Calanone, a novel coumarin from Calophyllum teysmannii

Phenolics and triterpenoids from stem bark of Calophyllum lanigerum var. austrocoriaceum (Whitmore) P. F. Stevens and their cytotoxic activities

Genus Calophyllum is well-known for its phenolic constituents, especially coumarins, which have shown to have a wide range of significant biological activities. In this study, four known phenolic constituents and two triterpenoids have been isolated from the stem bark of Calophyllum lanigerum. The compounds were two pyranochromanone acids are known as caloteysmannic acid (1), isocalolongic acid (2), a simple dihydroxyxanthone, namely euxanthone (3), one coumarin named calanone (4), and two common triterpenoids, friedelin (5), and stigmasterol (6). Chromanone acids were reported for the first time in this Calophyllum species. Cytotoxic evaluations were carried out on n-hexane extract (87.14 ± 2.04 µg/mL; 81.46 ± 2.42 µg/mL) followed by the chromanone acids (1 [79.96 ± 2.39 µM; 83.41 ± 3.39 µM] & 2 [57.88 ± 2.34; 53.04 ± 3.18 µM]) against two cancerous cell lines, MDA-MB-231 and MG-63 cell lines, respectively. The results showed that all tested samples exhibited moderate cytotoxicity.

Chemical constituents from the stem barks of Calophyllum recurvatum P.F. Stevens and Calophyllum andersonii P.F. Stevens, and their in-vitro hepatotoxic activity

Bioactive phenolics can be found in abundance in Calophyllum species. Phytochemical studies are carried out on the stem bark of Calophyllum recurvatum and Calophyllum andersonii, which has led to the isolation and elucidation of phytochemicals, thwaitesixanthone (1), teysmanone A (2), soulattrolide (3), calanone (4), isocalanone (5) and friedelin (6), respectively. The cytotoxic activities of compounds (2), (3), (4) and (5) as well as plant extracts were tested against HeLa Chang liver, HepG2 and HL-7702 cell lines. Phenylpyranocoumarins, teysmanone A (2) and soulattrolide (3) portrayed appreciable cytotoxicity activities at 42.57 ± 1.20 and 34.53 ± 3.41 µg/mL, respectively against HepG2 cell line comparable to the positive control, curcumin. Meanwhile, n-hexane extract from C. recurvatum exhibited cytotoxicity with the IC50 value of 36.43 ± 0.64 and 26.25 ± 4.83 µg/mL against HeLa Chang liver and HepG2 cell lines. All the tested compounds and plant extracts displayed non-cytotoxic properties on HL-7702 cell line.

Identification of Antioxidant Metabolites from Five Plants (Calophyllum inophyllum, Gardenia taitensis, Curcuma longa, Cordia subcordata, Ficus prolixa) of the Polynesian Pharmacopoeia and Cosmetopoeia for Skin Care

Oxidative stress contributes to impairment of skin health, the wound healing process, and pathologies such as psoriasis or skin cancer. Five Polynesian medicinal plants, among the most traditionally used for skin care (pimples, wounds, burns, dermatoses) are studied herein for their antioxidant properties: Calophyllum inophyllum, Gardenia taitensis, Curcuma longa, Cordia subcordata, and Ficus prolixa. Plant extracts were submitted to in vitro bioassays related to antioxidant properties and their bioactive constituents were identified by a metabolomic analytical approach. High performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS) analysis was performed leading to the characterization of 61 metabolites. Compounds annotated for F. prolixa and C. subcordata extracts were reported for the first time. Antioxidant properties were evaluated by total phenolic content (TPC), free radical scavenging DPPH (1,1-diphenyl-2-picryl-hydrazyl), and Ferric Reducing Antioxidant Power activity (FRAP) assays. F. prolixa extract was the most active one and showed antioxidant intracellular activity on keratinocytes by Anti Oxydant Power 1 assay. Online HPLC-DPPH allowed the identification of phenolic bioactive compounds such as quercetin-O-rhamnoside, rosmarinic acid, chlorogenic acid, procyanidins, epicatechin, 5-O-caffeoylshikimic acid, and curcumin as being responsible for the scavenging properties of these plant extracts. These results highlight the potential of F. prolixa aerial roots as a source of antioxidants for skin care applications.

Traditional Medicinal Plants as a Source of Antituberculosis Drugs: A System Review

Medicinal plants are the chief components in the different oriental formulations in different traditional medical systems worldwide. As a thriving source of medicine, the medicinal plants with antituberculosis (TB) properties inspire the pharmacists to develop new drugs based on their active components or semimetabolites. In the present review, the anti-TB medicinal plants were screened from the scientific literatures, based on the botanical classification and the anti-TB activity. The obtained anti-TB medicinal plants were categorized into three different categories, viz., 159 plants critically examined with a total 335 isolated compounds, 131 plants with their crude extracts showing anti-TB activity, and 27 plants in literature with the prescribed formula by the traditional healers. Our systemic analysis on the medicinal plants can assist the discovery of novel and more efficacious anti-TB drugs.

Naturally Occurring Calanolides: Occurrence, Biosynthesis, and Pharmacological Properties Including Therapeutic Potential

Calanolides are tetracyclic 4-substituted dipyranocoumarins. Calanolide A, isolated from the leaves and twigs of Calophyllum lanigerum var. austrocoriaceum (Whitmore) P. F. Stevens, is the first member of this group of compounds with anti-HIV-1 activity mediated by reverse transcriptase inhibition. Calanolides are classified pharmacologically as non-nucleoside reverse transcriptase inhibitors (NNRTI). There are at least 15 naturally occurring calanolides distributed mainly within the genus Calophyllum, but some of them are also present in the genus Clausena. Besides significant anti-HIV properties, which have been exploited towards potential development of new NNRTIs for anti-HIV therapy, calanolides have also been found to possess anticancer, antimicrobial and antiparasitic potential. This review article provides a comprehensive update on all aspects of naturally occurring calanolides, including their chemistry, natural occurrence, biosynthesis, pharmacological and toxicological aspects including mechanism of action and structure activity relationships, pharmacokinetics, therapeutic potentials and available patents.

Biological importance of structurally diversified chromenes

Compounds incorporating the chromene scaffold are largely present in natural products and display a wide variety of biological activities. Their low toxicity combined to the broad pharmacological properties have inspired medicinal chemists in the search for new therapeutic agents. This review covers the literature between 1993 and on the biological activity of 2H- and 4H-chromenes, both from natural and synthetic origin. Includes a section that identifies a selection of chromene-based natural products, followed by recent literature on bioactive natural chromenes and the corresponding source, covering plants and fruits. Synthetic chromenes are equally important and a separate section addresses the use of these derivatives as new leads for drug discovery. Different biological targets were identified, namely those associated with anticancer, antimicrobial, anti-inflammatory, antithrombotic and antipsychotic activities.

Two new 4-arylcoumarins from the seeds of Calophyllum polyanthum

Two new 4-arylcoumarins, 7,4'-dihydroxy-6,8-dimethoxy-4-phenylcoumarin (1) and 7-hydroxy-6,8,4'-trimethoxy-4-phenylcoumarin (2), together with four known compounds were isolated from the seeds of Calophyllum polyanthum. The structures of the new compounds were determined by extensive spectroscopic analyses, and the structure of compound 2 was confirmed by X-ray crystallography analysis. Both new compounds exhibited significant cell protective activities against H(2)O(2)-induced human umbilical vein endothelial cell damage.

Inophyllin A, a new pyranoxanthone fromCalophyllum inophyllum(Guttiferae)

In the authors' continuing search for new natural products, their recent studies on the roots of Calophyllum inophyllum (Guttiferae) have yielded a new prenylated pyranoxanthone, Inophyllin A together with the common triterpenes friedelin and stigmasterol. Structural elucidations of these compounds were achieved through (1)H, (13)C, DEPT, COSY, HSQC and HMBC experiments. The molecular mass was determined using MS techniques. The authors report here the isolation of and structural elucidation for Inophyllin A as well as its toxicity test result. The discovery of this new natural product from the unexploited Malaysian forest will certainly contribute to the search for potential natural larvicides.

Sundaicumones A and B, polyprenylated acylphloroglucinol derivatives from Calophyllumsundaicum with weak activity against the glucocorticoid receptor

Bioassay-directed fractionation using a glucocorticoid receptor assay led to the isolation of two new, weakly active polyprenylated acylphloroglucinol derivatives, sundaicumones A (1) and B (2), from the leaves of Calophyllum sundaicum collected in Singapore. The structures of 1 and 2, which were established by spectroscopic methods, contain a 3-substituted hexanoic acid unit not previously reported in other polyprenylated acylphloroglucinols.

Two pyranocoumarins from the seeds of Calophyllum polyanthum

Two new pyranocoumarin diastereoisomers, calopolyanolides C (1) and D (2), were isolated from the ethanolic extract of the seeds of Calophyllum polyanthum, along with calopolyanolide A (3), calopolyanolide B (4), calanolide E2 (5), 5,7,3',4'-tetrahydroxyisoflavone (6), 3,4-dihydroxybenzoic acid (7), 3,4,5-trihydroxybenzoic acid (8), 2-hydroxy-4-methoxybenzoic acid (9), beta-sitosterol (10), beta-daucosterol (11), 3,5-dihydroxy-4-methoxybenzoic acid (12), 3,5-dimethoxybenzoic acid (13), and ursolic acid (14). Their structures were determined by MS, UV, and IR data and HMQC, HMBC, and NOESY experiments or by comparing them with authentic samples. X-ray crystallographic analysis confirmed the structure and relative configuration of 1.

Chemical constituents of Calophyllum brasiliense. 2. Structure of three new coumarins and cancer chemopreventive activity of 4-substituted coumarins

Continuing our search for cancer chemopreventive agents from natural sources, we examined constituents of the stem bark of Calophyllum brasiliense. Three new 4-substituted coumarins named brasimarins A (2), B (3), and C (4) were isolated and characterized, along with 11 known coumarins belonging to the calanolides or inophyllums. We also discuss the inhibitory effects of these coumarins on Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells.

Cytotoxic coumarins and lignans from extracts of the northern prickly ash (Zanthoxylum americanum)

Four pyranocoumarins; dipetaline, alloxanthoxyletin, xanthoxyletin and xanthyletin; and two lignans; sesamin and asarinin were isolated from the northern prickly ash, Zanthoxylum americanum. To varying degrees, all inhibited the incorporation of tritiated thymidine into human leukaemia (HL-60) cells. Dipetaline was the most active with an IC(50) of 0.68 ppm, followed by alloxanthoxyletin (1.31 ppm), sesamin (2.71 ppm), asarinin (4.12 ppm), xanthoxyletin (3.48 ppm) and xanthylletin (3.84 ppm).

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.

Xanthones from Calophyllum teysmannii var. inophylloide

Further study of the wood of Calophyllum teysmannii Miq. var. inophylloide from Thailand yielded the xanthones 1,2,8-trimethoxyxanthone, 6-hydroxy-1,2,5,7-tetramethoxyxanthone and 3-(3'-carboxybutyl)-4-methoxyxanthone (teysmannic acid) in addition to scriblitifolic acid, 1,7-dihydroxyxanthone and the benzoic acid derivative leiocarpic acid.

Pyranocoumarins from tropical species of the genus Calophyllum: a chemotaxonomic study of extracts in the National Cancer Institute collection

(+)-Calanolide A, a novel dipyranocoumarin from the Malesian tree Calophyllum lanigerum var. austrocoriaceum, and a closely related compound, (-)-calanolide B, isolated from Calophyllum teysmannii var. inophylloide, are representatives of a distinct class of nonnucleoside HIV-1 specific reverse-transcriptase inhibitor under development as an AIDS chemotherapeutic. NCI repository specimens totalling 315 organic extracts from 31 taxa of Calophyllum were analyzed for related pyranocoumarins using a simple TLC system. A total of 127 extracts was initially classified as "positive"; eight out of the 31 taxa examined, representing perhaps 28 species already described (1/7-1/8 of all the species in this genus), contained prenylated coumarins, suggesting that these compounds, while sometimes abundantly present, are not widespread in the genus. Representative members of the TLC-positive extracts were partitioned between CH2C12 and 25% aqueous MeOH; the CH2C12-soluble materials were then analyzed by TLC and 1H NMR to confirm the presence of pyranocoumarins. The anti-HIV activity of the partitioned extracts are also presented. This study suggested that there are several distinctive coumarin chemotaxonomic markers distinguishing species of this genus.

Synthesis, chromatographic resolution, and anti-human immunodeficiency virus activity of (+/-)-calanolide A and its enantiomers

The anti-HIV agent (+/-)-calanolide A (1) has been synthesized in a five-step approach starting with phloroglucinol [-->5-->6-->11-->18-->(+/-)-1], which includes Pechmann reaction, Friedel-Crafts acylation, chromenylation with 4,4-dimethoxy-2-methylbutan-2-ol, cyclization, and Luche reduction. Cyclization of chromene 11 to chromanone 18 was achieved by employing either acetaldehyde diethyl acetal or paraldehyde in the presence of trifluoroacetic acid and pyridine or PPTS. Luche reduction of chromanone 18 at lower temperature preferably yielded (+/-)-1. Reduction of chromone 12, synthesized by Kostanecki-Robinson reaction from chromene 11, failed to afford (+/-)-1. The synthetic (+/-)-1 has been chromatographically resolved into its optically active forms, (+)- and (-)-1. The anti-HIV activities for synthetic (+/-)-1, as well as resultant (+)- and (-)-1, have been determined. Only (+)-1 accounted for anti-HIV activity, which was similar to the data reported for the natural product, and (-)-1 was inactive.