Four new diterpenoids from the aerial parts of Leucas zeylanica (L.) R. Br.

Four new undescribed halimane- and labdane-type diterpenoids, named zeylleucapenoids E-H (1-4), along with four known analogues (5-8), were isolated from the aerial parts of Leucas zeylanica (L.) R. Br. Their structures were determined by comprehensive spectroscopic analysis and computational calculations. Compounds 1 and 2 are the highly modified halimane diterpenoids featuring a 6/6/6-fused tricyclic system with an unusual six-membered 6,11-ether ring. Compound 8 exhibits nontoxic effects for zebrafish embryo, while it displays efficient reduction against NO production in a dose-dependent manner and strongly suppresses the secretion of LPS-induced TNF-α and IL-6 cytokines in RAW264.7 macrophages. In addition, marked reductions of iNOS and COX-2 expression were observed. Molecular docking analysis indicated that 8 has high affinities with the target amino acid residues on protein-binding sites, which may be a possible mechanism contributing to the anti-inflammatory potential of this molecule.

Alkaloid-metabolites from the mangrove-derived fungus Penicillium robsamsonii HNNU0006.

Nine metabolites, including three undescribed alkaloids pyripyropenes VW (1-2), penicioxa A (4), two previously reported pyripyropene A (3), oxaline (5), three grisephenone-type xanthone derivatives (6-8), and a diphenyl ether derivative 4-chloro-7,4'-dihydroxy-5,2'-dimethoxy-2-methylformate-6'-methybenzophone (9), were isolated from cultures of the mangrove-derived fungus Penicillium robsamsonii HNNU0006. Their structures were determined by spectroscopic analysis, ECD calculations, together with DP4+ probability analysis. Furthermore, all the isolated compounds were tested for cytotoxicity and anti-phytopathogenic fungal activities. Compounds 6-8 showed moderate cytotoxicity against tumor cell lines A549, with IC50 values ranging from 5.68 ± 0.21 to 9.71 ± 0.34 µg/mL, respectively.

New alkaloids from the noni juice with potential α-glucosidase inhibitory activity.

Four new alkaloids, nonialkaloids A-D (1-4) and six known analogues (5-10) were isolated from the noni juice. Among the new compounds, 1 and 2 are indole alkaloids with a seven-membered fused N-heterocyclic ring, 3 and 4 are quaternary ammonium derivatives. The structures were elucidated by extensive NMR and MS analysis, while the absolute configurations of the stereogenic carbons were established based on quantum-chemical electronic circular dichroism calculations or the modified Mosher's method. All the isolates were tested for α-glucosidase inhibitory activities. Compounds 1 and 3 displayed potent inhibitory activity against α-glucosidase with the IC50 values of 413.7 and 364.4 µM, respectively.

Phenolic glycosides from the stems of Homalium stenophyllum.

The phytochemical investigation of the stems of Homalium stenophyllum afforded seven new phenolic glycosides (1-5 and 8-9) and two known compounds (6 and 7). Their structures were elucidated by comprehensive analyses of NMR spectroscopic, mass spectrometric data and chemical hydrolysis. Additionally, their anti-inflammatory activities against the NO production in LPS-induced macrophages were evaluated.

A new coumarin derivative from the stems of the endangered plant Ulmus elongata.

A preliminary phytochemical investigation of the stems of the endangered plant Ulmus elongata led to the isolation of a new coumarin derivative (named ulmuselactone A, 1) and eight known compounds (2-9). The new structure was elucidated by detailed analysis of comprehensive spectroscopic methods, and its absolute configuration was established by comparing experimental and calculated electronic circular dichroism (ECD) spectra. The isolated compounds were evaluated for their antibacterial activities.

Secondary metabolites from the mangrove sediment-derived fungus Penicillium pinophilum SCAU037.

Five new funicone derivatives, pinophilones A-E (1a/1b and 2-4), along with 18 biosynthetically related known analogues (5-22), were obtained from the culture of a mangrove sediment-derived fungus Penicillium pinophilum SCAU037. Their structures were established by analysis of 1D/2D NMR and MS data, while the absolute configurations of the new compounds were determined by ECD calculation based on time-dependent density functional theory (TD-DFT). The dihydrofuran moiety in 1a and 1b was first reported for funicone derivatives. Compound 22 exhibited antibacterial activity against Mycobacterium smegmatis and Staphylococcus aureus with IC50 of 23.5 and 2.6 µM, respectively, while 16, 18 and 22 showed significant α-glucosidase inhibitory activity with IC50 of 51.9, 78.4 and 33.8 µM, respectively.

Antifouling Compounds from the Marine-Derived Fungus Aspergillus terreus SCSGAF0162.

A new cyclic tetrapeptide, asperterrestide B (1), and 11 known compounds (2-12) were isolated from a marine-derived fungus Aspergillus terreus SCSGAF0162. The structure of 1 was elucidated by spectroscopic analysis, and the absolute configuration of 1 was determined by Mosher ester and Marfey's methods. Compounds 4, 6, and 8 had potent antifouling activity against larvae of the barnacle Balanus amphitrite, with EC50 values of 17.1 ± 1.2, 11.6 ± 0.6, and 17.1 ± 0.8 µg x mL(-1), respectively.

Alkaloids from Xylariaceae sp., a marine-derived fungus.

A new pyridine derivative, 5-(2'-hydroxypropyl)pyridin-3-ol (1), with seven known alkaloids, 3-hydroxy-5-methyl-5,6-dihydro-7H-cyclopenta[b]pyridin-7-one (2), penicillenol A1 (3), penicillenol A2 (4), a mixture of quinolactacin AI (5a) and quinolactacin A2 (5b), and a mixture of quinolactacin C1 (6a) and quinolactacin C2 (6b), were isolated from the culture broth of a marine-derived fungus Xylariaceae sp. SCSGAF0086. Their structures were elucidated by spectroscopic methods. Compound 2 showed weak antimicrobial activity against Bacillus subtilis, and a mixture of 6a and 6b exhibited strong antifouling activity toward Bugula neritina larval settlement.

Two new compounds from gorgonian-associated fungus Aspergillus sp.

One new gamma-lactone derivative 5-hydroxy-3-isopropyl-4-methoxyfuranone (1) and one new lactam derivative dehydrated-marinamide (2), along with two known compounds marinamide (3) and marinamide methyl ester (4) were isolated from the fermentation broth of the marine gorgonian-associated fungus Aspergillus sp. SCSGAF0093. Their structures were elucidated on the basis of spectroscopic and spectrometric analysis. Compound 1 showed significant toxicity to brine shrimp (Artemia salina) with a median lethal concentration (LC50) of 1.25 microM, and 3 inhibited protein tyrosine phosphatase 1B (PTP1B) with a half maximal inhibitory concentration (IC50) of 23.3 microg/mL.

Cytotoxic dihydrothiophene-condensed chromones from the marine-derived fungus Penicillium oxalicum.

Two new dihydrothiophene-condensed chromones and a new natural chromone, namely oxalicumones A-C (1-3), respectively, were isolated from a culture broth of a marine-derived fungus, Penicillium oxalicum. The structures of 1-3 and acetylated derivatives of 1 (4-7) were elucidated on the basis of spectroscopic methods and chemical reactions. The absolute configuration of 1 and 2 were established by using the modified Mosher ester method and circular dichroism data of an in situ formed [Rh2(OCOCF3)4] and [Mo2(OAc)4] complex. (R)-MTPA ester of 1 showed cytotoxicity against A375, SW-620, and HeLa carcinoma cell lines with IC50 values of 8.9, 7.8, and 18.4 µM, respectively. Compound 1 displayed cytotoxicity against A375 and SW-620 cell lines with IC50 values of 11.7 and 22.6 µM, respectively. The structure-biological activity relationship of 1 was discussed.

Cytotoxic dihydrothiophene-condensed chromones from marine-derived fungus Penicillium oxalicum.

Two new dihydrothiophene-condensed chromones and a new natural chromone, namely oxalicumones A-C (1-3), respectively, were isolated from a culture broth of a marine-derived fungus Penicillium oxalicum SCSGAF 0023, Meripilaceae family. The structures of 1-3 and acetylated derivatives of 1 (4-7) were elucidated on the basis of spectroscopic methods and chemical reactions. The absolute configuration of 1 was established by using the modified Mosher ester method and circular dichroism data of in situ formed [Rh2(OCOCF3)4] and [Mo2(OAc)4] complexes. (R)-MTPA ester of 1 showed cytotoxicity against A375, SW-620, and HeLa carcinoma cell lines with IC50 values of 8.9, 7.8, and 18.4 µM, respectively. Compound 1 displayed cytotoxicity against A375 and SW-620 cell lines with IC50 values of 11.7 and 22.6 µM, respectively. The structure-biological activity relationship of 1 is discussed.