Digenetic trematodes of the genus Clinostomum are widely distributed in many species of freshwater fish and are known to cause the zoonotic disease Halzoun. Humans may become accidental hosts if they ingest raw freshwater fish containing metacercaria of Clinostomum complanatum, which causes pharyngitis or laryngitis. The yellow grub parasitizing cultivated ayu (Plecoglossus altivelis) and loach (Misgurnus anguillicaudatus) was one of the most serious problems in fish farms from 1977 to 1979 in Taiwan. The present study revealed, for the first time, frequent occurrence of C. complanatum metacercaria in various fish species in a natural environment, the Dahan River, in Taiwan. We examined 1503 fish specimens belonging to four families and 162 snails representing six species. C. complanatum metacercaria was mainly from the fish family Cyprinidae, and only cercaria from the snail Radix swinhoei was recovered. The prevalence and mean intensity of metacercaria were 9.8% and 9.35 parasites/infected fish, respectively. The prevalence of cercaria was low, 0.62%, in snails. Acrossocheilus paradoxus, Zacco barbata, Zacco pachycephalus, Zacco platypus, Onychostoma barbatula, and Hemibarbus labeo are new host records. Metacercariae were primarily found in the operculum, mandible, muscle, and oral cavity of fish. Morphological description and molecular analysis with 18S rDNA sequencing allowed for rapidly identifying C. complanatum. Encysted and excysted metacercariae cultivated at 22 °C in physiological saline died within 60 h. The mean intensity of infection increased with an increasing length of Z. pachycephalus. We found no association between monthly parasite prevalence and mean intensity at each sampling location. No C. complanatum metacercaria survived after 8 h of salting. The Dahan River has suitable conditions and hosts (snails, fish, and fish-eating birds) for maintaining the life cycle of C. complanatum.

The unique advantages conferred by incorporation of all-substituted carbon stereocenters in organic molecules have gained widespread recognition. In this work, we describe a three-component cyclization to access C-2 fluoroalkylated oxazolidines by fragments assembly of readily available silyl enol ether, fluoroalkyl halide, and chiral amino alcohol in a single reaction vessel, which provides an efficient strategy for expanding the pool of pharmaceutically important heterocycles featuring an all-substituted carbon stereocenter. This process proceeds efficiently in a chemo-, regio-, and stereoselective fashion under mild reaction conditions at room temperature and exhibits broad functional group tolerance. The successful realization of this controlled heteroannulation sequence relies on distinctive perfluoroalkylation, regio-and stereoselective radical cyclization through visible-light photoredox catalysis. Moreover, a one-pot procedure directly employing ketone as substrate has also been achieved.

In the present study, five new ent-kaurane diterpenes including 4α-hydroxy-17,19-dinor-ent-kaurane-16-one (1), 4β-hydroxy-16β-H-18-nor-ent-kaurane-17-oic acid (2), 4β,17-dihydroxy-16α-acetoxy-18-nor-ent-kaurane (3), Annosquamosin Z (4) and 16α-H-ent-kaurane-17,18-dioic acid, 17-methy ester (5) were isolated from Annona squamosa L.pericarp. The compounds were also evaluated for their cytotoxic activities against SMMC-7721 and HepG2 cell lines, amomg which compound 3 exhibited potent cytotoxicity with IC 50 value of less than 20 μM.

An efficient transition metal‐free approach to achieve the selective cleavage of the α‐carbonyl C(sp3)−H bond in alkyl esters by using inexpensive, low‐toxic, and insensitive perfluoroalkyl iodide as the radical initiator has been developed. A variety of enamides, N‐heterocycles, amides, thiophenols, and phenols could be successfully incorporated into functionalized alkyl groups by intermolecular amination, thioetherification, and etherification. The distinguishing features of this CDC reaction are its broad substrate scope, synthetic simplicity, and mild reaction conditions.magnified image