Marine Bromotyrosine Derivatives in Spotlight: Bringing Discoveries and Biological Significance.

The Verongida order comprises several sponge families, such as Aplysinellidae, Aplysinidae, Ianthellidae, and Pseudoceratinidae, reported for producing bromotyrosine-derived compounds. First identified in 1913, bromotyrosine derivatives have since captivated interest notably for their antitumor and antimicrobial properties. To date, over 360 bromotyrosine derivatives have been reported. Our review focuses specifically on bromotyrosine derivatives newly reported from 2004 to 2023, by summarizing current knowledge about their chemical diversity and their biological activities.

Characterization of thymol derivatives from Eupatorium fortunei Turcz. aerial parts.

From the aerial parts of Eupatorium fortunei, four thymol derivatives (1-4) were isolated and structurally elucidated by NMR and mass spectroscopic methods. Of which, a new dimeric thymol derivative (1) was characterized and its absolute configuration was established by electronic circular dichroism quantum method. In addition, the 1D and 2D NMR as well as HR-ESI mass spectral data of 2 were provided for the first time. Compounds 2-4 were evaluated for their inhibitory activity against α-glucosidase and acetylcholinesterase enzymes. All tested compounds showed weak inhibition at the concentration range of 1-256 µg/mL in both enzymatic assays.

Patulinervones A and B, two novel α-glucosidase inhibitory spiro-lignans from Melicope patulinervia (Merr. & Chun) C.C. Huang.

(±)-Patulinervones A (1) and B (2), two diastereomers of spiro-lignans sharing an unprecedented dimethyl-spiro[furan-2,2'-furo[2,3-b]furan] 5/5/5 tricyclic moiety were isolated from the leaves of Melicope patulinervia (Merr. & Chun) C.C. Huang. Their structures were established by extensive spectroscopic data and electronic circular dichroism (ECD) analyses. The racemates (±)-1 and 2 and their enantiomers exhibited α-glucosidase inhibitory effect with IC50 values range of 10.08 ± 1.24 - 25.58 ± 1.97 µM.

Chemical constituents of Antidesma bunius aerial parts and the anti-AGEs activity of selected compounds.

Thirty-three natural products were isolated from the aerial parts of Antidesma bunius, Euphorbiaceae, a plant used in Vietnamese traditional medicine against rheumatoid arthritis. All compounds were reported the first time for this species, and nine constituents resembled undescribed natural products, noticeably three coumarinolignans with 2,2-dimethyl-1,3-dioxolane moiety, two cyclopeptides, and two furofuran-type lignans connected with a phenylpropanoid moiety. The individual structures were elucidated by combining NMR and MS data, and their configuration was established by NOESY and ECD experiments and NMR calculations. Compounds with sufficient amount were analyzed for their inhibition of advanced glycation endproducts (AGEs) formation, metabolites involved in many diseases like Alzheimer, joint diseases or diabetes. With IC50 values below 0.2 mM rutin and p-hydroxyphenethyl trans-ferulate showed to be moderately active, both still being 10-times more active than the positive control aminoguanidine.

Isolation of Sesquiterpenoids and Steroids from the Soft Coral Sinularia brassica and Determination of Their Absolute Configuration.

Two undescribed rearranged cadinane-type sesquiterpenoids (1-2), named sinulaketol A-B, together with one new chlorinated steroid (3), one new gorgosterol (4), one known sesquiterpene (5), one known dibromoditerpene (6) and two known polyhydroxylated steroids (7-8) were isolated from the soft coral Sinularia brassica. The structures of these compounds were established by extensive spectroscopic analysis, including HRESIMS, 1D, and 2D NMR spectroscopy. Their absolute configurations were also determined by the ECD calculations and DP4+ probability analysis. Antileishmanial activity of compounds 1-8 was evaluated in vitro against the amastigote forms of Leishmania donovani, in which compounds 3, 6, and 7 inhibited the growth of L. donovani by 58.7, 74.3, 54.7%, respectively, at a concentration of 50 µM. Antimicrobial effect of the isolated compounds were also evaluated against Candida albicans, Staphylococcus aureus, and Escherichia coli. Compound 6, a brominated diterpene, exhibited antimicrobial effect against S. aureus.

New oligomeric neolignans from the leaves of Magnolia officinalis var. biloba.

Six new oligomeric neolignans including two trimeric neolignans (1 and 2) and four dimeric neolignans (3-6) were isolated from the leaves of Magnolia officinalis var. biloba. Their structures were determined based on HR-ESIMS and NMR data, as well as electronic circular dichroism (ECD) calculations. Compound 1 is formed from two obovatol moieties directly linked to an aromatic ring of the remaining obovatol moiety, which is an unprecedented type of linkage between monomers. All isolates were assessed for their inhibitory effects on NO production in LPS-stimulated RAW 264.7 macrophage cells. Compounds 1 and 3 showed significantly inhibitory activities with IC50 values of 6.04 and 3.26 µmol·L-1, respectively.

Fissistigma genus - a review on phytochemistry and pharmacological activities.

The genus Fissistigma belongs to Annonaceae family and is mainly distributed in tropical areas of Asia. Many species from this genus have long been used for medicinal purposes in China and Vietnam. To date, there have been a number of studies on both phytochemical and pharmacological aspects of Fissistigma species, which indicated that the genus is a rich source of diverse and novel bioactive compounds, including alkaloids, terpenoids and phenolic derivatives. The review aims to summarise past study results as well as analyse future directions of Fissistigma species research.

Ethnopharmacology, Phytochemistry, and Pharmacology of Syzygium nervosum.

Syzygium nervosum, which belongs to the Myrtaceae plant family, is widely distributed and cultivated in South East Asian countries. The decoction of S. nervosum leaves and flower buds has been consumed regularly as a beverage among the Vietnamese and Chinese communities. In addition, it has also been used in traditional medicine for a variety of purposes, notably for influenza, skin diseases, and digestive conditions. To date, there has been a considerable number of publications on chemical profiling and pharmacological activities of S. nervosum crude extract and pure isolated compounds. Our analysis indicated the characteristic chemical scaffolds and potential bioactivities on cancer, diabetes, and inflammatory diseases of this plant. The review aims to summarize up-to-date past study results and suggest future research direction on this species, in order to promote clinical applications of S. nervosum.

Patulignans A-C, three structurally unique lignans from the leaves of Melicope patulinervia.

(±)-Patulignans A-C (1-3), three unique pairs of lignan enantiomers were isolated from the leaves of Melicope patulinervia. Patulignan A (1) possesses an unprecedented dimethyloxonane moiety in nature, meanwhile patulignans B (2) and C (3) are epimers carrying a novel dimethyl-1,6-dioxaspiro[4.5]decane skeleton. Their structures were established by spectroscopy methods and electronic circular dichroism (ECD) calculations. Compounds 1-3 showed significant inhibitory activity against α-glucosidase.