Many fungi, lichens, and bacteria produce xanthones (derivatives of 9H-xanthen-9-one, “xanthone” from the Greek “xanthos”, for “yellow”) as secondary metabolites. Xanthones are typically polysubstituted and occur as either fully aromatized, dihydro-, tetrahydro-, or, more rarely, hexahydro-derivatives. This family of compounds appeals to medicinal chemists because of their pronounced biological activity within a notably broad spectrum of disease states, a result of their interaction with a correspondingly diverse range of target biomolecules. This has led to the description of xanthones as “privileged structures”.(1) Historically, the total synthesis of the natural products has mostly been limited to fully aromatized targets. Syntheses of the more challenging partially saturated xanthones have less frequently been reported, although the development in recent times of novel and reliable methods for the construction of the (polysubstituted) unsaturated xanthone core holds promise for future endeavors. In particular, the fascinating structural and biological properties of xanthone dimers and heterodimers may excite the synthetic or natural product chemist.

Xanthones from fungi, lichens, and bacteria : the natural products and their synthesis

Marine natural products.

Fungal phytotoxic secondary metabolites are poisonous substances to plants produced by fungi through naturally occurring biochemical reactions. These metabolites exhibit a high level of diversity in their properties, such as structures, phytotoxic activities, and modes of toxicity. They are mainly isolated from phytopathogenic fungal species in the genera of Alternaria, Botrytis, Colletotrichum, Fusarium, Helminthosporium, and Phoma. Phytotoxins are either host specific or non-host specific phytotoxins. Up to now, at least 545 fungal phytotoxic secondary metabolites, including 207 polyketides, 46 phenols and phenolic acids, 135 terpenoids, 146 nitrogen-containing metabolites, and 11 others, have been reported. Among them, aromatic polyketides and sesquiterpenoids are the main phytotoxic compounds. This review summarizes their chemical structures, sources, and phytotoxic activities. We also discuss their phytotoxic mechanisms and structure–activity relationships to lay the foundation for the future development and application of these promising metabolites as herbicides.

Phytotoxic Secondary Metabolites from Fungi

Six new prenylated indole diketopiperazine alkaloids, asperthrins A-F (1-6), along with eight known analogues (7-14), were isolated from the marine-derived endophytic fungus Aspergillus sp. YJ191021. Their planar structures and absolute configurations were elucidated by HR-ESI-MS, 1D/2D NMR data, and time-dependent density functional theory (TDDFT)/ECD calculation. The isolated compounds were assayed for their inhibition against three agricultural pathogenic fungi, four fish pathogenic bacteria, and two agricultural pathogenic bacteria. Compound 1 exhibited moderate antifungal and antibacterial activities against Vibrioanguillarum, Xanthomonas oryzae pv. Oryzicola, and Rhizoctoniasolani with minimal inhibitory concentration (MIC) values of 8, 12.5, and 25 μg/mL, respectively. Furthermore, 1 displayed notable anti-inflammatory activity with IC50 value of 1.46 ± 0.21 μM in Propionibacteriumacnes induced human monocyte cell line (THP-1).

https://www.mdpi.com/1660-3397/19/3/157/pdf

Bioactive Indole Diketopiperazine Alkaloids from the Marine Endophytic Fungus Aspergillus sp. YJ191021.

Fungi have been proved as promising and prolific sources of functional secondary metabolites with potent agricultural applications. In this study, 14 xanthone derivatives (1-14), including six new ones, versicones I-N (1-4, 7, 11), and a biogenetically related derivative (15), were isolated from the alga-derived fungus Aspergillus versicolor D5. Their structures were elucidated by comprehensive spectroscopic methods. Versicone L (4) exhibited a broad antifungal spectrum and prominent inhibitory effects on Botrytis cinerea at a minimum inhibitory concentration (MIC) of 152 μM, 7-fold stronger than that of the positive control, carbendazim (MIC = 1.05 × 103 μM). Dihydrosterigmatocystin (13) showed strong antifungal activity toward B. cinerea at MIC = 38.3 μM, almost 30-fold stronger than that of carbendazim. Meanwhile, 13 exhibited potent herbicidal activity toward Amaranthus retroflexus L. with an MIC of 24.5 μM, approximately 4-fold stronger than that of the positive control, glyphosate (MIC = 94.7 μM). Additionally, 13 also displayed remarkable activity against other weeds belonging to Amaranth sp. Analysis of the structure-herbicidal activity relationship indicated that the bifuranic ring played an important role in xanthone phytotoxicity and the presence of a double bond in the furan ring could decrease phytotoxicity. This study indicated that xanthones can be served as promising candidates for lead compounds of agrochemicals.

Herbicidal and Antifungal Xanthone Derivatives from the Alga-Derived Fungus Aspergillus versicolor D5.

The utility model provides a water spray cleaning device sways relates to plastics warmhouse booth and sways water spray cleaning machine field, this water spray cleaning device sways includes power supply, main frame, first side link, connecting rod, second side link and water conduit fitting assembly, power supply and main frame fixed connection, and first side link and power supply fixed connection, the connecting rod is articulated with the connecting rod with the articulated just second side link of first side link, second side link and main hinged rack, hinge four -bar linkage, water conduit fitting assembly and second side link fixed connection are constituteed to main frame, first side link, connecting rod and second side link. This water spray cleaning device sways can realize that high -pressure squirt shower nozzle drives the reciprocal water spray that waves down at the rocker, before it sprays high -pressure rivers coverability and rinses with rinse after the region, realize moist to regional filth before rinsing on the one hand, on the other hand realizes that it is effectual to spray water, does benefit to the improvement cleaning performance to the washing of regional filth after rinsing.

Water spray cleaning device sways

The invention provides a wild chrysanthemum essential oil for controlling phytophthora and application thereof, and relates to the technical field of phytophthora pathogen control. The preparation method of the wild chrysanthemum essential oil for controlling phytophthora comprises the following steps that wild chrysanthemums and water are mixed and stood, the supersonic extraction is carried outto obtain an ultrasonic extraction mixture, stream distillation is performed on the ultrasonic extraction mixture, and distillate is collected; the distillate is extracted with normal hexane, organicphases are separated and dried to obtain wild chrysanthemum essential oil. The wild chrysanthemum essential oil has the advantages that the mycelial growth and spore germination of Phytophthora nicotianae are effectively inhibited, the minimum inhibition concentration can reach 200MuL/L, and the bacteriostasis rate under the concentration fumigation of 157.48MuL/L can reach 92.68%. The mechanism of bacteriostasis of the wild chrysanthemum essential oil may result from the incompleteness of cell walls and cell membranes. The wild chrysanthemum essential oil lays a foundation for the developmentof botanical pesticides for controlling phytophthora and even soil-borne diseases.

Wild chrysanthemum essential oil for controlling phytophthora and application thereof

The utility model discloses a medicine machine is spouted in electronic beta pruning, including power transmission system, liquid medicine feed system and the installation power transmission system frame with the liquid medicine feed system, power transmission system mainly comprises a plurality of external gears and sector gear, transmits the knife section to the moment of torsion of motor, realizes cuting, the liquid medicine feed system mainly comprises solenoid valve, trident joint, hose and shower nozzle, and the liquid medicine of medicine machine is spouted with supplying with to pinchto control, the frame mainly comprises handle, backup pad and operating switch, and it provides the support and provide operation section for the operator for power transmission system and liquid medicine feed system mainly to be, the utility model discloses it is small, conveniently carry the operation of specially adapted mountainous and hilly land to novel structure, safe and reliable, low in production cost, easy operation is convenient, has effectively reduced operator's intensity of labour.

Medicine machine is spouted in electronic beta pruning

The utility model discloses a belt cleaning device of big -arch shelter shed roof, including water jet equipment, cleaning area, running gear, water jet equipment is delivery pipe and water spray portion, delivery pipe switch -on water spray portion, and water spray portion presses close to there is the hole for water spraying shed roof one side, to the surperficial water spray of shed roof. Water spray portion is hollow structure's base member, and the base member is the tube -like piece of loop configuration. The base member possesses relative first side and second side, is provided with first water spray portion and second water spray portion on first side and second side respectively. The base member laminate naturally in the shed roof is connected with the both ends on the cleaning area length direction, the last power device of being provided with of running gear places respectively on the gutter of big -arch shelter shed roof both sides, is connected with the both ends on the cleaning area length direction, drives whole cleaning area and wash big -arch shelter shed roof surface repeatedly by rubbing with the hands on width direction.

Wen Mingxia

Papers

Herbicidal and Antifungal Xanthone Derivatives from the Alga-Derived Fungus Aspergillus versicolor D5.

Water spray cleaning device sways

Wild chrysanthemum essential oil for controlling phytophthora and application thereof

Medicine machine is spouted in electronic beta pruning

Belt cleaning device of big -arch shelter shed roof