Abstract! Clusianone (1) was isolated from Garcinia parvifolia and structurally modified using semisynthetic methods to obtain compounds 2-4. The structural derivatization included methylation (2), hydrogenation (3), and the addition of a methylamine group [(4) to (1)]. Cytotoxic effects of these compounds were assessed on MRC5 fibroblasts, A549 lung adenocarcinoma, HK1 squamous nasopharynx carcinoma, and NP69 normal nasopharyngeal epithelial cell lines. Clusianone (1) showed cytotoxic activity against A549 cells with an IC 50 value of 3.06 µM. Compound (4) showed cytotoxic activities against both A549 and HK1 cells with IC 50 values of 4.09 µM and 3.43 µM, respectively. The results of the cytotoxicity assay provide a correlation on the structure activity relationship of clusianone against HK1 and A549 cells, which can be further investigated as a potential antiproliferative compound.
Key wordsGarcinia parvifolia · Clusiaceae · clusianone analogues · semisynthetic methods · cytotoxic activity Supporting information available online at http://www.thieme-connect.de/products Natural clusianone belongs to compounds classified as type B polyprenylated polycyclic acylphloroglucines (PPAPs) that are found in plants of the Clusiaceae (Guttiferae) family [1,2]. To date, natural clusianone has been found in various parts of the targeted Clusiaceae plants, including fruits [3], flowers [4,5], leaves [6], roots [7], stems, and bark [8,9]. Naturally occurring 1 has shown potential anticancer activity [9] and further investigations of clusianone-treated HepG2 hepatocarcinoma cells revealed cytotoxic effects by mitochondrial impairment [10]. In the last decade, clusianone (1) has gained substantial interest from the synthetic community leading to a breakthrough in total synthesis of this compound [11][12][13][14]. Synthetic clusianone was tested for cytotoxicity in several cancer cell lines: HeLa (cervix carcinoma), MIAPaCa-2 (pancreatic carcinoma), and MCF7 (breast adenocarcinoma). The IC 50 values ranged from 3.0 µM to 8.3 µM for the three cancer cell lines [15,16]. In our studies, we extracted clusianone using a previously published method [6]. The isolation and abundance of clusianone from the leaves of Garcinia parvifolia (Miq.) Miq. has made chemical modifications readily attainable as compared to clusianone isolated from the dried stem bark of Garcinia assigu [9] and the roots of Hypericum hypericoides (L.) Crantz [7]. X-ray crystallography was identical in previous reports, and a detailed comparison of our and previously reported NMR data [8] was established.This method provided a quantity of over 0.5 g (0.05% yield) of 1 to be used as starting material for synthesizing sufficient quantities of clusianone derivatives (2-4). All products were purified via column chromatography. The products 1-4 exhibited the predicted fragmentation and mass m/z when analyzed by ESI-MS (l " Fig. 1). In addition, further characterizations of 1-4 were conducted utilizing 1 HNMR and 13 CNMR spectroscopy to characterize both tautomers (a/b)...