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Two naturally occurring xanthones, ananixanthone (1) and β-mangostin (2), were isolated using column chromatographic method from the n-hexane and methanol extracts of Calophyllum teysmannii, respectively. The major constituent, ananixanthone (1), was subjected to structural modifications via acetylation, methylation and benzylation yielding four new xanthone derivatives, ananixanthone monoacetate (3), ananixanthone diacetate (4), 5-methoxyananixanthone (5) and 5-O-benzylananixanthone (6). Compound 1 together with its four new derivatives were subjected to MTT assay against three cancer cell lines; SNU-1, K562 and LS174T. The results indicated that the parent compound has greater cytotoxicity capabilities against SNU-1 and K562 cell lines with IC 50 values of 8.97 ± 0.11 and 2.96 ± 0.06 μg/mL, respectively. Compound 5 on the other hand exhibited better cytotoxicity against LS174T cell line with an IC 50 value of 5.76 ± 1.07 μg/mL.

Jacareubin is a xanthone isolated from the heartwood of Calophyllum brasiliense with antibacterial and gastroprotective properties and the intention for clinical use as an anti-cancer treatment (due to the similar chemical structure to other anti-neoplastic drugs) requires an investigation of whether this compound can generate adverse effects on non-transformed cells. Jacareubin (0.5-1000μM in DMSO) was more cytotoxic on phytohemagglutinin (PHA)-stimulated normal human peripheral blood mononuclear cells (PBMCs; IC 50 at 72h by MTT: 85.9μM) than on G 0 phase-PBMCs (IC 50 315.6μM) using trypan blue exclusion and formazan metabolism assays. Jacareubin had lower toxicity on PBMCs than Taxol (1μM). Jacareubin presented cytostatic activity because it inhibited PHA-stimulated PBMCs proliferation (from 2.5μM; CFSE dilution and replication index). Jacareubin induced PBMCs arrest in G 0 /G 1 phase of the cell cycle (from 5μM) as evaluated by DNA content. Moreover, Jacareubin generated genotoxicity by breaking DNA strands selectively in PHA-stimulated PBMCs (from 5μM) rather than on resting PBMCs using the single-cell gel electrophoresis assay and increasing the frequency of micronucleated (MN) PBMCs in vitro (from 5μM) and frequency of hypodiploid cells (from 10μM). When 100mg/kg Jacareubin was injected i.p. into mice (a fifth of the LD 50 ; 0.548g/kg. Approximately to 300μM in vitro), we observe no increase in the MN level in bone marrow cells. Jacareubin can be consider for further anti-tumoural activity due to its preferential genotoxic, cytotoxic and cytostatic actions on proliferating cells rather than on resting cells and the lack of in vivo genotoxicity., (Copyright © 2017 Elsevier Inc. All rights reserved.)

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.