A tissue-specific profile of miRNAs and their targets related to paeoniaflorin and monoterpenoids biosynthesis in Paeonia lactiflora Pall. by transcriptome, small RNAs and degradome sequencing.

Paeonia lactiflora Pall. (Paeonia) has aroused many concerns due to its extensive medicinal value, in which monoterpene glucoside paeoniflorin and its derivatives are the active chemical components. However, little is known in the molecular mechanism of monoterpenoids biosynthesis, and the regulation network between small RNAs and mRNAs in monoterpenoids biosynthesis has not been investigated yet. Herein, we attempted to reveal the tissue-specific regulation network of miRNAs and their targets related to paeoniaflorin and monoterpenoids biosynthesis in Paeonia by combining mRNA and miRNA expression data with degradome analysis. In all, 289 miRNAs and 30177 unigenes were identified, of which nine miRNAs from seven miRNA families including miR396, miR393, miR835, miR1144, miR3638, miR5794 and miR9555 were verified as monoterpenoids biosynthesis-related miRNAs by degradome sequencing. Moreover, the co-expression network analysis showed that four monoterpenoids-regulating TFs, namely AP2, MYBC1, SPL12 and TCP2, were putatively regulated by five miRNAs including miR172, miR828, miR858, miR156 and miR319, respectively. The present study will improve our knowledge of the molecular mechanisms of the paeoniaflorin and monoterpenoids biosynthesis mediated by miRNA to a new level, and provide a valuable resource for further study on Paeonia.

Toll-like receptor 4 deficiency alleviates lipopolysaccharide-induced intestinal barrier dysfunction.

BACKGROUND: The intestinal tract is considered the body's "engine" and the most impacted organ during sepsis. In this study, we explored toll-like receptor 4 (TLR4) functions in sepsis-induced intestinal barrier dysfunction. METHODS: Wild-type and TLR4-knockout (KO) mice were used to establish a sepsis-induced dysfunctional intestinal barrier model via the intraperitoneal injection of lipopolysaccharide (LPS, 10 mg/kg). Hematoxylin and eosin staining, Transmission electron microscope, enzyme linked immunosorbent assay, western blot, quantitative real-time polymerase chain reaction, TdT-mediated dUTP nick end labeling staining, 16 S rRNA gene sequencing were used to explore differences in inflammatory cytokines, apoptosis, tight junction (TJ) protein expression, and intestinal flora diversity between groups. RESULTS: TLR4-deficiency reduced procalcitonin and C-reactive protein to prevent sepsis, and also inhibited inflammatory response by decreasing interleukin (IL)- 1ß, IL-6 and tumor necrosis factor-α levels. Also, BAX/Bcl2 and cleaved-caspase 3 expressions were decreased in TLR4-KO mice to suppress the intestinal mucosal cell apoptosis. TJ proteins, including zonula occludens protein, Occludin and Claudin-5 were significantly increased and intestinal fatty acid binding protein, myosin light chain and myosin light chain kinase were reduced in TLR4-KO mice. Additionally, 16 S rRNA gene sequencing indicated that TLR4-deficiency improved flora diversity and altered normal and abnormal bacterial proportions. CONCLUSIONS: TLR4 deficiency alleviated LPS-induced intestinal barrier dysfunction by reducing inflammatory responses and apoptosis, impairing intestinal damage, and regulating intestinal flora disturbance.

Corrigendum: Polysaccharides of Dendrobium officinale Kimura & Migo leaves protect against ethanol-induced gastric mucosal injury via the AMPK/mTOR signaling pathway in vitro and vivo.

[This corrects the article DOI: 10.3389/fphar.2020.526349.].

[Effect of Tetrastigma hemsleyanum on sepsis and mechanism based on network pharmacology and experimental verification].

Based on network pharmacology and in vivo experiment, this study explored the therapeutic effect of Tetrastigma hemsle-yanum(SYQ) on sepsis and the underlying mechanism. The common targets of SYQ and sepsis were screened out by network pharmacology, and the "SYQ-component-target-sepsis" network was constructed. The protein-protein interaction(PPI) network was established by STRING. Gene Ontology(GO) term enrichment and Kyoto Encyclopedia of Genes and Genomes(KEGG) pathway enrichment were performed based on DAVID to predict the anti-sepsis mechanism of SYQ. The prediction results of network pharmacology were verified by animal experiment. The network pharmacology results showed that the key anti-sepsis targets of SYQ were tumor necrosis factor(TNF), interleukin(IL)-6, IL-1ß, IL-10, and cysteinyl asparate specific proteinase 3(caspase-3), which were mainly involved in Toll-like receptor 4(TLR4)/myeloid differentiation factor 88(MyD88)/nuclear factor kappaB(NF-κB) signaling pathway. The results of animal experiment showed that SYQ can decrease the content of C-reactive protein(CRP), procalcitonin(PCT), lactate dehydrogenase(LDH), IL-6, TNF-α, and IL-1ß, increase the content of IL-10, and down-regulate the protein levels of Bcl-2-associa-ted X(Bax)/B-cell lymphoma 2(Bcl2), cleaved caspase-3, TLR4, MyD88, and p-NF-κB p65/NF-κB p65. In summary, SYQ plays an anti-inflammatory role in the treatment of sepsis by acting on the key genes related to inflammation and apoptosis, such as TNF-α, IL-6, IL-lß, IL-10, Bax, Bcl2, and cleaved caspase-3. The mechanism is the likelihood that it suppresses the TLR4/MyD88/NF-κB signaling pathway, which verifies relative prediction results of network pharmacology.

Electroacupuncture at Zusanli Alleviates Sepsis by Regulating the TLR4-MyD88-NF-Kappa B Pathway and Diversity of Intestinal Flora.

Background: Electroacupuncture (EA) at the Zusanli acupoint (ST36) has shown therapeutic potential for sepsis due to its ability to limit inflammation and to regulate gastrointestinal tract symptoms. However, the mechanisms contributing to the effects of EA at ST36 on sepsis and connections with the intestinal flora remain unclear. This study was designed to explore the effects of EA at ST36 on Toll-like receptor 4 signaling and the intestinal flora. Methods: ICR mice were randomly divided into 4 groups: control group, model group, EA group, and sham EA group. EA at ST36 was performed at 2.5 mA and 2 to 100 Hz, and the 30 min of dense wave was achieved over 5 days. A sepsis model was built by intraperitoneal injection of lipopolysaccharide (LPS, 10 mg/mL). The levels of expression of interleukin-1ß (IL-1ß), IL-6, tumor necrosis factor-α (TNF-α), and IL-10 were detected by enzyme-linked immunosorbent assays, and lactate dehydrogenase (LDH) levels in serum were measured by biochemical tests. Expression levels of Bax, Bcl2, cleaved caspase-3, Toll-like receptor (TLR4), nuclear factor-kappa B (NF-κB), and myeloid differentiation factor 88 (MyD88) were assessed by the Western blotting. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining was used to evaluate apoptosis. The intestinal microecology was assessed via 16S rRNA gene sequencing. Results: EA at ST36 reduced the expression of IL-1ß, IL-6, and TNF-α and increased the expression of IL-10 to inhibit the inflammatory response. EA at ST36 also inhibited apoptosis, as measured by TUNEL staining, and decreased the Bax/Bcl2 ratio and levels of caspase-3 and cleaved caspase-3, as well as LDH release. Our results suggest that alleviation of sepsis may correlate with the downregulation of levels of TLR4, NF-κB, and MyD88. Importantly, EA at ST36 improved the diversity of the intestinal flora and increased the abundance of Firmicutes and Actinobacteria. Conclusion. EA at ST36 prevented sepsis from worsening by inhibiting inflammation and apoptosis, which correlated with the regulation of the TLR4/NF-κB/MyD88 signaling axis and modulation of the intestinal flora.

Tetrastigma hemsleyanum Diels et Gilg ameliorates lipopolysaccharide induced sepsis via repairing the intestinal mucosal barrier.

OBJECTIVE: Sepsis causes excessive systemic inflammation and leads to multiple organ dysfunction syndrome (MODS). The intestine plays a key role in the occurrence and development of sepsis. Tetrastigma hemsleyanum Diels et Gilg (San ye qing, SYQ), a precious Chinese medicine, has been widely used for centuries due to its high traditional value, such as a remarkable anti-inflammatory effect. However, the role of SYQ in intestinal permeability during the development of sepsis needs to be discovered. METHODS: Mice were intraperitoneally injected with lipopolysaccharide (LPS) to simulate intestinal mucosal barrier function damage in sepsis. Pathological section, inflammatory cytokines, tight junctions, cell apoptosis, and intestinal flora were detected to evaluate the protective effect of SYQ on intestinal mucosal barrier injury in LPS-induced septic mice. RESULTS: The results showed that SYQ treatment obviously attenuated LPS-induced intestinal injury and reduced the production of tumor necrosis factor α (TNF-α), interleukin 1ß (IL-1ß), and interleukin 6 (IL-6). Besides, SYQ also up-regulated the expressions of tight junctions, including Zonula occludens 1 (ZO-1), Claudin-5, and Occludin along with a decreased in the levels of myosin light chain kinase (MLCK) and myosin light chain (MLC). In addition, SYQ down-regulated the expression of Bax/Bcl2 as well as that of cleaved caspase-3 to prevent the cells from undergoing apoptosis. Further, SYQ restored the diversity of the intestinal flora, increased the abundance of Firmicutes, and decreased the abundance of Bacteroidota. CONCLUSIONS: The study indicated that SYQ exerted its protective effect on intestinal mucosal barrier injury in LPS-induced septic mice by reducing inflammatory response, improving the tight junction protein expression, inhibiting cell apoptosis, and adjusting the intestinal flora structure.

Soporific effect of modified Suanzaoren Decoction on mice models of insomnia by regulating Orexin-A and HPA axis homeostasis.

AIM: Modified Suanzaoren Decoction (MSZRD) is obtained by improving Suanzaoren Decoction (SZRT), a traditional Chinese herbal prescription that has been used to treat insomnia for more than thousands of years. Our previous study showed that MSZRD can improve the gastrointestinal discomfort related insomnia by regulating Orexin-A. This study is the first study to evaluate the effects and possible mechanisms of MSZRD in mice with insomnia caused by p-chlorophenylalanine (PCPA) combined with multifactor random stimulation. METHODS: After 14 days of multifactor stimulation to ICR mice, a PCPA suspension (30 mg/mL) was injected intraperitoneally for two consecutive days to establish an insomnia model. Three different doses of MSZRD (3.6, 7.2, and 14.4 g/kg/day) were given to ICR mice for 24 days. The food intake and back temperature were measured, and behavioral tests and pentobarbital sodium-induced sleep tests were conducted. The levels of Orexin-A, corticotropin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH), and adrenocortical hormones (CORT) in the serum and 5-hydroxytryptamine (5-HT), dopamine (DA), and norepinephrine (NE) in hypothalamus were measured using enzyme-linked immunosorbent assay (ELISA) kits. The levels of γ-aminobutyric acid (GABA) and glutamic acid (Glu) were measured by high-performance liquid chromatography (HPLC). The expression of 5HT1A receptor (5-HTRIA) and orexin receptor 2 antibody (OX2R) was measured by Western blot (WB) and immunohistochemical staining (ICH). Hematoxylin and eosin (H&E) staining and Nissl staining were used to assess the histological changes in hypothalamus tissue. RESULTS: Of note, MSZRD can shorten the sleep latency of insomnia mice (P < 0.05, 0.01), prolonged the sleep duration of mice (P < 0.05, 0.01), and improve the circadian rhythm disorder relative to placebo-treated animals. Furthermore, MSZRD effectively increased the content of 5-HT and 5-HTR1A protein in the hypothalamus of insomnia mice (P < 0.05, 0.01), while downregulated the content of DA and NE (P < 0.05, 0.01). Importantly, serum GABA concentration was increased by treatment with MSZRD (P < 0.05), as reflected by a decreased Glu/GABA ratio (P < 0.05). Moreover, MSZRD decreased the levels of CORT, ACTH, and CRH related hormones in HPA axis (P < 0.05, 0.01). At the same time, MSZRD significantly downregulated the serum Orexin-A content in insomnia mice (P < 0.05), as well as hypothalamic OX2R expression (P < 0.05). In addition, MSZRD also improved the histopathological changes in hypothalamus in insomnia mice. CONCLUSION: MSZRD has sleep-improvement effect in mice model of insomnia. The mechanism may be that regulating the expression of Orexin-A affects the homeostasis of HPA axis and the release of related neurotransmitters in mice with insomnia.

Uncovering the Pharmacology of Xiaochaihu Decoction in the Treatment of Acute Pancreatitis Based on the Network Pharmacology.

BACKGROUND: Xiaochaihu decoction (XD) has demonstrated the pharmacodynamics on acute pancreatitis. This study was aimed at investigating the material and molecular basis of Xiaochaihu decoction. METHODS: Firstly, compounds of seven herbs containing XD were collected from the TCMSP, ETCM, and BATMAN-TCM databases, and the putative targets of pancreatitis were obtained from the OMIM, TTD, and GeneCards databases. Then, the PPI network was constructed according to the matching results between XD potential targets and pancreatic neoplasm targets. Furthermore, enrichment analysis on GO and KEGG by DAVID utilized bioinformatics resources. Finally, molecular docking was performed to simulate the interaction between the active compound of XD and putative targets. In an in vitro experiment, AR42J cells were induced by LPS and then treated with Quercetin (25, 50, and 100 µM) or XCHD. The IL-6, TNF-α, and IL-1ß levels were detected by ELISA kit, MAPK3 and TP53 mRNA expressions were measured by qRT-PCR, and the proteins of MAPK3 and TP53 expressions were measured by WB. RESULTS: A total of 196 active ingredients and 91 putative targets were selected. The PPI network analysis demonstrated that Quercetin was the candidate agent and MAPK3, IL-6, and TP53 were the potential targets for the XD treatment of acute pancreatitis. The KEGG analysis revealed that pathways in cancers, TNF signaling way, and MAPK signaling way might play an important role in pancreatitis therapy. And molecular docking results showed that Quercetin combined well with MAPK3, IL-6, and TP53. An in vitro experiment indicated that XCHD and Quercetin inhibited the IL-6, TNF-α, and IL-1ß levels and MAPK3 and TP53. CONCLUSION: This study illustrated that XCHD and Quercetin contained in XD played an important role in the treatment of acute pancreatitis by acting on the key genes of MPAK3, IL-6, and TP53 which were associated with inflammation and apoptosis.

Polysaccharides of Dendrobium officinale Kimura & Migo Leaves Protect Against Ethanol-Induced Gastric Mucosal Injury via the AMPK/mTOR Signaling Pathway in Vitro and vivo.

Ethanol-induced gastric mucosal injury is a common gastrointestinal disorder. Polysaccharides separated from herbs have been shown to be effective for ethanol-induced gastric mucosal injury, but whether the polysaccharides from Dendrobium officinale Kimura & Migo leaves (LDOP-1) protected mucosa from ethanol-induced injury remains unknown. Thus, the present study carried out gastric mucosal protection and the mechanism of LDOP-1 in vivo and vitro. The chemical composition of LDOP-1 was a heteropolysaccharide comprising mannose, galacturonic acid, glucose, galactose, and arabinose at a molar ratio of 2.0:1.1:0.7:0.5:0.4. Pharmacological results showed that LDOP-1 significantly reduced gastric mucosal injury score and pathological injury, improved antioxidant capacity, reduced the level of reactive oxygen species, and reversed the apoptosis of GES-1 in vivo and vitro. Research showed that LDOP-1 pretreatment upregulated the expression level of p-AMPK, LC3ß, HO-1, and Beclin-1; downregulated the expression level of p-mTOR and p62; and reversed the expression level of caspase3, Bax, and Bcl-2. This study was the first to demonstrate that LDOP-1 could protect against ethanol-induced gastric mucosal injury via the AMPK/mTOR signaling pathway in vitro and vivo.

Anti-inflammatory effect of Ganluyin, a Chinese classic prescription, in chronic pharyngitis rat model.

BACKGROUND: Ganluyin (GLY) is a famous classical prescription with a long history of use as a treatment for inflammatory conditions such as chronic pharyngitis (CP) in many parts of China. However, it has not been developed as a modern pharmaceutic and its anti-inflammatory mechanisms remain unclear. The aim of this study was to assess the anti-inflammatory efficacy of GLY and potential mechanisms in a rat model of CP. METHODS: The chemical profile of GLY was analyzed by HPLC-UV. We used a mouse model of ear edema and a rat model of paw edema. Specifically, xylene was used to induce edema on the surface of one ear in mice, and carrageenan was injected subcutaneously into the right hind paws of rats to induce paw edema. The paw thickness, ear weight, and ear perfusion were measured and recorded. The CP model in rats was induced by irritating the throat with 5% ammonia and was used to evaluate the therapeutic efficacy of GLY. Levels of interleukin-6 (IL-6), interleukin-1ß (IL-1ß), tumor necrosis factor (TNF-α), and prostaglandin E2 (PGE2) were measured by ELISA in serum, and protein expression of cyclooxygenase-2 (COX-2) and nuclear factor kappa-B p65 (NF-κB p65) in the throat were detected by immunohistochemistry and Western blot to evaluate the anti-inflammatory mechanism of GLY. Hematological assays were also conducted. RESULTS: There were four flavonoids identified in GLY: naringin, neohesperidin, baicalin, and wogonoside. The oral administration of GLY showed a significant inhibitory effect on xylene-induced ear swelling and ear blood flow in mice and significantly ameliorated rat right hind paw edema at doses of 6.2 and 12.4 g/kg. Mechanistic studies found that the anti-inflammatory activity of GLY was related to the inhibition of pro-inflammatory cytokines such as IL-1ß, IL-6, TNF-α, and PGE2 and that GLY reduced the expression of COX-2 and NF-κB p65 proteins in the throat, attenuated throat injury, and reduced inflammatory exudates. Hematological analysis showed that treatment with GLY prevented increases in white blood cell (WBC), neutrophil (NEUT), lymphocyte (LYMPH) and monocyte (MONO) levels. CONCLUSIONS: These studies indicated that GLY has beneficial anti-inflammatory effects on CP and that it acts through reducing pro-inflammatory factors such as IL-1ß, IL-6, TNF-α, and PGE2, as well as decreasing WBC, NEUT, LYMPH and MONO levels and decreasing the expression of COX-2 and NF-κB p65 proteins. These findings may lay the groundwork for further studies of GLY as a suitable candidate for the treatment of inflammatory diseases such as CP.

Soporific Effect of Modified Suanzaoren Decoction and Its Effects on the Expression of CCK-8 and Orexin-A.

Suanzaoren decoction (SZRT), a classic Chinese herbal prescription, has been used as a treatment for insomnia for more than a thousand years. However, recent studies have found no significant effects of SZRT as a treatment for insomnia caused by gastric discomfort. Herein, we studied the effects of modified Suanzaoren decoction (MSZRD) on gastrointestinal disorder-related insomnia. The main constituents of MSZRD were spinosin (2.21 mg/g) and 6-feruloylspinosin (0.78 mg/g). A pentobarbital-induced animal model of insomnia showed that MSZRD shortened sleep latency and prolonged sleep time of the male Institute of Cancer Research (ICR) mice treated for 7 days with oral MSZRD. Sprague-Dawley male rats were treated daily with oral MSZRD or placebo for 11 days and then deprived of sleep for the last 4 days to establish a model of insomnia. Of note, MSZRD-treated animals had significantly improved body weight, organ index scores, and fecal moisture relative to placebo-treated animals, as well as reduced temperature. Sleep-deprived rats exhibited more exploratory behaviors in an open-field anxiety test; however, this effect was significantly reduced in MSZRD-treated animals. We found that MSZRD treatment decreased gastric acid pH, decreased the production of gastrin, pepsin, and Orexin-A, and increased the expression of MTL and CCK-8. Importantly, serum GABA concentration was increased by treatment with MSZRD, as reflected by a decreased Glu/GABA ratio. Treated animals had increased the expression of GAD1, GABARA1, and CCKBR but decreased the expression of Orexin R1. In summary, these results suggest that MSZRD has soporific and gastroprotective effects that may be mediated by differential expression of CCK-8 and Orexin-A.

Dendrobium officinale polysaccharides protected against ethanol-induced acute liver injury in vivo and in vitro via the TLR4/NF-κB signaling pathway.

Alcohol-induced liver injury is characterized by strong inflammation. Polysaccharides separated from herbs can prevent ethanol-induced liver injury. Dendrobium officinale Kimura et Migo leaves (D. officinale) are a new food resource that contains a certain amount of polysaccharide. However, the hepatoprotective effects and the potential mechanisms of D. officinale polysaccharide (DOP) remain unknown. Thus, this study aimed to assess the hepatoprotective effects and potential mechanism in vivo and in vitro of DOP. Male Sprague-Dawley rats were used to establish alcohol-induced liver injury models through the oral gavage of absolute alcohol (5 mL/kg) after the oral administration of DOP (400 and 100 mg/kg) for 30 days. Hematoxylin-eosin staining was used for the histological assessments of hepatocyte degeneration, and the AST and ALT levels in the serum and liver tissue were measured. The inflammatory markers were evaluated using ELISA and immunohistochemistry. The potential mechanism of DOP in alcohol-induced liver cell (LO2) injury in vitro was further identified. Results showed that DOP clearly decreased the AST in the serum and hepatic tissue, obviously reduced the production of inflammatory cytokines (such as IL-1ß, IL-6, and TNF-α), and can successfully inhibit NF-κB phosphorylation in vivo. In vitro experiments indicated that DOP increased the LO2 cell viability; prevented LDH release prominently; reduced the secretion of IL-1ß, IL-6, and TNF-α; and reversed the expression of IL-1ß, IL-6, TNF-α, caspase 1, NLRP3, p-NF-κB, and TLR4. Overall, DOP can alleviate ethanol-induced acute liver injury via the TLR4/NF-κB signaling pathway.

Beneficial Effects of Macroporous Resin Extract of Dendrobium candidum Leaves in Rats with Hyperuricemia Induced by a High-Purine Diet.

Objectives. The incidence of hyperuricemia (HUA) is increasing year by year, and there are no ideal drugs for the treatment; the existing ones can cause serious liver and kidney damage. We have confirmed that the water extract of Dendrobium candidum leaves could reduce the level of uric acid in rats, but the active ingredients remain unknown, and the mechanism is not well understood. This research investigated the therapeutic effect of the macroporous resin extract of the Dendrobium candidum leaf (DLE) on hyperuricemia. In this study, hyperuricemia was induced in rats by a 5-week high-purine diet. After that, DLE was administered continuously for 9 weeks. The result showed that biochemical parameters of liver and kidney function, especially serum uric acid (UA) levels, were significantly improved with DLE, which may relate to the reduction of xanthine oxidase (XOD) and adenosine deaminase (ADA) in the liver. Moreover, DLE could significantly prevent kidney and liver from damage, and intestinal injury and reduce inflammation in hyperuricemic rats by inhibiting the expression of both NF-κB and TLR4 proteins. These results showed that the macroporous resin extract of the Dendrobium candidum leaves may be effective for the treatment of hyperuricemia in rats by inhibiting uric acid production and decreasing inflammation.

Physicochemical characterization of polysaccharide from the leaf of Dendrobium officinale and effect on LPS induced damage in GES-1 cell.

The polysaccharide was first successfully isolated from the leaf of Dendrobium officinale by hot water extraction and alcohol precipitation and further purified using DEAE-52 and Sephadex G-100 chromatography. The structure of LDOP-1 was characterized by HPLC, GPC, and FT-IR and NMR spectroscopy, and its protective effect on LPS-induced GES-1 cell injury was analyzed. Results showed that LDOP was a homogeneous polysaccharide with average molecular weight of 91.8 kDa and consisted of Man, Gla, Glc, Glc acid, and Ara at a molar ratio of 2.0:1.3:1.6:1.7:0.7. LDOP had two types of residues, including 1,6-linked α-d-Glup and 1,4-linked α-d-Manp. Activity studies indicated that LDOP-1 can significantly suppress the release of tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), and IL-6 from LPS-induced GES-1 cell injury, decreased the protein expressions of TLR4, phospho-NF-κB, ASC, NLRP3, cleaved-IL-1ß, IL-6, and Bax, increased the protein expression of Bcl-2, and downregulated the ratios of cleaved caspase-1 to pro-caspase-1, phospho-IκBα to IκBα, and phospho-NF-кB to NF-κB. These findings strongly suggested that LDOP can prevent LPS-induced GES-1 cell injury by inhibiting the release of inflammatory cytokines regulated via the TLR4/NF-κB signal pathways.

Optimization of Flavonoid Extraction in Dendrobium officinale Leaves and Their Inhibitory Effects on Tyrosinase Activity.

In order to establish the extraction technology of flavonoids from Dendrobium officinale leaves, a method combining Plackett-Burman design (PBD), steepest ascent design, and central composite design was developed to optimize the extraction of flavonoids. In addition, the tyrosinase activity inhibition of flavonoids was further tested in vitro. PBD results showed that ethanol concentration and number of extractions were key factors. Response surface methodology (RSM) indicated that the optimal extraction conditions were 78% ethanol concentration, six extraction times, 2 h, and 1:50 solid-liquid ratio. Under these conditions, the total flavonoid content could reach 35 mg/50 mL. In vitro tyrosinase experiment, the extracted total flavonoids had better inhibitory effect on tyrosinase activity than ß-arbutin, and its inhibition rate for monophenolase and diphenolase exceeded 100% and 70%, respectively. These results indicate that RSM can effectively improve the extraction of flavonoids from Dendrobium officinale leaves and the flavonoids have the prospect of being applied to foods and cosmetics.