Inhibitory potential of phenolic compounds of Thai colored rice (Oryza sativa L.) against α-glucosidase and α-amylase through in vitro and in silico studies.

BACKGROUND: This study investigated the inhibitory efficiency of phenolic compounds content methyl vanillate, syringic acid and vanillic acid against α-glucosidase and α-amylase. The phenolic compound contents of 10 Thai colored rice cultivars were also determined, and the relationship between the inhibitory efficiency of colored rice extract with methyl vanillate, syringic acid and vanillic acid was evaluated. RESULTS: The results revealed that the inhibition efficiency of methyl vanillate, syringic acid and vanillic acid was higher against α-glucosidase than against α-amylase. Inhibitory activity of vanillic acid against α-glucosidase and α-amylase was highest, with IC50 of 0.100 ± 0.01 and 0.130 ± 0.02 mmol L-1 , respectively. Docking study showed strong binding by three hydrogen bonds and four hydrogen bonds between vanillic acid with the amino acid in the binding site of α-glucosidase and α-amylase, respectively. Inhibition modes of these phenolic compounds were defined as a mixed type inhibition against α-glucosidase. Highest phenolic compound contents of methyl vanillate, syringic acid and vanillic acid were obtained from methanol extracts of all rice cultivars. The methanol extracts of all colored rice cultivars such as Khao Leum Pua also showed the highest inhibition potential against α-glucosidase and α-amylase. The results indicated that these phenolic compound contents were closely related to the inhibition potential of colored rice extracts against α-glucosidase and α-amylase. CONCLUSION: Our results suggest that rice, especially colored rice cultivars, has the source of phenolic compounds. Moreover, the phenolic compounds had the greatest source of natural inhibitor against α-glucosidase and α-amylase. © 2022 Society of Chemical Industry.

Content of Phenolic Compounds in Meadow Vegetation and Soil Depending on the Isolation Method.

The aim of this paper was to determine the effect of the hydrolysis method on the amounts of phenolic compounds in the plant material in soil and, as a consequence, on the parameters to determine the degree of lignins transformation in soils. The study included the plant material (hay, sward, and roots) and soil-Albic Brunic Arenosol (horizon A, AE, and Bsv) samples. Phenolic compounds were isolated at two stages by applying acid hydrolysis followed by alkaline re-hydrolysis. The quantitative and qualitative analysis of phenolic compounds was performed with high-performance liquid chromatography with a DAD. The content of phenolic compounds in the extracts depended on the hydrolysis method and it was determined by the type of the research material. The amounts of phenolic compounds contained in the alkaline hydrolysates accounted for 55.7% (soil, horizon Bsv)-454% (roots) of their content in acid hydrolysates. In the extracts from acid hydrolysates, chlorogenic and p-hydroxybenzoic acids were dominant. In the alkaline extracts from the plant material, the highest content was recorded for p-coumaric and ferulic acids, and in the extracts from soil, ferulic and chlorogenic acids. A combination of acid and alkaline hydrolysis ensures the best extraction efficiency of insoluble-bound forms of polyphenols from plant and soil material.

Anti-inflammatory effect of the compounds from the flowers of Trollius chinensis.

In order to investigate the anti-inflammatory activity of flavonoids, phenolic acids, and alkaloids from the flowers of Trollius chinensis, some representative compounds, namely, orientin, 2"-O-ß-L-galactopyranosylorientin, vitexin, quercetin, isoquercetin, luteolin, veratric acid, proglobeflowery acid, trollioside, and trolline were selected to study their inhibitory effects against LPS-induced NO, IL-6, and TNF-ß release in RAW264.7 cells. At the higher concentration, both phenolic acids and flavonoids inhibited the production of NO, whereas only phenolic acids showed this effect at the lower concentration. Although trolline had stronger cytotoxicity, it exhibited a potential effect of decreasing NO production induced by LPS in the non-toxic concentration range. In addition, all tested compounds decreased the production of IL-6 and TNF-a by almost 50% at both the higher and lower concentrations. It is concluded that the anti-inflammatory activity of the phenolic acids is stronger than that of the flavonoids.

First evidence of epicatechin vanillate in grape seed and red wine.

Flavan-3-ols are units incorporating condensed tannin, which are widely present in grape and wine. They play a considerable role in wine sensory perception such as astringency, bitterness and mouth-feel. In grape and wine, the flavan-3-ols reported to date are (epi)catechin, (epi)gallocatechin, (epi)gallocatechin gallate and (epi)catechin glycoside. This study now shows the presence of a new flavan-3-ol epicatechin vanillate in grape seed and red wine. A putative unknown flavan-3-ol derived from grape seed was targeted by LC-HRMS/MS. Fractionation and purification by centrifugal partition chromatography and Prep HPLC allowed us to obtain the pure new flavan-3-ol. NMR and HRMS data revealed this compound to be epicatechin-3-O-vanillate. Quantification analysis results showed that epicatechin vanillate present in grape seed and red wine in the µg/g dry seed and the µg/L concentration range, respectively.

Development and Validation of an Analytical Method Readily Applicable for Quality Control of Tabebuia impetiginosa (Taheebo) Ethanolic Extract.

The dried inner bark of Tabebuia impetiginosa, known as taheebo or red lapacho, has numerous beneficial effects on human health. This study presents the first simple and reliable quantitative method that could serve for the QC of taheebo. The method uses LC-UV spectroscopy to determine the veratric acid (VA; 3,4-dimethoxybenzoic acid) content of taheebo extracts (TEs). Sample preparation entailed the dissolution of TE in methanol (MeOH), facilitated by ultrasonic radiation for 10 min. The optimized conditions included chromatographic separation on an Agilent Eclipse Plus C18 column (4.6 × 150 mm, 5 µm) at 30°C. The mobile phase consisted of 1% acetic acid in water and MeOH, which was eluted under gradient mode at a flow rate of 1.0 mL/min. The detection wavelength was 254 nm. Using these conditions, VA was selectively resolved, and the entire chromatographic analysis time was 27 min. The method was linear in the range of 50-500 µg/mL (r2 = 0.9995), precise (≤3.97% RSD), and accurate (97.10-102.72%). The validated method was applied to three batches of TE samples, yielding an estimated VA content range of 14.92-15.58 mg/g. Thus, the proposed method could serve as an easy and practical method for the QC of TEs or related products containing TEs.

The Effect of Buckwheat Hull Extract on Lipid Oxidation in Frozen-Stored Meat Products.

This study investigated the effect of antioxidants on lipid stability of frozen-stored meat products. Buckwheat hull extract was used to enrich fried meatballs made from ground pork. During 180-d storage of meat products, lipid oxidation (peroxide and 2-thiobarbituric acid reactive substances [TBARS] value) was periodically monitored. The results were compared with butylated hydroxytoluene (BHT). The addition of antioxidants decreased lipid oxidation in stored meatballs. The highest ability to control peroxide and TBARS values was demonstrated for buckwheat hull extract. Moreover, buckwheat hull extract showed a higher 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity as well as higher Fe(II) ion chelating ability, as compared with BHT. The total content of phenolic compounds are highly correlated to the individual polyphenols in extract of buckwheat hull, among which the following were assayed: 3,4-dihydroxybenzoic acid, 4-hydroxybenzoic acid, gallic acid, isovanillic acid and p-coumaric acid, and flavonoids: isoorientin, quercetin, quercetin 3-d-glucoside, rutin, and vitexin. These results indicate that plant extracts can be used to prolong shelf life of products by protecting them against lipid oxidation and deterioration of their nutritional quality.

Effects of Hovenia dulcis Thunb. extract and methyl vanillate on atopic dermatitis-like skin lesions and TNF-α/IFN-γ-induced chemokines production in HaCaT cells.

OBJECTIVES: Here, we hypothesized that Hovenia dulcis branch extract (HDB) and its active constituents ameliorates 2,4-dinitrochlorobenzene-induced atopic dermatitis (AD)-like skin lesions by modulating the T helper Th1/Th2 balance in NC/Nga mice and TNF-α- and IFN-γ-induced production of thymus and activation-regulated chemokine (TARC) and macrophage-derived chemokine (MDC) in HaCaT cells. METHODS: HaCaT cells were stimulated by TNF-α/IFN-γ in the presence of HDB and its constituents. TARC and MDC were measured by ELISA and RT-PCR. For the in-vivo study, oral feeding of HDB was performed for 5 weeks with 2,4-dinitrochlorobenzene (DNCB) treatment every other day. The efficacy of HDB on parameters of DNCB-induced AD was evaluated morphologically, physiologically and immunologically. KEY FINDINGS: In-vitro studies showed that HDB and its constituents suppressed TNF-α/IFN-γ-induced production of TARC and MDC in HaCaT cells by inhibiting MAPK signalling. In-vivo studies showed that HDB regulated immunoglobulin (Ig) E and immunoglobulin G2a (IgG2a) levels in serum and the expression of mRNA for Th1- and Th2-related mediators in skin lesions. Histopathological analyses revealed reduced epidermal thickness and reduced infiltration of skin lesions by inflammatory cells. CONCLUSION: These results suggest that HDB inhibits AD-like skin diseases by regulating Th1 and Th2 responses in NC/Nga mice and in HaCaT cells.

Oral administration of veratric acid, a constituent of vegetables and fruits, prevents cardiovascular remodelling in hypertensive rats: a functional evaluation.

In our previous studies, veratric acid (VA) shows beneficial effect on hypertension and its associated dyslipidaemia. In continuation, this study was designed to investigate the effect of VA, one of the major benzoic acid derivatives from vegetables and fruits, on cardiovascular remodelling in hypertensive rats, primarily assessed by functional studies using Langendorff isolated heart system and organ bath system. Hypertension was induced in male albino Wistar rats by oral administration of N ω -nitro-l-arginine methyl ester hydrochloride (l-NAME) (40 mg/kg body weight (b.w.)) in drinking water for 4 weeks. VA was orally administered at a dose of 40 mg/kg b.w. l-NAME-treated rats showed impaired cardiac ventricular and vascular function, evaluated by Langendorff isolated heart system and organ bath studies, respectively; a significant increase in the lipid peroxidation products such as thiobarbituric acid-reactive substances and lipid hydroperoxides in aorta; and a significant decrease in the activities of superoxide dismutase, catalase, glutathione peroxidase and levels of GSH, vitamin C and vitamin E in aorta. Fibrotic remodelling of the aorta and heart were assessed by Masson's Trichrome staining and Van Gieson's staining, respectively. In addition, l-NAME rats showed increased heart fibronectin expression assessed by immunohistochemical analysis. VA supplementation throughout the experimental period significantly normalised cardiovascular function, oxidative stress, antioxidant status and fibrotic remodelling of tissues. These results of the present study conclude that VA acts as a protective agent against hypertension-associated cardiovascular remodelling.

Pharmacokinetics and tissue distributions of veratric acid after intravenous administration in rats.

The present study was designed to investigate the pharmacokinetics and tissue distributions of veratric acid following intravenous administration in rats. The concentrations of veratric acid in rat plasma at various times after administrated at doses of 2.5, 5, and 10 mg·kg(-1) were quantified by HPLC. The tissue distributions of veratric acid at various times after a single intravenous dose of 2.5 mg·kg(-1) were also analyzed. The plasma pharmacokinetic parameters at the three doses were as follows: t(1/2), (86.23 ± 6.83), (72.66 ± 4.10) and (71.20 ± 2.90) min; C0, (11.10 ± 1.47), (23.67 ± 1.24) and (39.17 ± 3.90) µg·mL(-1); and AUC(0→∞), (1 240.90 ± 129.14), (2 273.84 ± 132.47) and (3 516.4 ± 403.37) min·µg·mL(-1), respectively. The compound was distributed into tissues rapidly and extensively after intravenous administration and was mainly distributed into the liver, heart and kidneys.

Absorption properties and mechanism of trolline and veratric acid and their implication to an evaluation of the effective components of the flowers of Trollius chinensis.

AIM: To study the absorption properties and mechanism of two important components, trolline and veratric acid, from the flowers of Trollius chinensis, in order to better understand the contribution of these two compounds to the effectiveness of these flowers. METHOD: The human Caco-2 cell monolayer model was employed to study the transport of trolline and veratric acid from apical side (AP) to basal side (BL), and from BL to AP by determining the transport rates as the function of time and concentration and calculating apparent permeability coefficients (Papp). RESULTS: Trolline and veratric acid were transported across Caco-2 cell monolayer through different mechanisms in a concentration dependent manner. Trolline was transported at a Papp level of 10(-6) cm·s(-1) with a Papp AP→BL/Papp BL→AP ratio of more than 1.8 or less than 0.8, while veratric acid was transported at a Papp level of 10(-5)cm·s(-1) with a Papp AP→BL/Papp BL→AP ratio of close to 1.0. CONCLUSION: Trolline is moderately absorbed through an associative mechanism involving active and passive transport, and veratric acid is well-absorbed mainly through passive diffusion. These factors should be taken into account when chemically assessing the pharmacodynamic material basis of the flowers of T. chinensis.

A new aromatic glycoside from Glehnia littoralis.

A new aromatic glycoside (1) was isolated from the roots of Glehnia littoralis Fr. Schmidtex Miq. Its structure was elucidated as vanillic acid 1-O-[ß-D-apiofuranosyl-(1 → 6)-ß-D-glucopyranoside] ester mainly by analysing the NMR and MS spectral data. In the in vitro assays, compound 1 displayed some TNF-α secretion inhibitory activity.

Hovenia dulcis Thunb extract and its ingredient methyl vanillate activate Wnt/ß-catenin pathway and increase bone mass in growing or ovariectomized mice.

The Wnt/ß-catenin pathway is a potential target for development of anabolic agents to treat osteoporosis because of its role in osteoblast differentiation and bone formation. However, there is no clinically available anti-osteoporosis drug that targets this Wnt/ß-catenin pathway. In this study, we screened a library of aqueous extracts of 350 plants and identified Hovenia dulcis Thunb (HDT) extract as a Wnt/ß-catenin pathway activator. HDT extract induced osteogenic differentiation of calvarial osteoblasts without cytotoxicity. In addition, HDT extract increased femoral bone mass without inducing significant weight changes in normal mice. In addition, thickness and area of femoral cortical bone were also significantly increased by the HDT extract. Methyl vanillate (MV), one of the ingredients in HDT, also activated the Wnt/ß-catenin pathway and induced osteoblast differentiation in vitro. MV rescued trabecular or cortical femoral bone loss in the ovariectomized mice without inducing any significant weight changes or abnormality in liver tissue when administrated orally. Thus, natural HDT extract and its ingredient MV are potential anabolic agents for treating osteoporosis.

Distribution of Two bioactive compounds in flowers of Trollius chinensis.

A comprehensive procedure was established, which combined a high-performance liquid chromatography (HPLC) assay for the simultaneous quantification of 2″-O-ß-L-galactopyranosylorientin (OGA) and veratric acid and a gravimetric analysis for the determination of the mass fraction of the floral parts (calyx, corolla, stalk, stamens and pistils and ovary) of Trollius chinensis, to investigate the distribution and identify the enriched floral part(s) of these two compounds in the flowers. The calculated mean distributions of OGA in calyx, corolla, stamens and pistils, stalk and ovary were 83.62, 7.76, 4.35, 2.92 and 1.35%, respectively, whereas those of veratric acid in the corresponding floral parts were 46.41, 9.01, 18.41, 4.11 and 22.06%, respectively, indicating the uneven and noncorresponding distribution of these two compounds. This study extends the application of the HPLC assay and favors the production of OGA and veratric acid from the flowers of T. chinensis in addition to the benefits of breeding, cultivation and utilization of these flowers.

Two new phenolic glycosides from Inula cappa DC.

Two new phenolic glycosides were isolated from the ethanol extract of the roots of Inula cappa DC. Their structures were defined as 4-[(6-O-(E)-caffeoyl)-ß-D-glucopyranosyl]vanillic acid (1) and 3-O-[ß-D-apiofurarnosyl-(1-6)-ß-D-glucopyranoxy]-6-hydroxy-p-cymene (2) on the basis of spectral analysis.

[Study on chemical composition of ethylacetate fraction from Polygonum amplexicaule var. sinense].

OBJECTIVE: To study chemical composition of ethylacetate fraction from Polygonoum amplexicaule D. Don var. sinense Forb. METHODS: TLC, Normal-phase silica gel column, reveres-phase silica gel column, Sephadex-LH, semi-preparative HPLC column were used to isolate chemical compositions of ethylacetate fraction from Polygonoum var. sinense. RESULTS: Eight compounds were identified as: 1. P-Hydroxybenzoic acid, 2. P-Hydroxybenzoic ethanol, 3. Diisobutyl phthalate, 4. Vanillin, 5. Isovanillic acid, 6.3,4,5-trihydroxy-benzoic acid-butyl ester, 7. 4-hydroxy-3-methoxycinnamic acid, 8. 7-hydroxy-6-methoxycoumarin. CONCLUSION: Except of Diisobutyl phthalate, the others are isolated for the first from this plant, moreover, Vanillin, Isovanillic acid and P-hydro -xyphenethyl alcohol are gained from genus for the first time.

Antimicrobial antioxidant daucane sesquiterpenes from Ferula hermonis Boiss.

Seventeen daucane sesquiterpenoid esters, including a new one (4), were isolated from the root of Ferula hermonis Boiss. The structures of the isolated compounds were elucidated on the basis of spectroscopic evidence and correlated with known compounds. The relative stereochemistry of the new compound was determined using 2D NOESY and the most stable and the lowest energy conformation was determined using molecular modelling. The antimicrobial activity was evaluated by determination of MIC using the broth microdilution method against six bacterial strains and one fungal strain (Pseudomonas aeruginosa PAO1, Escherichia coli, Bacillus subtilis ATCC6633, Mycobacterium bovis BCG Pasteur, Mycobacterium tuberculosis H37Rv, Staphylococcus aureus ATCC6538 and Candida albicans SC5314). There was a significant indication that compounds 15, 16, 17 demonstrated potent activity against Gram +ve (S. aureus, B. subtilis), as well as Mycobacterium strains M. bovis BCG and M. tuberculosis H37Rv. None of the isolated compounds exhibited a significant antifungal activity. In the antioxidant study using the DPPH assay method, the highest radical scavenging activity was observed for compounds 15, 16, 17.

Antiinflammatory sesquiterpenes from the root oil of Ferula hermonis.

Ferula hermonis Boiss. (Apiaceae), commonly known as 'Shilsh-el-zallouh', 'Hashishat-al-kattira' or 'The Lebanese viagra', is a small shrub that grows abundantly on the Hermon Mountain between Syria and Lebanon. The seeds and roots of this plant have long been used in the Middle East as an aphrodisiac, and for the treatment of frigidity and impotence for both men and women. The antiinflammatory properties of three major daucane esters, ferutinin (1) teferin (2) and teferidin (3), isolated from the root oil of Ferula hermonis, were assessed by the carrageenan-induced oedema model in rats. The antiinflammatory effect of both 1 and 2 was observed with a dose of 100 mg/kg, while compound 3 did not show any antiinflammatory activity; conversely it produced a significant proinflammatory effect 2 and 3 h after carrageenan injection.

[Study on the chemical constituents of Phryma leptostachya].

OBJECTIVE: To study the chemical constituents of Phryma leptostachya. METHODS: The chemical constituents were isolated and purified by silica gel column, recrystallization and Pre-RP-HPLC and their structwes were elucidated by spectroscopic methods. RESULTS: Five compounds were obtained and identified as ursolic acid (1), quercetin (2), isovanillic acid (3), p-hydroxybenzoic acid (4), adenine arabinoside (5). CONCLUSION: Compounds 2 - 5 are isolated from this genus for the first time.

Two new C-glucosyl benzoic acids and flavonoids from Mallotus nanus and their antioxidant activity.

Two new 2-C-beta-D-glucopyranosyl benzoic acid derivatives named mallonanosides A (1) and B (2) were isolated from the methanolic extract of the leaves of Mallotus nanus along with five known flavonoids, kaempferin (3), juglanin (4), quercitrin (5), myricitrin (6), and rhoifolin (7). Their structures were established on the basis of spectral and chemical evidence. Their antioxidant activities were shown to depend on the number of hydroxyl groups, and the location and species of sugar moiety.

Antisickling properties of divanilloylquinic acids isolated from Fagara zanthoxyloides Lam. (Rutaceae).

Fagara zanthoxyloides Lam. (syn. Zanthoxylum zanthoxyloides) (Rutaceae) is the most cited Fagara species for the treatment and the prevention of sickle cell disease crisis. Sickle cell anemia (SCA) is a public health problem in many countries particularly in Africa. The present study was designed to evaluate the antisickling properties of three isomeric divanilloylquinic acids (3,4-O-divanilloylquinic acid or burkinabin A; 3,5-O-divanilloylquinic acid or burkinabin B and 4,5-O-divanilloylquinic acid or burkinabin C) identified previously by LC/MS/NMR analysis in the root bark of F. zanthoxyloides [Ouattara et al., 2004. LC/MS/NMR analysis of isomeric divanilloylquinic acids from the root bark of Fagara zanthoxyloides Lam. Phytochemistry 65, 1145-1151]. The three isomers showed interesting antisickling properties which increased from burkinabins A to C.