Phytochemical constituents from Melicope pteleifolia that promote neurite outgrowth in PC12 cells

A Review of the Ethnomedicinal, Phytochemical, and Anticancer Properties of Melicope Species

The genus Melicope, which consists of 230 species, stands out as the largest genus within the Rutaceae family. Melicope species are characterized by their evergreen nature and can range from shrubs to predominantly dioecious trees. The Melicope species have been utilized in traditional medicine to address a wide range of ailments, including fever, colds, cramps, and inflammation. These plants have gained significant attention due to their noteworthy ethnopharmacological and ethnomedicinal significance. Researchers have isolated numerous biologically active secondary metabolites from different Melicope species, which include polymethoxylated flavonoids, furanocoumarins, acetophenones, benzenoids, and quinolone alkaloids. These compounds exhibit diverse biological activities, such as antibacterial, antidiabetic, antifungal, and antiproliferative properties against human cancer cell lines. This review provides an update on the chemical constituents of the selected species of Melicope. The study also highlights the anticancer and cytotoxicity properties of the plant extracts and phytochemical constituents from Melicope species. Furthermore, the molecular mechanisms underlying the anticancer effects are elucidated. Overall, this review contributes to understanding the significant pharmacological potential of Melicope species and unlocking their chemical composition, emphasizing their relevance in the development of therapeutic agents, particularly in the field of cancer research.

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).

Biology of quinoline and quinazoline alkaloids

Quinoline and quinazoline alkaloids, two important classes of N-based heterocyclic compounds, have attracted scientific and popular interest worldwide since the 19th century. More than 600 compounds have been isolated from nature to date. To build on our two prior reviews, we reexamined the promising molecules described in previous reports and provided updated literature on novel quinoline and quinazoline alkaloids isolated over the past 5 years. This chapter reviews and discusses 205 molecules with a broad range of bioactivities, including antiparasitic and insecticidal, antibacterial and antifungal, cardioprotective, antiviral, anti-inflammatory, and other effects. This survey should provide new clues or possibilities for the discovery of new and better drugs from the original naturally occurring quinoline and quinazoline alkaloids.

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.

The phytochemistry, pharmacology and applications of Melicope pteleifolia: A review

ETHNOPHARMACOLOGY RELEVANCE

The leaves, stems and roots of Melicope pteleifolia (Champ. ex Benth.) T.Hartley (MP; Rutaceae, called sanyaku in Chinese; syn.: Euodia lepta), have been used traditionally for the treatment of sore throat, rheumatism, eczema, dermatitis, bruises, and insect, rat, snake bites based on traditional Chinese medicine concepts.

AIM OF THIS STUDY

This paper aims to provide a comprehensive and critical analysis of studies on MP and focusing on potential relationships between traditional uses and pharmacological effects, assessing the therapeutic potential as a medicine.

MATERIALS AND METHODS

Relevant data on MP were retrieved using the keywords "Melicope pteleifolia", "pharmacology", "toxicity" and "applications" in databases including "Pubmed", "SciFinder", "Springer", "Elsevier", "Wiley", "Web of Science", "Google Scholar", "China Knowledge Resource Integrated databases (CNKI)", "PhD" and "MSc dissertations", and a hand-search.

RESULTS AND DISCUSSION

The heat-clearing, dampness-removing and gallbladder-normalizing actions of MP have been linked to biomedical concepts like anti-inflammatory, antioxidant and hepatoprotective activities. The latter is potentially based on the presence of furaquinoline alkaloids, phenylpropanoids and flavonoids. Analgesic, antimicrobial and anti-tumor effects have also been reported. Currently limited evidence is available relating to potential toxicological risks especially of aqueous extracts with so far no reports signalling specific risks. Although some studies on the pharmacodynamics of MP have been reported, studies on action mechanisms of MP are still rare.

CONCLUSIONS

In the future and prior to initiating clinical trials, the safety, in vitro and in vivo pharmacology, and mechanism of action of MP needs to be assessed, including a focus on the link between traditional uses and modern applications. In addition, phytochemical and biological studies need to conduct on flowers and fruits of MP. Furthermore, strict quality control measures are needed in the studies investigating any aspect of the pharmacology, chemistry and biology of MP.

Constituents of the Edible Leaves of Melicope pteleifolia with Potential Analgesic Activity

Melicope pteleifolia has long been consumed as a popular vegetable and tea in Southeast Asian countries, including Malaysia and southern mainland China, and is effective in the treatment of colds and inflammation. In the search for active metabolites that can explain its traditional use as an antipyretic, six new phloroacetophenone derivatives (3-8) along with seven known compounds (1, 2, and 9-13) were isolated from the leaves of M. pteleifolia. Their chemical structures were confirmed by extensive spectroscopic analysis including NMR, IR, ECD, and HRMS. All compounds isolated from the leaves of M. pteleifolia (1-13) have a phloroacetophenone skeleton. Notably, the new compound 8 contains an additional cyclobutane moiety in its structure. The bioactivities of the isolated compounds were evaluated, and compounds 1, 6, and 7 inhibited tumor necrosis factor-α-induced prostaglandin E₂. Moreover, the major constituent, 3,5-di-C-β-d-glucopyranosyl phloroacetophenone (1), was found to be responsible for the antipyretic activity of M. pteleifolia based on in vivo experiments.

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

Meliquercifolins A (1), and B (2), two new coumarins are bearing an acetophenone derivative were isolated from the leaves of Melicope quercifolia along with three known compounds, melicodenines E (3), F (4) and I (5). Structures of two new compounds were identified based on spectroscopic analyses (UV, HR-ESI-MS, 1 D and 2 D NMR). Cytotoxic activities of compounds (1-5) towards three human cancer cells (HeLa, MCF-7, P-388), compounds 1, 4 and 5 showed very potent activity against Hela cells with IC₅₀ values 2.6; 0.8; 1.1 μM, respectively.

(±)-Meliviticines A and B: Rearranged prenylated acetophenone derivatives from Melicope viticina and their antimicrobial activity

Two new prenylated acetophenone derivatives racemates, meliviticines A (1) and B (2) with unprecedented rearranged skeletons, were isolated from Melicope viticina. Subsequent chiral resolution led to the separation of two pairs of enantiomers, (±)-meliviticines A (1a/1b) and (±)-meliviticines B (2a/2b). Their structures including absolute configurations were elucidated by extensive spectroscopic data, electronic circular dichroism analysis, and X-ray crystallography. A plausible biosynthetic pathway of 1 and 2, involving ring cleavage and rearrangement of the prenylated acetophenone backbone was proposed. All the isolates showed moderate antimicrobial activities with MIC values of 25-50 μg/mL against several bacterial and fungal strains.

Acetophenone derivatives from the roots of Melicope ptelefolia

Five new prenylated acetophenones, melicoptelins A-E (1-5), along with one known congener (6) were isolated from the roots of Melicope ptelefolia. Among them, compounds 2a/2b, 3a/3b, and 4a/4b were obtained as inseparable interconverting mixtures of keto and enol tautomers. Their structures were elucidated on the basis of extensive spectroscopic methods, including 1D, 2D NMR and HRESIMS. Compouds 2a/2b, 4a/4b and 5 exhibit protein tyrosine phosphatase 1B (PTP1B) inhibitory activity with IC₅₀ values of 34.4, 55.2 and 66.6 μM, respectively.

Biologically active quinoline and quinazoline alkaloids part II

To follow-up on our prior Part I review, this Part II review summarizes and provides updated literature on novel quinoline and quinazoline alkaloids isolated during the period of 2009-2016, together with the biological activity and the mechanisms of action of these classes of natural products. Over 200 molecules with a broad range of biological activities, including antitumor, antiparasitic and insecticidal, antibacterial and antifungal, cardioprotective, antiviral, anti-inflammatory, hepatoprotective, antioxidant, anti-asthma, antitussive, and other activities, are discussed. This survey should provide new clues or possibilities for the discovery of new and better drugs from the original naturally occurring quinoline and quinazoline alkaloids.

Extraction and in vitro screening of potential acetylcholinesterase inhibitors from the leaves of Panax japonicus

Ultrafiltration liquid chromatography-mass spectrometry (UFLC-MS) is an efficient method that can be applied to rapidly screen and identify ligands for acetylcholinesterase (AChE) from the leaves of Panax japonicus. Using this method, we identified 5 major compounds, chikusetsusaponins V, Ib, IV, IVa, and IVa ethyl ester, as potent AChE inhibitors, which were assessed for anti-Alzheimer disease activity using the PC12 cell model. A continuous online method, which consisted of microwave-assisted extraction, a solvent concentration tank, and centrifugal partition chromatography (MAE-SCT-CPC), was newly developed for scaled up production of these compounds with high purity and efficiency. The bioactivities of the compounds separated were assessed by the PC12 cell model. This novel approach of using UFLC-MS coupled with MAE-SCT-CPC and a PC12 cell model could be applied to efficiently screen, extract, and separate AChE inhibitors from complex samples, and could serve as an important platform for the large-scale production of functional food and nutraceutical ingredients.

Pteleifolols A-E, acetophenone di-C-glycosides and a benzopyran dimer from the leaves of Melicope pteleifolia

Four new acetophenone di-C-glycosides, pteleifolols A-D (1-4) and a new dimeric benzopyran, pteleifolol E (5), were isolated from the leaves of Melicope pteleifolia. Seven known compounds, including 2,4,6-trihydroxyacetophenone-3,5-di-C-glucopyranoside (6), were also isolated. Structures of the new compounds (1-5) were established by using spectroscopic and spectrometric techniques, including 1D and 2D nuclear magnetic resonance (NMR), UV, and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) data. Pteleifolols A-D (1-4) were E-p-coumaroyl, Z-p-coumaroyl, E-feruloyl, and benzoyl esters of 6, respectively. Pteleifolol E (5) was a dichromene dimerized through a C₂ unit.