Antioxidants from grape stalks and marc: Influence of extraction procedure on yield, purity and antioxidant power of the extracts

In vitro anti-aging activities of Terminalia chebula gall extract

CONTEXT

The Thai Lanna region has its own folklores and wisdoms in various fields such as traditional medicines. The galls of Terminalia chebula Retz. (Combretaceae) frequently appear in many Thai Lanna medicinal plant recipes for promoting longevity.

OBJECTIVES

To investigate the in vitro anti-aging activities of the extracts from 15 plants including T. chebula gall selected from the Thai medicinal plant recipes that have been traditionally used for longevity.

MATERIALS AND METHODS

The plant extracts were prepared by four extraction methods including hot (HW) and cold (CW) aqueous processes and hot (HM) and cold (CM) methanol processes. These extracts were tested for antioxidative and tyrosinase inhibition activity as well as the proliferative and MMP-2 inhibition activity on early aging human skin fibroblasts in order to evaluate their in vitro anti-aging activity.

RESULTS

At 0.1 mg/mL, the CW extract of T. chebula gall exhibited the highest DPPH radical scavenging activity with scavenging of 84.64% +/- 2.22%, whereas ascorbic acid, alpha-tocopherol and butylated hydroxyl toluene gave 96.50% +/- 0.1%, 35.74% +/- 0.2% and 27.43% +/- 0.1%, respectively. The CW extract of T. chebula gall indicated the highest stimulation index (SI) on normal human fibroblast proliferation of 1.441 which was more active than ascorbic acid (SI 1.21). This extract has also demonstrated MMP-2 inhibition on fibroblasts determined by zymography 1.37 times more potent than ascorbic acid.

DISCUSSION AND CONCLUSION

This study has confirmed the traditional use of T. chebula gall in many Thai medicinal plant recipes for longevity which will be beneficial for further development of anti-aging products.

Use of grape stalk, a waste of the viticulture industry, to obtain activated carbon

Grape stalk is an organic waste produced in great amounts in the industrialization processes of grape. This work presents the results of studies carried out to use this waste as raw material to prepare activated carbon through the physical and chemical route. The physicochemical characterization of this material suggests the presence of unusually high levels of ashes. Metal content was determined and high levels of potassium, sodium, iron, calcium and magnesium in carbonized and raw grape stalk were exhibited. This characteristic made difficult physical activation at high temperatures. A leaching step was included before the activation with steam, and adsorbents with surface areas between 700 and 900 m(2)/g were obtained. Physical activation was also performed at lower temperatures using carbonized grape stalk without leaching, leading to the development of some grade of porosity, with an area of 412 m(2)/g. These results would indicate the catalytic effect of the minerals present in this raw material. Chemical activation using phosphoric acid as activating agent seemed to be a very efficient method as final products with BET areas between 1000 and 1500 m(2)/g were obtained.

Fatty Acid Profile and in Vitro Antioxidant and Antibacterial Activities of Red Grape (Vitis Vinifera L. Cvs. Öküzgözü and Boğrazkere) Marc Extracts

The marcs of two red grape ( V. vinifera L.) varieties (Boğrazkere and Öküzgözü), grown in eastern Anatolia (Elaziğr), were evaluated for their fatty acid composition, and antioxidant and antibacterial activities. The hexane extracts of both varieties were found to contain linoleic, palmitic, stearic and oleic acids by GC-MS analyses. The major fatty acid (linoleic acid) was detected relatively as 57.13% in Öküzgözü and 59.07% in Boğrazkere in methylated hexane extracts. In addition, myristic and palmitoleic acids were observed in Boğrazkere as minor components. The free radical (DPPH) scavenging activity of Öküzgözü was higher than that of Boğrazkere. The IC50 values were calculated as 403.0 ± 7.8 μg/mL for Öküzgözü and 552.0 ± 23.6 μg/mL for Boğrazkere. The extracts were found to be effective on the four gram (+) and four gram (-) test bacteria, but not as good as standard antibiotic, gentamycine by MIC method.

Free radical scavenging of grape pomace extracts from Cabernet sauvingnon (Vitis vinifera)

Pressed grape pomace obtained from the wine production of Cabernet sauvignon (Vitis vinifera) vintage was dried until 9.8% moisture content, ground and submitted to extraction of soluble components from different extraction techniques. Low pressure extractions were performed with ethanol maceration followed by fractionation with n-hexane, dichloromethane, butanol and ethyl acetate. These solvents were furthermore applied for soxhlet extraction. Supercritical fluid extraction (SFE) was also performed to obtain grape pomace extracts by using pure CO2 and CO2 with ethanol as co-solvent in concentrations of 10, 15 and 20%w/w. The operating condition used in high pressure extractions was 150bar and 40 degrees C. The antioxidant activity of the grape pomace extracts was determined considering the free radical scavenging assay using 1,1-Diphenyl-2-picrylhydrazyl (DPPH) and was correlated with the total phenol content determined according to the Folin-Ciocalteu method. The results obtained in DPPH tests indicate the highest antioxidant activity of 96.6+/-0.3%AA, with an IC50 value of 13+/-1, for the extracts obtained with ethyl acetate in solid-liquid extraction. The highest yield values were achieved in soxhlet extraction with ethanol (13.2%w/w) and with butanol (12.2%w/w), and also by SFE with 15% ethanol (9.2%w/w). The lipophilic composition of grape pomace extracts was evaluated by gas chromatography-mass spectrometry with the identification of components like linoleic acid and ethyl linoleate, with important therapeutic activities.

Microwave-assisted efficient extraction of different parts of Hippophae rhamnoides for the comparative evaluation of antioxidant activity and quantification of its phenolic constituents by reverse-phase high-performance liquid chromatography (RP-HPLC)

The outcome of different extraction procedures (microwave, ultrasound, Soxhlet, and maceration) on the antioxidant activity of seeds, leaves, pulp, and fruits of Hippophae rhamnoides (sea buckthorn or SBT) was investigated by two different bioassays: 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) and 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays. The SBT extracts were found to possess strong antioxidant activity measured in terms of TEAC (2.03-182.13 and 6.97-282.75 mg/g) with ABTS and DPPH assays, respectively. In general, the antioxidant capacity of microwave-assisted extracts was found to be significantly higher than those obtained by ultrasound-assisted extraction (UAE) and maceration while being slightly higher than Soxhlet extracts. Further, microwave extracts of seeds were found to possess maximum antioxidant capacity followed by leaves, fruits, and pulp. Also, the chemical composition of extracts, studied in terms of the total phenolic content, was found to be in the range of 1.9-23.5 mg/g Gallic acid equivalent (GAE), which indicates a strong correlation between antioxidant activity and phenolic content present in the SBT. In addition, some of its bioactive phenolic constituents, such as rutin ( 1), quercetin-3- O-galactoside ( 2), quercetin ( 3), myricetin ( 4), kaempferol ( 5), and isorhamnetin ( 6), were also quantified in different extracts by reverse-phase high-performance liquid chromatography (RP-HPLC).