α-Stereoselective 3-Deoxy-d-manno-oct-2-ulosonoic Acid (Kdo) O-Glycosylation with a p-Toluenethioglycoside Donor by the (p-Tol)2SO/Tf2O Preactivation Strategy

A convenient and efficient approach was developed to synthesize α-Kdo O-glycosides based on the Tf₂O/(p-Tol)₂SO preactivation strategy using peracetylated Kdo thioglycoside as a donor. Under the optimized reaction conditions, several O-glycoside products, including α-(2 → 1)-, α-(2 → 2)-, α-(2 → 3)-, and α-(2 → 6)-Kdo products, were stereoselectively synthesized in high yields. Remarkably, a series of aromatic α-Kdo O-glycosides were first and successfully constructed in high yields. An S_N2-like mechanism was revealed by DFT calculations and experimental results.

Contact toxicity and repellent efficacy of Valerianaceae spp. to three stored-product insects and synergistic interactions between two major compounds camphene and bornyl acetate

In this work, the essential oil (EO) and supercritical CO₂ fluid extract (SF extract) of four Valerianaceae plants (Valeriana officinalis L., Valeriana officinalis L. var. latifolia Miq., Valeriana jatamansi Jones and Nardostachys chinensis Bat.) were chemically characterized. GC-MS analysis identified 74 compounds, representing 35.2%-82.4% of the total EOs and SF extracts. The EO was dominated by low-molecular-weight components while the SF extract was rich in fatty acids. Bornyl acetate and camphene were the characteristic compounds in EO and SF extracts. The efficacy of six extracts against three stored-product insects was investigated. In contact assays, V. officinalis exhibited strongest toxicity to red flour beetle (LD₅₀ = 10.0 μg/adult), and V. jatamansi EO was the most active one against the cigarette beetle (LD₅₀ = 17.6 μg/adult), while V. officinalis var. latifolia EO showed outstanding efficacy against the booklouse (LD₅₀ = 40.2 μg/cm²). Binary mixtures of two major compounds (camphene and bornyl acetate) were assessed for the contact toxicity to the red flour beetle. Additive effect existed in the natural proportion of V. officinalis, and synergism was observed in that of V. officinalis var. latifolia. This work confirmed the insecticidal efficacy of the species of the Valerianaceae family, and it would offer some information for the development of botanical insecticide.

Insecticidal and repellent efficacy against stored-product insects of oxygenated monoterpenes and 2-dodecanone of the essential oil from Zanthoxylum planispinum var. dintanensis

Essential oils (EOs) extracted from leaves (EL) and fruit pericarp (EFP) of Zanthoxylum planispinum var. dintanensis were analyzed for their chemical composition by GC-MS technique and evaluated for their fumigant, contact toxicity and repellency against three stored-product insects, namely Tribolium castaneum, Lasioderma serricorne, and Liposcelis bostrychophila adults. Results of GC-MS analysis manifested that EL and EFP of Z. planispinum var. dintanensis were mainly composed of oxygenated monoterpenes. Major components included linalool, sylvestrene and terpinen-4-ol. The obvious variation observed between two oil samples was that EL contained 2-dodecanone (11.52%) in addition to the above mentioned components, while this constituent was not detected in EFP. Bioassays of insecticidal and repellent activities were performed for EL, EFP as well as some of their individual compounds (linalool, terpinen-4-ol and 2-dodecanone). Testing results indicated that EL, EFP, linalool, terpinen-4-ol and 2-dodecanone exhibited potent insecticidal and repellent activities against the three target insects selected. Among the three individual compounds, 2-dodecanone was significantly toxic to T. castaneum (LD₅₀ = 5.21 μg/adult), L. serricorne (LD₅₀ = 2.54 μg/adult) and L. bostrychophila (LD₅₀ = 23.41 μg/cm²) in contact assays and had beneficial repellent effects on L. serricorne at 2 and 4 h post-exposure. The anti-insect efficacy of Z. planispinum var. dintanensis EO suggests it has potential to be used as botanical insecticide or repellent to control pest damage in warehouses and grain stores.

Seven herbs against the stored product insect: Toxicity evidence and the active sesquiterpenes from Atractylodes lancea

In this work, the essential oils (EO) were extracted from seven typical Chinese herbs, and their repellent and contact toxicities against Tribolium castaneum adults (red flour beetles) were evaluated. The experimental results showed that the above EOs presented the various levels of repellent and contact toxicities. The EOs extracted from A. lancea and A argyi of the Compositae (Asteraceae) family presented obvious repellent effects (Repellency Percentage > 90% at 3.15 nL/cm² after 4 h exposure) and strong contact toxicity with LD₅₀ values of 5.78 and 3.09 μg/adult respectively. Based on literature researches and screening results, the EO from A. lancea was analyzed by GC-MS and chosen for further identification of bioactive components. Altogether 59 chemical components were identified and 17 of them were recognized as sesquiterpene compounds, accounting for 57.8% of the total weight of the EO. From the identified sesquiterpenes, three individual compounds (β-eudesmol, hinesol, valencene) were selected for the laboratory bioassays of the toxicity against red flour beetles. It was found that all the three compounds expressed some repellent effects. Although β-eudesmol (31.2%) and hinesol (5.1%) were identified as main constituents and had been considered to be symbolic characteristics of high medicinal value, valencene (0.3%) showed strong repellent property which could be comparable to that of DEET (N, N‑diethyl‑3‑methylbenzamide), a powerful commercial pesticides, and it had best toxicity with LD₅₀ values of 3.25 (μg/adult) in the contact test. This work may provide toxicity evidence of seven common herbs against red flour beetles, add the information for the development and comprehensive utilization of A. lancea, and will contribute to the application of grain preservation.

Toxicity and repellency of essential oil from Evodia lenticellata Huang fruits and its major monoterpenes against three stored-product insects

In this work, the essential oil (EO) was extracted from the fruits of Evodia lenticellata, and the fumigant toxicity, contact toxicity and repellency against three stored-product insect species were evaluated for the obtained EO and several of its chemical components. The target insects were the adults of Tribolium castaneum (Coleoptera: Tenebrionidae), Lasioderma serricorne (Coleoptera: Anobiidae) and Liposcelis bostrychophila (Psocoptera: Liposcelididae). The EO was obtained with hydrodistillation and its chemical components were analyzed with the gas chromatography-mass spectrometry (GC-MS). Twenty-seven compounds, accounting for 83.1% of the total amount of the oil, were identified from the EO sample. The main compounds included linalool (12.0%), β-pinene (11.5%), 3-carene (9.6%), caryophyllene oxide (8.7%) and β-caryophyllene (7.9%). Among them, the amounts of monoterpenes and sesquiterpenes were as high as 52.7% and 22.7% to the total amount of EO respectively. The results of bioactivity test showed that the EO and its testing compounds had interspecific toxicity and repellent activity. So that, it might be expected that the EO extracted from the fruits of E. lenticellata could be developed to a new type of eco-friendly natural insecticide or repellent for the control of stored-product insects.

Supercritical carbon dioxide extract of Cinnamomum cassia bark: toxicity and repellency against two stored-product beetle species

The extract from Cinnamomum cassia Presl bark was obtained with supercritical CO₂ fluid extraction (SFE). Chemical components of the SFE extract were characterized by GC-MS spectrometry. The repellency and contact toxicity of the SFE extract were evaluated against the adults of Tribolium castaneum and Lasioderma serricorne along with those of its two main compounds. The results of GC-MS analysis indicated that 33 volatile constituents were identified from the extract. The main components included trans-cinnamaldehyde (32.1%), 3,3-dimethylhexane (10.6%) and 2,4-di-tert-butylphenol (7.9%). Testing results showed that the SFE extract had potent contact toxicity against T. castaneum and L. serricorne with LD₅₀ values of 3.96 and 23.89 μg/adult, respectively. LD₅₀ values of trans-cinnamaldehyde against T. castaneum and L. serricorne were 5.78 and 3.24 μg/adult, respectively. Additionally, percentage repellency values of the SFE extract and trans-cinnamaldehyde against T. castaneum and L. serricorne were rather high (PR = 100% and PR > 90%, respectively) at 78.63 and 15.73 nL/cm² at 2 h post-exposure. 2,4-Di-tert-butylphenol showed some repellency against both beetle species. Considering its insecticidal and repellent effects, the SFE extract from C. cassia bark might be used in integrated pest management programs for T. castaneum and L. serricorne.

Contact Toxicity and Repellency of the Essential Oils of Evodia lenticellata Huang and Evodia rutaecarpa (Juss.) Benth. Leaves against Three Stored Product Insects

The essential oils (EOs) extracted from Evodia lenticellata Huang and Evodia rutaecarpa (Juss.) Benth. leaves are screened to evaluate their contact toxicity and repellency towards Tribolium castaneum (Coleoptera: Tenebrionidae), Lasioderma serricorne (Coleoptera: Anobiidae) and Liposcelis bostrychophila (Psocoptera: Liposcelididae) adults. The EOs are obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS). The principal components in the E. lenticellata EO are identified to be caryophyllene oxide (28.5%), β-caryophyllene (23.1%), β-elemene (14.5%), and β-cubebene (4.7%), while the main components of the E. rutaecarpa EO are α-pinene (39.4%), β-elemene (13.5%), α-ocimene (7.6%), and α-selinene (4.0%). These two kinds of EOs and their individual compounds all showed different levels of contact toxicity and repellent activity against three stored-product insects.

Chemical Constituents of Murraya tetramera Huang and Their Repellent Activity against Tribolium castaneum

Sixteen compounds were isolated from the leaves and stems of Murrayatetramera Huang. Based on the NMR and MS spectral results, the structures were determined. It was confirmed that the isolated compounds included three new compounds (9, 10 and 13) and one new natural product (8), which were identified asmurratetra A (9), murratetra B (10), murratetra C (13) and [2-(7-methoxy-2-oxochromen-8-yl)-3-methylbut-2-enyl]3-methylbut-2-enoate (8), respectively. Meanwhile, the repellent activity against Tribolium castaneum was investigated for 13 of these isolated compounds. The results showed that the tested compounds had various levels of repellent activity against T. castaneum. Among them, compounds 1 (4(15)-eudesmene-1β,6α-diol), 11 (isoferulic acid) and 16 (2,3-dihydroxypropyl hexadecanoate) showed fair repellent activity against T. castaneum. They might be considered as potential leading compounds for the development of natural repellents.

Fumigant and repellent activities of essential oil extracted from Artemisia dubia and its main compounds against two stored product pests

The major chemical constituents of the essential oil extracted from Artemisia dubia wall. ex Bess. (Family: Asteraceae) were found as terpinolene (19.02%), limonene (17.40%), 2,5-etheno[4.2.2]propella-3,7,9-triene (11.29%), isoelemicin (11.05%) and p-cymene-8-ol (5.93%). Terpinolene and limonene were separated as main components from the essential oil. The essential oil showed fumigant toxicity against Tribolium castaneum and Liposcelis bostrychophila with LC₅₀ values of 49.54 and 0.74 mg/L, respectively. The essential oil and isolated compounds of A. dubia showed repellency activities against both insects. Terpinolene and limonene showed the fumigant toxicity against T. castaneum. Terpinolene showed obvious fumigant toxicity against L. bostrychophila. The results indicated that the essential oil of A. dubia had potential to be developed into natural insecticides for controlling stored product pests.

Chemical Composition of Essential Oils from Zanthoxylum bungeanum Maxim. and Their Bioactivities against Lasioderma serricorne

Two essential oil samples were obtained from the pericarp of Zanthoxylum bungeanum with the methods of hydrodistillation (HD) and supercritical fluid CO₂ extraction (SFE), their chemical components were identified, and their bioactivities against Lasioderma serricorne adults were evaluated. In the process of testing, the two samples showed significant bioactivities against Lasioderma serricorne adults. For an example, the SFE-sample expressed relatively stronger fumigant toxicity on Lasioderma serricorne adults (LC₅₀ = 3.99 μg/mL air) than that of the HD-sample (LC₅₀ = 12.54 μg/mL air). According to GC-MS analysis, the chemical components between two samples were different. The major chemical components for HD included linalool (25.99%), limonene (19.34%), linalyl anthranilate (12.22%), 4-terpinenol (10.49%), eucalyptol (6.53%) and α-terpineol (5.02%), while for SFE included nonanoic acid (21.43%), γ-terpinene (14.51%), eucalyptol (13.45%), α-terpineol (5.83%) and caryophyllene oxide (5.48%). The results showed that different chemical components result in different bioactivities. This work provides theoretical basis for traditional Chinese concept of antagonistic storage, and it also provides important information for the development and comprehensive utilization of Zanthoxylum bungeanum.

Chemical Constituents and Insecticidal Activities of Ajania fruticulosa Essential Oil

The insecticidal activity and chemical constituents of the essential oil from Ajania fruticulosa were investigated. Twelve constituents representing 91.0% of the essential oil were identified, and the main constituents were 1,8-cineole (41.40%), (+)-camphor (32.10%), and myrtenol (8.15%). The essential oil exhibited contact toxicity against Tribolium castaneum and Liposcelis bostrychophila adults with LD50 values of 105.67 μg/adult and 89.85 μg/cm(2) , respectively. The essential oil also showed fumigant toxicity against two species of insect with LC50 values of 11.52 and 0.65 mg/l, respectively. 1,8-Cineole exhibited excellent fumigant toxicity (LC50  = 5.47 mg/l) against T. castaneum. (+)-Camphor showed obvious fumigant toxicity (LC50  = 0.43 mg/l) against L. bostrychophila. Myrtenol showed contact toxicity (LD50  = 29.40 μg/cm(2) ) and fumigant toxicity (LC50  = 0.50 mg/l) against L. bostrychophila. 1,8-Cineole and (+)-camphor showed strong insecticidal activity to some important insects, and they are main constituents of A. fruticulosa essential oil. The two compounds may be related to insecticidal activity of A. fruticulosa essential oil against T. castaneum and L. bostrychophila.

Chemical Constituents and Activity of Murraya microphylla Essential Oil against Lasioderma serricorne

The chemical composition, contact and repellent activities of the essential oil from Murraya microphylla branches and leaves against Lasioderma serricorne adults were determined and six compounds from the essential oil were isolated as well. The essential oil of M microphylla obtained by hydrodistillation was analyzed by gas chromatography-mass spectrometric (GC-MS) analysis; 22 compounds were identified. The main constituents of the essential oil included β-caryophyllene (18.0%), α-pinene (13.8%), spathulenol (9.5%), α-humulene (6.0%), γ-elemene (5.1%) and zingiberene (4.6%), followed by α-cadinol (3.9%) and caryophyllene oxide (3.8%). Six of these compounds were isolated and fully identified as α-pinene, β-caryophyllene, α-humulene, caryophyllene oxide, spathulenol and α-cadinol. L. serricorne adults had different sensitivities to the crude essential oil and isolated compounds. α-Humulene exhibited the strongest contact activity against L. serricorne, showing an LD50 value of 13.1 µg adult(-1). However, spathulenol, the crude essential oil and α-cadinol showed stronger contact activity against L. serricorne than caryophyllene oxide and β-caryophyllene. The essential oil, α-humulene and spathulenol showed comparable repellency against L. serricorne adults at 2 h after exposure, relative to the positive control, DEET. The results demonstrate that the essential oil and isolated compounds exhibited important contact and repellent activities against L. serricorne. Thus, they could become potential natural insecticides or repellents for control of insects in stored products.

Chemical Constituents and Activity of Murraya microphylla Essential Oil against Lasioderma serricorne

The chemical composition, contact and repellent activities of the essential oil from Murraya microphylla branches and leaves against Lasioderma serricorne adults were determined and six compounds from the essential oil were isolated as well. The essential oil of M. microphylla obtained by hydrodistillation was analyzed by gas chromatography-mass spectrometric (GC-MS) analysis; 22 compounds were identified. The main constituents of the essential oil included β-caryophyllene (18.0%), α-pinene (13.8%), spathulenol (9.5%), α-humulene (6.0%), γ-elemene (5.1%) and zingiberene (4.6%), followed by α-cadinol (3.9%) and caryophyllene oxide (3.8%). Six of these compounds were isolated and fully identified as α-pinene, β-caryophyllene, α-humulene, caryophyllene oxide, spathulenol and α-cadinol. L. serricorne adults had different sensitivities to the crude essential oil and isolated compounds. α-Humulene exhibited the strongest contact activity against L. serricorne, showing an LD50 value of 13.1 μg adult−1. However, spathulenol, the crude essential oil and α-cadinol showed stronger contact activity against L. serricorne than caryophyllene oxide and β-caryophyllene. The essential oil, α-humulene and spathulenol showed comparable repellency against L. serricorne adults at 2 h after exposure, relative to the positive control, DEET. The results demonstrate that the essential oil and isolated compounds exhibited important contact and repellent activities against L. serricorne. Thus, they could become potential natural insecticides or repellents for control of insects in stored products.

Chemical Composition and Bioactivities of the Essential Oil from Etlingera yunnanensis against Two Stored Product Insects

The chemical composition of the essential oil of Etlingera yunnanensis rhizomes and its contact and repellent activities against Tribolium castaneum (Herbst) and Liposcelis bostrychophila (Badonnel) were investigated. The essential oil obtained from E. yunnanensis rhizomes with hydrodistillation was performed by gas chromatography-flame ionization detection and gas chromatography-mass spectrometry. The main components of the essential oil were identified to be estragole (65.2%), β-caryophyllene (6.4%), 1,8-cineole (6.4%), limonene (5.2%), and α-pinene (2.4%). It was found that the essential oil of E. yunnanensis rhizomes possessed contact toxicity against T. castaneum and L. bostrychophila (LD₅₀ = 23.33 μg/adult and LD₅₀ = 47.38 μg/cm², respectively). Estragole, 1,8-cineole, and limonene exhibited stronger contact toxicity (LD₅₀ values of 20.41, 18.86, and 13.40 μg/adult, respectively) than β-caryophyllene (LD₅₀ = 41.72 μg/adult) against T. castaneum adults. Estragole possessed stronger contact toxicity (LD₅₀ = 30.22 µg/cm²) than β-caryophyllene, 1,8-cineole, and limonene (LD₅₀ values of 74.11, 321.20, and 239.62 μg/adult, respectively) against L. bostrychophila adults. Repellency of the crude oil was also evaluated. The essential oil and constituents possessed strong repellent activity against T. castaneum adults. The four individual constituents showed weaker repellent activity than the essential oil against L. bostrychophila adults. The results indicated that the essential oil of E. yunnanensis rhizomes and the individual constituents had the potential to be developed as a natural insecticide and repellent for the control of T. castaneum and L. bostrychophila.

Bioactivity of Essential Oil of Zingiber purpureum Rhizomes and Its Main Compounds against Two Stored Product Insects

The insecticidal and repellent activities of the essential oil extracted from Zingiber purpureum Roscoe rhizomes were evaluated against Tribolium castaneum (Herbst) and Lasioderma serricorne (L.) adults. During our screening program for agrochemicals from Chinese medicinal herbs and wild plants, the essential oil of Z. purpureum rhizomes was found to possess strong contact toxicity against T. castaneum and L. serricorne adults, with LD50 values of 39.0 and 16.3 µg per adult, respectively, and also showed strong fumigant toxicity against the two grain storage insects with LC50 values of 13.6 and 9.3 mg/liter of air, respectively. The essential oil obtained by hydrodistillation was investigated by gas chromatography-mass spectrometry. The main components of the essential oil were identified to be sabinene (48.1%), terpinen-4-ol (25.1%), and γ-terpinene (6.7%), followed by α-terpinene (4.3%), β-thujene (3.4%), and α-phellandrene (2.7%). Sabinene, terpinen-4-ol, and γ-terpinene were separated and purified by silica gel column chromatography and preparative thin-layer chromatography. Terpinen-4-ol showed the strongest contact toxicity against T. castaneum and L. serricorne (LD50=19.7 and 5.4 µg per adult, respectively) and also the strongest fumigant toxicity against T. castaneum and L. serricorne (LC50=3.7 and 1.3 mg/liter of air, respectively). Otherwise, sabinene and terpinen-4-ol were strongly repellent against T. castaneum as well as the essential oil, while γ-terpinene exhibited weaker repellency against T. castaneum compared with the positive control, DEET (N, N-diethyl-3-methylbenzamide). Moreover, only the essential oil exhibited strong repellency against L. serricorne, the three compounds exhibited weaker repellency against L. serricorne relative to DEET.

Chemical constituents and activities of the essential oil from Myristica fragrans against cigarette beetle Lasioderma serricorne

Essential oil extracted from nutmeg seeds (Myristica fragrans Houtt.) by hydrodistillation was subjected to GC/MS and GC analysis. A total of 27 constituents were identified, of which eugenol (19.9%), methylisoeugenol (16.8%), methyleugenol (16.7%), sabinene (11.8%), and terpinen-4-ol (8.5%) were the major components. The essential oil was tested against Lasioderma serricorne for insecticidal and repellent activity, the LD50 value at the end of 24 h exposure period was 19.3 μg/adult. Six active compounds were isolated by bioassay-guided fractionation. They were identified as eugenol (1), methyleugenol (2), methylisoeugenol (3), elemicin (4), myristicin (5), and safrole (6). Among these isolates, 4 showed the strongest contact toxicity against L. serricorne adults with an LD50 value of 9.8 μg/adult. Repellency of crude oil and active compounds were also determined. Compounds 1, 2, 4, and 5 were strongly repellent against the cigarette beetle and exhibited the same level of repellency compared with the positive control, DEET. The results indicate that the essential oil of M. fragrans and its active constituents have potential for development as natural insecticides and repellents to control L. serricorne.

Chemical Composition and Insecticidal Activity of Essential Oils from Zanthoxylum dissitum Leaves and Roots against Three Species of Storage Pests

This work aimed to investigate chemical composition of essential oils obtained from Zanthoxylum dissitum leaves and roots and their insecticidal activities against several stored product pests, namely the cigarette beetle (Lasioderma serricorne), red flour beetle (Tribolium castaneum) and black carpet beetle (Attagenus piceus). The analysis by GC-MS of the essential oils allowed the identification of 28 and 22 components, respectively. It was found that sesquiterpenoids comprised a fairly high portion of the two essential oils, with percentages of 74.0% and 80.9% in the leaves and roots, respectively. The main constituents identified in the essential oil of Z. dissitum leaves were δ-cadinol (12.8%), caryophyllene (12.7%), β-cubebene (7.9%), 4-terpineol (7.5%) and germacrene D-4-ol (5.7%), while humulene epoxide II (29.4%), caryophyllene oxide (24.0%), diepicedrene-1-oxide (10.7%) and Z,Z,Z-1,5,9,9-tetramethyl-1,4,7-cycloundecatriene (8.7%) were the major components in the essential oil of Z. dissitum roots. The insecticidal activity results indicated that the essential oil of Z. dissitum roots exhibited moderate contact toxicity against three species of storage pests, L. serricorne, T. castaneum and A. piceus, with LD₅₀ values of 13.8, 43.7 and 96.8 µg/adult, respectively.

Bioactivity and chemical constituents of the essential oil from Dendranthema indicum (L.) Des Moul. against two stored insects

Dendranthema indicum (L.) Des Moul. is a perennial herb commonly used as a traditional Chinese medicine for a long time. In this work, we took Dendranthema indicum as a target plant and two stored insects which include Tribolium castaneum and Stegobium paniceum adults as target insects. Essential oil obtained from Dendranthema indicum was analyzed by gas chromatography-mass spectrometry (GC-MS). A total of 31 components representing 92.44% of the oil were identified and the main compounds were found to be chamazulene (15.93%), β-caryophyllene (13.78%), germacrene D (9.11%), and b-cis-farnesene (6.59%). With a further isolation, three constituents were obtained from the essential oil and identified as chamazulene, β-caryophyllene and eucalyptol. Significantly, in the progress of assay, it showed that the essential oil and chamazulene exhibited stronger insecticidal and repellent activities against Stegobium paniceum than Tribolium castaneum. The results indicate that additional to its traditional use as Chinese medicinal herb, the essential oil of Dendranthema indicum aerial parts and isolated compounds have potential to be developed into natural insecticides or repellents for control of insects in stored grains.

Bioactivity of essential oil from Artemisia stolonifera (Maxim.) Komar. and its main compounds against two stored-product insects

Artemisia stolonifera, a perennial herb, is widely distrbuted in China. The aim of this study was to analyze the essential oil from the aerial parts of Artemisia stolonifera, as well as to evaluate the bioactivity of the oil and its main constituents. The essential oil was analyzed by gas chromatography-flame ionization detector and gas chromatography-mass spectrometry that allowed characterizing 22 compounds. The main components were eucalyptol (32.93%), β-pinene (8.18%), camphor (6.12%) and terpinen-4-ol (6.11%), and obtained from the essential oil after a further isolation. During the contact toxicity tests, the essential oil (LD50 = 8.60 μg/adult) exhibited stronger toxicity against Tribolium castaneum adults than those isolated constituents, however, camphor and terpinen-4-ol showed 1 and 2 times toxicity against Lasioderma serricorne adults than the essential oil (LD50 = 12.68 μg/adult) with LD50 values of 11.30 and 5.42 μg/adult, respectively. In the fumigant toxicity tests, especially on Tribolium castaneum, the essential oil (LC50 = 1.86 mg/L air) showed almost the same level toxicity as positive control, methyl bromide (LC50 = 1.75 mg/L air). Moreover, the essential oil and its four isolated constituents also exhibited strong repellency against two stored-product insects.

Chemical constituents and insecticidal activities of the essential oil from Amomum tsaoko against two stored-product insects

The aim of this research was to determine the chemical constituents and toxicities of the essential oil derived from Amomum tsaoko Crevost et Lemarie fruits against Tribolium castaneum (Herbst) and Lasioderma serricorne (Fabricius). Essential oil of A. tsaoko was obtained from hydrodistillation and was investigated by gas chromatography-mass spectrometry (GC-MS). GC-MS analysis of the essential oil resulted in the identification of 43 components, of which eucalyptol (23.87%), limonene (22.77%), 2-isopropyltoluene (6.66%) and undecane (5.74%) were the major components. With a further isolation, two active constituents were obtained from the essential oil and identified as eucalyptol and limonene. The essential oil and the two isolated compounds exhibited potential insecticidal activities against two storedproduct insects. Limonene showed pronounced contact toxicity against both insect species (LD50 = 14.97 μg/adult for T. castaneum; 13.66 μg/adult for L. serricorne) and was more toxic than eucalyptol (LD50 = 18.83 μg/adult for T. castaneum; 15.58 μg/adult for L. serricorne). The essential oil acting against the two species of insects showed LD50 values of 16.52 and 6.14 μg/adult, respectively. Eucalyptol also possessed strong fumigant toxicity against both insect species (LC50 = 5.47 mg/L air for T. castaneum; 5.18 mg/L air for L. serricorne) and was more toxic than limonene (LC50 = 6.21 mg/L air for T. castaneum; 14.07 mg/L air for L. serricorne), while the crude essential oil acting against the two species of insects showed LC50 values of 5.85 and 8.70 mg/L air, respectively. These results suggested that the essential oil of A. tsaoko and the two compounds may be used in grain storage to combat insect pests.

Cytotoxic compounds isolated from Murraya tetramera Huang

A new compound and seven known compounds were isolated from Murraya tetramera Huang for the first time, and they were identified with NMR and MS spectral analysis. It was confirmed that the new compound was 10-methoxy-7-methyl-2H-benzo[g]chromen-2-one (3) and the others were β-eudesmol (1), trans-3β-(1-hydroxy-1-methylethyl)-8aβ-methyl-5-methylenedecalin-2-one (2), 5,7-dimethoxy-8-[(Z)-3'-methyl-butan-1',3'-dienyl]coumarin (4), 7-geranyloxy-6-methoxycoumarin (5), 5,7-dimethoxy-8-(3-methyl-2-oxo-butyl)coumarin (6), murrangatin acetate (7) and toddalenone (8). Furthermore, the cytotoxic activity against human lung adenocarcinoma (A549), human hepatocellular carcinoma cells (SMMC-7721), human bladder tumor cells (EJ), human cervical carcinoma cells (HeLa), and human B-lineage acute lymphoblastic leukemia 1 cells (BALL-1) was evaluated for all compounds. It was found that five of them displayed various degrees of cytotoxicity against different testing targets. Compound 1 showed significant cytotoxic activity against the five cell lines (A549, SMMC-7721, EJ, Hela and BALL-1). Compounds 2 and 5 showed significant cytotoxicity against three cell lines (A549, SMMC-7721 and BALL-1). Compound 4 showed significant cytotoxicity against three cell lines (A549, EJ and BALL-1). However, compound 3 only showed fair cytotoxicity against the BALL-1 cell line. The structure-active relationships were investigated as well. These active compounds might be potential lead compounds for the treatment of cancer.