Jinxin Wang

Studies on chemical structure modification and biology of a natural product, Gambogic acid (I): Synthesis and biological evaluation of oxidized analogues of gambogic acid

Gambogic acid (GA), a natural product, exhibits high potency in inhibiting cancer cell growth through the effective induction of apoptosis. In order to investigate the structure-activity relationships of GA derivatives, 11 oxidized derivatives of GA were synthesized. Some of them showed strong inhibitory effects on HT-29, Bel-7402, BGC-823, A549, and SKOV 3 cell lines. Moreover, in this paper the cellular growth inhibitor 39-hydroxy-6-methoxy-gambogic acid methyl ester (10) was identified as a HepG2 cell apoptosis inhibitor through Annexin-V/PI double staining assay and the expression of the related apoptotic proteins (Bax and Bcl-2). Compound 10 may serve as a potential lead compound for the development of new anticancer drugs. Further SAR studies of GA derivatives indicated that modification of carbon-carbon double bond at C-32/33 or C-37/38 and of the methyl groups at C-39/C-35 can improve antitumor activity.

Studies on chemical modification and biology of a natural product, gambogic acid (II): Synthesis and bioevaluation of gambogellic acid and its derivatives from gambogic acid as antitumor agents

Gambogic acid (GA) has been reported to be a potent apoptosis inducer. The fact that it is amenable to chemical modification makes GA an attractive molecule for the development of anticancer agents. We firstly reported the synthesis of gambogellic acid, which was generated under acid catalysis from readily available GA by a base-catalyzed diene intramolecular annelation. Sequentially, thirteen new compounds were synthesized and their inhibitory activity on HT-29, Bel-7402, BGC-823, and A549 cell lines were evaluated in vitro by MTT assay, and (38, 40)-epoxy-33-chlorogambogellic acid (4) was identified as a BGC-823 cell apoptosis inducer through MTT cell assay, observations of morphological changes, and Annexin-V/PI double-staining assay. Compound 4 showed significant effects in inducing apoptosis and might serve as a potential lead compound for discovery of new anticancer drugs. Further structure-activity relationships (SARs) of gambogic acid derivatives were discussed.

Pharmacology of mangostins and their derivatives: A comprehensive review

Mangosteen (Garcinia mangostana Linn.) is a well-known tropical tree indigenous to Southeast Asia. Its fruits pericarp abounds with a class of isoprenylated xanthones which are referred as mangostins. Numerous in vitro and in vivo studies have shown that mangostins and their derivatives possess diverse pharmacological activities, such as antibacterial, antifungal, antimalarial, anticarcinogenic, antiatherogenic activities as well as neuroprotective properties in Alzheimers disease (AD). This review article provides a comprehensive review of the pharmacological activities of mangostins and their derivatives to reveal their promising utilities in the treatment of certain important diseases, mainly focusing on the discussions of the underlying molecular targets/pathways, modes of action, and relevant structure-activity relationships (SARs). Meanwhile, the pharmacokinetics (PK) profile and recent toxicological studies of mangostins are also described for further druggability exploration in the future.

Studies on Chemical Structure Modification and StructureActivity Relationship of Derivatives of Gambogic Acid at C(39)

The natural product gambogic acid exhibits high potency in inhibiting cancer cell lines. Rational medicinal modifications on gambogic acid will improve its physicochemical properties and drug‐like characters. To investigate the structureactivity relationship of gambogic acid and also to find rational modification position on its chemical skeleton, we designed, synthesized, and characterized 16 derivatives of gambogic acid that were modified at C(39). The structureactivity relationships (SARs) were discussed. The anti‐proliferation data were accquired through MTT (=3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl‐2H‐tetrazolium bromide) assays of A549, BGC823, U251, HepG2, and MDA‐MB‐231 cancer cell lines. Most of the synthesized compounds showed strong inhibitory effects. The SAR study revealed that derivatives with aliphatic amino moieties at C(39) were more potent than those with other substituents. The C(39) position can undergo different kinds of chemical modifications without leading to loss of activity. Compounds 4 and 6 can serve as potential lead compounds for further development of new anticancer drugs.

Anticarcinogenic Effects of α-Mangostin: A Review.

Cancer chemoprevention is a promising strategy taken to block, reverse, or retard carcinogenesis. α-Mangostin, a natural xanthone isolated from the pericarps of mangosteen, represents one of the most studied chemopreventive agents. This compound has been reported to interfere with all the major stages of carcinogenesis: initiation, promotion, and progression. A number of mechanisms have been proposed for its anticarcinogenic activities. This review summarizes the current knowledge on the mechanisms that contribute to the observed activity of α-mangostin related to (i) modulation of carcinogenic biotransformation and mitigation of oxidative damage, (ii) induction of growth arrest and apoptosis, (iii) suppression of angiogenesis and metastasis, and (iv) combination with clinical chemotherapy drugs enhancing their efficacy and decreasing the toxic side effects. In addition, pharmacokinetic and toxicological studies of α-mangostin have also been highlighted in this review. Despite an overwhelming amount of knowledge in preclinical studies, there was almost no translation of α-mangostin into the clinic. It is hoped that continuous extensive and profound research will lead to the application of α-mangostin from experimental studies to evidence-based, clinically applicable pharmacotherapy.

Studies on Chemical-Structure Modification and StructureActivity Relationship of Gambogic Acid Derivatives at Carbon(34)

Gambogic acid (GA), a natural product, was identified as a promising antitumor agent. To further explore the structureactivity relationship of GA and discover novel GA derivatives as antitumor agents, 19 novel GA derivatives modified at C(34) were synthesized and evaluated against A549, BGC‐823, U251, HepG2, and MB‐231 cancer cell lines by cellular assays. Among them, 15 compounds were found to be more potent than GA against some cancer cell lines. Notably, compound 3 possessed potent inhibitory activities against five cell lines with IC50 values ranging between 0.24 and 1.09 μM. Compounds 9 and 18 were seven to eightfold more active than GA against A549 cell line. Chemical modification at C(34) of GA by introducing of hydrophilic aliphatic amines resulted in increased activity and improved drug‐like properties. These findings will enhance our understanding of the SAR of GA and can lead to the discovery of novel GA derivatives as potential antitumor agents.

Synthesis and anti-tumor activity of NO-donating derivatives of gambogic acid

Abstract Aim To find a potent apoptosis inducer from gambogic acid and its derivatives. Methods Eight new NO-donating derivatives of gambogic acid were synthesized as potential anti-tumor lead compounds and their inhibitory activity on the HT-29, Bel-7402, BGC-823, and A549 cell lines were evaluated in vitro by the MTT assay. Results Among these compounds, 4 with a hydroxyl group at C35 of the gambogic acid moiety was identified as a SKOV3 cell apoptosis inducer through the MTT cell assay, observations of morphological changes, and Annexin-V/PI double staining assay. Conclusion Compound 4 showed significant effects in inducing apoptosis and might serve as a potential lead compound for the discovery of new anticancer drugs.

Synthesis and biological evaluation of tanshinone IIA derivatives as novel endothelial protective agents

AIM Oxidative stress-induced endothelial injury is a main risk factor in the pathogenesis of cardiovascular diseases. Tanshinone IIA (Tan IIA) exerts protective functions on endothelial cells in response to oxidative stress. To exploit new bioactive compounds from this natural product, 12 derivatives were first synthesized and evaluated for endothelial protective activities. MATERIALS & METHODS Title compounds were prepared according to high-yielded synthetic routes, and their protective effects on human endothelial EA.hy926 cells were evaluated. To explore the mechanism, their inhibition on apoptosis of endothelial cells and Nrf2 activating activities were investigated. Furthermore, computational ADME prediction and water solubility assay were carried out for active compounds. RESULTS Most of them exhibited potent endothelial protective effects on EA.hy926 cells injured by H2O2. In particular, compounds I-2 and II showed increased activity and water solubility compared with Tan IIA. Moreover, they reduced H2O2-induced apoptosis of EA.hy926 cells. A further exploration on the two compounds suggested that their actions were mediated by upregulation of antioxidant genes through activating Nrf2 pathway. CONCLUSION These Tan IIA derivatives clearly showed related activities for the development of a new type of endothelial protective agents. [Formula: see text].

Synthesis and evaluation of xanthone derivatives as acid sphingomyelinase inhibitors: potential treatment for UV-induced skin damage

AIM ASM, which hydrolyzes sphingomyelin into ceramide, is recognized as a therapeutic target for UV-induced skin damage. Direct inhibitors for this enzyme are rare. Here we synthesized several series of 1,3,6,7-tetrahydroxy-xanthone derivatives as novel ASM inhibitors. RESULTS Several compounds were more potent than the lead compound, among which 5b was found competitively inhibiting the enzyme and dose-dependently reducing ceramide generation. Furthermore, 5b and 5c showed excellent protective effect to skin keratinocytes against UV. Quantitative structure-activity relationship investigation revealed detail relationships between molecular structure and biological activity. Insight into the binding mode was precisely illuminated by molecule docking. CONCLUSION This work would provide fresh ideas and strong supports for further development of ASM inhibitors and drug candidates for skin damage.

Structure-activity Relationship of Gambogic Acid

AIM: To investigate the basic structure-activity relationship of gambogic acid. METHODS: Through simplifying the complex skeleton of the natural gambogic acid, two series of derivatives of chromone and xanthone were synthesized and examined for their antitumor activities against several cancer cells in vitro by MTT method. RESULTS: The cytotoxic activities of all these small compounds with planar ring were much less potent than those of the natural gambogic acid, and the introduction of prenyl to these small molecular compounds could increase their antitumor activities. CONCLUSION: The structure-activity relationship of synthesized compounds indicated that the prenyl groups and the bridgecore in gambogic acid were very important for keeping its antitumor activities.