Zhiqing Ma

Synthesis and antifungal activity of carabrone derivatives.

Nine derivatives 6-14 of carabrone (1) were synthesized and tested in vitro against Colletotrichum lagenarium Ell et Halst using the spore germination method. Among all of the derivatives, compounds 6-8 and 12 showed more potent antifungal activity than 1. Structure-activity relationships (SAR) demonstrated that the γ-lactone was necessary for the antifungal activity of 1, and the substituents on the C-4 position of 1 could significantly affect the antifungal activity.

Design, Synthesis and Fungicidal Activities of Some Novel Pyrazole Derivatives

In order to discover new compounds with good fungicidal activities, 32 pyrazole derivatives were designed and synthesized. The structures of the target compounds were confirmed by 1H-NMR, 13C-NMR, and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), and their fungicidal activities against Botrytis cinerea, Rhizoctonia solani Kuhn, Valsa mali Miyabe et Yamada, Thanatephorus cucumeris (Frank) Donk, Fusarium oxysporum (S-chl) f.sp. cucumerinum Owen, and Fusarium graminearum Schw were tested. The bioassay results indicated that most of the derivatives exhibited considerable antifungal activities, especially compound 26 containing a p-trifluoromethyl- phenyl moiety showed the highest activity, with EC50 values of 2.432, 2.182, 1.787, 1.638, 6.986, and 6.043 μg/mL against B. cinerea, R. solani, V. mali, T. cucumeris, F. oxysporum, and F. graminearum, respectively. Moreover, the activities of compounds such as compounds 27–32 were enhanced by introducing isothiocyanate and carboxamide moieties to the 5-position of the pyrazole ring.

Comparative studies on mitochondrial electron transport chain complexes of Sitophilus zeamais treated with allyl isothiocyanate and calcium phosphide

With Sitophilus zeamais as the target organism, the present study for the first time attempted to elucidate the comparative effects between allyl isothiocyanate (AITC) and calcium phosphide (Ca3P2), exposure on mitochondrial electron transport chain (ETC.) complex I & IV and their downstream effects on enzymes relevant to reactive oxygen species (ROS). In vivo, both AITC and Ca3P2 inhibited complex I and IV with similar downstream effects. In contrast with Ca3P2, the inhibition of complex I caused by AITC was dependent on time and dose. In vitro, AITC inhibited complex IV more significantly than complex I. These results indicate that mitochondrial complex IV is the primary target of AITC, and that complex I is another potential target.

Repellent activity screening of 11 kinds of essential oils against Aedes albopictus Skuse: microcapsule preparation of Herba Schizonepetae oil and repellent bioassay on hand skin

BACKGROUND The main ingredient of most repellents on the market is DEET, an effective compound that has the disadvantages of toxic reactions as well as damaging effects on plastic and synthetic fabric. DEET alternatives are urgently needed. METHODS The repellent activities of 11 kinds of essential oils were tested against Aedes albopictus Skuse by a Y-tube olfactometer. Using essential oils with high repellent activity as core material and gelatin and gum arabic as wall materials, we prepared microcapsules of essential oils and optimized the preparation process. The microcapsule formulation was then subjected to repellent bioassay on hand skin. RESULTS when the dosage of essential oils was 5 µL, the cinnamon oil repellent rate was 87.5% within 10 min and the Herba Schizonepetae oil (HSO) repellent rate was 98.0% within 3 min. Up to 1.5% (w/v) gelatin and 1.5% (w/v) gum arabic (as wall materials), and HSO (as core material) were used to form microcapsules with a 1:1 ratio of core material to wall material. CONCLUSION The ointment preparations effectively protected hand skin exposed to a high-density A. albopictus Skuse rearing cage for 4-5 h. The HSO microcapsule repellent has broad application and development prospects.

Propamidine decreas mitochondrial complex III activity of Botrytis cinerea.

Propamidine, an aromatic diamidine compound, is widely used as an antimicrobial agent. To uncover its mechanism on pathogenetic fungi, Botrytis cinerea as an object was used to investigate effects of propamidine in this paper. The transmission electron microscope results showed that the mitochondrial membranes were collapsed after propamidine treatment, followed that mitochondria were disrupted. Inhibition of whole-cell and mitochondrial respiration by propamidine suggested that Propamidine is most likely an inhibitor of electron transport within Botrytis cinerea mitochondria. Furthermore, the mitochondrial complex III activity were inhibited by propamidine.

Bioassay‐guided isolation of potent aphicidal Erythrina alkaloids against Aphis gossypii from the seed of Erythrina crista‐galli L

BACKGROUND The cotton aphid (Aphis gossypii Glover) is one of the most invasive pests of cotton. Many botanical phytochemicals have a long history as a source of insecticides, and as templates for new insecticides. This study was undertaken to isolate aphicidal compounds from the seeds of Erythrina crista-galli L. using the bioassay-guided isolation method. RESULTS Three novel and 11 known Erythrina alkaloids were isolated. Erysodine (9), erysovine (10), erysotrine (8) and erythraline (11) showed moderate to excellent aphicidal activity with LD50 values of 7.48, 6.68, 5.13 and 4.67 ng aphid-1 , respectively. The Potter spray tower bioassay gave corresponding LC50 values of 186.81, 165.35, 163.74 and 112.78 µg ml-1 . A unique substructure, which presents an sp3 methylene at C-8, a non-oxygenated site at N-9 and a conjugated dienes group (Δ1,2 and Δ6,7 ), plays a crucial role in the aphicidal activity. Application of erythraline (11) led to different increases in the activities of superoxide dismutase, catalase and glutathione S-transferase. CONCLUSION The study demonstrated that the Erythrina alkaloids erysodine (9), erysovine (10), erysotrine (8) and erythraline (11) have potential use as botanical aphicides for commercial application, or as templates for the development of new insecticides.

Chemical Compositions of Ligusticum chuanxiong Oil and Lemongrass Oil and Their Joint Action against Aphis citricola Van Der Goot (Hemiptera: Aphididae)

In order to develop novel botanical insecticides, the joint action of Ligusticum chuanxiong oil (LCO) and lemongrass oil (LO) against Aphis citricola van der Goot was determined systematically indoors and outdoors. The chemical profiles of LCO and LO as determined by gas chromatography–mass spectrometry (GC-MS) analysis revealed that the main compounds from LCO were (Z)-ligustilide (44.58%) and senkyunolide A (26.92%), and that of LO were geranial (42.16%) and neral (32.58%), respectively. The mixture of LCO and LO showed significant synergy against A. citricola, with a common-toxicity coefficient (CTC) value of 221.46 at the optimal ratio of LCO to LO (4:1, w:w). Based on the results of solvents and emulsifiers screening, L. chuanxiong oil·Lemongrass oil 20% emulsifiable concentrate (20% LCO·LO EC) was developed, and its stability was confirmed with tests of cold and thermal storage. Field trials indicated that the insecticidal activity of the diluted 20% LCO·LO EC (1000 fold dilution) was comparable to conventional pesticide (20% imidacloprid EC) on A. citricola seven days after application. Thus, the mixture of LCO and LO has the potential to be further developed as a botanical pesticide.

New Cytotoxic Secondary Metabolites from Marine Bryozoan Cryptosula pallasiana

A new sterol, (23R)-methoxycholest-5,24-dien-3β-ol (1), two new ceramides, (2S,3R,4E,8E)-2-(tetradecanoylamino)-4,8-octadecadien-l,3-diol (6) and (2S,3R,2′R,4E,8E)-2-(tetradecanoylamino)-4,8-octadecadien-l,3,2′-triol (7), together with three known sterols (2–4), a lactone (5) and two ceramides (8,9), were isolated from the marine bryozoan Cryptosula pallasiana, collected at Huang Island of China. The structures of the new compounds were elucidated by extensive spectroscopic analyses, chemical methods and quantum electronic circular dichroism (ECD) calculations. Among the isolated compounds, sterol 1 possessed a rare side chain with a methoxy group at C-23, and a double bond between C-24 and C-25. Ceramides 6 and 7 possessed 14 carbons in their long-chain fatty acid base (FAB), which were different from the normal ceramides with 16 carbons in the FAB. Moreover, compounds 5 and 8 were isolated for the first time from marine bryozoans. Compounds 1–9 were evaluated for their cytotoxicity against human tumor cell lines HL-60, Hep-G2 and SGC-7901. The results showed that lactone 5 appears to have strong cytotoxicity against the test tumor cell lines, with IC50 values from 4.12 μM to 7.32 μM, and sterol 1 displayed moderate cytotoxicity with IC50 values between 12.34 μM and 18.37 μM, while ceramides 6–9 showed weak cytotoxicity with IC50 ranging from 21.13 μM to 58.15 μM.

Differential expressed analysis of Tripterygium wilfordii unigenes involved in terpenoid backbone biosynthesis

Abstract Tripterygium wilfordii Hook. f. is the traditional medicinal plants in China. Triptolide, wilforgine, and wilforine are the bioactive compounds in T. wilfordii. In this study, the contents of three metabolites and transcription levels of 21 genes involved in three metabolites biosynthesis in T. wilfordii were examined using high-performance liquid chromatography and reverse transcription PCR after application of methyl jasmonate (MeJA) on hairy roots in time course experiment (3–24 h). The results indicated that application of MeJA inhibited triptolide accumulation and promoted wilforgine and wilforine metabolites biosynthesis. In hairy roots, wilforgine content reached 693.36 μg/g at 6 h after adding MeJA, which was 2.23-fold higher than control. The accumulation of triptolide and wilforine in hairy roots increased the maximum at 9 h, which was 1.3- and 1.6-folds more than the control. Most of the triptolide secretes into the medium, but wilforgine and wilforine cannot secrete into the medium. The expression levels of unigenes which involved terpenoid backbone biosynthesis exist the correlation with marker metabolites (triptolide, wilforgine and wilforine) after induction by MeJA, and can be then used to infer flux bottlenecks in T. wilfordii secondary metabolites accumulation. These results showed that these genes may have potential applications in the metabolic engineering of T. wilfordii metabolites production.

Cloning, Expression Analysis and Functional Characterization of Squalene Synthase (SQS) from Tripterygium wilfordii

Celastrol is an active triterpenoid compound derived from Tripterygium wilfordii which is well-known as a traditional Chinese medicinal plant. Squalene synthase has a vital role in condensing two molecules of farnesyl diphosphate to form squalene, a key precursor of triterpenoid biosynthesis. In the present study, T. wilfordii squalene synthase (TwSQS) was cloned followed by prokaryotic expression and functional verification. The open reading frame cDNA of TwSQS was 1242 bp encoding 413 amino acids. Bioinformatic and phylogenetic analysis showed that TwSQS had high homology with other plant SQSs. To obtain soluble protein, the truncated TwSQS without the last 28 amino acids of the carboxy terminus was inductively expressed in Escherichia coli Transetta (DE3). The purified protein was detected by SDS-PAGE and Western blot analysis. Squalene was detected in the product of in vitro reactions by gas chromatograph-mass spectrometry, which meant that TwSQS did have catalytic activity. Organ-specific and inducible expression levels of TwSQS were detected by quantitative real-time PCR. The results indicated that TwSQS was highly expressed in roots, followed by the stems and leaves, and was significantly up-regulated upon MeJA treatment. The identification of TwSQS is important for further studies of celastrol biosynthesis in T. wilfordii.