Two novel coumarins bearing an acetophenone derivative from the leaves of Melicope Quercifolia

4-Propyl- and 4-phenylcoumarins from mesua lepidota T. Anderson and their cytotoxic activity

Two new 4-phenylcoumarins, mesulepidotins A (1) and B (2), one new 4-propylcoumarin, mesulepidotin C (3), and one known 4-phenylcoumarin (4) were isolated from Mesua lepidota stem barks. The structures of 4-propyl- and 4-phenylcoumarins were identified by analysing 1D and 2D NMR spectra combined with high-resolution ESIMS data. Compounds 1-4 were assayed to MCF-7 and HeLa cells for their cytotoxic activity. Mesulepidotin A (1) showed high activity with an IC50 value of 1.59 and 1.41 µM, respectively.

Natural-derived acetophenones: chemistry and pharmacological activities

Acetophenones are naturally occurring phenolic compounds which have found in over 24 plant families and also fungi strains. They are exist in both free or glycosides form in nature. The biological activities of these compounds have been assayed and reported including cytotoxicity, antimicrobial, antimalarial, antioxidant and antityrosinase activities. Herein, we review the chemistry and biological activity of natural acetophenone derivatives that have been isolated and identified until January 2024. Taken together, it was reported 252 acetophenone derivatives in which the genera Melicope (69) and Acronychia (44) were the principal species as producers of acetophenones.

Three novel quinolinone alkaloids from the leaves of Melicope denhamii

Three previously unreported quinolinone alkaloids: melicodenines J-L (1-3) and six known compounds (4-9), were isolated from the leaves of Melicope denhamii (Seem) T.G. Hartley. The structures of three quinolinone alkaloids were identified based on HRESIMS and NMR spectra. Compounds 1-9 were assayed in three cancer cells (MCF-7, HeLa, and P-388). Compounds 1 and 5 showed high cytotoxic activity against HeLa cells with IC₅₀ values of 1.8 and 0.8 µM, respectively.

Molecular networking-based discovery of anti-inflammatory chromene dimers from Melicope pteleifolia

With the aid of a feature-based molecular networking strategy, five undescribed C₂ and C₁ symmetric chromene dimers, namely, melptelchromenes A-E, were isolated from the leaves of Melicope pteleifolia. Four asymmetric dimers were found to be racemates and were resolved by chiral phase HPLC analyses. Their structures, including absolute configurations, were elucidated by HRMS, NMR spectroscopy, and quantum mechanical calculations of ECD spectra and NMR chemical shifts. Melptelchromenes A-D possess a unique ethylidene linkage via two 2H-chromene cores, while melptelchromene E represents the first example of a dimeric chromene featuring a 1,3-diarylbutan-1-ol moiety. Of these compounds, 6,6'-linked dimeric chromenes showed nitric oxide inhibitory activities on lipopolysaccharide-induced RAW 264 cells, and (-)- and (+)-melptelchromene E were the two most potent compounds (IC₅₀, 3.0 and 5.1 μM, respectively).

Do Uncommon Plant Phenolic Compounds Have Uncommon Properties? A Mini Review on Novel Flavonoids

Unique plants and their properties, once considered synonymous to medicine, remain a potent source for new compounds in modern science. Plant polyphenols and natural products continue to be investigated for effective treatments for the most persistent of human ailments. In this review, fifty novel plant phenolic compounds have been compiled and briefly described from the previous five years. Select compounds and notable plant species from genus Morinda and Sophora are further expanded on. Traditional medicine plants often contain rich and diverse mixtures of flavonoids, from which rare compounds should receive attention. The bioactivity of crude plant extracts, purified compounds and mixtures can differ greatly, requiring that these interactions and mechanisms of action be investigated in greater detail. Novel applications of uncommon natural products, namely mimosine and juglone, are explored within this review. The 2019 coronavirus pandemic has resulted in abrupt spike of related scientific publications: speculation is made regarding plant natural products and future of antiviral drug discovery.

New Acetophenones and Chromenes from the Leaves of Melicope barbigera A. Gray

The dichloromethane extract from leaves of Melicope barbigera (Rutaceae), endemic to the Hawaiian island of Kaua'i, yielded four new and three previously known acetophenones and 2H-chromenes, all found for the first time in M. barbigera. The structures of the new compounds obtained from the dichloromethane extract after purification by chromatographic methods were unambiguously elucidated by spectroscopic analyses including 1D/2D NMR spectroscopy and HRESIMS. The absolute configuration was determined by modified Mosher's method. Compounds 2, 4 and the mixture of 6 and 7 exhibited moderate cytotoxic activities against the human ovarian cancer cell line A2780 with IC₅₀ values of 30.0 and 75.7 µM for 2 and 4, respectively, in a nuclear shrinkage cytotoxicity assay.

Two new 2-arylbenzofurans from Sesbania grandiflora L. and their cytotoxicity towards cancer cell

Two new 2-arylbenzofurans, sesbagrandiflorain D (1) and E (2) along with two known 2-arylbenzofurans, spinosan A (3) and spinosan B (4) were isolated from the stem bark of Sesbania grandiflora L. The structure of two new compounds established by HRESIMS, 1 D NMR (¹H, ¹³C) and 2 D NMR (HMQC, HMBC) spectra. Compounds (1-4) assayed for their cytotoxicity towards three human cancer cells (MCF-7, HeLa, and WiDr). Compound 1 showed very high activity against MCF-7 and WiDr with an IC₅₀ value of 0.06 and 0.60 μg/mL, respectively.

Two new pyranoxanthones from the stem bark of Calophyllum pseudomolle P.F. Stevens

Two new pyranoxanthones, calotetrapterins D (1) and E (2), were isolated from the stem bark of Calophyllum pseudomolle P.F. Stevens along with α-mangostin (3). The structures of compounds 1-2 were determined based on 1D NMR (¹H, ¹³C) and 2D NMR (HMQC, HMBC), as well as HRESIMS spectroscopic analysis. Compounds 1-2 showed moderate activity against HeLa and murine leukaemia P-388 cells.