Xanthones from Calophyllum teysmannii var. inophylloide

Cytotoxic and anti-inflammatory constituents from roots of Hypericum beanii and the antitumor potential under the view of cancer-related inflammation

Hypericum beanii, a traditional folk medicine plant, has been employed in the treatment of various inflammation-related diseases and has demonstrated promising potential as an herbal remedy for cancer. In this study, we isolated 29 compounds from the roots of H. beanii. We evaluated their cytotoxic effects on five human cancer cell lines, which revealed that the ethanol extract, along with compounds 4 and 14, exhibited significant cytotoxic activity. Additionally, we assessed their anti-inflammatory properties by measuring the inhibition of nitric oxide (NO) production in LPS-stimulated RAW 264.7 macrophages. Our findings showed that the ethanol extract (IC50 = 7.41 ± 0.38 μg/mL), compound 4 (IC50 = 7.82 ± 0.42 μM), and compound 14 (IC50 = 3.05 ± 0.06 μM) displayed substantial anti-inflammatory activity. ELISA assays and qPCR analysis revealed that compounds 4 and 14 may exert their anti-inflammatory and antitumor effects by inhibiting the expression of iNOS, TNF-α, IL-1β, and IL-6 mRNA, shedding light on their role in cancer-related inflammation.

Cytotoxic Metabolites from Calophyllum tacamahaca Willd.: Isolation and Detection through Feature-Based Molecular Networking

Isocaloteysmannic acid (1), a new chromanone, was isolated from the leaf extract of the medicinal species Calophyllum tacamahaca Willd. along with 13 known metabolites belonging to the families of biflavonoids (2), xanthones (3-5, 10), coumarins (6-8) and triterpenes (9, 11-14). The structure of the new compound was characterized based on nuclear magnetic resonance (NMR), high-resolution electrospray mass spectrometry (HRESIMS), ultraviolet (UV) and infrared (IR) data. Its absolute configuration was assigned through electronic circular dichroism (ECD) measurements. Compound (1) showed a moderate cytotoxicity against HepG2 and HT29 cell lines, with IC₅₀ values of 19.65 and 25.68 µg/mL, respectively, according to the Red Dye method. Compounds 7, 8 and 10-13 exhibited a potent cytotoxic activity, with IC₅₀ values ranging from 2.44 to 15.38 µg/mL, against one or both cell lines. A feature-based molecular networking (FBMN) approach led to the detection of a large amount of xanthones in the leaves extract, and particularly analogues of the cytotoxic isolated xanthone pyranojacareubin (10).

Using 13 C-NMR dereplication to aid in the identification of xanthones present in the stem bark extract of Calophyllum brasiliense

INTRODUCTION

Xanthones are metabolites with a variety of biological properties. The Clusiaceae family, which until recently included the genus Calophyllum, is recognised for its production of monohydroxylated and polyhydroxylated xanthones. Presently, C. brasiliense is the only Calophyllum spp. known to occur in the Yucatan peninsula.

OBJECTIVE

To use a combination of traditional phytochemical methods and carbon-13 nuclear magnetic resonance (¹³ C-NMR) dereplication analysis to identify xanthones in the stem bark of C. brasiliense.

MATERIAL AND METHODS

Initial fractionation and purification of the stem bark extract of C. brasiliense produced macluraxanthone (1). Additional xanthones, together with chromanones and terpenoids, were identified using ¹³ C-NMR dereplication analysis in different semipurified fractions obtained from the low and medium polarity fractions of the stem bark extract of C. brasiliense.

RESULTS

Initial identification of macluraxanthone (1) was confirmed by ¹³ C-NMR dereplication analysis; additionally, ¹³ C-NMR dereplication analysis allowed the identification of a number of monohydroxylated and polyhydroxylated xanthones, together with chromanones and terpenoids.

CONCLUSION

This study confirms C. brasiliense as a rich source of xanthones and the ¹³ C-NMR dereplication analysis as a suitable method to quickly identify the presence of different families of secondary metabolites in semipurified fractions.

Carboxyxanthones: Bioactive Agents and Molecular Scaffold for Synthesis of Analogues and Derivatives

Xanthones represent a structurally diverse group of compounds with a broad range of biological and pharmacological activities, depending on the nature and position of various substituents in the dibenzo-γ-pyrone scaffold. Among the large number of natural and synthetic xanthone derivatives, carboxyxanthones are very interesting bioactive compounds as well as important chemical substrates for molecular modifications to obtain new derivatives. A remarkable example is 5,6-dimethylxanthone-4-acetic acid (DMXAA), a simple carboxyxanthone derivative, originally developed as an anti-tumor agent and the first of its class to enter phase III clinical trials. From DMXAA new bioactive analogues and derivatives were also described. In this review, a literature survey covering the report on carboxyxanthone derivatives is presented, emphasizing their biological activities as well as their application as suitable building blocks to obtain new bioactive derivatives. The data assembled in this review intends to highlight the therapeutic potential of carboxyxanthone derivatives and guide the design for new bioactive xanthone derivatives.

Antibacterial and EGFR-tyrosine kinase inhibitory activities of polyhydroxylated xanthones from Garcinia succifolia

Chemical investigation of the methanol extract of the wood of Garcinia succifolia Kurz (Clusiaceae) led to the isolation of 1,5-dihydroxyxanthone (1), 1,7-dihydroxyxanthone (2), 1,3,7-trihydroxyxanthone (3), 1,5,6-trihydroxyxanthone (4), 1,6,7-trihydroxyxanthone (5), and 1,3,6,7-tetrahydroxyxanthone (6). All of the isolated xanthones were evaluated for their antibacterial activity against bacterial reference strains, two Gram-positive (Staphylococcus aureus ATTC 25923, Bacillus subtillis ATCC 6633) and two Gram-negative (Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853), and environmental drug-resistant isolates (S. aureus B1, Enteroccoccus faecalis W1, and E. coli G1), as well as for their epidermal growth factor receptor (EGFR) of tyrosine kinase inhibitory activity. Only 1,5,6-trihydroxy-(4), 1,6,7-trihydroxy-(5), and 1,3,6,7-tetrahydroxyxanthones (6) exhibited antibacterial activity against Gram-positive bacteria, however none was active against vancomycin-resistant E. faecalis. Additionally, 1,7-dihydroxyxanthone (2) showed synergism with oxacillin, but not with ampicillin. On the other hand, only 1,5-dihydroxyxanthone (1) and 1,7-dihydroxyxanthone (2) were found to exhibit the EGFR-tyrosine kinase inhibitory activity, with IC₅₀ values of 90.34 and 223 nM, respectively.

Antifungal activity of xanthones: evaluation of their effect on ergosterol biosynthesis by high-performance liquid chromatography

The increasing resistance of pathogenic fungi to antifungal compounds and the reduced number of available drugs led to the search for therapeutic alternatives among natural products, including xanthones. The antifungal activity of 27 simple oxygenated xanthones was evaluated by determination of their minimal inhibitory concentration on clinical and type strains of Candida, Cryptococcus, Aspergillus and dermatophytes, and their preponderance on the dermatophytic filamentous fungi was observed. Furthermore, a simple and efficient HPLC method with UV detection to study the effect of the active xanthones on the biosynthesis of ergosterol was developed and validated. Using this methodology, the identification and quantification of fungal sterols in whole cells of Candida albicans, Cryptococcus neoformans, Aspergillus fumigatus, and Trichophyton mentagrophytes were accomplished. In summary, 1,2-dihydroxyxanthone was found to be the most active compound against all strains tested, showing its effect on sterol biosynthesis by reducing the amount of ergosterol detected.

Chemical and pharmacological aspects of the genus Calophyllum

The Calophyllum genus (Clusiaceae) is composed of ca. 200 species, with a pantropical distribution. Some species are used as medicinal agents to treat a large number of diseases, including gastric ulcers, infections, pain, tumors, and inflammatory processes, among others. A review of the literature regarding the chemical and biological aspects of these plants indicates cytotoxic activity against several cell lines, inhibition of HIV-1 reverse transcriptase, antisecretory and cytoprotective properties, antinociceptive, molluscicidal and antimicrobial effects, etc., related particularly to the presence of coumarins, xanthones, flavonoids, and triterpenes. This review, therefore, deals with the chemistry, and pharmacology or biology of the main plants belonging to the genus Calophyllum, with particular emphasis on C. brasiliense, studied by our research group.

Three new xanthones from the roots of Polygala japonica Houtt

Three new xanthones, 1,3-dihydroxy-2,5,6,7-tetramethoxyxanthone (1), 3-hydroxy-1,2,5,6,7-pentamethoxyxanthone (2), and 3,8-dihydroxy-1,2,6-trimethoxyxanthone (3), together with two known compounds were isolated from the roots of Polygala japonica Houtt. Their structures were determined on the basis of spectroscopic data.

Composition of fatty acids triacylglycerols and unsaponifiable matter in Calophyllum calaba L. oil from Guadeloupe

The composition of the kernel oils of two Calophyllum species (Calophyllum calaba L. and Calophyllum inophyllum L.) was investigated. The physico-chemical properties and fatty acid composition of the kernel oils were examined. In two species, oleic acid C18:1 (39.1-50%) is the dominating fatty acid followed by linoleic acid C18:2 (21.7-31.1%) as the second major fatty acid. Stearic C18:0 (13.4-14.3%) and palmitic C16:0 (11-13.7%) acids are the major saturates. The oils contains an appreciable amount of unsaturated fatty acids (70.8-73.10%). Most of the fatty acids are present as triacylglycerol (76.7-84%), twenty one triacylglycerols are detected with predominantly unsaturated triacylglycerols. The total unsaponifiable content, its general composition and the identity of the components of the sterol and tocopherol fractions are presented. In both species, analysis of the unsaponifiable fractions revealed the preponderance of phytosterols, mainly stigmasterol (35.8-45.1%) and beta-sitosterol (41.1-43.1%). Among the eight tocopherols and tocotrienols present in two species, variations exist; alpha-tocopherol (183 mg/kg) is the main tocopherol in Calophyllum calaba L. and Delta-tocotrienol (236 mg/kg) is the dominant tocotrienol in Calophyllum inophyllum L.

Antimicrobial and cytotoxic agents from Calophyllum inophyllum

The study of the chemical constituents of the root bark and the nut of Calophyllum inophyllum has resulted in the isolation and characterization of a xanthone derivative, named inoxanthone, 3, together with 12 known compounds: caloxanthones A, 4 and B, 5, macluraxanthone, 6, 1,5-dihydroxyxanthone, 7, calophynic acid, 8, brasiliensic acid, 9 inophylloidic acid, 10, friedelan-3-one, 11, calaustralin, 12, calophyllolide, 13, inophyllums C, 14 and E, 15. Their structures were established on the basis of spectral evidence. Their in vitro cytotoxicity against the KB cell line and their antibacterial activity and potency against a wide range of micro organisms were evaluated.

Chemical constituents of Calophyllum brasiliensis: structure elucidation of seven new xanthones and their cancer chemopreventive activity

The first study of chemical constituents of the stem bark of Calophyllum brasilienses collected in Brazil has led to the isolation and identification of seven new xanthones named brasixanthones A (1), B (4), C (5), D (6), E (2), F (3), and G (10), together with 10 known xanthones. Among the xanthones isolated in this study, 4, 5, 6, and 11 were found to exhibit significant inhibitory activity against 12-O-tetradecanoylphorbol-13-acetate induced Epstein-Barr virus early antigen activation in Raji cells.

Xanthones from Calophyllum teysmannii var. inophylloide

Further study of the wood of Calophyllum teysmannii Miq. var. inophylloide yielded xanthones 7-hydroxy-1,2,8-trimethoxyxanthone, 6-hydroxy-1,2,5-trimethoxyxanthone, and 2-carbomethoxy-6-methoxyxanthone in addition to 3,8-dihydroxy-1,2,4-trimethoxyxanthone, 3-hydroxy-2,4-dimethoxyxanthone, 1,7-dihydroxy-3-methoxyanthone (gentisin) and 2-hydroxyxanthone.

New xanthones from Calophyllum caledonicum

Four new xanthones, caledonixanthones A-D (1-4), were isolated from the trunk bark of Calophyllum caledonicum, in addition to 17 known compounds. The structures of 1-4 were determined by means of spectroscopic analysis and chemical derivatization.