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Dendrobium officinale Kimura & Migo in the genus Dendrobium of Orchidaceae is an important medicinal plant that produces various bibenzyl and phenanthrene derivatives. In some orchids, these derivatives have been reported to increase with fungal infection. Bibenzyl biosynthesis is regulated by bibenzyl synthase (BBS). Although six genes of the BBS family have been registered from D. officinale, their gene regulation mechanisms are unclear. The infection of Dendrobium with mycorrhizal fungi also reportedly increases the expression of genes involved in biosynthesis; however, the effect of mycorrhizal fungi on bibenzyl production is unknown. The present study examined the effects of three mycorrhizal fungi isolated from D. officinale on BBS gene expression and bibenzyl production over time. One of the Tulasnellaceae operational taxonomic units induced BBS gene expression and increased two representative bibenzyls, gigantol and dendrophenol, at specific time points. Furthermore, 19 BBS sequences were cloned from 12 Dendrobium species, and a phylogenetic analysis was performed. The results indicated that repeated BBS gene duplication occurred during the evolution of the genus, and further duplication occurred after speciation. These results suggest that it is possible to optimize metabolite production by selecting suitable symbiotic fungi. [ABSTRACT FROM AUTHOR]

As a frequent complication of diabetes mellitus (DM), diabetic retinopathy (DR) is now one of the major causes of blindness. Recent reports have shown that retinal pigment epithelial cell (RPEC) damage plays an essential part in DR development and progression. This work intended to explore the potential effects of Gigantol on high glucose (HG)-stimulated RPEC damage and identify potential mechanisms. Cell viability, cell damage, and cell apoptosis were evaluated by CCK-8, lactate dehydrogenase (LDH) and flow cytometry assays. The levels of oxidative stress biomarkers and pro-inflammatory cytokines were assessed using corresponding commercial kits and ELISA. Additionally, the levels of MTDH and NF-kB signaling pathway-related proteins were detected by western blotting. Gigantol dose-dependently enhanced cell viability and decreased apoptosis in HG-challenged ARPE-19 cells. Also, Gigantol notably relieved oxidative stress and inflammatory responses in ARPE-19 cells under HG conditions. Gigantol dose-dependently suppressed MTDH expression. In addition, MTDH restoration partially counteracted the protective effects of Gigantol on ARPE-19 cells subject to HG treatment. Mechanically, Gigantol inactivated the NF-kB signaling pathway, which was partly restored after MTDH overexpression. Our findings suggested that Gigantol protected against HG-induced RPEC damage by inactivating the NF-kB signaling via MTDH inhibition, offering a potent therapeutic drug for DR treatment. [ABSTRACT FROM AUTHOR]

Dendrobium officinale Kimura & Migo in the genus Dendrobium of Orchidaceae is an important medicinal plant that produces various bibenzyl and phenanthrene derivatives. In some orchids, these derivatives have been reported to increase with fungal infection. Bibenzyl biosynthesis is regulated by bibenzyl synthase (BBS). Although six genes of the BBS family have been registered from D. officinale, their gene regulation mechanisms are unclear. The infection of Dendrobium with mycorrhizal fungi also reportedly increases the expression of genes involved in biosynthesis; however, the effect of mycorrhizal fungi on bibenzyl production is unknown. The present study examined the effects of three mycorrhizal fungi isolated from D. officinale on BBS gene expression and bibenzyl production over time. One of the Tulasnellaceae operational taxonomic units induced BBS gene expression and increased two representative bibenzyls, gigantol and dendrophenol, at specific time points. Furthermore, 19 BBS sequences were cloned from 12 Dendrobium species, and a phylogenetic analysis was performed. The results indicated that repeated BBS gene duplication occurred during the evolution of the genus, and further duplication occurred after speciation. These results suggest that it is possible to optimize metabolite production by selecting suitable symbiotic fungi.

Background: Dendrobium officinale is a valuable medicinal food plant in China, and its component gigantol has various biological activities. However, due to the low extraction rate of gigantol, its application in the functional food industry is limited. This research aimed to explore an effective gigantol extraction method. Results: Ultrasonic-assisted dry grinding extraction of gigantol from D. officinale almost reached completion after 15 min. The extraction rate of gigantol reached 65%, which was higher than that of the conventional heating refluxing method of extraction. Most cells were broken, and particle size was approximately 410 nm when D. officinale was ground for 15 min. Conclusion: The results indicated that ultrasonic-assisted dry grinding is a highly effective gigantol extraction method that is valuable for the efficient use and low-cost extraction of gigantol from the medicinal food plant D. officinale. Furthermore, this method will be beneficial for the future application of gigantol in the functional food industry. [ABSTRACT FROM AUTHOR]

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In aging males, androgen production by testicular Leydig cells decreases at a rate of approximately 1% per year. Phenolic compounds may enhance testosterone biosynthesis and delay the onset of male hypogonadism. Gigantol is a bibenzyl compound isolated from several types of orchids of the genus Dendrobium. This compound has various biological activities, including antioxidant activity. However, its capacity to regulate gene expression and steroid production in testicular Leydig cells has never been evaluated. We investigated the effect of gigantol on MA-10 Leydig cells’ gene expression using an RNA-Seq approach. To further investigate the structure-function relationship of the hydroxy-methoxyphenyl moiety of gigantol, experiments were also performed with ferulic acid and isoferulic acid. According to transcriptomic analysis, all genes coding for cholesterol biosynthesis-related enzymes are increased in response to gigantol treatment, resulting in increased lipid droplets accumulation. Moreover, treatments with 10 μM gigantol increased StAR protein levels and progesterone production from MA-10 Leydig cells. However, neither ferulic acid nor isoferulic acid influenced StAR protein synthesis and progesterone production in MA-10 Leydig cells. Thus, our findings indicate that gigantol improves cholesterol and steroid biosynthesis within testicular Leydig cells.

Dendrobium, recognized as "Shihu" in traditional Chinese medicine, holds a rich history of medicinal utilization documented in the Chinese Pharmacopoeia. Ancient texts like "Shen Nong Ben Cao Jing" extol Dendrobium 's virtues as a superior herbal medicine fortifying "Yin" and invigorating the five viscera. Dendrobium is extensively employed for the treatment of gastrointestinal inflammatory disorders, showcasing significant therapeutic efficacy, particularly against ulcerative colitis (UC), within the realm of Chinese ethnopharmacology. Dendrobium plays crucial pharmacological roles due to its rich content of polysaccharides, alkaloids, phenanthrenes, and bibenzyls. Gigantol, a prominent bibenzyl compound, stands out as one of the most vital active constituents within Dendrobium , the gigantol content of Dendrobium leaves can reach approximately 4.79 μg/g. Its significance lies in being recognized as a noteworthy anti-inflammatory compound derived from Dendrobium. Given the pivotal role of gigantol as a primary active substance in Dendrobium , the therapeutic potential of gigantol for gastrointestinal diseases remains enigmatic. Our present investigation aimed to evaluate the therapeutic effects of gigantol on dextran sulfate sodium (DSS)-induced colitis and reveal its potential mechanism in countering UC activity. The protective efficacy of gigantol against colitis was assessed by examining the histopathological changes and conducting biochemical analyses of colon from DSS-challenged mice. Assessments focused on gigantol's impact on improving the intestinal epithelial barrier and its anti-inflammatory effects in colonic tissues of colitis mice. Investigative techniques included the exploration of the macrophage inflammatory signaling pathway via q PCR and Western blot analyses. In vitro studies scrutinized macrophage adhesion, migration, and chemotaxis utilizing transwell and Zigmond chambers. Furthermore, F-actin and Rac1 activation assays detailed cellular cytoskeletal remodeling. The potential therapeutic target of gigantol was identified and validated through protein binding analysis, competitive enzyme-linked immunosorbent assay (ELISA), cellular thermal shift assay (CETSA), and drug affinity responsive target stability (DARTS) assay. The binding sites between gigantol and its target were predicted via molecular docking. Gigantol ameliorated symptoms of DSS-induced colitis, rectified damage to the intestinal barrier, and suppressed the production of pro-inflammatory cytokines in colonic tissues. Intriguingly, gigantol significantly curtailed NF-κB signaling activation in the colons of DSS-induced colitis mice. Notably, gigantol impaired the β2 integrin-dependent adhesion and migratory capacity of RAW264.7 cells. Moreover, gigantol notably influenced the cytoskeleton remodeling of RAW264.7 cells by suppressing Vav1 phosphorylation and Rac1 activation. Mechanistically, gigantol interacted with β2 integrin, subsequently diminishing binding affinity with intercellular adhesion molecule-1 (ICAM-1). In conclusion, these findings elucidate that gigantol ameliorates DSS-induced colitis by antagonizing β2 integrin-mediated macrophage adhesion, migration, and chemotaxis, thus it may impede macrophage recruitment and infiltration into colonic tissues. This study suggests that gigantol shows promise as a viable candidate for clinical colitis therapy. [Display omitted] • Gigantol derived from Dendrobium remarkably mitigates DSS-induced colitis. • Gigantol restores intestinal barrier damage and suppresses cytokine production. • Gigantol suppressed NF-κB activation in vivo but it is not replicated in vitro. • Gigantol impairs macrophage β2 integrin-dependent adhesion and migration. • Gigantol interacts with β2 integrin and reduces its binding affinity with ICAM-1. [ABSTRACT FROM AUTHOR]

Cervical cancer is one of the leading malignant cancers that is the fourth prominent cause of malignancy‐related mortality in women globally. There is a predominant validation to a beneficial target in Wnt/β‐catenin signaling in cervical carcinogenesis as they are very much deregulated in cancer. Previous studies reported Gigantol (GG) showed suppressive properties on the Wnt/β‐catenin pathway in other tumor cells, but no evidence is available regarding GG suppressing Wnt/β‐catenin signaling cervical tumor cells. Hence, the current research was planned to examine the suppressive effects of GG on HeLa cells and investigate the mechanism of action. HeLa cells were treated by GG in various doses and then appraising cell viability, oxidant/antioxidant levels, ∆ѰM status, reactive oxygen species (ROS) generation, apoptosis, and cell proliferation via Wnt/β‐catenin signaling. We observed that GG noticeably inhibits cell proliferation, increased ROS generation, lipid peroxidation, mitochondrial membrane depolarization (∆ѰM), and increased apoptotic morphological changes of nuclear fragmentation and condensation. Moreover, GG effectively enhances proapoptotic, decreased ∆ѰM and antioxidant amounts, and mitigated Wnt/β‐catenin signaling. Concisely, these findings proved that activating apoptosis and suppression of cell proliferation in GG treated HeLa cells was documented by the alleviation of Wnt/β‐catenin signaling. Therefore, this study suggested that GG might develop a therapeutic effect against cervical carcinogenesis. [ABSTRACT FROM AUTHOR]

AIM: To investigate the protective effects of gigantol on aldose reductase(AR)pathway and oxidative stress induced by high glucose in human retinal microvascular endothelial cells(HRMECs).METHODS: HRMECs were cultured and divided into the five groups: normal glucose group, mannitol group,high glucose group, gigantol group and epalrestat group. Cell vitality was detected by the MTS assay, reactive oxygen species(ROS)levels were detected by DCFH-DA fluorescent probe, protein expressions of nuclear factor kappa B(NF-κB)were observed by Western blotting, mRNA levels of AR, hypoxia inducible factor-1α(HIF-1α)and vascular endothelial growth factor(VEGF)were measured by qRT-PCR.RESULTS: DCFH-DA fluorescent probe levels showed that gigantol reduced ROS generation obviously, and protein expressions of NF-κB, mRNA expressions of AR,HIF-1α and VEGF were all decreased. The expression trends of AR and NF-κB in epalrestat group were consistent with gigantol group.CONCLUSION: Gigantol and epalrestat could inhibit the activation of AR/NF-κB pathway, and gigantol also could inhibit high glucose induced oxidative stress and in HRMECs, which may have a protective effect on diabetic retinopathy(DR), and improve angiogenesis.

Background/Aim: c-Met (mesenchymal-epithelial transition factor) facilitates cancer progression and is recognized as a promising drug target. The molecular target of gigantol from Dendrobium draconis in suppressing cancer metastasis is largely unknown. Materials and Methods: Proteins affected by gigantol treatment were subjected to proteomic and bioinformatic analysis. Protein-Protein interaction (PPI) networks were constructed by the Search Tool for the Retrieval of Interacting Genes (STRING). The Kyoto Encyclopedia of Genes and Genomes (KEGG) database and hub gene were used to enrich the dominant pathways. Western blot analysis and immunofluorescence were used to validate the effect of gigantol on the target protein and signaling. Results: Gigantol down-regulates 41 adhesion proteins and 39-migratory proteins, while it upregulates 30 adhesion-related proteins and 22 proteins controlling cell migration. The key components of our constructed PPI network comprised 41 proteins of cell adhesion enriched in 40 nodes with 25 edges, 39 proteins of cell migration enriched in 39 nodes with 76 edges in downregulated proteins, 30 proteins of cell adhesion enriched in 30 nodes with 21 edges, and 22 proteins of cell migration enriched in 22 nodes with 22 edges in up-regulated protein. c-Met was identified as a central protein of the PPI network in the largest degree. KEGG mapper further suggested that c-Met, PI3K, and AKT were the regulatory proteins affected by gigantol. To confirm, the effects of gigantol on c-Met, the p-PI3K, PI3K, p-AKT, and AKT proteins were investigated by western blotting and the results showed a consistent effect of gigantol in the suppression of the c-Met/PI3K/AKT signal. Next, immunofluorescence showed a dramatic decrease in c-Met, PI3K and AKT activation in response to gigantol. Conclusion: c-Met is an important target of gigantol treatment in lung cancer cells. Gigantol suppresses metastasis-related cell motility through decreasing c-Met resulting in PI3K/AKT signaling disruption. [ABSTRACT FROM AUTHOR]

Gigantol, a bibenzyl compound extracted from various medicinal plants, has shown a number of biological activities, making it an attractive candidate for potential medical applications. This systematic review aims to shed light on gigantol's promising role in inflammation treatment and its underlying mechanisms. Gigantol exhibits potential anti-inflammatory properties in pre-clinical pharmacological test systems. It effectively reduced the levels of pro-inflammatory markers and arachidonic acid metabolites through various pathways, such as NF-κB, AKT, PI3K, and JNK/cPLA2/12-LOX. The in-silico investigations demonstrated that the MMP-13 enzyme served as the most promising target for gigantol with highest binding affinity (docking score = -8.8 kcal/mol). Encouragingly, the absorption, distribution, metabolism, excretion, and toxicity (ADMET) analysis of gigantol confirmed its compatibility with the necessary physiochemical, pharmacokinetic, and toxicity properties, bolstering its potential as a drug candidate. Gigantol, with its well-documented anti-inflammatory properties, could be a promising agent for treating inflammation in the near future.

Background: Hepatocellular carcinoma (HCC) is a common clinical malignant disease and the second leading cause of cancer-related death worldwide. Dendrobium is a commonly applied nourishing drug in traditional Chinese medicine. Gigantol is a phenolic compound extracted from Dendrobium. The compound has attracted attention for its anticancer effects. However, the mechanism of gigantol in HCC has not been extensively explored. Methods: Potential targets of gigantol were predicted by SwissTargetPrediction. HCC-related genes were obtained from the GeneCards, Online Mendelian Inheritance in Man (OMIM), Pharmacogenetics and Pharmacogenomics Knowledge Base (PharmGKB), Therapeutic Target Database (TTD) and DrugBank databases. The “gigantol-target-disease” network was constructed using Cytoscape software. Protein interaction network analysis was performed using STRING software. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were executed utilizing the R package to explore the possible regulatory mechanisms of gigantol in HCC. To authenticate the role of gigantol in HCC, Cell Counting Kit-8 (CCK-8) assay, 5-ethynyl-2’-deoxyuridine (EdU) assay, wound healing assay, Matrigel invasion assay and Western blot were performed. Results: Three core genes were screened from 32 closely linked genes. Pathway analysis yielded many signaling pathways associated with cancer. The CCK-8 assay and EdU assay indicated that gigantol suppressed the growth of HCC cells. The wound healing assay and Matrigel invasion assay showed the inhibition of migration and metastasis of HCC cells by gigantol. We verified from molecular docking and protein level that gigantol can exert regulatory effects through three targets, ESR1, XIAP and HSP90AA1. Furthermore, Western blot results tentatively revealed that gigantol may inhibit HCC progression through the HSP90/Akt/CDK1 pathway. Conclusions: Our results confirms anti-HCC proliferation activity of gigantol through PI3K pathway described in existing literature by different experimental approaches. Furthermore, it has discovered other proteins regulated by the drug that was not previously reported in the literature.These findings provide potential molecular and cellular evidence that gigantol may be a promising antitumor agent.

Abstract Background Gigantol is a bibenzyl compound derived from several medicinal orchids. This biologically active compound has been shown to have promising therapeutic potential against cancer cells, but its mechanism of action remains unclear. Methods The inhibitory effect of gigantol on Wnt/β-catenin signaling was evaluated with the SuperTOPFlash reporter system. The levels of phosphorylated low-density lipoprotein receptor related protein 6 (LRP6), total LRP6 and cytosolic β-catenin were determined by Western blot analysis. The expression of Wnt target genes was analyzed using real-time PCR. Cell viability was measured with a MTT assay. The effect of gigantol on cell migration was examined using scratch wound-healing and transwell migration assays. Results Gigantol decreased the level of phosphorylated LRP6 and cytosolic β-catenin in HEK293 cells. In breast cancer MDA-MB-231 and MDA-MB-468 cells, treatment with gigantol reduced the level of phosphorylated LRP6, total LRP6 and cytosolic β-catenin in a dose-dependent manner, resulting in a decrease in the expression of Wnt target genes Axin2 and Survivin. We further demonstrated that gigantol suppressed the viability and migratory capacity of breast cancer cells. Conclusion Gigantol is a novel inhibitor of the Wnt/β-catenin pathway. It inhibits Wnt/β-catenin signaling through downregulation of phosphorylated LRP6 and cytosolic β-catenin in breast cancer cells.

Background: Bladder cancer has long been recognized as one of the most common and aggressive human malignant carcinomas due to the increased invasiveness and metastasis. The discovery and development of natural compounds from Dendrobium species for cancer therapy have garnered increasing attention in recent years. Among those natural elements, the bibenzyl compound gigantol has promising therapeutic potential against several cancer cell lines; however, its roles on bladder tumor metastasis have not been investigated. Materials and Methods: Here in this in vitro study, we utilized viability tests, cell migration, cell invasion and apoptosis assays to evaluate the anti-tumor activity of gigantol on three human bladder cancer cell lines (SW780, 5637, and T24) and a normal human bladder cell line (SVHUC-1). Cells were treated with different concentrations of gigantol (0, 40, 80, and 160 μM) for 24, 48 and 72 h. Results: Here in this study, we showed that gigantol suppressed cancer cell proliferation but not normal SVHUC-1 cells. The inhibitory effect of the compound on cell migration and invasion was also exhibited in the cancer cell lines. Cell apoptosis assay by flow cytometry revealed enhanced apoptotic effects of gigantol on cancer cells. Gene expression analysis revealed that Wnt/EMT signaling might involve in the response of bladder cancer cells to gigantol. Conclusion: Therefore, the present data demonstrate gigantol as a strong anticancer reagent against bladder cancer possibly through Wnt/EMT signaling. [ABSTRACT FROM AUTHOR]

Background: Gigantol is a pharmacologically active bibenzyl compound exerting potential anticancer activities. At non-toxic concentrations, it reduces cancer stem cell properties and tumorigenicity. The mechanisms of the effects of gigantol on cancer cell growth are largely unknown. This study aimed to unravel the molecular profile and identify the prominent molecular mechanism of the effects of gigantol in controlling lung cancer cell proliferation. Materials and Methods: Proteomics and bioinformatics analysis were used accompanied by experimental molecular pharmacology approaches. Results: Gigantol exhibited antiproliferative effects on human lung cancer cells confirmed by 3-(4, 5- dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide proliferation assay and colony growth assay. The protein profile in response to gigantol treatment associated with regulation of cell proliferation was analyzed to determine the prominent protein targets. Among the significant hub proteins, MYC, an important proto-oncogene and proliferationpromoting transcription factor, was down-regulated with the highest number of protein-protein interactions. MYC downregulation was confirmed by western blot analysis. The upstream regulator of MYC, Glycogen synthase kinase 3 beta (GSK3ß) was found to be responsible for MYC destabilization mediated by gigantol. Gigantol facilitated GSK3ß function and resulted in the increase of MYC-ubiquitin complex as evaluated by immunoprecipitation. Conclusion: Gigantol was found to inhibit lung cancer proliferation through induction of GSK3ß-mediated MYC ubiquitin-proteasome degradation. These data suggest gigantol to be a promising candidate for novel strategy in inhibition of lung cancer. [ABSTRACT FROM AUTHOR]

Gigantol, a naturally occurring dibenzyl compound derived from various orchid species within the Dendrobium genus, exhibits notable pharmacological activity. We found that gigantol has significant anti-lung cancer properties, both in vitro and in vivo, which it exerts through the induction of ferroptosis. Furthermore, we found gigantol's specific interaction with the subunit solute carrier family 7 member 11 (SLC7A11) within the cystine/glutamate antiporter system (system Xc−), leading to the inhibition of glutathione (GSH) synthesis. This, in turn, disrupts redox homeostasis. Additionally, gigantol hinders the uptake of extracellular cystine via lung cancer cells, resulting in reduced cellular levels of cysteine, a vital precursor in GSH synthesis. This reduction, in turn, leads to an increase in the levels of glutamate. Simultaneously, our study reveals that the decrease in GSH significantly inhibits the activity of glutathione peroxidase 4 (GPX4), a key enzyme within the antioxidant system. Remarkably, N-acetylcysteine, a cystine precursor, effectively reverses gigantol-induced ferroptosis in lung cancer cells. This provides further confirmation that the anti-lung cancer mechanism of gigantol is to induce ferroptosis of lung cancer cells by targeting the SLC7A11-GPX4 signaling axis. In conclusion, our study underscores gigantol's potential as a promising candidate drug for the treatment of patients with lung cancer in clinical practice. • Gigantol exerts anti-lung cancer effect in vitro and in vivo. • Gigantol induces ferroptosis in lung cancer cells. • Gigantol via targeting SLC7A11-GPX4 axis induces ferroptosis in lung cancer cells. • NAC via activate SLC7A11 alleviates the inhibitory effect of Gigantol on lung cancer cells. [ABSTRACT FROM AUTHOR]

Rhynchostylis retusa (L.) Blume is traditionally used for the treatment of pain, inflammation, and skin diseases. The study aims the bioassay-guided isolation of chemical constituents from R. retusa using human breast cancer cell line MDA-MB-231 and murine RAW 264.7 macrophages. The cell viability assay revealed that crude extract, hexane, and chloroform fractions inhibited the viability of MDA-MB-231 and RAW 264.7 macrophages. The hexane fraction led to the isolation of four fatty acids; 1-octene (1), (9 Z ,12 Z ,15 Z)-octadeca-9,12,15-trienoic acid (2), methyl oleate (3), methyl linolenate (4); and one steroid, stigmasterol (5). The isolation and purification of chemical constituents from the most potent chloroform fraction yielded two phenylpropanoids, dihydroconiferyl dihydro- p -coumarate (6) and retusiusine B (7); one bis- nor -lignan, 3,3′-dimethoxy-4,4′-dihydroxy-9,9′-bis- nor -lignan (8) and one bibenzyl, gigantol (9); and vanillin (10). This is the first report of compounds 1 – 10 from R. retusa (L.) Blume and the genus Rhynchostylis. 3,3′-dimethoxy-4,4′-dihydroxy-9,9′-bis- nor -lignan (8) is new from natural sources. Gigantol (9) is a bioactive compound of R. retusa as it showed an inhibitory effect on the viability of MDA-MB-231 cells and RAW 264.7 macrophages. The bioactivity of R. retusa is possibly due to the presence of gigantol (9) in the plant. Thus, the study corroborates the traditional uses of R. retusa for the treatment of pain and inflammation. The chemophenetic significance of the isolated compounds is also discussed in this study. [Display omitted] • Compounds were isolated using MDA-MB-231 cells and RAW 264.7 macrophages. • All compounds 1– 10 were isolated from Rhynchostylis retusa for the first time. • 3,3′-Dimethoxy-4,4′-dihydroxy-9,9′-bis- nor -lignan (8) was new from natural sources. [ABSTRACT FROM AUTHOR]

The Dendrobium plants (members of the Orchidaceae family) are used as traditional Chinese medicinal herbs. Bibenzyl, one of the active compounds in Dendrobium officinale, occurs in low amounts among different tissues. However, market demands require a higher content of thes compounds to meet the threshold for drug production. There is, therefore, an immediate need to dissect the physiological and molecular mechanisms underlying how bibenzyl compounds are biosynthesized in D. officinale tissues. In this study, the accumulation of erianin and gigantol in tissues were studied as representative compounds of bibenzyl. Exogenous application of Methyl-Jasmonate (MeJA) promotes the biosynthesis of bibenzyl compounds; therefore, transcriptomic analyses were conducted between D. officinale-treated root tissues and a control. Our results show that the root tissues contained the highest content of bibenzyl (erianin and gigantol). We identified 1342 differentially expressed genes (DEGs) with 912 up-regulated and 430 down-regulated genes in our transcriptome dataset. Most of the identified DEGs are functionally involved in the JA signaling pathway and the biosynthesis of secondary metabolites. We also identified two candidate cytochrome P450 genes and nine other enzymatic genes functionally involved in bibenzyl biosynthesis. Our study provides insights on the identification of critical genes associated with bibenzyl biosynthesis and accumulation in Dendrobium plants, paving the way for future research on dissecting the physiological and molecular mechanisms of bibenzyl synthesis in plants as well as guide genetic engineering for the improvement of Dendrobium varieties through increasing bibenzyl content for drug production and industrialization.

Bone marrow mesenchymal stem cell (BMSC) transplants are promising for the treatment of certain central nervous system diseases. However, oxidative stress is one of the major factors that may limit the survival of the transplanted BMSCs. The present study investigated the effect of pretreatment with gigantol on hydrogen peroxide (H2O2)-induced apoptosis in rat BMSCs (rBMSCs) and the potential underlying mechanisms. The results demonstrated that gigantol pretreatment significantly inhibited H2O2-induced apoptosis of rBMSCs. rBMSCs were incubated with 600 µM H2O2 in the absence or presence of different doses of gigantol (1-100 µM). Cell viability and apoptosis ratios were assessed by MTT assays and flow cytometry, respectively. Morphological alterations and reactive oxygen species were measured by the fluorescent-based methods of Hoechst staining and dichlorodihydrofluorescein diacetate, respectively. Furthermore, the protein levels of phosphorylated-protein kinase B (Akt), B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X (Bax), caspase-3 and caspase-9 were investigated by western blotting. Following incubation with H2O2 for 2 h, gigantol significantly inhibited the H2O2-induced reductions in the cell viability of rBMSCs in a dose-dependent manner. Furthermore, gigantol upregulated Akt phosphorylation and Bcl-2 expression, downregulated Bax expression, and reduced the expression of caspase-3 and caspase-9 in H2O2-treated rBMSCs, whereas an opposite effect was detected when LY294002, an inhibitor of phosphatidylinositol 3-kinase, was administered in combination with gigantol. These results indicate that gigantol may be developed as a promising neuroprotective agent for successful MSC transplantation in ischemic diseases. [ABSTRACT FROM AUTHOR]

• Gigantol is a bibenzyl phytocompound from Chinese medicine Dendrobium catenatum Lindl. (Orchidaceae) with diverse pharmacological properties. • Gigantol enhanced the antimicrobial activity of colistin against mcr -positive Enterobacterales in vitro and in vivo. • Gigantol reduced the expression of MCR-1 and inhibited MCR-1 enzyme directly. • Gigantol was a promising adjuvant for colistin in treating infections caused by mcr -positive pathogens. The emergence and wide spread of plasmid-mediated colistin resistance gene (mcr-1) and its mutants have immensely limited the efficacy of colistin in treating multidrug-resistant (MDR) Gram-negative bacterial infections. The development of synergistic combinations of antibiotics with a natural product that coped with the resistance of MDR bacteria was an economic strategy to restore antibiotics activity. Herein, we investigated gigantol, a bibenzyl phytocompound, for restoring in vitro and in vivo , the sensitivity of mcr -positive bacteria to colistin. The synergistic activity of gigantol and colistin against multidrug-resistant Enterobacterales was studied via checkerboard assay and time-killing curve. Subsequently, the transcription and protein expression levels of mcr -1 gene were determined by RT-PCR and Western blots. The interaction of gigantol and MCR-1 was simulated via molecular docking and verified via site-directed mutagenesis of MCR-1. Hemolytic activity and cytotoxicity assay were used to evaluate the safety of gigantol. Finally, the in vivo synergistic effect was evaluated via two animal infection models. Gigantol restored the activity of colistin against mcr -positive bacteria E.coli B2 (MIC from 4 μg/ml to 0.25 μg/ml), Salmonella 15E343 (MIC from 8 μg/ml to 1 μg/ml), K. pneumoniae 19-2-1 (MIC from 32 μg/ml to 2 μg/ml) carrying mcr -1, mcr -3, mcr -8, respectively. Mechanistic studies revealed that gigantol down-regulated the expression of genes involved in LPS-modification, reduced the MCR-1 products and inhibited the activity of MCR-1 by binding to amino acid residues Tyr287 and Pro481 in its D-glucose-binding pocket. Safety evaluation showed that the addition of gigantol relieves the hemolysis caused by colistin. Compared with monotherapy, the combination of gigantol and colistin significantly improved the survival rate of Gallgallella mellonella larvae and mice infected by E.coli B2. Moreover, there was a considerable decrease in the bacterial load present in the viscera of mice. Our results confirmed that gigantol was a potential colistin adjuvant, and could be used to tackle multi-drug resistant Gram-negative pathogen infections combined with colistin. [Display omitted] [ABSTRACT FROM AUTHOR]

Gigantol is a bibenzyl compound derived from several medicinal orchids. This biologically active compound has shown promising therapeutic potential against diabetic cataracts, but whether this compound exerts beneficial effects on the other diabetic microvascular complications remains unclear. This study was carried out to examine effects of gigantol on high glucose-induced renal cell injury in cultured mouse kidney mesangial cells (MES-13). MES-13 cells were pretreated with gigantol (1, 5, 10 or 20 μmol/L) for 1 h followed by further exposure to high (33.3 mmol/L) glucose for 48 h. Gigantol concentration dependently enhanced cell viability followed by high glucose treatment in MES-13 cells. High glucose induced reactive oxygen species (ROS) generation, malondialdehyde production and glutathione deficiency were recoved in MES-13 cells pretreated with gigantol. High glucose triggered cell apoptosis via the the loss of mitochondrial membrane potential, depletion of adenosine triphosphate, upregulation of caspases 9 and 3, enhancement of cytochrome c release, and subsequent interruption of the Bax/Bcl-2 balance. These detrimental effects were ameliorated by gigantol. High glucose also induced activation of JNK, p38 mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) in MES-13 cells, which were blocked by gigantol. The results suggest that treatment MES-13 cells with gigantol halts high glucose-induced renal dysfunction through the suppression of the ROS/MAPK/NF-κB signaling pathways. Our data are of value to the understanding the mechanism for gigantol, and would benefit the study of drug development or food supplement for diabetes and nephropathy.

Ethnopharmacological relevance Dendrobium. chrysotoxum Lindl is a commonly used species of medicinal Dendrobium which belongs to the family of Orchidaceae, locally known as “Shihu” or “Huangcao”. D. chrysotoxum Lindl is widely known for medicinal values in traditional Chinese medicine as it possesses anti-inflammatory, anti-hyperglycemic induction, antitumor and antioxidant properties. Study aim To characterize the interaction between gigantol extracted from D. chrysotoxum Lindl and the AR gene, and determine gigantol's efficacy against cataractogenesis. Materials and methods Human lens epithelial cells (HLECs) were induced by glucose as the model group. Reverse transcription polymerase chain reaction (RT-PCR) was used to assess AR gene expression. Then, the mode of interaction of gigantol with the AR gene was evaluated by UV–visible spectroscopy, atomic force microscope (AFM) and surface-enhanced Raman spectroscopy (SERS). The binding constant was determined by UV–visible. Results Gigantol depressed AR gene expression in HLECs. UV–visible spectra preliminarily indicated that interaction between the AR gene and gigantol may follow the groove mode, with a binding constant of 1.85×10 3 L/mol. Atomic force microscope (AFM) data indicated that gigantol possibly bound to insert AR gene base pairs of the double helix. Surface-enhanced Raman spectroscopy (SERS) studies further supported these observations. Conclusion Gigantol extracted from D. chrysotoxum Lindl not only has inhibitory effects on aldose reductase, but also inhibits AR gene expression. These findings provide a more comprehensive theoretical basis for the use of Dendrobium for the treatment of diabetic cataract. [ABSTRACT FROM AUTHOR]

In order to optimize the extraction of gigantol from Dendrobium officinale, the influence of methanol concentration, ultrasonic temperature, and liquid ratio on extraction efficiency was analysed by the response surface analysis method. The results show that the extraction rate reached a maximum when the methanol concentration was 92.98%, the solid-liquid ratio was 27.2 mL/g, and the extraction temperature was 41.41 °C. The content of gigantol of Dendrobium officinale in leaves was significantly higher than that in stems, reaching 4.7942 μg/g. The content of gigantol in Dendrobium huoshanensis Fengdou was significantly higher than that of other species of Fengdou. This experiment has practical significance for improving the utilization rate of Dendrobium officinale, and provides a reference for the study of the pharmacological and biological activity of gigantol.

Gigantol is a phenolic component of precious Chinese medicine Dendrobii Caulis, which has many pharmacological activities such as prevent tumor and diabetic cataract. This paper aimed to investigate the molecular mechanism of gigantol in transmembrane transport in human lens epithelial cells(HLECs). Immortalized HLECs were cultured in vitro and inoculated in the laser scanning confocal microscopy(LSCM) medium at 5 000 cells/mL. The fluorescence distribution and intensity of gigantol marked by fluorescence in HLECs were observed by LSCM, and the absorption and distribution of gigantol were expressed as fluorescence intensity. The transmembrane transport process of gigantol in HLECs were monitored. The effects of time, temperature, concentration, transport inhibitors, and different cell lines on the transmembrane absorption and transport of gigantol were compared. HLECs were inoculated on climbing plates of 6-well culture plates, and the ultrastructure of HLECs was detected by atomic force microscopy(AFM) during the transmembrane absorption of non-fluorescent labeled gigantol. The results showed that the transmembrane absorption of gigantol was in time and concentration-dependent manners, which was also able to specifically target HLECs. Energy and carrier transport inhibitors reduced gigantol absorption by HLECs. During transmembrane process of gigantol, the membrane surface of HLECs became rougher and presented different degrees of pits, indicating that the transmembrane transport of gigantol was achieved by active absorption of energy and carrier-mediated endocytosis.

Background: Gigantol and syringic acid (SA) have been shown to synergistically prevent formation of diabetic cataract (DC). However, the exact mechanism of this effect is unknown. Here, we investigate the effect of these compounds on the activity of aldose reductase (AR) and cataract formation. Methods: We examined the synergistic anti-cataract efficacy of gigantol and SA in the high glucose- and streptozotocin -induced DC rat model; synergism was evaluated using Jin's formula. We investigated possible mechanisms of action by measuring AR expression and activity and levels of sorbitol using enzyme kinetics, Western blot, and RT-PCR. Finally, we examined binding interaction between AR and both compounds using a combination of site-directed mutagenesis, recombinant expression of wild-type and mutant proteins, and enzyme kinetics. Results: Combination treatment of gigantol and SA synergistically protected both HLECs(human lens epithelial cells) grown in vitro and DC formation in STZ-induced rats in vivo. Synergism was attributed to inhibition of AR activity, downregulation of AR expression via impaired transcription, and decreased sorbitol levels. Enzyme kinetics studies showed that the activity of an AR Asn160Ala mutant protein was significantly decreased compared to wild-type AR, confirming that Asn160 is a key residue for interaction between AR and both compounds. Conclusion: Combined administration of gigantol and SA synergize to enhance anti-cataract efficacy. The synergistic effect is mainly attributed to disruption of the polyol pathway and inhibition of AR activity. [ABSTRACT FROM AUTHOR]

Lung cancer has been the major cause of death within patients due to the high metastatic rate. One of the most essential processes of metastasis is the ability of cancer cells to resist the programmed cell death in a detached condition called anoikis. The discoveries of new natural compound that is able to sensitize anoikis in cancer cells have garnered the most interest in cancer pharmaceutical science. Gigantol, a bibenzyl compound extracted from Dendrobium draconis, has been a promising natural derived compound for cancer therapy due to several cytotoxic effects in cancer cells. This study has demonstrated for the first time that gigantol significantly decreases lung cancer cells' viability in a detached condition through anoikis and anchorage-independent assays. Western blotting analysis reveals that gigantol greatly decreases epithelial to mesenchymal transition (EMT) markers including N-cadherin, vimentin, and Slug leading to a significant suppression of protein kinase B (AKT), extracellular signal-regulated kinase (ERK), and caveolin-1 (cav-1) survival pathways during the detached condition. Therefore, gigantol could be a potential cancer therapeutic compound suggesting for further development for cancer therapy. [ABSTRACT FROM AUTHOR]

Ethnopharmacological relevance Dendrobium aurantiacum var. denneanumis widespread in southern China, locally known as “Shihu”, “Huangcao” or “Fengdou”, has long been used in traditional Chinese medicine for antipyretic, immunomodulatory, anti-aging effects and eye benefiting. Aim of this study To investigate the effects of gigantol extracted from the stem of D. aurantiacum var. denneanum on the formation of galactose-induced cataractogenesis and the potential mechanisms underlying these effects. Materials and methods Cataract lens models were induced by d -galactose both in vitro and in vivo . The transparency of the rat lenses in vitro and in vivo was observed with an anatomical microscope and a slit lamp microscope. The differential protein and action targets of gigantol were determined and compared among the control group, model group, and gigantol group using two-dimensional electrophoresis and mass spectrometry (MS). Enzyme kinetics was used to show the ability of gigantol to respress aldose reductase (AR) and inducible nitric oxide synthase (iNOS). Quantitative real-time PCR (RT-qPCR). was used to detect repression of the expression of AR and iNOS genes. Molecular docking and dynamic simulation were used to predict the interaction points and combination patterns between gigantol, AR, and iNOS. Results Gigantol was found to prevent galactose-induced damage to the rat lenses both in vitro and in vivo , to delay lens turbidity, and to keep the lenses transparent. Differential proteomes, MS, and RT-qPCR showed AR and iNOS to be the target proteins of gigantol. Gigantol reduced the galactose-induced AR and iNOS mRNA expression by 51.2% and 60.9%, respectively. The IC50 of gigantol for inhibition of AR and iNOS activities were 65.67 μg/mL and 8.768 μg/mL, respectively. Gigantol–AR binding sites were Trp111, His110, Tyr48, and Trp20, and gigantol–iNOS binding sites were Ile195 and Gln257. The main forms of interaction were hydrophobic forces, hydrogen bonds, and van der Waals forces. Conclusion Gigantol extracted from D. aurantiacum var. denneanum was found to inhibit galactose-induced formation of cataracts through repression of the gene expression and activity of AR and iNOS. [ABSTRACT FROM AUTHOR]

Background: Alzheimer's disease (AD) is a progressively developing neurodegenerative disorder of the brain in the elderly people. Vanda roxburghii Rbr. root has been used traditionally in Bangladesh as tonic to brain and in the treatment of nervous system disorders including AD. Therefore, we aimed to investigate the cholinesterase inhibitory activities and antioxidant properties of the extracts from V roxburghii. Methods: The crude methanol extract from the roots of plant was sequentially fractionated with petroleum ether, chloroform, ethylacetate and water to yield their corresponding extracts. The extracts were assessed for acetylcholinesterase and butyrylcholinesterase inhibitory activity by modified Ellman method and antioxidant property by several assays including ferric reducing antioxidant power, scavenging of 1,1 -diphenyl-2-picrylhydrazyl (DPPH) free radical and hydroxyl radical, and inhibition of lipid peroxidation. Endogenous substances in the extracts were analyzed by the standard phytochemical methods and active compound was isolated by the chromatographic methods. Results: Chloroform extract was shown to demonstrate strong ferric-reducing antioxidant power and scavenging activity against DPPH and hydroxyl free radicals when compared with the other extracts and the reference standard catechin. The antioxidant effect was further verified by inhibition of lipid peroxidation in rat brain homogenates. Likewise, the chloroform extract exhibited the highest inhibition against both the acetylcholinesterase and butyrylcholinesterase enzymes with IC50 values of 221.13 and 82.51 ug/ml, respectively. Phytochemical screening revealed a large amount of phenolics and flavonoids in the chloroform extract. Bioactivity guided separation techniques led to the isolation of a strong antioxidant from the chloroform extract and its structure was determined as gigantol on the basis of spectral studies. Conclusion: These results suggest that the chloroform extract of V. roxburghii, possibly due to its phenolic compounds, exert potential antioxidant and cholinesterase inhibitory activities, which may be useful in the treatment of AD. [ABSTRACT FROM AUTHOR]

ABSTRACT Gigantol is a typical bibenzyl compound isolated from Dendrobii Caulis that has been widely used as a medicinal herb in China for the treatment of diabetic cataract, cancer and arteriosclerosis obliterans and as a tonic for stomach nourishment, saliva secretion promotion and fever reduction. However, few studies have been carried out on its in vivo metabolism. In the present study, a rapid and sensitive method based on ultra-performance liquid chromatography/electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UPLC-Q/TOF-MS) in positive ion mode was developed and applied to identify the metabolites of gigantol in rat urine after a single oral dose (100 mg/kg). Chromatographic separation was performed on an Acquity UPLC HSS T3 column (100 × 2.1 mm i. d., 1.8 µm) using acetonitrile and 0.1% aqueous formic acid as mobile phases. A total of 11 metabolites were detected and identified as all phase II metabolites. The structures of the metabolites were identified based on the characteristics of their MS, MS2 data and chromatographic retention times. The results showed that glucuronidation is the principal metabolic pathway of gigantol in rats. The newly identified metabolites are useful to understand the mechanism of elimination of gigantol and, in turn, its effectiveness and toxicity. As far as we know, this is the first attempt to investigate the metabolic fate of gigantol in vivo. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Lung cancer is identified as a major cause of cancer-related death. Death in this cancer associates with the acquisition of apoptosis avoidance mechanism. Apoptosis, a programmed cell death mechanism, plays an important role on normal cell development and tissue homeostasis. The aberrances on cell death mechanism contribute to several pathogenesis including cancers. Several efforts have been paid in investigation of anticancer agents from natural sources. Gigantol (GG), an agent isolated from Thai orchid, Dendrobium draconis, possesses various pharmacological activities; however, its effect on cancer apoptosis was not investigated before. This study demonstrates for the first time that GG induced lung cancer cells apoptosis which was prevented by the addition of Z-VAD-FMK, caspase 3 inhibitor. Western blot analysis reveals that anti-apoptotic Bcl-2 and Mcl-1 were dramatically downregulated, in concomitance with an upregulation of proapoptotic Bax protein in response to GG treatment. Anti-apoptosis FLIP was not significantly changed, suggesting that GG-mediated apoptosis was through mitochondrial-dependent mechanism. Interestingly, the fact that GG showed no cytotoxic effect on normal keratinocyte Hacat cells, supports its selectivity on cancer cells. This finding sheds light on an anticancer activity of GG, providing an evidence for development of this agent for cancer therapy. [ABSTRACT FROM AUTHOR]

Abstract: Several analogs of gigantol (1) were synthesized to evaluate their effect on the complexes Ca2+–calmodulin (CaM) and Ca2+–CaM–CaM sensitive phosphodiesterase 1 (PDE1). The compounds belong to four structural groups including, 1,2-diphenylethanes (2–11), diphenylmethanes (13–15), 1,3-diphenylpropenones (16–18), and 1,3-diphenylpropanes (20–22). In vitro enzymatic studies showed that all compounds except 11 inhibited the complex Ca2+–CaM–PDE1 with IC50 values ranging from 9 to 146 μM. On the other hand, all analogs but 11, 12 and 15 quenched the extrinsic fluorescence of the CaM biosensor hCaM–M124C–mBBr to different extent, then revealing different affinities to CaM; their affinity constants (Km ) values were in the range of 3–80 μM. Molecular modeling studies indicated that all these compounds bound to CaM at the same site that the classical inhibitors trifluoperazine (TFP) and chlorpromazine (CPZ). Some of these analogs could be worthy candidates for developing new anti-tumor, local anesthetics, antidepressants, antipsychotic, or smooth muscle relaxant drugs, with anti-CaM properties due to their good affinity to CaM and the straightforwardness of their synthesis. In addition they could be valuable tools for the study of Ca2+–CaM functions. [Copyright &y& Elsevier]

Abstract: The methanol extracts from Encyclia michuacana tubercles yielded the new 8-C-(6-deoxy-β-d-glucopyranosyl)apigenin (1) together with known 1-(3′-hydroxy-5′-methoxyphenyl)-2-(4″-hydroxy-5″-methoxyphenyl)ethane (2) and 2-(4-hydroxybenzyl)malic acid (3). The new structure was elucidated using spectroscopic methods, mainly 1D and 2D NMR. The β-anomer for 1 was supported by comparison of the experimental 1H–1H coupling constant values with those generated employing a generalized Karplus-type relationship using dihedral angles extracted from DFT calculations. [Copyright &y& Elsevier]

Non-small cell lung cancer (NSCLC) is a common type of cancer, with a mortality of >80% worldwide. Gigantol is a bibenzyl compound that displays anticancer activity. The aim of the present study was to determine the biological activity of gigantol in NSCLC and to elucidate the underlying molecular mechanism of its action. The expression of DEK proto-oncogene (DEK) was measured in NSCLC tissues and cell lines by reverse transcription-quantitative PCR (RT-qPCR). The results suggested that DEK levels were significantly increased in NSCLC tissues and cell lines compared with adjacent non-tumor tissues and BEAS-2B normal bronchial epithelial cells, respectively. A549 cells were exposed to a series of gigantol concentrations (0, 25, 50 and 100 µM) and transfected with DEK small interfering RNA. The results of cell viability measured by MTT assay indicated that gigantol significantly decreased cell viability. Additionally, cell proliferation was assessed by CCK-8 and apoptosis was measured by flow cytometry. In comparison with the control group, gigantol treatment inhibited cell proliferation and promoted apoptosis, whereas DEK knockdown increased gigantol-induced suppression of proliferation and acceleration of apoptosis. Additionally, DEK overexpression reversed gigantol-induced effects on proliferation and apoptosis. Moreover, compared with the control group, gigantol treatment decreased Ki-67 and Bcl-2 expression levels, increased Bax expression levels and inactivated the Wnt/β-catenin signaling pathway, as assessed by RT-qPCR and/or western blot. DEK knockdown further increased gigantol-induced effects, but DEK overexpression reversed gigantol-induced effects. To conclude, the results of the present study suggested that gigantol inhibited cell proliferation and induced apoptosis by decreasing Ki-67 and Bcl-2 expression, increasing Bax expression and activating the Wnt/β-catenin signaling pathway by regulating DEK. The present study indicated the therapeutic potential of gigantol in patients with NSCLC. In addition, DEK may serve as a novel therapeutic target to enhance the effects of gigantol treatment. [ABSTRACT FROM AUTHOR]

Background: Hepatocellular carcinoma (HCC) is a common clinical malignant disease and the second leading cause of cancer-related death worldwide. Dendrobium is a commonly applied nourishing drug in traditional Chinese medicine. Gigantol is a phenolic compound extracted from Dendrobium. The compound has attracted attention for its anticancer effects. However, the mechanism of gigantol in HCC has not been extensively explored., Methods: Potential targets of gigantol were predicted by SwissTargetPrediction. HCC-related genes were obtained from the GeneCards, Online Mendelian Inheritance in Man (OMIM), Pharmacogenetics and Pharmacogenomics Knowledge Base (PharmGKB), Therapeutic Target Database (TTD) and DrugBank databases. The "gigantol-target-disease" network was constructed using Cytoscape software. Protein interaction network analysis was performed using STRING software. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were executed utilizing the R package to explore the possible regulatory mechanisms of gigantol in HCC. To authenticate the role of gigantol in HCC, Cell Counting Kit-8 (CCK-8) assay, 5-ethynyl-2'-deoxyuridine (EdU) assay, wound healing assay, Matrigel invasion assay and Western blot were performed., Results: Three core genes were screened from 32 closely linked genes. Pathway analysis yielded many signaling pathways associated with cancer. The CCK-8 assay and EdU assay indicated that gigantol suppressed the growth of HCC cells. The wound healing assay and Matrigel invasion assay showed the inhibition of migration and metastasis of HCC cells by gigantol. We verified from molecular docking and protein level that gigantol can exert regulatory effects through three targets, ESR1, XIAP and HSP90AA1. Furthermore, Western blot results tentatively revealed that gigantol may inhibit HCC progression through the HSP90/Akt/CDK1 pathway., Conclusions: Our results confirms anti-HCC proliferation activity of gigantol through PI3K pathway described in existing literature by different experimental approaches. Furthermore, it has discovered other proteins regulated by the drug that was not previously reported in the literature.These findings provide potential molecular and cellular evidence that gigantol may be a promising antitumor agent., Competing Interests: The authors declare no conflict of interest., (© 2022 The Author(s). Published by IMR Press.)

In aging males, androgen production by testicular Leydig cells decreases at a rate of approximately 1% per year. Phenolic compounds may enhance testosterone biosynthesis and delay the onset of male hypogonadism. Gigantol is a bibenzyl compound isolated from several types of orchids of the genus Dendrobium. This compound has various biological activities, including antioxidant activity. However, its capacity to regulate gene expression and steroid production in testicular Leydig cells has never been evaluated. We investigated the effect of gigantol on MA-10 Leydig cells' gene expression using an RNA-Seq approach. To further investigate the structure-function relationship of the hydroxy-methoxyphenyl moiety of gigantol, experiments were also performed with ferulic acid and isoferulic acid. According to transcriptomic analysis, all genes coding for cholesterol biosynthesis-related enzymes are increased in response to gigantol treatment, resulting in increased lipid droplets accumulation. Moreover, treatments with 10 μM gigantol increased StAR protein levels and progesterone production from MA-10 Leydig cells. However, neither ferulic acid nor isoferulic acid influenced StAR protein synthesis and progesterone production in MA-10 Leydig cells. Thus, our findings indicate that gigantol improves cholesterol and steroid biosynthesis within testicular Leydig cells.

Gigantol is a bibenzyl compound isolated from orchids of the genus Dendrobium. Gigantol has been demonstrated to possess various pharmacologic (including anticancer) effects. Cisplatin (DDP) has been used and studied as the first-line agent for breast cancer (BC) treatment. Often, its efficacy is jeopardized due to intolerance and organ toxicity. We investigated if gigantol could enhance the anticancer effects of DDP in BC cells and its underlying mechanism of action. The potential pathway of gigantol in BC cells was detected by network-pharmacology and molecular-docking studies. The proliferation and apoptosis of BC cell lines were measured by the MTT assay, colony formation, Hoechst-33342 staining, and flow cytometry. Protein expression was measured by western blotting. Gigantol could inhibit proliferation of BC cells and enhance DDP-induced apoptosis. According to the results of western blotting, gigantol reinforced DDP-induced anticancer effects through downregulation of the phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) signaling pathway in BC cells. The effects were consistent with those of the pathway inhibitor LY294002. Our data might provide new insights into the underlying antitumor effect of gigantol in BC cells. This enhancement effect in the combination of gigantol and DDP may provide many therapeutic benefits in clinical treatment regimens against BC. [ABSTRACT FROM AUTHOR]

The Dendrobium plants (members of the Orchidaceae family) are used as traditional Chinese medicinal herbs. Bibenzyl, one of the active compounds in Dendrobium officinale, occurs in low amounts among different tissues. However, market demands require a higher content of thes compounds to meet the threshold for drug production. There is, therefore, an immediate need to dissect the physiological and molecular mechanisms underlying how bibenzyl compounds are biosynthesized in D. officinale tissues. In this study, the accumulation of erianin and gigantol in tissues were studied as representative compounds of bibenzyl. Exogenous application of Methyl-Jasmonate (MeJA) promotes the biosynthesis of bibenzyl compounds; therefore, transcriptomic analyses were conducted between D. officinale-treated root tissues and a control. Our results show that the root tissues contained the highest content of bibenzyl (erianin and gigantol). We identified 1342 differentially expressed genes (DEGs) with 912 up-regulated and 430 down-regulated genes in our transcriptome dataset. Most of the identified DEGs are functionally involved in the JA signaling pathway and the biosynthesis of secondary metabolites. We also identified two candidate cytochrome P450 genes and nine other enzymatic genes functionally involved in bibenzyl biosynthesis. Our study provides insights on the identification of critical genes associated with bibenzyl biosynthesis and accumulation in Dendrobium plants, paving the way for future research on dissecting the physiological and molecular mechanisms of bibenzyl synthesis in plants as well as guide genetic engineering for the improvement of Dendrobium varieties through increasing bibenzyl content for drug production and industrialization. [ABSTRACT FROM AUTHOR]

Leishmaniasis is a neglected tropical disease caused by trypanosomatid parasite belonging to the genera Leishmania. Leishmaniasis is transmitted from one human to other through the bite of sandflies. It is endemic in around 98 countries including tropical and subtropical regions of Asia, Africa, Southern America, and the Mediterranean region. Sterol C-24 methyltransferase (LdSMT) of Leishmania donovani (L. donovani) mediates the transfer of CH3-group from S-adenosyl methionine to C-24 position of sterol side chain which makes the ergosterol different from cholesterol. Absence of ortholog in human made it potential druggable target. Here, we performed virtual screening of library of natural compounds against LdSMT to identify the potential inhibitor for it and to fight leishmaniasis. Gigantol, flavan-3-ol, and parthenolide showed the best binding affinity towards LdSMT. Further, based on absorption, distribution, metabolism, and excretion properties and biological activity prediction, gigantol showed the best lead-likeness and drug-likeness properties. Therefore, we further elucidated its antileishmanial properties. We found that gigantol inhibited the growth and proliferation of promastigotes as well as intra-macrophagic amastigotes. Gigantol exerted its antileishmanial action through the induction of reactive oxygen species in dose-dependent manner. Our study, suggested the possible use of gigantol as antileishmanial drug after further validations to overcome leishmaniasis., (© 2021 Wiley Periodicals LLC.)

Lung cancer has long been recognized as an important world heath concern due to its high incidence and death rate. The failure of treatment strategies, as well as the regrowth of the disease driven by cancer stem cells (CSCs) residing in the tumor, lead to the urgent need for a novel CSC-targeting therapy. Here, we utilized proteome alteration analysis and ectopic tumor xenografts to gain insight on how gigantol, a bibenzyl compound from orchid species, could attenuate CSCs and reduce tumor integrity. The proteomics revealed that gigantol affected several functional proteins influencing the properties of CSCs, especially cell proliferation and survival. Importantly, the PI3K/AKT/mTOR and JAK/STAT related pathways were found to be suppressed by gigantol, while the JNK signal was enhanced. The in vivo nude mice model confirmed that pretreatment of the cells with gigantol prior to a tumor becoming established could decrease the cell division and tumor maintenance. The results indicated that gigantol decreased the relative tumor weight with dramatically reduced tumor cell proliferation, as indicated by Ki-67 labeling. Although gigantol only slightly altered the epithelial-to-mesenchymal and angiogenesis statuses, the gigantol-treated group showed a dramatic loss of tumor integrity as compared with the well-grown tumor mass of the untreated control. This study reveals the effects of gigantol on tumor initiation, growth, and maintain in the scope that the cells at the first step of tumor initiation have lesser CSC property than the control untreated cells. This study reveals novel insights into the anti-tumor mechanisms of gigantol focused on CSC targeting and destabilizing tumor integrity via suppression of the PI3K/AKT/mTOR and JAK/STAT pathways. This data supports the potential of gigantol to be further developed as a drug for lung cancer.