Bibenzyl and naphthalene derivatives from Dendrobium chrysanthum and their anti-hepatic-steatosis activities.

In this study, 16 new compounds, six bibenzyls (1-6) and 10 naphthalenes (7-13), including three pairs of naphthalene enantiomers and three known compounds (14-16), were isolated from Dendrobium chrysanthum. Structurally, compounds 1-5 are previously undescribed dimeric bibenzyls, uniquely linked by unusual carbon bonds. The structures of the compounds were determined using spectroscopy and X-ray crystallography. The screening results indicated that 1, 2, and 5 showed remarkable lipid-lowering activities in FFA-induced HepG2 cells, with EC50 values ranging from 3.13 to 6.57 µM. Moreover, 1, 2, and 5 significantly decreased both the mRNA and protein levels of the target SREBP-1c, and 5 also reduced PPARα mRNA and protein levels. Therefore, 1, 2, and 5 are potential drugs against hepatic steatosis by targeting PPARα or SREBP-1c.

Two new bibenzyl methylglucosides as SIRT3 activators obtained through microbial transformation.

Microbial transformation of dihydroresveratrol (DHRSV) using Beauveria bassiana has produced two new methylglucosylated derivatives of DHRSV (1 and 2), whose structures were characterized as 4'-O-(4″-O-methyl-ß-D-glucopyranosyl)-dihydroresveratrol (4'-O-MG DHRSV, 1) and 3-O-(4″-O-methyl-ß-D-glucopyranosyl)-dihydroresveratrol (3-O-MG DHRSV, 2) on the basis of spectroscopic methods. They showed moderate SIRT3 agonistic activity, and compound 2 exhibited the best deacetylation of 406.63% at 10 µM. The activity of 2 increased by 3.12-fold compared with that of DHRSV, since 2 performed better in molecular docking assay (GScore -8.445).

Recent Advances in the Phytochemistry of Bryophytes: Distribution, Structures and Biological Activity of Bibenzyl and Bisbibenzyl Compounds.

Research on bryophyte phytochemistry has revealed the presence of different phytochemicals like fatty acids, terpenoids, small phenolic molecules, etc. Small phenolic molecules, i.e., bibenzyls (of two aromatic rings) and bisbibenzyls (four aromatic rings), are unique signature molecules of liverworts. The first bisbibenzyls marchantin A and riccardin A were discovered in two consecutive years, i.e., 1982 and 1983, respectively, by Asakawa and coworkers. Since then, about 70 bisbibenzyls have been reported. These molecules are characterized and identified using different spectroscopic techniques and surveyed for different bioactivity and structure-activity relations. Biochemistry is determined by the season, geography, and environment. In this review, quantitative and qualitative information on bibenzyls and bisbibenzyl compounds and their distribution in different liverworts across, geographies along withtraditional to advanced extraction methods, and characterization techniques are summarized. Also, a comprehensive account of characteristic spectra of different bisbibenzyl compounds, their subtypes, and their basic skeleton patterns are compared. A comprehensive table is provided here for the first time presenting the quantity of bibenzyls, bisbenzyls, and their derivatives found in bryophytes, mentioning the spectroscopic data and mass profiles of the compounds. The significance of these compounds in different bioactivities like antibiotic, antioxidative, antitumor, antivenomous, anti-influenza, insect antifeedant, cytotoxic, and anticancerous activities are surveyed and critically enumerated.

[Effects of mycorrhizal planting on small molecular chemical components of Dendrobium officinale].

This study aimed to provide a scientific basis for the application of the mycorrhizal planting technology of Dendrobium officinale by investigating the effects of mycorrhizal planting on the fingerprints of D. officinale and the content of six chemical components. Seventeen samples of D. officinale under mycorrhizal and conventional planting were collected from four regions, such as Jinhua of Zhejiang. The HPLC fingerprints were established to evaluate the similarity of the samples. The content of six chemical components of the samples was determined by HPLC. There were 15 common peaks in the fingerprints, and five of them were identified by marker compounds, which were naringenin, 4,4'-dihydroxy-3,5-dimethoxybibenzyl, 3,4'-dihydroxy-5-methoxybibenzyl, 3',4-dihydroxy-3,5'-dimethoxybibenzyl(gigantol), and 3,4-dihydroxy-4',5-dimethoxybibenzyl(DDB-2). The similarities of the fingerprints of mycorrhizal and conventional planting samples and the control fingerprint were in the ranges of 0.733-0.936 and 0.834-0.942, respectively. The influences of mycorrhizal planting on fingerprints were related to planting regions, the germplasm of D. officianle, and the amount of fungal agent. The content of six chemical components in the samples varied greatly, and the content of DDB-2 was the highest, ranging from 69.83 to 488.47 µg·g~(-1). The mycorrhizal planting samples from Chongming of Shanghai and Taizhou of Jiangsu showed an increase in the content of 5-6 components, while samples from Zhangzhou of Fujian and Jinhua of Zhejiang showed an increase in the content of 1-2 components. The results showed that mycorrhizal planting technology did not change the chemical profile of small molecular chemical components of D. officinale, but affected the content of chemical components such as bibenzyls, which has a good application prospect.

Phytochemical Analysis of Pinus cembra Heartwood-UHPLC-DAD-ESI-MSn with Focus on Flavonoids, Stilbenes, Bibenzyls and Improved HPLC Separation.

The heartwood of the Swiss Stone Pine, Pinus cembra L., has been scarcely investigated for secondary metabolites for a long period of time. Considering age and relative simplicity of heartwood investigations dating back to the 1940s to 1960s, we conducted the first investigation of P. cembra heartwood by HPLC, using UHPLC-DAD-ESI-MSn and HPLC-DAD techniques in combination with isolation and NMR spectroscopy, with focus on stilbenes, bibenzyls and flavonoids. Analytical problems in the HPLC analysis of Pinus stilbenes and flavonoids on reversed stationary phases were also challenged, by comparing HPLC on pentafluorophenyl (PFP) and C18 stationary phases. Seven flavonoids (1, 2, 3, 7, 8, 11, 12), four stilbenes (4, 6, 10, 13), two bibenzyls (5, 9), three fatty acids (14, 16, 17) and one diterpenic acid (15) were detected in an ethanolic extract of Pinus cembra heartwood. HPLC comparison of reversed stationary phases in HPLC showed that the antifungal, antibacterial and chemosensitizing dihydropinosylvin monomethyl ether (9) and pinosylvin monomethyl ether (10) can be separated on PFP, but not on C18 material, when eluting with a screening gradient of 20-100% acetonitrile. Flavonoid separation showed additional benefits of combining analyses on different stationary phases, as flavonoids 7 and 8 could only be separated on one of two C18 stationary phases. Earlier phytochemical results for heartwood investigations were shown to be mostly correct, yet expandable. Substances 5 to 12 were found in alignment with these references, proving remarkable phytochemical analyses at the time. Evidence for the described presence of pinobanksin could not be found. Substances 1 to 4 and 13 have to our knowledge not yet been described for P. cembra.

Structural diversification of bioactive bibenzyls through modular co-culture leading to the discovery of a novel neuroprotective agent.

Bibenzyls, a kind of important plant polyphenols, have attracted growing attention for their broad and remarkable pharmacological activities. However, due to the low abundance in nature, uncontrollable and environmentally unfriendly chemical synthesis processes, these compounds are not readily accessible. Herein, one high-yield bibenzyl backbone-producing Escherichia coli strain was constructed by using a highly active and substrate-promiscuous bibenzyl synthase identified from Dendrobium officinale in combination with starter and extender biosynthetic enzymes. Three types of efficiently post-modifying modular strains were engineered by employing methyltransferases, prenyltransferase, and glycosyltransferase with high activity and substrate tolerance together with their corresponding donor biosynthetic modules. Structurally different bibenzyl derivatives were tandemly and/or divergently synthesized by co-culture engineering in various combination modes. Especially, a prenylated bibenzyl derivative (12) was found to be an antioxidant that exhibited potent neuroprotective activity in the cellular and rat models of ischemia stroke. RNA-seq, quantitative RT-PCR, and Western-blot analysis demonstrated that 12 could up-regulate the expression level of an apoptosis-inducing factor, mitochondria associated 3 (Aifm3), suggesting that Aifm3 might be a new target in ischemic stroke therapy. This study provides a flexible plug-and-play strategy for the easy-to-implement synthesis of structurally diverse bibenzyls through a modular co-culture engineering pipeline for drug discovery.

Methoxylated bibenzyls and isoflavones from Baphia massaiensis Taub.

Chemical investigation of the stem bark of Baphia massaiensis Taub. led to the isolation of two new natural compounds named 3-hydroxy-2,5,2'-trimethoxybibenzyl (1) and 2'-hydroxy-2,3,5,6-tetramethoxybibenzyl (2), the latter has been previously reported as a synthetic compound, together with twelve known compounds 3-14. The chemical structures of the isolated compounds were elucidated by using NMR analysis and mass spectrometry, as well as comparisons with the reported data in the literature. Known bibenzyls 3-5, bauhinoxepin J (6), and isoflavones 7-10 and 12-14, were reported from genus Baphia for the first time. The isolated compounds were evaluated for their antibacterial activities in-vitro against Staphylococcus aureus and Escherichia coli. The bioactivity evaluation revealed that bibenzyls 1 and 2 showed weak inhibitory activity with MIC values of 1000 µg/mL against S. aureus and bauhinoxepin J (6) showed moderate inhibitory activity with MIC value of 63 µg/mL against S. aureus.

Identification of bibenzyls and evaluation of imitative wild planting techniques in Dendrobium officinale by HPLC-ESI-MSn.

Dendrobium officinale is a traditional Chinese herb with beneficial properties. Modern pharmacological studies show that bibenzyl is one of the antitumor active ingredients, but there is no effective quality control method for identifying ingredients. In this study, the composition of bibenzyls in Dendrobium officinale was studied by high-performance liquid chromatography coupled with electrospray ionization multistage mass spectrometry (HPLC-ESI-MSn ). A total of nine isolated bibenzyls and their glycosides, 22 bis (bibenzyls), and two phenylpropanol bibenzyl derivatives were identified. The results of HPLC characteristic chromatogram analysis and statistical analysis showed that the relative content of bibenzyls in wild imitation cultivation of samples had been significantly higher than that in greenhouse cultivation. In addition, the relative content of bibenzyls increased with the growth of the original plant. This study provided a scientific reference for controlling the quality of bibenzyls in Dendrobium officinale, developing the cultivation technology and improving the quality of Dendrobium officinale. HIGHLIGHTS: HPLC-ESI-MS/MS method for the analysis of bibenzyls and bis (bibenzyls) in Dendrobium officinale. Easy-to-use method facilitating rapid measurement of large sample quantities. The method requires only small volumes of samples for the analysis. Applicable for the establishment of Chinese medicine studies and the quality control standard of Chinese herbs.

New polychlorinated bibenzyls from Rhododendron minutiflorum.

Five new polychlorinated bibenzyls (1-5) along with 3 known compounds (6-8) were isolated from the stems and leaves of Rhododendron minutiflorum. The chemical structures of all the isolates were determined by spectroscopic methods, and compounds 1 and 2 were further verified by single-crystal X-ray diffraction analyses. Compounds 1-5 were halogenated compounds which bear three to five chlorine atoms in their chemical structures. Biologically, compounds 2, 5 and 6 showed varying degrees of toxicity toward the Asian citrus psyllid (Diaphorina citri) with LD50 values 27.15, 17.02 and 16.20 mg/L, respectively. These values were comparable to the positive control matrine (LD50 = 11.86 mg/L), which were calculated using observations on day 6. Meanwhile, compound 4 had α-glucosidase inhibitory activity with IC50 value of 17.87 ± 0.74 µM.

Modern interpretation of the traditional application of Shihu - A comprehensive review on phytochemistry and pharmacology progress of Dendrobium officinale.

ETHNOPHARMACOLOGICAL RELEVANCE: The traditional Chinese medicine (TCM) "Shihu" has a long history of medicinal use in China from some species of Dendrobium. D. officinale is a major source of "Shihu" and is widely cultivated in south of China and listed separately as "Tiepi Shihu" by the Chinese Pharmacopoeia in now time. Traditionally, D. officinale has been widely used in daily health care and the treatment of diabetes and gastrointestinal diseases. AIM OF THIS REVIEW: In order to better develop and utilize D. officinale, we conducted this systematic review of previous studies, showed clear structure of all isolates from D. officinale together with pharmacological progress, hoping to provide references for further research and utilization. In addition, specific display of the chemical components and the research progress of related activities can help to better understand the traditional records and modern pharmaceutical applications of the plant medicine. MATERIALS AND METHODS: Information on phytochemistry and pharmacological studies of D. officinale was collected from various scientific databases including Web of Science, SciFinder, ACS, Springer, Scopus, PubMed, ScienceDirect, Google Scholar and CNKI. RESULTS: More than 180 compounds isolated from D. officinale, including bibenzyls, phenols, phenylpropanoids, lignans, flavonoids and polysaccharides are listed in this review. Furthermore, modern pharmacological researches such as hypoglycemia, immune regulation, antioxidant, cardiovascular regulation and gastrointestinal protection are summarized. CONCLUSION: Based on the summary of the research work of D. officinale, we systematically show the chemical composition of the plant, and concluded the relationship of those composition with plant habitat together with the relationship between the structure of chemical components and pharmacological activity. Moreover, we suggest that some of small molecule compounds could also be quality control of D. officinale besides polysaccharides.

Effects of mycorrhizal planting on small molecular chemical components of Dendrobium officinale / 中国中药杂志

This study aimed to provide a scientific basis for the application of the mycorrhizal planting technology of Dendrobium officinale by investigating the effects of mycorrhizal planting on the fingerprints of D. officinale and the content of six chemical components. Seventeen samples of D. officinale under mycorrhizal and conventional planting were collected from four regions, such as Jinhua of Zhejiang. The HPLC fingerprints were established to evaluate the similarity of the samples. The content of six chemical components of the samples was determined by HPLC. There were 15 common peaks in the fingerprints, and five of them were identified by marker compounds, which were naringenin, 4,4'-dihydroxy-3,5-dimethoxybibenzyl, 3,4'-dihydroxy-5-methoxybibenzyl, 3',4-dihydroxy-3,5'-dimethoxybibenzyl(gigantol), and 3,4-dihydroxy-4',5-dimethoxybibenzyl(DDB-2). The similarities of the fingerprints of mycorrhizal and conventional planting samples and the control fingerprint were in the ranges of 0.733-0.936 and 0.834-0.942, respectively. The influences of mycorrhizal planting on fingerprints were related to planting regions, the germplasm of D. officianle, and the amount of fungal agent. The content of six chemical components in the samples varied greatly, and the content of DDB-2 was the highest, ranging from 69.83 to 488.47 μg·g~(-1). The mycorrhizal planting samples from Chongming of Shanghai and Taizhou of Jiangsu showed an increase in the content of 5-6 components, while samples from Zhangzhou of Fujian and Jinhua of Zhejiang showed an increase in the content of 1-2 components. The results showed that mycorrhizal planting technology did not change the chemical profile of small molecular chemical components of D. officinale, but affected the content of chemical components such as bibenzyls, which has a good application prospect.

Structural diversification of bioactive bibenzyls through modular co-culture leading to the discovery of a novel neuroprotective agent

Bibenzyls, a kind of important plant polyphenols, have attracted growing attention for their broad and remarkable pharmacological activities. However, due to the low abundance in nature, uncontrollable and environmentally unfriendly chemical synthesis processes, these compounds are not readily accessible. Herein, one high-yield bibenzyl backbone-producing Escherichia coli strain was constructed by using a highly active and substrate-promiscuous bibenzyl synthase identified from Dendrobium officinale in combination with starter and extender biosynthetic enzymes. Three types of efficiently post-modifying modular strains were engineered by employing methyltransferases, prenyltransferase, and glycosyltransferase with high activity and substrate tolerance together with their corresponding donor biosynthetic modules. Structurally different bibenzyl derivatives were tandemly and/or divergently synthesized by co-culture engineering in various combination modes. Especially, a prenylated bibenzyl derivative ( 12) was found to be an antioxidant that exhibited potent neuroprotective activity in the cellular and rat models of ischemia stroke. RNA-seq, quantitative RT-PCR, and Western-blot analysis demonstrated that 12 could up-regulate the expression level of an apoptosis-inducing factor, mitochondria associated 3 (Aifm3), suggesting that Aifm3 might be a new target in ischemic stroke therapy. This study provides a flexible plug-and-play strategy for the easy-to-implement synthesis of structurally diverse bibenzyls through a modular co-culture engineering pipeline for drug discovery.

Recent Research Progress on Natural Stilbenes in Dendrobium Species.

Dendrobium is the second biggest genus in the Orchidaceae family, and many of them have been utilized as a traditional Chinese medicine (TCM) for thousands of years in China. In the last few decades, constituents with great chemical diversity were isolated from Dendrobium, and a wide range of biological activities were detected, either for crude extracts or for pure compounds. Stilbene compound is one of the primary active constituents in the genus Dendrobium. At present, 267 stilbene compounds with clarified molecular structures have been extracted and isolated from 52 species of Dendrobium, including 124 phenanthrenes and 143 bibenzyls. At the same time, activity studies have indicated that 157 compounds have pharmaceutical activity. Among them, most of the compounds showed antitumor activity, followed by antioxidant, anti-inflammatory and anti-α-glucosidase inhibitory activities. Additionally, 54 compounds have multiple pharmacological activities, such as confusarin (14), 2,4,7-trihydroxy-9,10-dihydro-phenanthrene (43), moscatilin (148), gigantol (150) and batatasin III (151). This review summarizes current knowledge about the chemical composition of stilbene, bioactivities and pharmacologic effects in 52 species of Dendrobium. We also expect to provide a reference for further research, development and utilization of stilbene constituents in the Dendrobium genus.

Spatial Distribution, Antioxidant Capacity, and Spore Germination-Promoting Effect of Bibenzyls from Marchantia polymorpha.

Liverworts, considered to be the first plant type to successfully make the transition from water to land, can resist different oxidative stress. As characteristic constituents of liverworts, the bibenzyls are efficient antioxidants. In this study, spatial distributions of the bibenzyls within Marchantia polymorpha L., the model species of liverworts, were mapped using airflow-assisted desorption electrospray ionization imaging mass spectrometry. Bibenzyls were found to largely exist in the female receptacle of M. polymorpha, where lunularic acid was found to focus in the central region and bisbibenzyls were enriched in the periphery. The region-specific gene expression and antioxidant activities were characterized. In line with the spatial feature of bibenzyls, higher MpSTCS1A and Mp4CL expression levels and antioxidant ability were exhibited in the archegoniophore. The expression level of MpSTCS1A, and the content of total phenolic acid was increased after UV-B irradiation, suggesting bibenzyls play an important role in UV-B tolerance. Moreover, lunularic acid and extract of archegoniophore at a certain concentration can stimulate the spore germination under normal conditions and UV-B stress. These works broaden our understanding of the significance of bibenzyls in spore propagation and environmental adaptation.

Chemical constituents from the stems of Dendrobium gratiosissimum and their biological activities.

Eight C6-C3-based bibenzyl derivatives (dengraphenols A-G, K), three mono-bibenzyls (dengraphenols I, L-M), one bis-bibenzyl (dengraphenol H), one oxyneolignane (dengraphenol J), one phenanthrene (dengraphenol N), and one picrotoxane-type sesquiterpene (dengrasusane A) were isolated from the stems of Dendrobium gratiosissimum. The resolution of dengraphenols A-J by chiral HPLC afforded ten pairs of enantiomers [(±)-dengraphenols A-J]. Their structures with absolute configurations were elucidated on the basis of comprehensive spectroscopic analyses, computational calculation methods and single-crystal X-ray diffraction, among which twenty-four [(±)-dengraphenols A-E, (+)-dengraphenol F, (±)-dengraphenols G-J, dengraphenols K-N, dengrasusane A] were undescribed. Ten compounds [(±)-dengraphenol B, (±)-dengraphenols D-E, (±)-dengraphenol H, (-)-dengraphenol I and dengraphenol N)] showed potent cytotoxicity against eight human cancer cell lines (A431, A2780, H460, HCT8, BGC823, SW1990, Daoy, and HGC27) with IC50 values of 3.77-9.75 µM. At a concentration of 10 µM, (-)-dengraphenol C, (±)-dengraphenol F, and (±)-dengraphenol K exhibited remarkable hepatoprotective activity against APAP-induced toxicity with a cell survival rate of 65.8%, 70.6% and 73.5%, respectively; dengraphenol N displayed significant anti-inflammatory effects; and dengraphenol K showed strong inhibitory activity against α-glucosidase with IC50 values of 5.71 µM. These results would provide potential compounds for drug discovery.

Isopentenylated Bibenzyls and Phenolic Compounds from Dendrobium chrysotoxum Lindl.

Two new isopentenyl bibenzyls, denchrysotonols A and B (1-2), along with 26 known phenolic compounds, were isolated from the stems of cultivated Dendrobium chrysotoxum Lindl. Their chemical structures were clearly elucidated by extensive spectroscopic analysis. Biological evaluation of isolated compounds revealed that phenanthrenes (14, 16-17, 20, and 22) and fluorenone 25 exhibited anti-inflammatory activities which inhibited nitric oxide (NO) production in LPS-activated RAW264.7 macrophages with the IC50 values ranging from 9.4 to 32.5 µM. Moreover, bibenzyls (1-2 and 7) showed good anti-proliferative activities against triple-negative breast cancer (TNBC) cells (HCC1806, MDA-MB-231, and MB-MB-468) with the IC50 values ranging from 8.1 to 18.6 µM, of which 1 and 2 seemed preferentially inhibit MDA-MB-231 cells.

Identification and Characterization of Two Bibenzyl Glycosyltransferases from the Liverwort Marchantia polymorpha.

Liverworts are rich in bibenzyls and related O-glycosides, which show antioxidant activity. However, glycosyltransferases that catalyze the glycosylation of bibenzyls have not yet been characterized. Here, we identified two bibenzyl UDP-glucosyltransferases named MpUGT737B1 and MpUGT741A1 from the model liverwort Marchantia polymorpha. The in vitro enzymatic assay revealed that MpUGT741A1 specifically accepted the bibenzyl lunularin as substrate. MpUGT737B1 could accept bibenzyls, dihydrochalcone and phenylpropanoids as substrates, and could convert phloretin to phloretin-4-O-glucoside and phloridzin, which showed inhibitory activity against tyrosinase and antioxidant activity. The results of sugar donor selectivity showed that MpUGT737B1 and MpUGT741A1 could only accept UDP-glucose as a substrate. The expression levels of these MpUGTs were considerably increased after UV irradiation, which generally caused oxidative damage. This result indicates that MpUGT737B1 and MpUGT741A1 may play a role in plant stress adaption. Subcellular localization indicates that MpUGT737B1 and MpUGT741A1 were expressed in the cytoplasm and nucleus. These enzymes should provide candidate genes for the synthesis of bioactive bibenzyl O-glucosides and the improvement of plant antioxidant capacity.

[Bibenzyls from Dendrobium officinale].

Fifteen bibenzyls were isolated and purified from the ethyl acetate extract of the stems of Dendrobium officinale by macroporous resin, MCI, silica gel, Sephadex LH-20, and ODS column chromatographies, as well as preparative thin-layer chromatography and preparative HPLC. The structures of compounds were identified according to the spectra data of ~1H-NMR, ~(13)C-NMR, and MS, and the physical and physiochemical properties: dendrocandin X(1), 3,4'-dihydroxy-4,5-dimethoxybibenzyl(2), 6″-de-O-methyldendrofindlaphenol A(3), 3,4-dihydroxy-4',5-dimethoxybibenzyl(4), dendrosinen B(5), 3,4,4'-trihydroxy-5-methoxybibenzyl(6), 3,3'-dihydroxy-4,5-dimethoxybibenzyl(7), 3,4'-dihydroxy-5-methoxybibenzyl(8), moscatilin(9), gigantol(10), 4,4'-dihydroxy-3,5-dimethoxybibenzyl(11), 3,4',5-trihydroxy-3'-methoxybibenzyl(12), 3-O-methylgigantol(13), dendrocandin U(14), and dendrocandin N(15). Compound 1 was a novel compound. Compound 2 was isolated from Dendrobium species for the first time. Compounds 3-7 were isolated from D. officinale for the first time.

Dengratiols A-D, four new bibenzyl derivatives from Dendrobium gratiossimum.

Dengratiol A (1), an unprecedented bibenzyl derivative bearing a tropolone unit together with three pairs of bibenzyl enantiomers (±)-dengratiols B-D [(±)-2-(±)-4], were isolated from Dendrobium gratiossimum Rchb.f. The resolution of enantiomers was performed with chiral HPLC. Their structures were characterized by extensive spectroscopic data analysis and calculated electronic circular dichroism (ECD). A hypothetical biosynthetic pathway for 1 is proposed. Biological assay revealed that (-)-2 showed moderate antiviral effect against IAV with IC50 value of 6.3 µM, and (±)-2 displayed cytotoxic activities against five human tumor cell lines with IC50 values ranging from 15.5 to 42.5 µM.

Mechanisms and Active Compounds Polysaccharides and Bibenzyls of Medicinal Dendrobiums for Diabetes Management.

BACKGROUND: Medicinal dendrobiums are used popularly in traditional Chinese medicine for the treatment of diabetes, while their active compounds and mechanism remain unclear. This review aimed to evaluate the mechanism and active compounds of medicinal dendrobiums in diabetes management through a systematic approach. METHODS: A systematic approach was conducted to search for the mechanism and active phytochemicals in Dendrobium responsible for anti-diabetic actions using databases PubMed, Embase, and SciFinder. RESULTS: Current literature indicates polysaccharides, bibenzyls, phenanthrene, and alkaloids are commonly isolated in Dendrobium genusin which polysaccharides and bibenzyls are most aboundant. Many animal studies have shown that polysaccharides from the species of Dendrobium provide with antidiabetic effects by lowering glucose level and reversing chronic inflammation of T2DM taken orally at 200 mg/kg. Dendrobium polysaccharides protect pancreatic ß-cell dysfunction and insulin resistance in liver. Dendrobium polysaccharides up-regulate the abundance of short-chain fatty acid to stimulate GLP-1 secretion through gut microbiota. Bibenzyls also have great potency to inhibit the progression of the chronic inflammation in cellular studies. CONCLUSION: Polysaccharides and bibenzyls are the major active compounds in medicinal dendrobiums for diabetic management through the mechanisms of lowering glucose level and reversing chronic inflammation of T2DM by modulating pancreatic ß-cell dysfunction and insulin resistance in liver as a result from gut microbita regulation.