We abstracted data from 62 published reports of EPA-registered mosquito repellents. The conventional repellent picaridin has the strongest data to support its use as a second-line agent, while IR3535 and oil of lemon eucalyptus are reasonably effective natural products. Citronella, catnip, and 2-undecanone offer limited protection or have limited data. These results can be used by pharmacists and other health care professionals to advise patients on the selection of an EPA-registered mosquito repellent. Regardless of the repellent chosen, it is vital for patients to follow all instructions/precautions in the product labeling to ensure safe and effective use.

Assessment of Angelica sinensis (Oliv.) Diels as a repellent for personal protection against mosquitoes under laboratory and field conditions in northern Thailand

Background

Angelica sinensis (Oliv.) hexane extract (AHE) has been reported as a proven and impressive repellent against laboratory-reared female Aedes aegypti mosquitoes. With the aim of promoting products of plant origin as a viable alternative to conventional synthetic substances, this study was designed to transform AHE-based repellents for exploitable commercial production by enhancing their efficacy and assessing their physical and biological stability as well as repellency against mosquitoes under laboratory and field conditions.

Methods

The chemical profile of AHE was analyzed by qualitative gas chromatography-mass spectrometry (GC-MS) technique. AHE was supplemented with vanillin, as a fixative, and then investigated for repellency and comparison to the standard synthetic repellent, DEET, under both laboratory and field conditions. Determination of physical and biological stability as a repellent was carried out after keeping AHE samples under varying temperatures and for different storage times.

Results

GC-MS analysis revealed that AHE contained at least 21 phytochemical compounds, constituting 95.74 % of the total content, with the major constituent of 3-N-butylphthalide (66.67 %). Ethanolic formulations of AHE and DEET showed improvement of repellency in a dose-dependent manner when vanillin was added in laboratory assessment. While 5–25 % AHE alone provided median complete-protection times of 2.0–6.5 h against Ae. aegypti, these times were increased to 4.0–8.5 h with a combination of AHE and 5 % vanillin (AHEv). Protection times against Ae. aegypti were extended from 2.25 to 7.25 h to 4.25–8.25 h when 5–25 % DEET was combined with 5 % vanillin (DEETv). In determining stability, all stored AHE samples exhibited similar characteristics such as liquid phases with aromatic odor comparable to those of fresh preparations. Furthermore, repellent activity of stored AHE samples lasted for at least six months, with varied efficacy (4.5–10.0 h) against Ae. aegypti. Field trials revealed strong repellency from both 25 % AHEv and 25 % DEETv, with complete protection (100 %) against a wide range of local mosquito populations. A total of 5,718 adult female mosquitoes, with the most predominant being Culex quinquefasciatus (41.47 %), Armigeres subalbatus (41.13 %), and Culex vishnui (10.53 %), was collected during field applications. No local skin reaction or other allergic responses was observed during both laboratory and field study periods.

Conclusions

Angelica sinensis proved to have not only impressive repellency against both laboratory Ae. aegypti and a wide range of natural mosquito populations, but also relative stability in physical and biological performance.

Field Method for Testing Repellency of an Icaridin-Containing Skin Lotion against Vespid Wasps

Vespid wasps are ecologically beneficial predators of insects but their stings also pose a human health risk. Current control methods based on killing vespids are suboptimal. Here, the repellent effect against Vespula vulgaris of a 20% icaridin skin lotion was evaluated under field conditions. An experimental setup was designed in which six artificial skin pieces (10 × 10 cm) were video-recorded for 1 h, to count each min the numbers of flying and feeding vespids. Prior to monitoring, five pieces were successively smeared with 2 mg of cream per cm², in 30 min intervals, from t = −120 min to 0. The sixth sheet remained untreated to serve as a control. One milliliter of an attractant, fruit jam, was deposited on each of the six surfaces at t = 0. The control surface was free of any flying or feeding vespid during an average period of 25 min, whereas the other five surfaces (treated at t = −120, −90, −60, −30, and 0 min) remained vespid-free for 39, 40, 45, 49, and 51 min, respectively. The skin lotion remained significantly active for at least 2 h. The experimental methodology is adjustable and allows the study of repellents against vespids in semi-natural conditions.

Remarkable repellency of Ligusticum sinense (Umbelliferae), a herbal alternative against laboratory populations of Anopheles minimus and Aedes aegypti (Diptera: Culicidae)

Background

For personal protection against mosquito bites, user-friendly natural repellents, particularly from plant origin, are considered as a potential alternative to applications currently based on synthetics such as DEET, the standard chemical repellent. This study was carried out in Thailand to evaluate the repellency of Ligusticumsinense hexane extract (LHE) against laboratory Anopheles minimus and Aedes aegypti, the primary vectors of malaria and dengue fever, respectively.

Methods

Repellent testing of 25% LHE against the two target mosquitoes; An. minimus and Ae. aegypti, was performed and compared to the standard repellent, DEET, with the assistance of six human volunteers of either sex under laboratory conditions. The physical and biological stability of LHE also was determined after keeping it in conditions that varied in temperature and storage time. Finally, LHE was analysed chemically using the qualitative GC/MS technique in order to demonstrate a profile of chemical constituents.

Results

Ethanol preparations of LHE, with and without 5% vanillin, demonstrated a remarkably effective performance when compared to DEET in repelling both An. minimus and Ae. aegypti. While 25% LHE alone provided median complete-protection times against An. minimus and Ae. aegypti of 11.5 (9.0–14.0) hours and 6.5 (5.5–9.5) hours, respectively, the addition of 5% vanillin increased those times to 12.5 (9.0–16.0) hours and 11.0 (7.0–13.5) hours, respectively. Correspondingly, vanillin added to 25% DEET also extended the protection times from 11.5 (10.5–15.0) hours to 14.25 (11.0–18.0) hours and 8.0 (5.0–9.5) hours to 8.75 (7.5–11.0) hours against An. minimus and Ae. aegypti, respectively. No local skin reaction such as rash, swelling or irritation was observed during the study period. Although LHE samples kept at ambient temperature (21–35°C), and 45°C for 1, 2 and 3 months, demonstrated similar physical characteristics, such as similar viscosity and a pleasant odour, to those that were fresh and stored at 4°C, their colour changed from light- to dark-brown. Interestingly, repellency against Ae. aegypti of stored LHE was presented for a period of at least 3 months, with insignificantly varied efficacy. Chemical analysis revealed that the main components of LHE were 3-N-butylphthalide (31.46%), 2, 5-dimethylpyridine (21.94%) and linoleic acid (16.41%), constituting 69.81% of all the extract composition.

Conclusions

LHE with proven repellent efficacy, no side effects on the skin, and a rather stable state when kept in varied conditions is considered to be a potential candidate for developing a new natural alternative to DEET, or an additional weapon for integrated vector control when used together with other chemicals/measures.

Celery Seed and Related Extracts with Antiarthritic, Antiulcer, and Antimicrobial Activities

Celery preparations have been used extensively for several millennia as natural therapies for acute and chronic painful or inflammatory conditions. This chapter reviews some of the biological and chemical properties of various celery preparations that have been used as natural remedies. Many of these have varying activities and product qualities. A fully standardized celery preparation has been prepared known as an alcoholic extract of the seeds of a plant source derived from northern India. This is termed, Celery Seed Extract (CSE) and has been found to be at least as effective as aspirin, ibuprofen, and naproxen in suppressing arthritis in a model of polyarthritis. CSE can also reduce existing inflammation in rats. CSE has also been shown to provide analgesia in two model systems. CSE, in addition to acting as an analgesic and inflammatory agent, has been shown to protect against and/or reduce gastric irritation caused by NSAIDs, as well as act synergistically with them to reduce inflammation. The CSE was fractionated by organic solvent extractions, then subjected to column chromatography followed by HPLC and was characterized by mass spectrometry. This yielded a purified component that had specific inhibitory effects on Helicobacter pylori but was not active against Campylobacter jejuni or Escherichia coli. Additionally, toxicology studies did not reveal any clear signs of toxicity at doses relevant to human use. Also, unlike many dietary supplements, the available data suggest that CSE does not significantly affect the p450 enzyme systems and thus is less likely to alter the metabolism of drugs the individual may be taking. CSE may be a prototype of a natural product that can be used therapeutically to treat arthritis and other inflammatory diseases.

Synergistic repellent and irritant effect of combined essential oils on Aedes aegypti (L.) mosquitoes

This study was designed to compare the behavioral responses of Aedes aegypti to a single essential oil and to a mixture of two or three essential oils using an excito-repellency test chamber. Mixtures were prepared from essential oils extracted from Litsea cubeba (LC), Litsea salicifolia (LS), and Melaleuca leucadendron (ML). In general, the mixture of essential oils produced a much stronger escape response by Ae. aegypti, regardless of the test conditions. No significant difference in escape responses was seen when the mixture of oils was compared with a standard commercial product containing DEET. Greater contact irritancy was seen from mixed oils of LC and LS than with other mixed oils. Mixtures of LC and LS at 0.075% showed the highest synergistic action (65.5% escaped) compared to that with unmixed oil alone at the same concentration (LC/20% and LS=32.2%). In addition, mixtures of LC and LS at 0.075% demonstrated the highest non-contact repellency (62.7%) and showed a greater effect than the use of LC (20%) or LS (20.3%) alone. We conclude that mixtures of two essential oils show potential as active ingredients for mosquito repellents.

Larvicidal, Repellent, and Irritant Potential of the Seed-Derived Essential oil of Apium graveolens Against Dengue Vector, Aedes aegypti L. (Diptera: Culicidae)

Aedes aegypti L. is one of the primary disease vectors spreading various dreadful diseases throughout the world, specifically over tropics and subtropics. Keeping in view the adverse effects of chemical insecticides-based intervention measures, the eco-friendly and bio-degradable essential oil extracted from the seeds of celery, Apium graveolens were investigated for its efficacy against Ae. aegypti. Larvicidal bioassay carried out with the seed oil against early fourth instars of Ae. aegypti caused an LC₅₀ and LC₉₀ values of 16.10 and 29.08 ppm, respectively, after an exposure to 24 h. The cidal effect of the celery seed oil augmented by 1.2-fold; after an exposure to 48 h; revealing an LC₅₀ value of 13.22 ppm. Interestingly, the seed oil did not cause immediate larval mortality, suggesting a delayed toxicity against the larval stage. Present investigations also revealed remarkable effective repellency of the oil leading to 100% protection till 165 min as compared to control that did not result in any repellency against adult Ae. aegypti. Interestingly, only one bite was recorded in the 165th-min after which only two bites were scored until 180 min of exposure of the adult mosquitoes to the oil. An exciting observation was that the knocked-down effect in adults exposed to 10% oil-impregnated papers. The contact irritancy assays with paper impregnated with 1% celery seed oil caused first flight only after 4 s resulting in an average of 63.66 flights during 15 min of exposure revealing the relative irritability of 26.97. The qualitative phytochemical analysis of the seed oil showed the presence of flavonoids, lactones, and terpenoids as the major constituents suggesting their probable role in the toxicity. Our results confirmed that celery seed essential oil can be used as an efficient larvicide and repellent against Ae. aegypti. The identification of the bioactive components, their mode of action, and studying effects on non-target organisms and the environment would help in devising mosquito-management strategies.

Plant based products: use and development as repellents against mosquitoes: A review

Global warming and deforestation have resulted in the relocation of many living creatures including insects during the recent years. This has affected the population balance of disease vectors including mosquitoes resulting in outbreaks. Traditionally, mankind has been using plants as means of protection from the mosquitoes which are considered to be environment friendly unlike the synthetic chemicals that cause major risk to human health and the ecosystem. Researchers explored mainly, essential oils and traditional plants using different testing methodologies to find out repellent molecules effective against mosquitoes which is the main focus of this review. Among the promising plant species, Eucalyptus spp., Ocimum spp. and Cymbopogon spp. are the most cited. Data of repellency produced from the bioassay systems is difficult to quantify because of different parameters, testing system and standards of material used against mosquitoes. Mainly, the human forearm based bioassays have been used with different sizes of treatment area in the laboratory and the results have not been tested in the field conditions for residual activity. In addition, effectiveness of essential oils and their protection time can be increased by using vanillin as synergist and formulation techniques like microencapsulation and nanoemulsion. There is a need to develop an alternate in vitro bioassay system that can address the problems of uniformity of the results.

Chemical composition, larvicidal action, and adult repellency of Thymus magnus against Aedes albopictus

Thymus magnus, an endemic species, is found in the Republic of Korea. The volatile compounds extracted by SPME from T. magnus were investigated for their chemical composition and electrophysiological response against the Asian tiger mosquito, Aedes albopictus. The volatile compounds of T. magnus as determined by gas chromatography mass spectrometry were gamma-terpinene (33.0%), thymol (29.9%), beta-bisabolene (8.9%), p-cymene (8.3%), alpha-terpinene (5.0%), myrcene (4.7%), beta-caryophyllene (4.0%), alpha-thujene (2.7%), camphene (1.3%), carvacrol (1.2%), and alpha-pinene (1.1%). Among these candidates, thymol exhibited complete (100%) repellent activity against female Ae. albopictus, an effect that was confirmed through evaluating the electrophysiological response on the antenna of Ae. albopictus. The effectiveness of a binary 1:2 mixture of thymol and vanillin (0.05:0.1 microl per cm2) was found to be significantly more effective than thymol alone for a period of 120 min. In addition, thymol, alpha-terpinene, and carvacrol showed high larvicidal activity against on the third-stage larvae with LC50 values of 0.9 microl per 100 ml.

Plant-based insect repellents: a review of their efficacy, development and testing

Plant-based repellents have been used for generations in traditional practice as a personal protection measure against host-seeking mosquitoes. Knowledge on traditional repellent plants obtained through ethnobotanical studies is a valuable resource for the development of new natural products. Recently, commercial repellent products containing plant-based ingredients have gained increasing popularity among consumers, as these are commonly perceived as "safe" in comparison to long-established synthetic repellents although this is sometimes a misconception. To date insufficient studies have followed standard WHO Pesticide Evaluation Scheme guidelines for repellent testing. There is a need for further standardized studies in order to better evaluate repellent compounds and develop new products that offer high repellency as well as good consumer safety. This paper presents a summary of recent information on testing, efficacy and safety of plant-based repellents as well as promising new developments in the field.

Plant-based insect repellents: a review of their efficacy, development and testing

Plant-based repellents have been used for generations in traditional practice as a personal protection measure against host-seeking mosquitoes. Knowledge on traditional repellent plants obtained through ethnobotanical studies is a valuable resource for the development of new natural products. Recently, commercial repellent products containing plant-based ingredients have gained increasing popularity among consumers, as these are commonly perceived as "safe" in comparison to long-established synthetic repellents although this is sometimes a misconception. To date insufficient studies have followed standard WHO Pesticide Evaluation Scheme guidelines for repellent testing. There is a need for further standardized studies in order to better evaluate repellent compounds and develop new products that offer high repellency as well as good consumer safety. This paper presents a summary of recent information on testing, efficacy and safety of plant-based repellents as well as promising new developments in the field.

Enhanced repellency of binary mixtures of Zanthoxylum armatum seed oil, vanillin, and their aerosols to mosquitoes under laboratory and field conditions

The repellency of Zanthoxylum armatum seed oil (ZA-SO), alone or in combination with vanillin (VA), its six major constituents, and another four major previously known Zanthoxylum piperitum fruit oil constituents, as well as aerosol products containing 5 or 10% ZA-SO and 5% VA, was evaluated against female Aedes aegypti in laboratory and field studies. Results were then compared with those of N,N-diethyl-3-methylbenzamide (DEET) as a standard. Hand in cage laboratory tests showed that 0.2, 0.1, and 0.05 mg/cm2 ZA-SO resulted in > 92% protection through 30-min postexposure and was not significantly different than 0.05 mg/cm2 DEET. Skin treated with linalool and limonene (from Z. armatum) provided > 80% repellency to female Ae. aegypti at 10-min exposure, whereas cuminaldehyde, citronellal, geranyl acetate, and cuminyl alcohol (from Zanthoxylum piperitum) provided > 90% protection during this same time period. Only cuminaldehyde and citronellal provided complete protection comparable to DEET at 10-min postexposure. After that time, repellency of all plant constituents to mosquitoes was considerably decreased (< approximately 65%). An increase in repellency and duration of effectiveness was produced by a binary 1:4 mixture of ZA-SO and VA (0.05:0.2 mg/cm2) that was significantly more effective than 0.05 mg/cm2 DEET through 90 min. In field tests, an aerosol formulation containing 5 or 10% ZA-SO plus 5% VA gave 100% repellency at 60-min postexposure. Although these formulations were equal to the level of protection afforded by 10% DEET, repellency to the binary ZA-SO aerosol formulations at 90 min was significantly less effective than DEET. However, mixtures formulated from ZA-SO and VA merit further study as potential repellents for protection of humans and domestic animals from biting and nuisance caused by mosquitoes.

Evaluation of selected South African ethnomedicinal plants as mosquito repellents against the Anopheles arabiensis mosquito in a rodent model

Background

This study was initiated to establish whether any South African ethnomedicinal plants (indigenous or exotic), that have been reported to be used traditionally to repel or kill mosquitoes, exhibit effective mosquito repellent properties.

Methods

Extracts of a selection of South African taxa were tested for repellency properties in an applicable mosquito feeding-probing assay using unfed female Anopheles arabiensis.

Results

Although a water extract of the roots of Chenopodium opulifolium was found to be 97% as effective as DEET after 2 mins, time lag studies revealed a substantial reduction in efficacy (to 30%) within two hours.

Conclusions

None of the plant extracts investigated exhibited residual repellencies >60% after three hours.

Gastric antiulcer, antisecretory and cytoprotective properties of celery (Apium graveolens) in rats

In the present investigation, an ethanol extract of celery [Apium graveolens L. (Apiaceae/Umbelliferae)], at doses of 250 and 500 mg/kg body weight, was evaluated for antigastric ulcer activity using various experimental gastric ulcer models in rats. Ulcers were induced by indomethacin, cytodestructive agents (80% ethanol, 0.2 M NaOH and 25% NaCl) and cold restraint stress. Gastric secretory studies were undertaken by using pylorus ligation (Shay rat model). In addition to gastric wall mucus (GWM), non-protein sulfhydryl (NP-SH) and malondialdehyde (MDA) were also estimated in gastric tissues after 80% ethanol treatment. Pretreatment of celery extract produced dose-dependent reduction in all experimentally induced gastric lesions. Ethanol (80%) decreased the levels of GWM, NP-SH and increase in MDA concentration in gastric tissue. Celery extract showed the ability to significantly replenish the ethanol-induced depleted levels of GWM and gastric mucosal NP-SH. The gastric mucosal MDA level was also significantly lowered in extract pretreated rats. The celery extract showed stomach protection against the models used for ulcerogenesis. Results were further confirmed by using histopathological assessment. The phytochemical screening showed the presence of various chemical constituents such as flavonoids, tannins, volatile oils, alkaloids, sterols and/or triterpenes. Acute toxicity test revealed no deleterious or toxic symptoms or mortality over a period of 14 days. However, the LD(50) was found to be 7.55 g/kg, and showed a large margin of safety. The results suggest that Apium graveolens extract significantly protects the gastric mucosa and suppresses the basal gastric secretion in rats, possibly through its antioxidant potential.

Evaluation of larvicidal and nymphicidal potential of plant extracts against Anopheles subpictus Grassi, Culex tritaeniorhynchus Giles and Aphis gossypii Glover

The acetone, chloroform, ethyl acetate, hexane and methanol extracts of peel and leaf extracts of Citrus sinensis, Ocimum canum, Ocimum sanctum and Rhinacanthus nasutus were tested against fourth instar larvae of malaria vector, Anopheles subpictus Grassi, Japanese encephalitis vector, Culex tritaeniorhynchus Giles (Diptera: Culicidae) and feeding deterrence to nymphs of cotton pest, Aphis gossypii Glover (Homoptera: Aphididae). The larval and nymph mortality were observed after 24 h of exposure. All extracts showed moderate larvicidal and nymphicidal effects; however, the highest mortality was found in peel chloroform extract of C. sinensis, leaf ethyl acetate extracts of O. canum and O. sanctum and leaf chloroform extract of R. nasutus against the larvae of A. subpictus (LC(50) = 58.25, 88.15, 21.67 and 40.46 ppm; LC(90) = 298.31, 528.70, 98.34 and 267.20 ppm), peel methanol extract of C. sinensis, leaf methanol extract of O. canum, ethyl acetate extracts of O. sanctum and R. nasutus against the larvae of C. tritaeniorhynchus (LC(50) = 38.15, 72.40, 109.12 and 39.32 ppm; LC(90) = 184.67, 268.93, 646.62 and 176.39 ppm), peel hexane extract of C. sinensis, leaf methanol extracts of O. canum and R. nasutus and leaf ethyl acetate extract of O. sanctum against the nymph of A. gossypii (LC(50) = 162.89, 80.99, 73.27 and 130.19 ppm; LC(90) = 595.40, 293.33, 338.74 and 450.90 ppm), respectively. These results suggest that the peel methanol extracts of C. sinensis and O. canum, ethyl acetate leaf extract of O. sanctum and leaf chloroform and ethyl acetate extract of R. nasutus have the potential to be used as an ideal eco-friendly approach for the control of the A. subpictus, C. tritaeniorhynchus and A. gossypii.

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.

Repellent activity of selected essential oils against Aedes aegypti

Essential oils extracted from ten plant species were screened for repellency against Aedes aegypti mosquitoes. Three oils; Zanthoxylum piperitum, Anethum graveolens and Kaempferia galanga, exerted protection against A. aegypti, with median complete-protection times of 1, 0.5 and 0.25 h, respectively. The protection times were increased significantly by incorporating 10% vanillin. The highest potential was established from Z. piperitum oil +10% vanillin (2.5 h, range=1-2.5 h). Mixtures from pairs of the effective oils possessed slight repellency that ranged from 0-0.5 h. None of the oil combinations repelled A. aegypti for longer than their constituent oil alone. With vanillin added, however, each oil mixture provided improved protection, which was approximately equal to oil on its own. GC/MS analysis revealed that the main component of Z. piperitum fruit oil was limonene (37.99%), with minor amounts of sabinene (13.30%) and beta-myrcene (7.17%). Repellent testing of stored samples of Z. piperitum fruit oil against A. aegypti demonstrated that repellent activity of those kept at -20 degrees C or 4 degrees C was present for a period of at least 3 months. Therefore, the essential oil of Z. piperitum fruit may prove useful in the development of mosquito repellents as an effective personal protection measure against mosquito bites.

Laboratory evaluation of dimethyl phthalate against Anopheles stephensi and Culex pipiens

Two repellents includes Iranian and Merck dimethyl phthalate (DMP) were evaluated against Anopheles stephensi and Culex pipiens, using American Society for Testing and Material (ASTM) standard ED 951-83 procedure, a free choice method based on the variable dose-fixed time. Also a modified of ASTM method we used for determination of effective dosages of the repellents. In ASTM method there were no significant differences between the two repellents (Iranian and Merck's DMP) as indicated by the ED50 and ED95 values (p > 0.05). But, there were significant differences in repellent sensitivity between An. stephensi and Cx. pipiens at the ED95 level. In modified ASTM method there were no significant differences between the two repellents against An. stephensi, as indicated by the ED50 values (p > 0.05). But, there are significant differences between the two repellents against Cx. pipence based on ED50 value. Results of this study showed that the Iranian synthesized DMP has necessary potential and specificity to compare with Merck manufactured product.

Effectiveness of Zanthoxylum piperitum-derived essential oil as an alternative repellent under laboratory and field applications

Recently, there were considerable efforts made to promote the use of environmentally friendly and biodegradable natural insecticides and repellents, particularly from botanical sources. In this study, Zanthoxylum piperitum-derived essential oil isolated by steam distillation was investigated and compared to the standard synthetic repellent, N,N-diethyl-3-methylbenzamide (DEET), for repellency against mosquitoes under laboratory and field conditions. The oil of Z. piperitum alone and also with 5% vanillin added repelled laboratory-reared female Aedes aegypti with the median protection times of 1.5 and 2.5 h, respectively. These repellency times were proven to be significantly lower than those of DEET-based products: 25% DEET and 25% DEET + 5% vanillin demonstrating 3.5 and 5.5 h, respectively. However, when applied under field conditions, Z. piperitum oil + 5% vanillin was found to provide better protection against a wide range of natural mosquito populations than 25% DEET + 5% vanillin. While the product of DEET was effective in reducing bites with 99.7% protection, the protective effect of Z. piperitum oil product appeared complete (100%). It had a protective effect against Aedes gardnerii, Anopheles barbirostris, Armigeres subalbatus, Culex tritaeniorhynchus, Culex gelidus, Culex vishnui group, and Mansonia uniformis. The better repellency against a wide range of field mosquitoes derived from Z. piperitum oil products suggested an advantage of efficacy by providing a broad spectrum of activity. Therefore, Z. piperitum could have potential for use in the development of combined repellents as a natural active ingredient, synergist, or additive to conventional synthetic chemicals, particularly in situations when DEET is ineffective and impractical.