Bioactive components and antioxidant activities of oak cup crude extract and its four partially purified fractions by HPD-100 macroporous resin chromatography

Transcriptome analysis reveals important regulatory factors for condensed tannins synthesis in acorn

Condensed tannins are widely present in the fruits and seeds of plants and effectively prevent them from being eaten by animals before maturity due to their astringent taste. In addition, condensed tannins are a natural compound with strong antioxidant properties and significant antibacterial effects. Four samples of mature and near-mature Quercus fabri acorns, with the highest and lowest condensed tannin content, were used for genome-based transcriptome sequencing. The KEGG enrichment analysis revealed that the differentially expressed genes (DEGs) were highly enriched in phenylpropanoid biosynthesis and starch and sucrose metabolism. Given that the phenylpropanoid biosynthesis pathway is a crucial step in the synthesis of condensed tannins, we screened for significantly differentially expressed transcription factors and structural genes from the transcriptome data of this pathway and found that the expression levels of four MADS-box, PAL, and 4CL genes were significantly increased in acorns with high condensed tannin content. The quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) experiment further validated this result. In addition, yeast one-hybrid assay confirmed that three MADS-box transcription factors could bind the promoter of the 4CL gene, thereby regulating gene expression levels. This study utilized transcriptome sequencing to discover new important regulatory factors that can regulate the synthesis of acorn condensed tannins, providing new evidence for MADS-box transcription factors to regulate the synthesis of secondary metabolites in fruits.

Antioxidant and Antifungal Activities and Characterization of Phenolic Compounds Using High-Performance Liquid Chromatography and Mass Spectrometry (HPLC-MS) in Empetrum rubrum Vahl ex Willd

In searching for compounds with antioxidant and antifungal activity, our study focused on the subshrub species Empetrum rubrum Vahl ex Willd. (Ericaceae). We measured the antioxidant activity of its methanolic extract (MEE) obtained from the aerial parts (leaves and stems) and of its methanolic extract (MEF) obtained from the lyophilized fruits. The antioxidant activity of the MEE and MEF was evaluated in vitro via a 2,2-Diphenyl-1-picrylhydrazyl (DPPH) free radical and 2,2'-Azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) cationic radical. The results were expressed in gallic acid and Trolox equivalents for the DPPH and ABTS assays, respectively. The antioxidant activities, for the DPPH and ABTS assays, were also evaluated by considering the IC50 values. Concerning the antioxidant activity, the total phenolic content (TPC) in the MEE and MEF was determined using the Folin-Ciocalteu method. Polyphenols contained in the leaves, stems, and fruits of E. rubrum were determined qualitatively by employing high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS) analysis. The antifungal activity of the MEE obtained from the aerial parts of E. rubrum was tested against Rhizoctonia solani. The results of IC50 values measured by the DPPH and ABTS methods with MEE were 0.4145 ± 0.0068 mg mL-1 and 0.1088 ± 0.0023 mg mL-1, respectively, and the IC50 values for MEF were 6.4768 ± 0.0218 mg mL-1 and 0.7666 ± 0.0089 mg mL-1 measured by the DPPH and ABTS methods, respectively. The HPLC-MS analysis revealed the presence of anthocyanins, phenolic acids derivatives, and flavonols. In vitro, mycelial growth of this fungus was reduced from 90% to nearly 100% in the presence of MEE. The observed antifungal effect is related to the presence of the abovementioned phenols, detected in the MEE.

Pinobanksin from peony seed husk: A flavonoid with the potential to inhibit the proliferation of SH-SY5Y

Pinobanksin, as one of the flavonoids, has powerful biological activities but has been under-recognized. In this study, we optimized the extraction method of phragmites from peony seed shells by using organic solvent extraction. The yield of PSMS was 10.54 ± 0.13% under the conditions of ethanol volume fraction 70%, extraction temperature 70°C, material-liquid ratio 1:25 g/mL, and extraction time 60 min; the optimized PSMS could be effectively separated in S-8 macroporous resin coupled with C18. The relative content of PSMS was increased from 0.42% in PSMS to 92.53% after C18 purification; the antioxidant activity test revealed that pinobanksin could exert antioxidant ability by binding catalase (CAT) enzyme. Second, it was found that pinobanksin could effectively inhibit the proliferation of SH-SY5Y cells, mainly by binding to BCL2-associated X (BAX), B-cell lymphoma-2 (BCL-2), and cyclin-dependent Kinase 4/6 (CDK4/6) to produce more hydrogen bonds to inhibit their activities. This study confirms the medicinal potential of pinobanksin and provides the basis for the proper understanding of pinobanksin and the development of related products.

Effect of mixing oak leaf biomass with soil on cadmium toxicity and translocation in tomato genotypes

The environmental non-element cadmium (Cd) is toxic to all forms of life, and it also has a negative impact on plant development and growth. In order to ascertain the effects of cadmium on tomato growth and the function of oak leaf biomass in the reduction of toxicity and translocation of cadmium in different parts of tomato genotypes, two tolerant and two sensitive tomato genotypes were exposed to cadmium stress through the availability or unavailability of oak leaf biomass. The experiment involved two factors. The first factor was the various treatment levels, including soil without Cd treatment and sodium hydroxide (NaOH) oak leaf biomass pretreatment (COC-control), soil with Cd treatment and without NaOH oak leaf biomass pretreatment (CdC), and soil with Cd treatment and NaOH oak leaf biomass pretreatment (CdOBC). The second element consists of four tomato genotypes. Comparing to control conditions, all tomato genotypes spotted significant reductions in all morphological traits under Cd stress in the presence or absence of NaOH oak leaf pretreatment. Related to CdC conditions, root length, shoot length, root fresh weight per plant, shoot fresh weight per plant, root dry weight per plant, shoot dry weight per plant, and total fruit weight per plant were significantly improved by 4.25%, 9.75%, 23.24%, 10.10%, 28.10%, 9.08%, and 4.61%, respectively, under the availability of pretreatment of oak leaf biomass. The tolerant genotypes (Karazi and Sirin) exhibited the greatest increase in all traits evaluated, with the exception of root length, under the CdOBC condition compared to the CdC statement. Significant increases in leaf biochemical parameters were seen with the availability or absence of NaOH pretreatment of oak leaf biomass in the soil. The maximum values of proline content, soluble sugar content, antioxidant activity, and guaiacol peroxidase were stated in the presence of oak biomass under Cd conditions (CdOBC), with mean values of 1772.46 μg g -1, 687.18 μg g -1, 1025.74 μg g -1-, and 0.43 units min -1 g -1, respectively. The in vitro-tolerant genotypes exhibited the maximum values of all biochemical parameters. The concentration of cadmium in the studied tomato genotypes revealed that cadmium accumulated more in the roots than other parts. According to these outcomes, NaOH pretreatment of oak leaf biomass can be employed to diminish the hazard of cadmium absorption by edible parts.

Traits variation of acorns and cupules during maturation process in Quercus variabilis and Quercus aliena

Quercus variabilis and Quercus aliena are two native tree species in China, which have similar habitats, and their regeneration mainly depends on acorn dispersal. This study analyzed the contents of water, soluble sugar, starch, soluble protein, and total phenolics in acorns and cupules during the whole development process to explore the difference between species. Thereinto, starch and total phenol occupied the dominant roles as their high contents. The acorn starch contents increased sharply during development in both species, but the contents in Q. variabilis were almost twice those of Q. aliena when mature. Similarly, high expression levels of starch synthase, soluble starch synthase 2 (SSS2) were also found in the acorns of Q. variabilis. The total phenol contents in Q. variabilis acorns were high at the early stages, and decreased sharply to similar contents in Q. aliena when mature. Additionally, the cupules in Q. variabilis had high contents of total phenols during the whole development period. Similar trends were also found in the expression patterns of UGT84A13 and SDH. The high total phenols in acorns and cupules of Q. variabilis probably protect the acorns from Mechoris ursulus, as only Q. aliena suffered a severe pest infestation in the early development stages. This study not only clarifies the interspecific difference between storage and defense substances during the development process in acorns and cupules, but also deepens understanding the specialized mechanisms of plant-pest/animal interactions in Quercus.

Catechin, rutin and quercetin in Quercus mongolica Fisch leaves exert inhibitory effects on multiple cancer cells

We aimed to identify anti-tumor agents in Quercus mongolica Fisch (QMF). Bioactive compounds in QMF leaves, which were extracted using ethanol as a co-solvent. Five point zero six grams of flavonoids were obtained from 100 g of QMF leaves. Catechin (18.4%), rutin (6.3%), ellagic acid (34.9%), quercetin (5.1%) and kaempferol (20.6%) are the main ingredients of the extracts and were further purified by HPLC. CCK-8 cell proliferation assay showed that catechin and ellagic acid exerted strong inhibitory effects on the proliferation of all cancer cells with lower IC₅₀ values against MCF-7 human breast cancer cell lines, SMMC-7721 human hepatocellular carcinoma cells, HeLa human cervical carcinoma cell lines and SKOV3 human ovarian carcinoma cell lines (p < .05). Catechin, rutin and quercetin induced a higher rate of apoptosis and inhibited all cancer cell proliferation by inducing the G0/G1 phase and G2/M phase arrest (p < .05). However, ellagic acid induced tumor cell death, not through apoptosis and there may be other molecular mechanisms. High levels of catechin and ellagic acid in QMF can be developed as potential drugs to treat different types of cancer cells. PRACTICAL APPLICATIONS: Quercus species have been widely studied because of their antioxidant, anti-inflammatory, antimicrobial, and anti-tumor properties. Bioactive compounds in the leaves of Quercus mongolica Fisch have high levels of catechin and ellagic acid, which exert significant inhibitory properties on the proliferation of various types of cancer cells. Therefore, the bioactive compounds may be potential natural drugs in the prevention of cancer development and progression.

Antibacterial composition of bioautographic fractions, characteristics, and stability of Carica papaya seed extract

The present work aimed to evaluate the potential of Carica papaya seed extract (CPSE) as an antibacterial agent against Salmonella Enteritidis, Bacillus cereus, Vibrio vulnificus, and Proteus mirabilis. The bioautography of the CPSE on thin-layer chromatography (TLC) plates was performed, followed by fractionation of the CPSE by column chromatography using hexane:ethyl acetate (1:1) eluent. Minimum Inhibitory Concentration (MIC), toxicity, composition, and stability of the crude, fractions, and sub-fractions of the CPSE were evaluated. The bioautographic fractions of the CPSE at MIC of 5.63 mg/mL had shown that hexane:ethyl acetate (1:1) fraction and its sub-fraction 3C (Rf = 0.94 ± 0.03) demonstrated the equivalent MIC value (5.63 mg/mL) with the crude CPSE. However, the hexane:ethyl acetate (1:1) fraction and sub-fraction 3C had higher toxicity (LC50 = 1.797 ± 0.305 and 0.332 ± 0.059 mg/mL, respectively) than the crude CPSE (LC50 = 5.505 ± 0.718 mg/mL). Thus, only the crude CPSE was subjected to stability study. The dominant cis-vaccenic acid in sub-fraction 3C demonstrated the lowest MIC against B. cereus (1.41 mg/mL), P. mirabilis (1.41 mg/mL), and S. Enteritidis (0.70 mg/mL) in its pure form. Hence, these results signified the potency of the cis-vaccenic acid as an antibacterial compound from the CPSE. The stability study of the crude CPSE solution showed that at MIC of 5.63 mg/mL, the crude CPSE solution acted as a potent antibacterial agent in acidic condition (pH 4), water activity (Aw) < 0.950, and temperature < 40°C.

Optimization of Enzyme-Assisted Extraction and Purification of Flavonoids from Pinus koraiensis Nut-Coated Film and Antioxidant Activity Evaluation

Pinus koraiensis nut-coated film is a kind of by-product of nut processing, which has been shown to contain flavonoids, polyphenols, and other substances that can be used to produce natural antioxidant extracts. In this study, response surface methodology (RSM) was used to optimize the extraction process of flavonoids of P. koraiensis nut-coated film (PNF), and macroporous resin HPD600 was used to purify PNF (P-PNF). Its antioxidant activity was examined by DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging capacity, oxygen free radical absorption capacity (ORAC), total oxygen radical capture (TRAP), and iron ion reduction capacity. Under the ideal extraction conditions comprising a cellulase dosage of 90 U/g, a material/liquid ratio of 1:20 (g/mL), and an extraction time of 2 h, the PNF yield was 3.37%. Purification conditions were sample concentration of 2.0 mg/mL, pH of 5, water washing volume of 3 bed volume (BV), eluent ethanol concentration of 50%, and volume of 2 BV. The P-PNF recovery was 84.32%, and purity increased from 33.80% to 61.70%. Additionally, P-PNF showed increased antioxidant activity compared to PNF. Cumulatively, this study obtained the optimal values for the process parameters in order to achieve the maximum rates of extraction of PNF for economically optimal production at an industrial scale.

Antioxidant evaluation-guided chemical profiling and structure-activity analysis of leaf extracts from five trees in Broussonetia and Morus (Moraceae)

Morus and Broussonetia trees are widely used as food and/or feed. Among 23 phenolics identified from leaves of five Moraceae species using UPLC–QTOF–MS/MS, 15 were screened using DPPH/ABTS-guided HPLCs, including seven weak (flavonoids with one hydroxyl on B-ring) and eight strong (four caffeoylquinic acids and four flavonoids, each with a double hydroxyl on B-ring) antioxidants. We then determined the activity and synergistic effects of individual antioxidants and a mixture of the eight strongest antioxidants using DPPH-guided HPLC. Our findings revealed that (1) flavonoid glucuronide may have a more negative effect on antioxidant activity than glucoside, and (2) other compounds in the mixture may exert a negative synergistic effect on antioxidant activity of the four flavonoids with B-ring double hydroxyls but not the four caffeoylquinic acids. In conclusion, the eight phenolics with the strongest antioxidant ability reliably represented the bioactivity of the five extracts examined in this study. Moreover, the Morus alba hybrid had more phenolic biosynthesis machinery than its cross-parent M. alba, whereas the Broussonetia papyrifera hybrid had significantly less phenolic machinery than B. papyrifera. This difference is probably the main reason for livestock preference for the hybrid of B. papyrifera over B. papyrifera in feed.

Hypoglycemic Effects in Alloxan-Induced Diabetic Rats of the Phenolic Extract from Mongolian Oak Cups Enriched in Ellagic Acid, Kaempferol and Their Derivatives

Our previous reports showed that crude extract prepared with 50% ethanol (ethanol crude extract, ECE) from Mongolian oak cups possessed excellent in vitro antioxidant capacities as well as inhibitory activities against α-glucosidase, α-amylase and protein glycation caused by its enrichment in phenolics, including mainly ellagic acid, kaempferol and their derivatives. Nevertheless, few in vivo studies on antidiabetic activities of these phenolics were conducted. The present study investigated hypoglycemic effects with normal and diabetic rats being administrated orally without or with ECE at 200 and 800 mg/kg for 15 days. In normal rats, no significant differences were exhibited after ECE administration in body weight, fasting blood glucose level, levels of cholesterol, triglyceride, LDL and AST in serum, organ indexes, and levels of GSH and MDA in organs. In diabetic rats, the fasting blood glucose level, indexes of heart and liver, and levels of cholesterol and triglyceride in serum and MDA in heart tissue were significantly decreased. Moreover, HDL levels in serum and SOD activities in the four organs of diabetic rats were significantly improved after ECE administration at 800 mg/kg. Thus, in addition to inhibiting α-glucosidase, α-amylase and protein glycation reported previously, oak cups might contain novel dietary phytonutrients in preventing abnormal changes in blood glucose and lipid profile and attenuating oxidant stress in vivo. The results also implied that it is ellagic acid, kaempferol and their derivatives enriched in ECE that might play vital roles in managing type 1 as well as type 2 diabetes.

Comparative evaluations on phenolic antioxidants of nine adulterants and anti-inflammation of four alternatives with their original herb Erycibe schmidtii

Erycibe schmidtii is widely used as folk medicine in China for treatments of various inflammations.