Activities of muscadine grape skin and quercetin against Helicobacter pylori infection in mice

Aims: To explore the preventative potential of muscadine grape skin (MGS) and the single flavonoid, quercetin, as an alternative means for ameliorating Helicobacter pylori infection and/or the H. pylori‐induced inflammatory response in mice. Methods and Results: The antimicrobial and anti‐inflammatory properties of MGS and quercetin, a major phenolic constituent, were evaluated against H. pylori in vitro and in vivo. The antimicrobial activity of quercetin was evaluated against 11 H. pylori strains in vitro with inhibition of all strains at 128–64 μg ml^?1. In vivo studies showed a moderate reduction in H. pylori counts following treatment with 5 and 10% MGS or quercetin (25 mg kg^?1 body weight) in addition to significantly reduced inflammatory cytokines (TNF‐α, IL‐1β and IFN‐γ) when compared with untreated mice. Conclusions: MGS and quercetin did not significantly reduce H. pylori growth in a mouse model. However, these products were effective in regulating the inflammatory response to H. pylori infection. Significance and Impact of the Study: Our results suggest that H. pylori infection may be reduced or prevented via the consumption of fruits rich in certain phenolic compounds (e.g. quercetin) such as muscadine grapes.     

Genetic engineering approach for the production of rhamnosyl and allosyl flavonoids from Escherichia coli

The main functions of glycosylation are stabilization, detoxification and solubilization of substrates and products. To produce glycosylated products, Escherichia coli was engineered by overexpression of TDP‐L ‐rhamnose and TDP‐6‐deoxy‐D ‐allose biosynthetic gene clusters, and flavonoids were glycosylated by the overexpression of the glycosyltransferase gene from Arabidopsis thaliana. For the glycosylation, these flavonoids (quercetin and kaempferol) were exogenously fed to the host in a biotransformation system. The products were isolated, analyzed and confirmed by HPLC, LC/MS, and ESI‐MS/MS analyses. Several conditions (arabinose, IPTG concentration, OD₆₀₀, substrate concentration, incubation time) were optimized to increase the production level. We successfully isolated approximately 24 mg/L 3‐O‐rhamnosyl quercetin and 12.9 mg/L 3‐O‐rhamnosyl kaempferol upon feeding of 0.2 mM of the respective flavonoids and were also able to isolate 3‐O‐allosyl quercetin. Thus, this study reveals a method that might be useful for the biosynthesis of rhamnosyl and allosyl flavonoids and for the glycosylation of related compounds. Biotechnol. Bioeng. 2010;107: 154–162. © 2010 Wiley Periodicals, Inc.     

Polyphenols,flavonoids, antioxidant activity in leaves and flowers of Tunisian Globularia alypum L. (Globulariaceae)

Leaves and flowers from Tunisian Globularia alypum were assessed for their phenolic and flavonoid contents and antioxidant activity. Phenolic (15.5–22.30 mg GAE g^?1 DW) and flavonoid (3.63–4.72 mg RE g^?1 DW) contents varied according to plant part. Globularia alypum leaves exhibited the highest phenol and flavonoid contents, and displayed the highest antioxidant activity, based on radical‐scavenging activity (295 μmol TEAC g^?1 DW) and ferric reducing power (24.27 mmol Fe2+/l). The obtained results demonstrated that some of the isolated compounds play an important role for the antioxidant activity of G. alypum and give a scientific basis to the use of this plant in traditional medicine. The methanolic extract of G. alypum could be considered as a source of potential antioxidants and will promote the reasonable usage of this plant in food technology and processing as well as for medical use.     

Antioxidant,anti‐inflammatory,and enzyme inhibitory activity of natural plant flavonoids and their synthesized derivatives

The synthesized flavonoid derivatives were examined for their antioxidant, anti‐inflammatory, xanthine oxidase (XO), urease inhibitory activity, and cytotoxicity. Except few, all the flavonoids under this study showed significant antioxidant activity (45.6%–85.5%, 32.6%–70.6%, and 24.9%–65.5% inhibition by DPPH, ferric reducing/antioxidant power, and oxygen radical absorption capacity assays) with promising TNF‐α inhibitory activity (42%–73% at 10 μM) and IL‐6 inhibitory activity (54%–81% at 10 μM) compared with that of control dexamethasone. The flavonoids luteolin, apigenin, diosmetin, chrysin, O^3?, O⁷‐dihexyl diosmetin, O^4?, O⁷‐dihexyl apigenin, and O⁷‐hexyl chrysin, showed an inhibition with IC₅₀ values (4.5‐8.1 μg/mL), more than allopurinol (8.5 μg/mL) at 5 μM against XO and showing more than 50% inhibition at a final concentration (5 mM) with an IC₅₀ value of ranging from 4.8 to 7.2 (μg/mL) in comparison with the positive control thiourea (5.8 μg/mL) for urease inhibition. Thus, the flavonoid derivatives may be considered as potential antioxidant and antigout agents.     

Seed Polyphenolic Profile,Antioxidative Activity,and Fatty Acids Composition of Wild and Cultivated Carthamus Species

Total flavonoid content (TFC) and cyanidin‐3‐glucoside (Cyd‐3‐glu) of seed and seed coat extract of 16 genotypes from five species of Carthamus were studied, and their major polyphenolic compounds and antioxidant activity of the seed coat extracts were determined using HPLC analysis and DPPH assay, respectively. Additionally, fatty acids composition of the seed oil was analyzed by GC. In general, TFC and Cyd‐3‐glu content of seed coat extracts were higher than those of seed extracts. A novel breeding line with black seed coat (named A82) depicted lower TFC (3.79 mg QUE/g DW) but higher Cyd‐3‐glu (24.64 mg/g DW) compared to the white and other seed‐pigmented genotypes. DPPH radical scavenging activity showed a strong association with Cyd‐3‐glu content (r = 0.84), but no correlation with TFC (r = ?0.32). HPLC analysis of seed coat extracts revealed that four compounds were dominant constituents including rutin (7.23 – 117.95 mg/100 g DW), apigenin (4.37 – 64.88 mg/100 g DW), quercetin (3.09 – 14.10 mg/100 g DW), and ferulic acid (4.49 – 30.41 mg/100 g DW). Interestingly, the genotype A82 with an appropriate polyunsaturated/saturated fatty acids index (5.46%) and a moderate linoleic fatty acid content (64.70%) had higher nutritional and pharmaceutical value than all the other genotypes.     

Flavonoid glucuronides are substrates for human liver beta-glucuronidase

Quercetin glucuronides are the main circulating metabolites of quercetin in humans. We hypothesise that the potential availability of the aglycone within tissues depends on the substrate specificity of the deconjugating enzyme beta-glucuronidase towards circulating flavonoid glucuronides. Human tissues (small intestine, liver and neutrophils) exhibited beta-glucuronidase against quercetin glucuronides. The various quercetin glucuronides were deconjugated at similar rates, but liver cell-free extracts were the most efficient and the activity was completely inhibited by saccharo-1,4-lactone (a beta-glucuronidase inhibitor). Furthermore, pure recombinant human beta-glucuronidase hydrolysed various flavonoid glucuronides, with a 20-fold variation in catalytic efficiency (k(cat)/K(m)=1.3x10(3) M(-1) s(-1) for equol-7-O-glucuronide and 26x10(3) M(-1) s(-1) for kaempferol-3-O-glucuronide). Similar catalytic efficiencies were obtained for quercetin O-glucuronides substituted at different positions. These results show that flavonoid glucuronides can be deconjugated by microsomal beta-glucuronidase from various human cells.     

Stereoselective Degradation of alpha‐Cypermethrin and Its Enantiomers in Rat Liver Microsomes

Alpha‐cypermethrin (α‐CP), [(RS)‐a‐cyano‐3‐phenoxy benzyl (1RS)‐cis‐3‐(2, 2‐dichlorovinyl)‐2, 2‐dimethylcyclopropanecarboxylate], comprises a diastereoisomer pair of cypermethrin, which are (+)‐(1R‐cis‐αS)–CP (insecticidal) and (?)‐(1S‐cis‐αR)–CP (inactive). In this experiment, the stereoselective degradation of α‐CP was investigated in rat liver microsomes by high‐performance liquid chromatography (HPLC) with a cellulose‐tris‐ (3, 5‐dimethylphenylcarbamate)‐based chiral stationary phase. The results revealed that the degradation of (?)‐(1S‐cis‐αR)‐CP was much faster than (+)‐(1R‐cis‐αS)‐CP both in enantiomer monomers and rac‐α‐CP. As for the enzyme kinetic parameters, there were some variances between rac‐α‐CP and the enantiomer monomers. In rac‐α‐CP, the V_max and CL_int of (+)‐(1R‐cis‐αS)–CP (5105.22 ± 326.26 nM/min/mg protein and 189.64 mL/min/mg protein) were about one‐half of those of (?)‐(1S‐cis‐αR)–CP (9308.57 ± 772.24 nM/min/mg protein and 352.19 mL/min/mg protein), while the K_m of the two α‐CP enantiomers were similar. However, in the enantiomer monomers of α‐CP, the V_max and K_m of (+)‐(1R‐cis‐αS) ‐CP were 2‐fold and 5‐fold of (?)‐(1S‐cis‐αR)‐CP, respectively, which showed a significant difference with rac‐α‐CP. The CL_int of (+)‐(1R‐cis‐αS)–CP (140.97 mL/min/mg protein) was still about one‐half of (?)‐(1S‐cis‐αR)–CP (325.72 mL/min/mg protein) in enantiomer monomers. The interaction of enantiomers of α‐CP in rat liver microsomes was researched and the results showed that there were different interactions between the IC₅₀ of (?)‐ to (+)‐(1R‐cis‐αS)‐CP and (+)‐ to (?)‐(1S‐cis‐αR)‐CP(IC_50(?)/(+) / IC_50(+)/(?) = 0.61). Chirality 28:58–64, 2016. © 2015 Wiley Periodicals, Inc.     

Characterization and functional activity of murine monoclonal antibodies specific for α1,6-glucan chain of Helicobacter pylori lipopolysaccharide

Background: The outer core region of H. pylori lipopolysaccharide (LPS) contains α1,6‐glucan previously shown to contribute to colonizing efficiency of a mouse stomach. The aim of the present study was to generate monoclonal antibodies (mAbs) specific for α1,6‐glucan and characterize their binding properties and functional activity. Materials and Methods: BALB/c mice were injected intraperitoneally with 10⁸ formalin‐fixed H. pylori O:3 0826::Kan cells 3× over 56 days to achieve significant titer. Anti‐α1,6‐glucan‐producing hybridomas were screened by indirect ELISA using purified H. pylori O:3 0826::Kan LPS. One clone, 1C4F9, was selected for further characterization. The specificities of mAbs were determined by indirect and inhibition ELISA using structurally defined H. pylori LPS and synthetic oligosaccharides, and whole‐cell indirect ELISA (WCE) of clinical isolates. They were further characterized by indirect immunofluorescent (IF) microscopy and their functional activity in vitro determined by serum bactericidal assays against wild‐type and mutant strains of H. pylori. Results: The generated anti‐α1,6‐glucan IgM, 1C4F9, has demonstrated an excellent specificity for the glucan chain containing 5 to 6 α1,6‐linked glucose residues and showed surface accessibility by IF microscopy with H. pylori cells adherent to gastric adenocarcinoma cells monolayers. Of 38 isolates from Chile, 17 strains reacted with antiglucan mAbs in WCE (OD₄₅₀ ≥ 0.2). Bactericidal activity was observed against selective wild‐type and mutant H. pylori strains exhibiting OD₄₅₀ values of ≥0.45 in WCE. Conclusions: Anti‐α1,6‐glucan mAbs could have potential application in typing and surveillance of H. pylori isolates as well as offer insights into structural requirements for the development of LPS‐based vaccine against H. pylori infections.     

Androgen glucuronides: I. Direct formation in rat accessory sex organs

A simple one-step procedure is described on the isolation of androgen glucuronides from various rat tissues. This procedure uses polyacrylamide gel electrophoresis, and permits a quantitative isolation of a single band containing the total androgen glucuronides without the contamination of free androgens and androgen sulfates. This procedure was used to determine the ability of various tissues of the rat to form androgen glucuronides directly when they were incubated with 1,2-[³H]-testosterone (0.1 μM) $\text{in}$$\text{vitro}$. Of eleven organs studied, only the accessory sex organs (ventral prostate, seminal vesicle, and coagulating gland), liver, and kidney were capable of forming androgen glucuronides. At the end of a one-hour incubation period, approximately 1% of the total radiolabeled steroids in the prostatic tissue minces were in the form of glucuronide conjugates. The predominant androgen glucuronide formed in the accessory sex organs was 5α-androstane-3α,17β-diol 17β-d-glucuronide. This is in contrast to the rat liver and kidney in which testosterone glucuronide was the predominant conjugate.A similar amount of labeled glucuronide conjugates was formed from either [³H]-testosterone, [³H]-dihydrotestosterone or [³H]-androstenedione, whereas negligible amount of steroid conjugates was formed from [³H]-cortisol. The formation of androgen glucuronides requires metabolically active tissues; furthermore, the conjugation process was inhibited by the antiandrogen, cyproterone acetate, or by metabolic inhibitors, such as oligomycin or N-ethylmaleimide.     

Antibacterial activity of naringin derivatives against pathogenic strains

Aims: To study the antimicrobial activity of naringin (NAR), a flavonoid extracted from citrus industry waste, and NAR derivatives [naringenin (NGE), prunin and alkyl prunin esters] against pathogenic bacteria such as L. monocytogenes, E. coli O157:H7 and S. aureus. The relationship between the structure of the chemical compounds and their antagonistic effect was also analysed. Methods and Results: The agar dilution technique and direct contact assaying were applied. NGE, prunin and NAR showed no antimicrobial activity at a concentration of 0·25 mmol l^?1. Similarly, fatty acids with a chain length between C2 and C18 showed no antimicrobial activity at the same concentration. However, prunin‐6″‐O‐acyl esters presented high antibacterial activity, mainly against Gram‐positive strains. This activity increased with increasing chain length (up to 10–12 carbon atoms). Alkyl prunin esters with 10–12 carbon atoms diminished viability of L. monocytogenes by about 3 log orders and S. aureus by 6 log orders after 2 h of contact at 37°C and at a concentration of 0·25 mmol l^?1. The compounds examined were not effective against any of the Gram‐negative strains assayed, even at the highest concentration. Conclusions: Addition of sugars to the aglycone did not enhance its antimicrobial activity. Attachment of a saturated aliphatic chain with 10–12 carbon atoms to the A ring of the flavonoid (or to sugars attached to this ring), seems to be the most promising modification. In conclusion, alkyl prunin esters with a chain length of C10–C12 have promising features as antimicrobial agents because of their high antilisterial and antistaphylococcal activity. Significance and Impact of the Study: This study shows that it is possible to obtain NAR derivatives with important antimicrobial activity, especially against Gram‐positive pathogenic bacteria. It also provides guidelines on the structural modifications in similar molecules to enhance the antimicrobial activity.     

Characterization of a highly Al3+‐selective fluorescence probe based on naphthalimide‐Schiff base and its application to practical water samples

A new fluorescent Al³⁺‐probe, N‐allyl‐4‐[3,3′‐((2‐aminoethyl)azanediyl)‐bis(N´‐(2‐hydroxybenzylidene)propanehy‐drazide)]‐1,8‐naphthalimide ( L ), was designed and synthesized based on 1,8‐naphthalimide. The probe L contains 1,8‐naphthalimide moiety as the fluorophore and a Schiff base as the recognition group. The structure of L was determined by single crystal X‐ray. L emission at 526 nm increased on addition of Al³⁺ under excitation wavelength at 350 nm. L exhibited high selectivity and sensitivity fluorescence emission towards to Al³⁺ in ethanol/Tris–HCl buffer solution (1:1, v/v, pH = 7.2) as compared with other tested metal ions. A good linearity with a correlation coefficient (R²) of 0.99 was observed in the concentration range 2–10 μM. The binding constant and the detection limit of L for Al³⁺ were calculated to 2.6 × 10⁴ M^?1 and 0.34 μM, respectively. The results of experiments that including Job plot, ultraviolet–visible (UV–Vis) light titration, fluorescence titration, ESI‐MS and ¹H NMR titration, indicated a 1:1 stoichiometric complex between L and Al³⁺. L was highly effective in monitoring Al³⁺ in real‐life Yellow River and tap water samples.     

Flavonoid variation in Lasthenia burkei

The flavonoid chemistry of Lasthenia burkei has been re-examined. The flavonoid profile of the species is based upon quercetin, patuletin and an unidentified aglycone. Glucosides, glucuronides, xylosides, diglucosides and glucosylxylosides were identified. Small amounts of a patuletin triglycoside were also detected. One hundred and eight individual plants, representing five populations, three in Lake County and two in Sonoma County (California), were compared chromatographically. Two flavonoid races were observed based upon occurrence of xylosyl-based glycosides, quercetin and patuletin diglycosides and distribution of quercetin and patuletin glucuronides. Distinctions between the races was not absolute in all cases but the differences in frequencies of occurrence of the various types of compounds is marked.     

Cloning and characterization of α-L-arabinofuranosidase and bifunctional α-L-arabinopyranosidase/β-D-galactopyranosidase from Bifidobacterium longum H-1

Aims: This study focused on the cloning, expression and characterization of recombinant α‐l ‐arabinosidases from Bifidobacterium longum H‐1. Methods and Results: α‐l ‐Arabinofuranosidase (AfuB‐H1) and bifunctional α‐l ‐arabinopyranosidase/β‐d ‐galactosidase (Apy‐H1) from B. longum H‐1 were identified by Southern blotting, and their recombinant enzymes were overexpressed in Escherichia coli BL21 (DE3). Recombinant AfuB‐H1 (rAfuB‐H1) was purified by single‐step Ni²⁺‐affinity column chromatography, whereas recombinant Apy‐H1 (rApy‐H1) was purified by serial Q‐HP and Ni²⁺‐affinity column chromatography. Enzymatic properties and substrate specificities of the two enzymes were assessed, and their kinetic constants were calculated. According to the results, rAfuB‐H1 hydrolysed p‐nitrophenyl‐α‐l ‐arabinofuranoside (pNP‐αL‐Af) and ginsenoside Rc, but did not hydrolyse p‐nitrophenyl‐α‐l ‐arabinopyranoside (pNP‐αL‐Ap). On the other hand, rApy‐H1 hydrolysed pNP‐αL‐Ap, p‐nitrophenyl‐β‐d ‐galactopyranoside (pNP‐βD‐Ga) and ginsenoside Rb2. Conclusions: Ginsenoside‐metabolizing bifidobacterial rAfuB‐H1 and rApy‐H1 were successfully cloned, expressed, and characterized. rAfuB‐H1 specifically recognized the α‐l ‐arabinofuranoside, whereas rApy‐H1 had dual functions, that is, it could hydrolyse both β‐d ‐galactopyranoside and α‐l ‐arabinopyranoside. Significance and Impact of the Study: These findings suggest that the biochemical properties and substrate specificities of these recombinant enzymes differ from those of previously identified α‐l ‐arabinosidases from Bifidobacterium breve K‐110 and Clostridium cellulovorans.     

Flavonoid chemistry ofBlennospermatinae, a trans-Pacific disjunct subtribe ofSenecioneae (Asteraceae)

The flavonoid profiles of seven species ofAbrotanella and one species ofIschnea have been shown to be based upon kaempferol 3- and quercetin 3-O-glycosides and a delphinidin glycoside. Glucosides, glucuronides, arabinosides, diglucosides, and rutinosides of the flavonols were identified. The profile ofIschnea consisted solely of quercetin 3-O-glucoside and 3-O-arabinoside whereas the profiles of theAbrotanella species were more varied. Although infraspecific variation was not investigated in this study, the flavonoid chemistry of the two genera is in accordance with the flavonoid variation described for other members ofSenecioneae which are primarily flavonol producers. Based on the known phylogeny and biogeography, the flavonoid distribution from the perspective of long-distance dispersals across the Pacific is discussed. Such events should lead to genetic bottle-neck situations and depauperate flavonoid profiles. A summary of current flavonoid knowledge in theSenecioneae is supplied.     

Genistein as a potential inducer of the anti-atherogenic enzyme paraoxonase-1: studies in cultured hepatocytes in vitro and in rat liver in vivo

A number of cardioprotective effects, including the reduced oxidation of the low‐density lipoprotein (LDL) particles, have been attributed to dietary soy isoflavones. Paraoxonase 1 (PON1), an enzyme mainly synthesized in the liver, may exhibit anti‐atherogenic activity by protecting LDL from oxidation. Thus, dietary and pharmacological inducers of PON1 may decrease cardiovascular disease risk. Using a luciferase reporter gene assay we screened different flavonoids for their ability to induce PON1 in Huh7 hepatocytes in culture. Genistein was the most potent flavonoid with regard to its PON1‐inducing activity, followed by daidzein, luteolin, isorhamnetin and quercetin. Other flavonoids such as naringenin, cyanidin, malvidin and catechin showed only little or no PON1‐inducing activity. Genistein‐mediated PON1 transactivation was partly inhibited by the oestrogen‐receptor antagonist fulvestrant as well as by the aryl hydrocarbon receptor antagonist 7‐ketocholesterol. In contrast to genistein, the conjugated genistein metabolites genistein‐7‐glucuronide, genistein‐7‐sulfate and genistein‐7,4′‐disulfate were only weak inducers of PON1 transactivation. Accordingly, dietary genistein supplementation (2 g/kg diet over three weeks) in growing rats did not increase hepatic PON1 mRNA and protein levels as well as plasma PON1 activity. Thus, genistein may be a PON1 inducer in cultured hepatocytes in vitro, but not in rats in vivo.     

Chemical Composition and Antimicrobial Activity of Ageratina deltoidea

The chemical study of Ageratina deltoidea afforded grandiflorenic acid ( 1 ), ent‐kaurenoic acid ( 2 ), and eight benzylbenzoates ( 3  –  10 ), two of them, 3,5‐dimethoxybenzyl 2,3,6‐trimethoxybenzoate ( 5 ) and 4‐(β‐d ‐glucopyranosyloxy)‐3‐hydroxybenzyl 2,6‐dimethoxybenzoate ( 9 ), described for the first time. In addition, the new sesquiterpene lactone deltoidin C ( 13 ), together with the known 11 and 12 , the phenolic compounds: ayanin, 2,6‐dimethoxybenzoic acid, methyl 3,4‐dihydroxycinnamate, chlorogenic acid, and 3,5‐dicaffeoylquinic acid were also isolated. The structures of these compounds were determined by spectroscopic methods and chemical reactions. The antibacterial and antifungal activities of compounds 1  –  12 were evaluated on Staphylococcus aureus, Escherichia coli, and Candida albicans. Deltoidin A ( 11 ) was the most active antibacterial agent (MIC 16.0 μg ml^?1) against E. coli, and the ent‐kaurenoid derivatives ( 1  –  2 ) showed activity (MIC 31.0 μg ml^?1) against S. aureus.     

Mutations in the major gas vesicle protein GvpA and impacts on gas vesicle formation in Haloferax volcanii

Gas vesicles are proteinaceous, gas‐filled nanostructures produced by some bacteria and archaea. The hydrophobic major structural protein GvpA forms the ribbed gas vesicle wall. An in‐silico 3D‐model of GvpA of the predicted coil‐α1‐β1‐β2‐α2‐coil structure is available and implies that the two β‐chains constitute the hydrophobic interior surface of the gas vesicle wall. To test the importance of individual amino acids in GvpA we performed 85 single substitutions and analyzed these variants in Haloferax volcanii ΔA + A_mut transformants for their ability to form gas vesicles (Vac⁺ phenotype). In most cases, an alanine substitution of a non‐polar residue did not abolish gas vesicle formation, but the replacement of single non‐polar by charged residues in β1 or β2 resulted in Vac^– transformants. A replacement of residues near the β‐turn altered the spindle‐shape to a cylindrical morphology of the gas vesicles. Vac^– transformants were also obtained with alanine substitutions of charged residues of helix α1 suggesting that these amino acids form salt‐bridges with another GvpA monomer. In helix α2, only the alanine substitution of His53 or Tyr54, led to Vac^– transformants, whereas most other substitutions had no effect. We discuss our results in respect to the GvpA structure and data available from solid‐state NMR.     

Variations in the Components and Antioxidant and Tyrosinase Inhibitory Activities of Styphnolobium japonicum (L.) Schott Extract during Flower Maturity Stages

Styphnolobium japonicum (L.) S chott is widely cultivated in China, and its flowers and flower buds (FFB‐SJ) are commonly used as traditional Chinese medicine. This work aimed to assess variations in the chemical components and antioxidant and tyrosinase inhibitory activities of S. japonicum extract during five flower maturity stages (ES1–ES5). The results showed that the contents of total flavonoids, rutin, and narcissin were highest at ES1, whereas the contents of quercetin and isorhamnetin were highest at ES3. ES1 presented considerable antioxidant activities in terms of reducing power (RP) and 1,1‐diphenyl‐2‐picrylhydrazyl radical (DPPH^.) and hydroxyl radical (^.OH) scavenging capacity, whereas ES3 showed excellent tyrosinase inhibitory activity and 2,2′‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid) radical (ABTS^.+)‐ and O₂^.?‐scavenging capacity. Rutin and quercetin are the main bioactive components of FFB‐SJ with antioxidant and tyrosinase inhibition, and the immature flower buds of S. japonicum (S2 and S3) with excellent biological activities and relatively high extract yields were the best for product development.