Seco-cyclic phorbol derivatives and their anti-HIV-1 activities.

Phorbol esters are recognized for their dual role as anti-HIV-1 agents and as activators of protein kinase C (PKC). The efficacy of phorbol esters in binding with PKC is attributed to the presence of oxygen groups at positions C20, C3/C4, and C9 of phorbol. Concurrently, the lipids located at positions C12/C13 are essential for both the anti-HIV-1 activity and the formation of the PKC-ligand complex. The influence of the cyclopropane ring at positions C13 and C14 in phorbol derivatives on their anti-HIV-1 activity requires further exploration. This research entailed the hydrolysis of phorbol, producing seco-cyclic phorbol derivatives. The anti-HIV-1 efficacy of these derivatives was assessed, and the affinity constant (Kd) for PKC-δ protein of selected seco-cyclic phorbol derivatives was determined through isothermal titration calorimetry. The findings suggest that the chemical modification of cyclopropanols could affect both the anti-HIV-1 activity and the PKC binding affinity. Remarkably, compound S11, with an EC50 of 0.27 µmol·L-1 and a CC50 of 153.92 µmol·L-1, demonstrated a potent inhibitory effect on the intermediate products of HIV-1 reverse transcription (ssDNA and 2LTR), likely acting at the viral entry stage, yet showed no affinity for the PKC-δ protein. These results position compound S11 as a potential candidate for further preclinical investigation and for studies aimed at elucidating the pharmacological mechanism underlying its anti-HIV-1 activity.

Synthesis and anti-HIV activities of phorbol derivatives.

In this study, 37 derivatives of phorbol esters were synthesized and their anti-HIV-1 activities evaluated, building upon our previous synthesis of 51 phorbol derivatives. 12-Para-electron-acceptor-trans-cinnamoyl-13-decanoyl phorbol derivatives stood out, demonstrating remarkable anti-HIV-1 activities and inhibitory effects on syncytia formation. These derivatives exhibited a higher safety index compared with the positive control drug. Among them, 12-(trans-4-fluorocinnamoyl)-13-decanoyl phorbol, designated as compound 3c, exhibited the most potent anti-HIV-1 activity (EC50 2.9 nmol·L-1, CC50/EC50 11 117.24) and significantly inhibited the formation of syncytium (EC50 7.0 nmol·L-1, CC50/EC50 4891.43). Moreover, compound 3c is hypothesized to act both as an HIV-1 entry inhibitor and as an HIV-1 reverse transcriptase inhibitor. Isothermal titration calorimetry and molecular docking studies indicated that compound 3c may also function as a natural activator of protein kinase C (PKC). Therefore, compound 3c emerges as a potential candidate for developing new anti-HIV drugs.

Tigliane-Type Diterpene Esters from the Fruits of Shirakiopsis indica and Their Anti-HIV Activity.

Four new diterpene esters, shirakindicans A-D (1-4), along with eight related known diterpene esters (5-12), were isolated from the fruits of the Bangladeshi medicinal plant Shirakiopsis indica. The structures of 1-4 were elucidated by spectroscopic data analysis and electronic circular dichroism (ECD) calculations. Shirakindican A (1) was assigned as a tigliane-type diterpene ester possessing an unusual 6ß-hydroxy-1,7-dien-3-one structure, while shirakindican B (2) exhibits a tiglia-1,5-dien-3,7-dione structure. The anti-HIV activities of the isolated diterpene esters were evaluated and showed significant activities for sapintoxins A (5) and D (11), with EC50 values of 0.0074 and 0.044 µM, respectively, and TI values of 1 100 and 5 290. Sapatoxin A (12) also exhibited anti-HIV activity with an EC50 value of 0.13 µM and a TI value of 161.

Effects of 3'-isovaleryl-4'-senecioylkhellactone from Peucedanum japonicum Thunberg on PMA-Stimulated Inflammatory Response in A549 Human Lung Epithelial Cells.

Peucedanum japonicum Thunberg (PJT) has been used in traditional medicine to treat colds, coughs, fevers, and other inflammatory diseases. The goal of this study was to investigate whether 3'-isovaleryl-4'-senecioylkhellactone (IVSK) from PJT has anti-inflammatory effects on lung epithelial cells. The anti-inflammatory effects of IVSK were evaluated using phorbol 12-myristate 13-acetate (PMA)-stimulated A549 cells and regular human lung epithelial cells as a reference. IVSK reduced the secretion of the inflammatory mediators interleukin (IL)-8 and monocyte chemoattractant protein-1 (MCP-1), and the mRNA expression of IL-6, IL-8, MCP-1, and IL-1ß. Additionally, it inhibited the phosphorylation of IκB kinase (IKK), p65, Iκ-Bα, and mitogen-activated protein kinases (MAPKs) p38, JNK, and ERK in A549 cells stimulated with PMA. Moreover, the binding affinity of activator protein-1 (AP-1) and nuclear factor-κB (NF-κB) was significantly reduced in the luciferase assay, while nuclear translocation was markedly inhibited by IVSK in the immunocytochemistry. These findings indicate that IVSK can protect against inflammation through the AP-1 and NF-κB pathway and could possibly be used as a lead compound for the treatment of inflammatory lung diseases.

12-Deoxyphorbol 13-acetate inhibits RANKL-induced osteoclastogenesis via the attenuation of MAPK signaling and NFATc1 activation.

Osteoporosis, characterized by bone loss and microstructure damage, occurs when osteoclast activity outstrips osteoblast activity. Natural compounds with inhibitory effect on osteoclast differentiation and function have been evidenced to protect from osteoporosis. After multiple compounds screening, 12-deoxyphorbol 13-acetate (DPA) was found to decline RANKL-induced osteoclastogenesis dose-dependently by attenuating activities of NFATc1 and c-Fos, followed by decreasing the level of osteoclast function-associated genes and proteins including Acp5, V-ATPase-d2 and CTSK. Mechanistically, we found that DPA suppressing RANKL-induced downstream signaling pathways, including MAPK signaling pathway and calcium oscillations. Furthermore, the in vivo efficacy of DPA was further confirmed in an OVX-induced osteoporosis mice model. Collectively, the results in our presentation reveal that DPA might be a promising compound to manage osteoporosis.

DP from Euphorbia fischeriana S. mediated apoptosis in leukemia cells via the PI3k/Akt signaling pathways.

ETHNOPHARMACOLOGICAL RELEVANCE: Euphorbia fischeriana S. (E. fischeriana) is a classic Chinese herb with toxicity that is mainly used for cancer treatment and in insect repellent, anti-inflammatory and anti-edema applications (Liu et al., 2001). 12-Deoxyphorbol13-palmitate (DP), a tetracyclic diterpene monomer compound, was extracted from the roots of E. fischeriana by our research groups. AIM: Previous studies found that DP could inhibit the proliferation of leukemia cells in vitro. However, the underlying mechanism of DP in leukemia is unknown. Hence, DP's pharmacological effect on leukemia cells was investigated in this study. MATERIALS AND METHODS: DP was obtained from the Natural Medicine Chemistry Laboratory of Qiqihaer Medical University. In vitro, K562 cells and HL60 cells were incubated with DP or DP combined with LY294002 at different concentrations. Cell proliferation and apoptosis were detected by the relevant experimental methods. In vivo, nude mouse xenograft models were established by injecting K562 cells. DP was intraperitoneally administered to observe the influence on the growth of transplanted tumors. Gene detection and immunoblot analysis were performed to validate the mechanisms. RESULTS: The cell counting kit-8 (CCK-8) assay proved that DP inhibited the growth of K562 and HL60 cells in a time- or dose-dependent manner. At 12 h, DP could induce apoptosis by Annexin V-FITC/propidium iodide (PI) dual labeling, loss of mitochondrial membrane potential (MMP), intracellular reactive oxygen species (ROS), acridine orange/ethidium bromide (AO/EB) staining and transmission electron microscopy (TEM) observation in K562 or HL60 cells. Furthermore, in an assay of gene and protein expression, we found that DP could downregulate the gene and protein expression levels of Bcl-2, upregulate the gene and protein expression levels of Bax and Bim, and downregulate the protein expression levels of PI3k, p-Akt, and p-FoxO3a. Moreover, the effects of DP on proliferation and apoptosis in K562 cells were enhanced by LY294002. Then, we tested the antitumor effects of DP in vivo. Nude mouse xenograft models were established by subcutaneously injecting K562 cells. We found that tumor volume was significantly decreased in DP-treated xenograft nude mice. Morphologic changes, apoptosis degree, and related gene and protein expression levels in transplanted tumor tissue of DP-treated nude mice were assessed by different experimental methods. CONCLUSIONS: The in vivo and in vitro experimental results indicated that DP might inhibit the proliferation and induce the apoptosis of leukemia cells, which might be a result of suppressing the PI3k/Akt signaling pathways.

Lophira alata Suppresses Phorbol Ester-Mediated Increase in Cell Growth via Inhibition of Protein Kinase C-α/Akt in Glioblastoma Cells.

BACKGROUND: Medicinal plants serve as sources of compounds used to treat other types of cancers. The root of the plant Lophira alata (Ochnaceae) has been used as a component of traditional herbal decoctions administered to cancer patients in southwestern Nigeria. However, the mechanism of the cytotoxic effects of Lophira alata alone or in the presence of phorbol ester has not been investigated in brain tumor cells. OBJECTIVE: This study aimed to examine the cytotoxic potential of the methanolic fraction of Lophira alata root on malignant glioma invasive cellular growth and survival. METHODS: The methanolic fraction of Lophira alata (LAM) was subjected to high-performance liquid chromatography to determine the fingerprints of the active molecules. The antiproliferative effects of Lophira alata were assessed using the MTT and LDH assays. Protein immunoblots were carried out to test the effects of Lophira alata, alone or in the presence of phorbol ester, on survival signaling pathways, such as Akt, mTOR, and apoptotic markers such as PARP and caspases. RESULTS: The methanolic fraction of Lophira alata (LAM) induced a concentration-dependent and time-dependent decrease in glioma cell proliferation. In addition, LAM attenuated phorbol ester-mediated signaling of downstream targets such as Akt/mTOR. Gene silencing using siRNA targeting PKC-alpha attenuated LAM-mediated downregulation of Akt. In addition, LAM induced both PARP and caspase cleavages. The HPLC fingerprint of the fraction indicates the presence of flavonoids. CONCLUSION: LAM decreases cell proliferation and induces apoptosis in glioma cell lines and thus could serve as a therapeutic molecule in the management of gliomas.

Traditional detoxification of Jatropha curcas L. seeds.

ETHNOPHARMACOLOGICAL RELEVANCE: Jatropha curcas L. is a plant with high cultural significance for quilombola communities of Oriximiná (Pará State, Brazil). Although the plant is highly toxic, its seeds are used in these communities to treat tuberculosis and related diseases and symptoms. AIM OF THE STUDY: This study was designed to provide a scientific rationale for the traditional detoxification method and use of J. curcas seeds in quilombola communities of Oriximiná. MATERIALS AND METHODS: J. curcas seeds were manually separated into testa, tegmen, endosperm, and embryo, and then methanolic extracts of each sample were prepared. The traditional preparation of J. curcas seeds consists of a water extract of endosperms that is known as "milk of pinhão-branco". The content of phorbol esters (PEs) in the extracts was analyzed by High-Performance Liquid Chromatography with Diode-Array Detection (HPLC-DAD). The cytotoxic activity was evaluated in human monocytic cell line THP-1 by Resazurin Reduction Assay, and antimycobacterial activity was assessed by determining Minimal Inhibitory Concentration (MIC) values against H37Rv and BCG strains using the Resazurin Microtiter Assay (REMA). RESULTS: The content analysis revealed that the distribution of PEs within the seeds is not homogeneous. High contents were found in tegmens (4.22 ±â€¯0.25-15.52 ±â€¯0.06 mg/g) and endosperms (1.61 ±â€¯0.07-5.00 ±â€¯0.42 mg/g), while concentrations found in testas and embryos were all below 0.5 mg/g. The traditional preparation derived from the endosperm of J. curcas contained significantly less PEs than the endosperms (0.01 ±â€¯0.005 mg/g). Against THP-1 cells, all the parts of the seed showed cytotoxic activity, while the traditional preparation was considered non-cytotoxic. Nevertheless, only the tegmen and endosperm of J. curcas were considered active against M. tuberculosis and M. bovis (MIC = 200 µg/mL). CONCLUSION: The results of this study indicated that the traditional processing performed by the quilombola people from Oriximiná is effective in reducing the toxicity of J. curcas seeds. Although inactive against mycobacteria, the extensive use of the traditional preparation and its low toxicity encourage further studies to investigate other biological activities.

Reactivation of latent HIV-1 in vitro using an ethanolic extract from Euphorbia umbellata (Euphorbiaceae) latex.

Euphorbia umbellata (E. umbellata) belongs to Euphorbiaceae family, popularly known as Janauba, and its latex contains a combination of phorbol esters with biological activities described to different cellular protein kinase C (PKC) isoforms. Here, we identified deoxi-phorbol esters present in E. umbellata latex alcoholic extract that are able to increase HIV transcription and reactivate virus from latency models. This activity is probably mediated by NF-kB activation followed by nuclear translocation and binding to the HIV LTR promoter. In addition, E. umbellata latex extract induced the production of pro inflammatory cytokines in vitro in human PBMC cultures. This latex extract also activates latent virus in human PBMCs isolated from HIV positive patients as well as latent SIV in non-human primate primary CD4+ T lymphocytes. Together, these results indicate that the phorbol esters present in E. umbellata latex are promising candidate compounds for future clinical trials for shock and kill therapies to promote HIV cure and eradication.

Identification of small-molecule ion channel modulators in C. elegans channelopathy models.

Ion channels are important therapeutic targets, but the discovery of ion channel drugs remains challenging due to a lack of assays that allow high-throughput screening in the physiological context. Here we report C. elegans phenotype-based methods for screening ion channel drugs. Expression of modified human ether-a-go-go-related gene (hERG) potassium channels in C. elegans results in egg-laying and locomotive defects, which offer indicators for screening small-molecule channel modulators. Screening in worms expressing hERGA561V, which carries a trafficking-defective mutation A561V known to associate with long-QT syndrome, identifies two functional correctors Prostratin and ingenol-3,20-dibenzoate. These compounds activate PKCε signaling and consequently phosphorylate S606 at the pore region of the channel to promote hERGA561V trafficking to the plasma membrane. Importantly, the compounds correct electrophysiological abnormalities in hiPSC-derived cardiomyocytes bearing a heterozygous CRISPR/Cas9-edited hERGA561V. Thus, we have developed an in vivo high-throughput method for screening compounds that have therapeutic potential in treating channelopathies.

Javamide-II Found in Coffee Is Better than Caffeine at Suppressing TNF-α Production in PMA/PHA-Treated Lymphocytic Jurkat Cells.

Recent studies have suggested positive benefits of coffee consumption on inflammation-related diseases, such as liver diseases and diabetes, where activated lymphocytes and TNF-α are critically implicated. Interestingly, some reports suggested that javamide-II found in coffee may have anti-inflammatory activity greater than that of caffeine, but there is limited information about its effect on TNF-α production by activated lymphocytes. Therefore, the inhibitory effect of javamide-II on TNF-α was investigated in PMA/PHA-treated lymphocytic Jurkat cells. At 5 µM, javamide-II, not caffeine, inhibited TNF-α production in the cells (45 ± 4%, P < 0.001). To elucidate the underlying mechanism, the phosphorylation of MAP kinases (ERK, p38, and JNK) was investigated in the Jurkat cells. Javamide-II had little effect on JNK or p38 phosphorylation, but javamide-II (<20 µM) decreased ERK phosphorylation, consequently reducing TNF-α mRNA expression in the cells ( P < 0.001). The involvement of ERK phosphorylation was also confirmed by an ERK1/2 inhibitor (SCH772984). Furthermore, javamide-II was also found to inhibit IL-2 production, which is up-regulated by ERK phosphorylation in cells ( P < 0.001). These data suggested that javamide-II may be a potent compound to suppress TNF-α production more efficiently than caffeine by inhibiting ERK phosphorylation in Jurkat cells.

The Croton megalobotrys Müll Arg. traditional medicine in HIV/AIDS management: Documentation of patient use, in vitro activation of latent HIV-1 provirus, and isolation of active phorbol esters.

ETHNOPHARMACOLOGICAL RELEVANCE: Current HIV therapies do not act on latent cellular HIV reservoirs; hence they are not curative. While experimental latency reversal agents (LRAs) can promote HIV expression in these cells, thereby exposing them to immune recognition, existing LRAs exhibit limited clinical efficacy and high toxicity. We previously described a traditional 3-step medicinal plant regimen used for HIV/AIDS management in Northern Botswana that inhibits HIV replication in vitro. Here we describe use of one component of the regimen that additionally contains novel phorbol esters possessing HIV latency-reversal properties. AIM OF THE STUDY: We sought to document experiences of traditional medicine users, assess the ability of traditional medicine components to reverse HIV latency in vitro, and identify pure compounds that conferred these activities. MATERIALS AND METHODS: Experiences of two HIV-positive traditional medicine users (patients) were documented using qualitative interview techniques. Latency reversal activity was assessed using a cell-based model (J-Lat, clone 9.2). Crude plant extracts were fractionated by open column chromatography and reverse-phase HPLC. Compound structures were elucidated using NMR spectroscopy and mass spectrometry. RESULTS: Patients using the 3-step regimen reported improved health over several years despite no reported use of standard HIV therapies. Crude extracts from Croton megalobotrys Müll Arg. ("Mukungulu"), the third component of the 3-step regimen, induced HIV expression in J-lat cells to levels comparable to the known LRA prostratin. Co-incubation with known LRAs and pharmacological inhibitors indicated that the active agent(s) in C. megalobotrys were likely to be protein kinase C (PKC) activator(s). Consistent with these results, two novel phorbol esters (Namushen 1 and 2) were isolated as abundant components of C. megalobotrys and were sufficient to confer HIV latency reversal in vitro. CONCLUSION: We have identified novel LRAs of the phorbol ester class from a medicinal plant used in HIV/AIDS management. These data, combined with self-reported health effects and previously-described in vitro anti-HIV activities of this traditional 3-step regimen, support the utility of longitudinal observational studies of patients undergoing this regimen to quantify its effects on plasma viral loads and HIV reservoir size in vivo.

Anti-HIV Activities and Mechanism of 12-O-Tricosanoylphorbol-20-acetate, a Novel Phorbol Ester from Ostodes katharinae.

APOBEC3G is a member of the human cytidine deaminase family that restricts Vif-deficient viruses by being packaged with progeny virions and inducing the G to A mutation during the synthesis of HIV-1 viral DNA when the progeny virus infects new cells. HIV-1 Vif protein resists the activity of A3G by mediating A3G degradation. Phorbol esters are plant-derived organic compounds belonging to the tigliane family of diterpenes and could activate the PKC pathway. In this study, we identified an inhibitor 12-O-tricosanoylphorbol-20-acetate (hop-8), a novel ester of phorbol which was isolated from Ostodes katharinae of the family Euphorbiaceae, that inhibited the replication of wild-type HIV-1 and HIV-2 strains and drug-resistant strains broadly both in C8166 cells and PBMCs with low cytotoxicity and the EC50 values ranged from 0.106 µM to 7.987 µM. One of the main mechanisms of hop-8 is to stimulate A3G expressing in HIV-1 producing cells and upregulate the A3G level in progeny virions, which results in reducing the infectivity of the progeny virus. This novel mechanism of hop-8 inhibition of HIV replication might represents a promising approach for developing new therapeutics for HIV infection.

Isolation and Structure Characterization of Cytotoxic Phorbol Esters from the Seeds of Croton tiglium.

Nine new and eleven known phorbol esters were isolated from an acetone extract of the seeds of Croton tiglium. Their structures were determined by extensive analysis of spectroscopic data. Eleven of these compounds were evaluated for their inhibition activity on human tumor cell lines HL-60 and lung carcinoma A549. 12-O-Tiglylphorbol-13-acetate (11), 12-O-(2-methyl)-butyrylphorbol-13-aetate (12), and 12-O-tiglylphorbol-13-isobutyrate (13) exhibited strong inhibition activity against both HL-60 and A549 cell lines with IC50 values ≤ 0.02 and ≤ 0.1 µg/mL, respectively. Compound 18 showed strong inhibition activity against the HL-60 cell line with an IC50 value of 0.02 µg/mL.

Molecular dynamics simulations reveal ligand-controlled positioning of a peripheral protein complex in membranes.

Bryostatin is in clinical trials for Alzheimer's disease, cancer, and HIV/AIDS eradication. It binds to protein kinase C competitively with diacylglycerol, the endogenous protein kinase C regulator, and plant-derived phorbol esters, but each ligand induces different activities. Determination of the structural origin for these differing activities by X-ray analysis has not succeeded due to difficulties in co-crystallizing protein kinase C with relevant ligands. More importantly, static, crystal-lattice bound complexes do not address the influence of the membrane on the structure and dynamics of membrane-associated proteins. To address this general problem, we performed long-timescale (400-500 µs aggregate) all-atom molecular dynamics simulations of protein kinase C-ligand-membrane complexes and observed that different protein kinase C activators differentially position the complex in the membrane due in part to their differing interactions with waters at the membrane inner leaf. These new findings enable new strategies for the design of simpler, more effective protein kinase C analogs and could also prove relevant to other peripheral protein complexes.Natural supplies of bryostatin, a compound in clinical trials for Alzheimer's disease, cancer, and HIV, are scarce. Here, the authors perform molecular dynamics simulations to understand how bryostatin interacts with membrane-bound protein kinase C, offering insights for the design of bryostatin analogs.

Gallic Acid Content in Taiwanese Teas at Different Degrees of Fermentation and Its Antioxidant Activity by Inhibiting PKCδ Activation: In Vitro and in Silico Studies.

Teas can be classified according to their degree of fermentation, which has been reported to affect both the bioactive components in the teas and their antioxidative activity. In this study, four kinds of commercial Taiwanese tea at different degrees of fermentation, which include green (non-fermented), oolong (semi-fermented), black (fully fermented), and Pu-erh (post-fermented) tea, were profiled for catechin levels by using high performance liquid chromatography (HPLC). The result indicated that the gallic acid content in tea was directly proportional to the degree of fermentation in which the lowest and highest gallic acid content were 1.67 and 21.98 mg/g from green and Pu-erh tea, respectively. The antioxidative mechanism of the gallic acid was further determined by in vitro and in silico analyses. In vitro assays included the use of phorbol ester-induced macrophage RAW264.7 cell model for determining the inhibition of reactive oxygen species (ROS) production, and PKCδ and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunit (p47) activations. The results showed that only at a concentration of 5.00 µM could gallic acid significantly (p < 0.05) reduce ROS levels in phorbol ester-activated macrophages. Moreover, protein immunoblotting expressed similar results in which activations of PKCδ and p47 were only significantly (p < 0.05) attenuated by 5.00 µM treatment. Lastly, in silico experiments further revealed that gallic acid could block PKCδ activation by occupying the phorbol ester binding sites of the protein.

Hyperbaric Oxygen Reduces Production of Reactive Oxygen Species in Neutrophils from Polytraumatized Patients Yielding in the Inhibition of p38 MAP Kinase and Downstream Pathways.

Trauma represents the leading cause of death among young people in western countries. Among the beneficial role of neutrophils in host defence, excessive priming and activation of neutrophils after major trauma lead to an overwhelming inflammatory response and secondary host tissue injury due to the release of toxic metabolites and enzymes. Hyperbaric oxygen (HBO) therapy has been proposed to possess antiinflammatory effects and might represent an appropriate therapeutic option to lower inflammation in a broad range of patients. Here, we studied the effects of HBO on the activity of neutrophils isolated from severely injured patients (days 1-2 after trauma), in fact on the production of reactive oxygen species (ROS) and release of neutrophil extracellular traps (NETs). We found exposure to HBO therapy to significantly diminish phorbol-12-myristate-13-acetate (PMA)-induced ROS production in neutrophils isolated from patients and healthy volunteers. At the same time, marked decrease in NETs release was found in control cells and a less pronounced reduction in patient neutrophils. Impaired ability to produce ROS following exposure to HBO was demonstrated to be linked to a strong downregulation of the activity of p38 MAPK. Only slight suppression of ERK activity could be found. In addition, HBO did not influence neutrophil chemotaxis or apoptosis, respectively. Collectively, this study shows for the first time that HBO therapy suppresses ROS production in inflammatory human neutrophils, and thus might impair ROS-dependent pathways, e.g. kinases activation and NETs release. Thus, HBO might represent a feasible therapy for patients suffering from systemic inflammation, including those with multiple trauma.

Antiproliferative Effect of Synadenium grantii Hook f. stems (Euphorbiaceae) and a Rare Phorbol Diterpene Ester.

Synadenium grantii is frequently used for the treatment of various diseases such as allergies, gastric disorders, and especially cancer. The aim of this study was to evaluate the possible antiproliferative potential of the methanol extract, fractions, and pure compounds from the stems of S grantii Phytochemical analysis was carried out by conventional chromatographic techniques, and the antiproliferative activity was analyzed using the sulforhodamine B assay and an MTT-based assay. Nonpolar fraction and its subfractions from the stems of S grantii exhibited promising cytostatic effect against several human tumor cell lines (glioma, breast, kidney, and lung), with total grown inhibition values ranging from 0.37 to 2.9 µg/mL. One of the active principles of this plant was identified as a rare phorbol diterpene ester, denoted as 3,4,12,13-tetraacetylphorbol-20-phenylacetate. This compound demonstrated antiproliferative activity against glioma, kidney, lung, and triple-negative breast cancer cell lines. These results demonstrate that S grantii stems produce active principles with relevant antiproliferative potential.

Antiallergic Phorbol Ester from the Seeds of Aquilaria malaccensis.

The Aquilaria malaccensis (Thymelaeaceae) tree is a source of precious fragrant resin, called agarwood, which is widely used in traditional medicines in East Asia against diseases such as asthma. In our continuous search for active natural products, A. malaccensis seeds ethanolic extract demonstrated antiallergic effect with an IC50 value less than 1 µg/mL. Therefore, the present research aimed to purify and identify the antiallergic principle of A. malaccensis through a bioactivity-guided fractionation approach. We found that phorbol ester-rich fraction was responsible for the antiallergic activity of A. malaccensis seeds. One new active phorbol ester, 12-O-(2Z,4E,6E)-tetradeca-2,4,6-trienoylphorbol-13-acetate, aquimavitalin (1) was isolated. The structure of 1 was assigned by means of 1D and 2D NMR data and high-resolution mass spectrometry (HR-MS). Aquimavitalin (1) showed strong inhibitory activity in A23187- and antigen-induced degranulation assay with IC50 values of 1.7 and 11 nM, respectively, with a therapeutic index up to 71,000. The antiallergic activities of A. malaccensis seeds and aquimavitalin (1) have never been revealed before. The results indicated that A. malaccensis seeds and the pure compound have the potential for use in the treatment of allergy.

A Natural Product from Polygonum cuspidatum Sieb. Et Zucc. Promotes Tat-Dependent HIV Latency Reversal through Triggering P-TEFb's Release from 7SK snRNP.

The latent reservoirs of HIV represent a major impediment to eradication of HIV/AIDS. To overcome this problem, agents that can activate latent HIV proviruses have been actively sought after, as they can potentially be used in combination with the highly active antiretroviral therapy (HAART) to eliminate the latent reservoirs. Although several chemical compounds have been shown to activate latency, they are of limited use due to high toxicity and poor clinical outcomes. In an attempt to identify natural products as effective latency activators from traditional Chinese medicinal herbs that have long been widely used in human population, we have isolated procyanidin C-13,3',3"-tri-O-gallate (named as REJ-C1G3) from Polygonum cuspidatum Sieb. et Zucc., that can activate HIV in latently infected Jurkat T cells. REJ-C1G3 preferentially stimulates HIV transcription in a process that depends on the viral encoded Tat protein and acts synergistically with prostratin (an activator of the NF-κB pathway) or JQ1 (an inhibitor of Brd4) to activate HIV latency. Our mechanistic analyses further show that REJ-C1G3 accomplishes these tasks by inducing the release of P-TEFb, a host cofactor essential for Tat-activation of HIV transcription, from the cellular P-TEFb reservoir 7SK snRNP.