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Drone detection is a significant research topic due to the potential security threats posed by the misuse of drones in both civilian and military domains. However, traditional drone detection methods are challenged by the drastic scale changes and complex ambiguity during drone flight, and it is difficult to detect small target drones quickly and efficiently. We propose an information-enhanced model based on improved YOLOv5 (TGC-YOLOv5) for fast and accurate detection of small target drones in complex environments. The main contributions of this paper are as follows: First, the Transformer encoder module is incorporated into YOLOv5 to augment attention toward the regions of interest. Second, the Global Attention Mechanism (GAM) is embraced to mitigate information diffusion among distinct layers and amplify the global cross-dimensional interaction features. Finally, the Coordinate Attention Mechanism (CA) is incorporated into the bottleneck part of C3, enhancing the extraction capability of local information for small targets. To enhance and verify the robustness and generalization of the model, a small target drone dataset (SUAV-DATA) is constructed in all-weather, multi-scenario, and complex environments. The experimental results show that based on the SUAV-DATA dataset, the AP value of TGC-YOLOv5 reaches 0.848, which is 2.5% higher than the original YOLOv5, and the Recall value of TGC-YOLOv5 reaches 0.823, which is a 3.8% improvement over the original YOLOv5. The robustness of our proposed model is also verified on the Real-World open-source image dataset, achieving the best accuracy in light, fog, stain, and saturation pollution images. The findings and methods of this paper have important significance and value for improving the efficiency and precision of drone detection.

Natural products are an abundant and environmentally friendly source for controlling plant pathogens and insect pests. Toward the development of new natural product-based pesticides, here, a series of osthole-based isoxazoline derivatives were prepared by [3 + 2] annulation and evaluated for their insecticidal activities and toxicities. The structures of all osthole-based isoxazoline derivatives were characterized by various spectral analyses, and derivative

Infections caused by multidrug-resistant (MDR) bacteria are increasing worldwide, and with limited clinically available antibiotics, it is urgent to develop new antimicrobials to combat these MDR bacteria. Here, a class of novel amphiphilic xanthohumol derivatives were prepared using a building-block approach. Bioactivity assays showed that the molecule

To improve the insecticidal activity of (+)-nootkatone, a series of 42 (+)-nootkatone thioethers containing 1,3,4-oxadiazole/thiadiazole moieties were prepared to evaluate their insecticidal activities against

Magnolol and honokiol, derived from a Magnolia officinalis Rehd. et Wils, are a class of natural biphenolic lignans. Currently, the discovery of new α-glucosidase inhibitors from natural analogues is of interest. Here, four series of thirty new Mannich base analogues of magnolol/honokiol were prepared and evaluated for their α-glucosidase inhibitory activities. Among these Mannich base analogues of magnolol/honokiol, 3k and 3l exhibited more potent inhibitory effects on α-glucosidase than the reference drug acarbose, and their IC

Majucin-type Illicium sesquiterpenes with potent neurotrophic activity are considered to be promising candidates for the treatment of various neurodegenerative disease. Owing to the low-abundance metabolites in Illicium genus, there are few studies on their structural modifications, structure-activity relationships, and pharmacophoric motif. Herein, structural modifications were conducted on the hydroxyl groups at C-3 and C-6 positions of two majucin-type compounds neomajucin (1) and majucin (2), and 39 neomajucin/majucin based esters were synthesized and evaluated for their neurite outgrowth-promoting activities. Among all the target derivatives, compounds 1a, 1j, 1r, 2b, 2d, 3a, 3b, 3d and 3h displayed more potent neurite outgrowth-promoting activity than their precursors. Some interesting structure-activity relationships (SARs) were also observed. Moreover, compound 1a showed good neuroprotective effect on MPP

Many phytopathogenic fungi can easily infect crops, resulting in crop yield reductions. In continuation of our effort to develop natural product (NP)-based antifungal agents, a series of N -phenylpyrazole sarisan hybrids 6a - v were prepared via I 2 -mediated oxidative cyclization, and their structures were determined by various spectral analyses including IR, 1 H NMR and ESI-MS. Among all N- phenylpyrazole sarisan hybrids, compounds 6a , 6b , 6e , 6i , 6j and 6r showed more potent antifungal activity against at lest two phytopathogenic fungi than the commercial fungicide hymexazol. In particular, compound 6a exhibited more broad-spectrum and promising antifungal activity against three phytopathogenic fungi ( V. mali , F. oxysporum f.sp.niveum , and F. graminearum ) with the EC 50 values of 18.5, 37.4 and 12.6 μg/mL, respectively. Moreover, the structure-activity relationships (SARs) were also observed. Additionally, compounds 6a and 6e also exhibited relative low toxicity on normal LO2 cells. This work indicates that these N -phenylpyrazole sarisan hybrids would shed light on developing novel NP-based antifungal agents.

To improve the insecticidal activities of fraxinellone, two series of fraxinellone-based N-(1,3-thiazol-2-yl)carboxamides containing 25 compounds were prepared by structural modification. Their structures were determined by melting point, optical rotation, IR, 1H NMR and ESI-MS. The steric configurations of compounds 6i, 7d and 7i were unambiguously confirmed by X-ray diffraction further. The bioassay showed that compounds 6b and 6i exhibited more potent larvicidal and growth inhibitory activities against Plutella xylostella Linnaeus and Mythimna separata Walker, respectively. Moreover, compounds 6b and 6i also displayed low cytotoxicity to noncancerous mammalian cells. The structure–activity relationships (SARs) of all target compounds were also observed.

Many phytopathogenic fungi cause severe damage to crop yields. In continuation of our research aimed at the discovery and development of natural products-based fungicides, a series of thirty-one sarisan attached 3-phenylisoxazolines were synthesized and evaluated for their antifungal activities against five phytopathogenic fungi ( B. cinerea , C. lagenarium , A. solani, F. solani , and F. graminearum ). Among all title sarisan derivatives, compounds IV2 , IV14 and IV23 showed potent antifungal activity against some phytopathogenic fungi. In particular, compound IV2 exhibited a broad-spectrum and more potent antifungal activity against A. solani , F. solani, and F. graminearum than the commercial fungicide Hymexazol. In addition, compounds IV2 , IV14 and IV23 also displayed relative low toxicity on normal NRK-52E cells. This work will give some insights into the development of sarisan derivatives as new fungicide candidates in plant protection.

Natural products (NPs) are very important sources for the development of new drugs. Merrillianone and cycloparvifloralone, isolated from the roots, stems, and fruits of Illicium henryi Diels, are two natural sesquiterpene compounds. In continuation of our effort to discovery more effective neurotrophic compounds from NPs, a series of novel merrillianone/cycloparviforalone based esters 2a-i, 3a-g and 3i-q were prepared and their structures were characterized by 1H NMR, 13C NMR and IR spectral analyses. Furthermore, the spatial structure of compound 2h was unambiguously confirmed by X-ray crystallography. The neurite outgrowth-promoting activity results indicated that most of the target derivatives exhibited more potent neurite outgrowth-promoting activity than merrillianone and cycloparviforalone. Among all target derivatives, the neurite outgrowth-promoting activity of compounds 2a, 3a and 3b was about 2-fold stronger than that of their precursors merrillianone and cycloparviforalone, respectively. Besides, compounds 2a and 3a displayed relatively low cytotoxicity to normal GES-1 cells. Moreover, these derivatives had good hydrolytic stability. Finally, some interesting results of the structure-activity relationships (SARs) were also discussed. This work will pave the way for the development of merrillianone/cycloparviforalone derivatives as potential neurotrophic agents.

Natural products are very important sources for the development of new pesticides. Osthole, derived from many medical plants such as Cnidium, Angelica and Citrus plants, is a naturally occurring coumarin compound. To discover the new natural products-based insecticides, thirty-one osthole-based esters containing O-acyl-hydroxylamine groups were prepared, and their structures were identified by different spectral analysis methods. Derivatives A7, A17, A20 and A25 displayed more potent growth inhibitory (GI) activity than the botanical insecticide, toosendanin. Over half of target osthole derivatives had more effective larvicidal effect on P. xylostella than toosendanin. Among all title derivatives, compound A18 displayed more pronounced larvicidal activity (LC50 = 0.64 μmol mL−1) when compared with toosendanin (LC50 = 0.94 μmol mL−1). Some interesting results of structure–activity relationships (SARs) of these osthole derivatives were also discussed. In addition, the hemolysis and cytotoxicity assays indicated that these osthole derivatives showed very low toxicity toward normal mammalian cells.

A series of sarisan analogs containing 1,3,4-oxadiazole moieties were synthesized by iodine-mediated oxidative cyclization and screened in vitro for their antifungal activities at 50 μg/mL against five phytopathogenic fungi such as Valsa mali, Curvularia lunata, Alternaria alternate, Fusarium solani and Fusarium graminearum. 1,3,4-Oxadiazole derivatives 7e, 7p, 7r, 7t and 7u exhibited potent and a broad spectrum of antifungal activities against at least three phytopathogenic fungi at the concentration of 50 μg/mL. Especially, compound 7r displayed more potent antifungal activities against five phytopathogenic fungi than the positive control hymexazol. The EC50 of 7r against V. mali, C. lunata and A. alternate were 12.6, 14.5 and 17.0 μg/mL, respectively. Additionally, some interesting results of structure-activity relationships (SARs) were also observed.

In continuation of our program to discover new potential pesticidal agents, thirty-one piperine analogs containing isoxazoline/pyrazoline scaffold were prepared, and confirmed by infrared spectra, proton/carbon-13 nuclear magnetic resonance spectra, and high-resolution mass spectra. The structures of compounds VIIb and VIIIc were further determined by

Fraxinellone, a degraded limonoid, has been mainly isolated from some renewable plants in Meliaceae and Rutaceae. In a continuous effort to discover new natural products-based pesticides, two series of fraxinellone derivatives containing N-phenylpyrazole moiety were designed, synthesized and evaluated for their pesticidal activities against Mythimna separata Walker and Plutella xylostella Linnaeus. Two structures of compounds 7g and 8k were unambiguously determined by X-ray diffraction further. The bioassay showed that over half of the target compounds exhibited better insecticidal activity against M. separata than the precursor fraxinellone. Among all the target compounds, the compounds 7g–i and 8g–j exhibited more potent insecticidal activity than toosendanin, a commercial botanical pesticide. Furthermore, the compound 8g displayed more promising larvicidal activity with the LC50 value of 0.31 μmol mL−1 than the toosendanin against P. xylostella. The structure–activity relationship (SAR) revealed that introduction of polyhalogenated phenylpyrazole ring on furyl-ring of fraxinellone could lead more potent compounds both against M. separata and P. xylostella than that of monohalogenated phenylpyrazole ring or electron-donating groups substituted phenylpyrazole ring.

Due to their structural diversity and biological characteristics, natural products appear to be received much attention as lead compounds. Podophyllotoxin, a naturally sustainable aryltetralin lignan, is isolated from the roots and rhizomes of Podophyllum hexandrum. To discover new potentially natural product-based pesticidal agents, a series of isoxazole esters were regioselectively prepared by structural modification of podophyllotoxin. Compared with their precursor podophyllotoxin, compounds IId, IIIc and IIId exhibited the potent insecticidal activity, and compounds IIb, IIc, IIIc and IIId showed the pronounced acaricidal activity; especially compounds IIIc (X = Cl, R = 4-ClC6H4) and IIId (X = Cl, R = 4-FC6H4) exhibited the most promising pesticidal activities against Mythimna separata Walker and Tetranychus cinnabarinus Boisduval.

Podophyllotoxin is isolated as a sustainable natural bioresource from the roots and rhizomes of Podophyllum hexandrum and Juniperus Sabina . In continuation of our program aimed at the discovery of biorenewable natural product-based pesticides, a series of 4α-acyloxy derivatives of 2'-chloro-5-bromopicropodophyllotoxin or 2',5-dibromopicropodophyllotoxin were synthesized by structural modification of podophyllotoxin, and evaluated as insecticidal and acaricidal agents against two serious agricultural pests, Mythimna separata Walker and Tetranychus cinnabarinus Boisduval. Among all derivatives, compounds 6a and 7a exhibited more promising insecticidal and acaricidal activities than podophyllotoxin, and the final mortality rates of 6a , 7a and 1 against M. separata (at 1 mg/mL) and T. cinnabarinus (at 0.5 mg/mL) were 50%/53.3%/36.7%, and 33%/41.8%/1.6%, respectively. This suggested that introduction of the acetoxy moiety at the C-4 position of 2'-chloro-5-bromopicropodophyllotoxin/2',5-dibromopicropodophyllotoxin was necessary for the insecticidal and acaricidal activities.

In continuation of our program to discover new natural-product-based crop protection agents, we prepared a series of esters and oxime esters/sulfonates from furyl-ring-based acetylation derivatives as pesticidal agents by structural modification of fraxinellone, a biorenewable degraded limonoid isolated from Meliaceae and Rutaceae plants. The structural assignment was based on the spectroscopic and X-ray analysis data. Their insecticidal activity was evaluated against a crop-threatening agricultural insect pest, Mythimna separata Walker. Among all derivatives, compounds 9a and 10i exhibited the most promising pesticidal activity. Their structure–activity relationships were also discussed.

Fraxinellone, a naturally occurring degraded limonoid, is mainly isolated from Dictamnus dasycarpus and Melia azedarach . In continuation of our program aimed at the discovery of plant natural products-based insecticidal agents, twenty-two new ethers from furyl-ring-based acylation derivatives were prepared by structural modifications of fraxinellone. Their insecticidal activity was evaluated against the pre-third-instar larvae of Mythimna separata Walker in vivo . Among them, compounds 5e and 5j exhibited more potent insecticidal activity than toosendanin with the final mortality rates greater than 60%. Their structure-activity relationships were also discussed.

Infections caused by clinical methicillin-resistant Staphylococcus aureus (MRSA) are a serious public problem. Triphenyl-sesquineolignans from Illicium genus possess antibacterial activity, but few researches have reported their antibacterial spectrums, structure–activity relationships (SARs) and antibacterial mechanism. In this study, three triphenyl-sesquineolignans, dunnianol (1), macranthol (2) and isodunnianol (3) were isolated from the stems and leaves of I. simonsii Maxim, and seven dunnianol derivatives were prepared through esterification, etherification and halogenation reactions. Among all triphenyl-sesquineolignan analogues, compound 6 showed the best antibacterial activity against four Gram-positive bacteria (MICs = 1–2 µg/mL) and ten clinical MRSA strains (MICs = 2–8 µg/mL), and also exhibited characteristics of killing MRSA more rapidly than tigecycline. Meanwhile, compound 6 did not only show a low probability of drug resistance development, but also exhibited relatively low hemolysis, and good stability in 50% plasma. Further mechanism studies revealed that 6 could kill bacterial strains by disrupting bacterial membranes. These results suggested that 6 may be developed into a new antibacterial candidate for combating MRSA infections.

Nowadays, the discovery and development of α-glucosidase inhibitors from natural products or their derivatives represents an attractive approach. Here we reported studies on a series of novel N-acyl-2-aminothiazoles fused (+)-nootkatone and evaluation for their α-glucosidase inhibitory activities. Most of (+)-nootkatone derivatives exhibited more potent α-glucosidase inhibitory ability than the positive drug acarbose. In particular, compounds II7 and II14 showed the most promising α-glucosidase inhibitory ability with IC50 values of 13.2 and 13.8 µM. II7 and II14 also exhibited relatively low cytotoxicities towards normal LO2 cells. Kinetic study indicated that compounds II7 and II14 inhibited the α-glucosidase in a noncompetitive manner, and molecular docking results were in line with the noncompetitive characteristics that II7 and II14 did not bind to the known active sites (Asp214, Glu276 and Asp349). Based on our findings, these (+)-nootkatone derivatives could be used as antidiabetic candidates.

(+)-Nootkatone, a non-food bioactive natural bicyclic sesquiterpene ketone, is isolated from Chamaecyparis nootkatensis [D. Don] Spach as a renewable forest resource. In continuation of our effort to develop synthetic natural derived insecticides from non-food bioactive products, a small library of thirty N-(1,3- thiazol-2-yl)carboxamides fused (+)-nootkatone was prepared by molecular hybridization and characterized by 1H/13C NMR, HR-MS, and IR spectroscopy. Their insecticidal activities against Mythimna separata Walker and Plutella xylostella Linnaeus were evaluated. Compounds B6, B7, B9, B19–21 and B24 showed better insecticidal activity against M. separata than the botanical insecticide azadirachtin, and their LC50 values ranged from 0.55−0.68 mg/mL. Particularly, compound B9 exhibited 1.87-fold more pronounced insecticidal activity against M. separata than azadirachtin. The insecticidal activity of B21 against P. xylostella was 1.37-fold of that of azadirachtin. Through acetylcholinesterase (AChE) inhibitory activity and molecular docking studies, AChE may be the insecticidal target of B9 against M. separata. In addition, three pronounced compounds B9, B21 and B24 exhibited low hemolytic and cytotoxic activities on normal mammalian cells. These findings will give insights into the further development of (+)-nootkatone derivatives as potentially synthetic natural derived insecticides for pest management.

Sesamol, a natural phenolic compound with good antioxidant activity, is a nonoil component of sesame seed oil. Two series of novel Mannich bases, 4-(aminoalkyl)-6-allyl-sesamols were synthesized from sesamol, substituted benzaldehydes and piperidine/morpholine via the one-pot reaction. An efficient way using toluene as solvent, catalyst-free and one-pot reaction for the synthesis of these sesamol derivatives was developed. The structures of all 4-(aminoalkyl)-6-allyl-sesamols were determined by spectral analysis. Compound 6f was unambiguously confirmed by X-ray diffraction further. The antioxidant assays have demonstrated that the sesamol derivative 7i displayed excellent antioxidant activity. The structure–activity relationships (SARs) of these sesamol derivatives were also observed. Further, the representative compounds 7a, 7g and 7i exhibited relative low toxicity to normal cells. Based on these characteristics, these sesamol derivatives will have great potential application in food and drugs.

(+)-Nootkatone, isolated from the heartwood of Alaska yellow cedar, Citrus Rutaceae and Alpinia Zingiberaceae, is a natural bicyclic sesquiterpene. Toward the discovery of new natural products-based insecticides, twenty-five novel (+)-nootkatone derivatives containing isoxazoline moiety were designed and prepared by [3 + 2] cycloaddition. Structures of all (+)-nootkatone derivatives were confirmed by different spectral analyses, in which compound 2 h was further identified by X-ray diffraction. Compounds 2 g, 2i, 2q, 2 u, 2 w and 2y displayed more effective insecticidal activities against both Mythimna separata Walker and Plutella xylostella Linnaeus than the botanical insecticide, toosendanin. Especially, derivatives 2i and 2 w showed significant growth inhibitory (GI) activity with the final mortality rates (FMRs) both of 73.3%. Derivative 2 r exhibited pronounced larvicidal activity with LC50 values of 0.23 μmol mL−1. In addition, the structure–activity relationships (SARs) of these (+)-nootkatone derivatives were also observed. Moreover, the potent compounds 2 h, 2 l, 2p, 2 r and 2 w exhibited relative low toxicity to mammalian cells (RAW 264.7).

Toward the search of new antibacterial agents to control methicillin-resistant Staphylococcus aureus (MRSA), a class of new norfloxacin-1,3,4-oxadiazole hybrids were designed and synthesized. Antibacterial activities against drug-sensitive bacteria S. aureus and clinical drug resistant isolates of MRSA were evaluated. Compound 5k exhibited excellent antibacterial activities against S. aureus (MIC: 2 μg/mL) and MRSA1–3 (MIC: 0.25–1 μg/mL). The time-kill kinetics demonstrated that compound 5k had an advantage over commonly used antibiotics vancomycin in killing S. aureus and MRSA. Moreover, compound 5k could inhibit the bacteria and destroy their membranes in a short time, and showed very low cytotoxicity to NRK-52E cells. Some interesting structure-activity relationships (SARs) were also discussed. These results indicated that these norfloxacin-1,3,4-oxadiazole hybrids could be further developed into new antibacterial agents against MRSA.

Introduction of the halogen atom or the acyl group at the C-ring of fraxinellone was investigated. Some unexpected halogenation products were obtained with the different chlorination/bromination reagents, and their possible reaction mechanisms were also proposed. Seven key steric structures of 2a’, 2b, 2b’, 2c’, 3a, 3b, and one isomer (5’α-Cl) of 2a were further confirmed by single-crystal X-ray diffraction. Especially compounds 2a, 2a’, 3a and 3c exhibited more potent insecticidal activity than toosendanin. Some structure-activity relationships of tested compounds were also described.