Coffee silverskin (CS) is the major by-product of coffee roasting and a source of caffeine and chlorogenic acids (CGA), recognized modulators of sugar metabolism [1,2].

In this work, the effect of a CS extract on glucose and fructose uptake by human intestinal epithelial (Caco-2) cells was ascertained. Freeze-dried aqueous extracts were prepared using an ultrasound probe. The obtained powder was characterized regarding its caffeine content and CGA profile by RP-HPLC-DAD [2]. Caco-2 cells were incubated (37°C, 24h) with 1 mg/mL of extract and then glucose and fructose uptake were measured by incubating the cells (37 °C, 6 min) with 10 nM ³H-deoxy-D-glucose (³H-DG) or 100 nM ¹⁴C-fructose (¹⁴C-FRU), respectively [3]. The effects of the major compounds identified were similarly assessed using standards, individually and combined. Furthermore, the mRNA levels of intestinal transporters of these sugars (SGLT1, GLUT2, and GLUT5) were quantified by RT-qPCR after cell treatment (24h) with CS extract [4].

Caffeine was the main component of the extract and 5-caffeoylquinic acid (5-CQA) was the major CGA, followed by 5-feruloylquinic acid (5-FQA). Other isomers were found in minor amounts (3-CQA, 4-CQA, and 4-FQA). CS was able to reduce significantly ³H-DG and ¹⁴C-FRU uptake (~17% and ~19%, respectively). These effects were not related to cytotoxicity, as confirmed by the lactate dehydrogenase assay. When testing individual compounds at the concentrations present in the extract, neither caffeine nor 5-CQA influenced ³H-DG and ¹⁴C-FRU uptake, but significant inhibitions were found when combined (~16% and ~18%, respectively). This synergistic activity suggests their major role in CS effects. The extract also decreased the expression levels of GLUT2 transporter by ~71%, without influence on SGLT1 and GLUT5 transporters, thus evidencing the importance of GLUT2 on sugars uptake results. Overall, these findings highlight the beneficial effects that CS might have on type 2 diabetes and other metabolic disorders.

References

1. Alves, R.C.; Casal, S.; Oliveira, B. Benefícios do café na saúde: mito ou realidade? Química Nova 2009, 32, 2169-2180, doi:10.1590/s0100-40422009000800031.
2. Puga, H.; Alves, R.C.; Costa, A.S.; Vinha, A.F.; Oliveira, M.B.P.P. Multi-frequency multimode modulated technology as a clean, fast, and sustainable process to recover antioxidants from a coffee by-product. Journal of Cleaner Production 2017, 168, 14-21, doi:10.1016/j.jclepro.2017.08.231.
3. Andrade, N.; Silva, C.; Martel, F. The effect of oxidative stress upon intestinal sugar transport: an in vitro study using human intestinal epithelial (Caco-2) cells. Toxicology Research 2018, 7, 1236-1246, doi:10.1039/c8tx00183a.
4. Andrade, N.; Araújo, J.R.; Correia-Branco, A.; Carletti, J.V.; Martel, F. Effect of dietary polyphenols on fructose uptake by human intestinal epithelial (Caco-2) cells. J Funct Foods 2017, 36, 429-439, doi:10.1016/j.jff.2017.07.032.

Acknowledgments: To BICAFÉ that provided silverskin. This research was supported by: UIDB/50006/2020, funded by FCT/MCTES (Portugal); AgriFood XXI I&D&I (NORTE-01-0145-FEDER-000041) cofinanced by ERDF, through the NORTE 2020; U2SCOFFEE project (POCI/01/0247/FEDER/033351), financed by ERDF. J.A.B.P. (2021/07329/BD) and R.C.A. (CEECIND/01120/2017) are grateful to FCT. N.A. thanks for the post-doc grant under the UIDB/50006/2020 project.

Winery wastes are rich in polyphenols with great added value to be used in cosmetics, pharmaceuticals and agri-food products. Polyphenols display a wide range of positive health effects, thus helping in the prevention or treatment of some diseases because of their great antioxidant, anti-inflammatory, antimicrobial and antineoplastic properties.

This work aims at characterizing the polyphenols recovered from various wastes generated during the wine production processes using chromatographic techniques. Phenolic acids, flavonoids and related compounds have been extracted from different types of oenological residues, such as lees of malolactic fermentation and husks, by liquid extraction using aqueous or hydro-organic solvents. The resulting extracts have been further analyzed by liquid chromatography with UV/vis and mass spectrometric (MS) detection. The chromatographic separation has been carried out in reversed-phase mode on a core-shell C18 column using 0.1% formic acid in water and acetonitrile as the components of the mobile phase. Chromatograms have been acquired with UV detection at 250, 280, 325 and 370 nm while MS detection, with both low- and high-resolution analyzers, has been performed using different acquisition modes including Full Scan, Data-Dependent Acquisition (DDA) and Multiple Reaction Monitoring (MRM).

The most abundant polyphenols in the extracts have been identified as follows: caftaric acid with a concentration of 20 mg L^-1, and trans-coutaric acid, cis-coutaric acid, caffeic acid and p-coumaric acid with concentrations of 5 mg L^-1 or less. Other minor polyphenols such as gallic acid, 3,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, syringic acid, chlorogenic acid, ethyl gallate, ferulic acid, catechin, epicatechin, rutin, astilbin and resveratrol have been also found.

Australia is a minor producer of chilli, with the industry producing around 2,500 tonnes of chillies per year. Due to the small size of the industry, there is currently limited research on the typical levels of capsaicinoids in the Australian crop and the relationship between these constituents and other agronomic and nutritional factors. This study applied a rapid, maceration-based extraction protocol with end-over-end shaking, coupled with a HPLC-DAD method for the analysis of capsaicin and dihydrocapsaicin in 20 Habanero chilli samples from Queensland, Australia. All samples were from the same growing season (2020) but were taken from different within-field locations to ensure that all of the variability within the growing site was sampled. In addition to the capsaicinoid measurements, the total phenolic content was measured using the Folin-Ciocalteu assay, while antioxidant activity was measured using the Ferric Reducing Antioxidant Power (FRAP) method.

The capsaicin concentration of the samples ranged from 1500-4000 mg/kg, while the dihydrocapsaicin content ranged between 600-1800 mg/kg, giving total pungencies of approximately 34,000 to 89,000 Scoville Heat Units. Similarly, the total phenolic content varied from 1000-1600 mg gallic acid equivalents/100 g, while the antioxidant activity ranged from 300 to 450 mg Trolox equivalents/100 g.

Pearson linear correlation analysis revealed that the capsaicin and dihydrocapsaicin contents were strongly positively correlated with one another (R² = 0.73; P<0.001), with a mean capsaicin: dihydrocapsaicin ratio of 2.4:1. Furthermore, there was a moderate positive correlation between the total capsaicinoid content and total phenolic content of the samples (R² = 0.58; P<0.01), as well as a strong correlation between the total capsaicinoid content and FRAP (R² = 0.81; P<0.001). However, dry matter content was not significantly correlated with capsaicinoid content, total phenolic content or antioxidant activity (P>0.05 for all). These results may be used to inform future breeding programs for high-capsaicin chilli varieties and support further research into the agronomic and genetic factors driving capsaicin and dihydrocapsaicin content.

Yavagu or rice gruels are used as daily food items in Kerala and southern part of India, as they are light to digest. “Panchakola siddha yavagu” is a medicated rice gruel mentioned in classical Ayurveda book Charaka Samhita, Sutrasthana “Apamarga tanduliya”chapter. And it is used in inflammatory conditions like Gout arthritis. It contains drugs such as Pippali [ Piper longum], Pippalimoola [Root of Piper nigrum], Nagara [Zingiber officinale], Chavya [Piper chaba] and Chitraka [ Plumbago zeylanica] which are all processed in six times of water along with rice. In case of Gouty arthritis, in Ayurvedic point of view, it is due to improper digestion of food in body associated with doshas like vata and rakta. It causes reddish discolouration, debility, looseness and cutting or pulsating type of pain in knees, ankles, hips, shoulders, fingers and toes. The drugs mentioned in Panchakola Siddha Yavagu ie Shogaol present in dry ginger [Nagara], Plumbagin present in fire plant [Chitraka], Piperine present in Long pepper [Pippali], Long pepper root [ Pippali moola], and Wild pepper [Chavya] is proved to be having anti-inflammatory action. So that by consuming rice gruel containing these drugs will help to reduce symptoms like inflammation, looseness and pain present in joints in conditions like Gouty arthritis.

Pulsed light (PL) is a novel technology based on heating a xenon lamp with a high-voltage current to generate a broadband light emission with an important UV component. This high-voltage does not require extreme electricity consumption because it is produced thanks to the use of capacitors that store electricity from the main during relatively long times and are discharged to the lamp in very short times. The kinetics of polyphenol oxidase (PPO) inactivation by this technology was measured and some associated structural changes were investigated by fluorometry and spectrophotometry in order to gain insight into the inactivation mechanism. To this, residual activity, tryptophan fluorescence, KI fluorescence quenching and turbidity were measured. The inactivation followed the Weibull model. The decrease in tryptophan fluorescence and the increase in Stern-Volmer constant with the progress of the PL treatment indicate the unfolding of the enzyme; a constant turbidity indicates no aggregation. The Trp fluorescence phase-diagram shows no evidence of intermediates. Therefore, these results support the idea that PL inactivates PPO by modifying its tertiary structure in an all-or-none process.