Binary solvent extraction system and extraction time effects on phenolic antioxidants from kenaf seeds (Hibiscus cannabinus L.) extracted by a pulsed ultrasonic-assisted extraction

Insights into the Chemical Composition and In Vitro Bioactive Properties of Mangosteen (Garcinia mangostana L.) Pericarp

The industrial processing of mangosteen (Garcinia mangostana L.) generates high amounts of waste, as ~60% of the fruit is formed by an inedible pericarp. However, its pericarp has been explored as a source of xanthones; nevertheless, studies addressing the recovery of other chemical compounds from such biomass are still scarce. Hence, this study intended to elucidate the chemical composition of the mangosteen pericarp, including fat-soluble (tocopherols and fatty acids) and water-soluble (organic acids and phenolic compound non-xanthones) compounds present in the following extracts: hydroethanolic (MT80), ethanolic (MTE), and aqueous (MTW). In addition, the antioxidant, anti-inflammatory, antiproliferative and antibacterial potentials of the extracts were assessed. The mangosteen pericarp showed a composition with seven organic acids, three tocopherol isomers, four fatty acids and fifteen phenolic compounds. Regarding the extraction of phenolics, the MT80 was the most efficient (54 mg/g extract), followed by MTE (19.79 mg/g extract) and MTW (4.011 mg/g extract). All extracts showed antioxidant and antibacterial activities; however, MT80 and MTE extracts were more efficient than MTW. Only MTW did not show anti-inflammatory properties, whereas MTE and MT80 showed inhibitory activities towards tumor cell lines. Notwithstanding, MTE showed cytotoxicity towards normal cells. Our findings support the idea that the ripe mangosteen pericarp is a source of bioactive compounds, although their recovery is dependent on the extraction solvent.

Ultrasonic-Assisted Extraction of Phenolic Compounds, Flavonoids, and Antioxidants from Dill (Anethum graveolens L.)

This study evaluated the effect of ultrasonic-assisted extraction (UAE) on the isolation of phenolic compounds, flavonoids, and antioxidants from dill. UAE improved the extraction yields of total phenolic compounds and total flavonoid content as well as increased the antioxidant activities of all dill extracts. The optimum UAE condition to obtain highest total phenolic compounds, total flavonoid content, and antioxidant activities was 50% ethanol for 30 min giving 135.88 ± 3.23 mg gallic acid equivalent/g extract and 229.53 ± 4.97 mg rutin equivalent/g extract, respectively. Lowest IC₅₀ values against 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals were 0.034 ± 0.00 mg/mL and 0.12 ± 0.00 mg/mL, respectively. Results indicated the capability of UAE in extracting biologically active compounds from dill as a prospective functional material.

A review on extraction techniques and therapeutic value of polar bioactives from Asian medicinal herbs: Case study on Orthosiphon aristatus, Eurycoma longifolia and Andrographis paniculata

Medicinal plants have gained much interest in the prevention and treatment of common human disease such as cold and fever, hypertension and postpartum. Bioactive compounds from medicinal plants were synthesised using effective extraction methods which have important roles in the pharmaceutical product development. Orthosiphon aristatus (OA), Eurycoma longifolia (EL) and Andrographis paniculata (AP) are among popular medicinal herbs in Southeast Asia. The major compounds for these medicinal plants are polar bioactive compounds (rosmarinic acid, eurycomanone and andrographolide) which have multiple benefits to human health. The bioactive compounds are used as a drug to function against a variety of diseases with the support of scientific evidence. This paper was intended to prepare a complete review about the extraction techniques (e.g. OA, EL and AP) of these medicinal plants based on existing studies and scientific works. Suitable solvents and techniques to obtain their major bioactive compounds and their therapeutic potentials were discussed.

Effect of steam blanching and high temperature drying on the physicochemical properties, antioxidant activities and consumer acceptability of Hibiscus cannabinus leaves tea

Kenaf (Hibiscus cannabinus) leaves are produced as the by product when kenaf stems were harvested. The kenaf leaves was examed for the applicable possibility as herbal tea due to their rich phenolic content. In this study, the effect of steam blanching and high temperature drying on physicochemical properties, antioxidant activity and consumer acceptability of the kenaf tea leaves were studied. Results showed that steam blanching prior oven-drying improved the extractability of phenolic compounds, leading to the increase in total flavonoid content, 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity, and ferric reducing antioxidant power. Drying at 120 °C was able to preserve more phenolic compounds, at the same time developing better taste, mouthfeel, and overall acceptability of kenaf leaves tea. Caffeic acid, tannic acid, catechin, and chlorogenic acid in kenaf tea leaves infusion were analyzed by ultra high performances liquid chromatography. In conclusion, steam blanching prior to 120 °C oven-drying was the best process method for the production of kenaf leaves into acceptable tea type.

Synergistic effects of ultrasound and extraction solvent on the bioactive compound in kenaf seed oil

Kenaf seed oil was extracted with 3 different solvents, i.e. hexane, ethanol and aqueous enzymatic medium with or without ultrasonic assistance. The synergistic effects of ultrasound and extraction solvent on the content of bioactive compound in kenaf seed oil was investigated. Results show that ultrasound-assisted extraction with hexane obtained the highest yield (84.71%), while yield with aqueous enzymatic medium was the lowest (51.12%). Two endothermic peaks exhibited on the melting curve of kenaf seed oil at the temperature range - 37 to - 25 °C and - 12 to - 2 °C, respectively. Linoleic, oleic and palmitic acid are the major fatty acids, accounting for above 96% of the total fatty acids. The content of vitamin E, phosphatide, total phenols and sterol are 92.38-105.01 mg/100 g oil, 0.38-22.28 g/kg, 0.51-71.02 mg GAE/100 g and 161.79-533.12 mg/100 g, respectively. The solvent employed has significant effect (p < 0.05) on the thermal property, fatty acid composition and bioactive constituents of the extracted kenaf seed oil. The oil extracted with ethanol contained more nervonic acid and bioactive components such as β-carotene, phosphatide, total phenols and sterols. The introduction of ultrasound reduced the extraction time remarkably. The results demonstrate that extraction with ethanol combined with ultrasound is an effective method to extract kenaf seed oil, as more reasonable fatty acid composition and higher content of bioactive components can be achieved.

Kenaf (Hibiscus cannabinus L.) Seed and its Potential Food Applications: A Review

Kenaf belongs to the family Malvaceae noted for their economic and horticultural importance. Kenaf seed is a valuable component of kenaf plant. For several years, it has been primarily used as a cordage crop and secondarily as a livestock feed. The potential for using kenaf seeds as a source of food-based products has not been fully exploited. Consumers are becoming more interested in naturally healthy plant-based food products. Kenaf seed, the future crop with a rich source of essential nutrients and an excellent source of phytocompounds, might serve suitable roles in the production of value-added plant-based foods. At present kenaf seed and its value-added components have not been effectively utilized for both their nutritional and functional properties as either ingredient or major constituent of food products. This review focuses on the possible food applications of kenaf seed and its value-added components based on their nutritional composition and functional properties available in literature, with the purpose of providing an overview on the possible food applications of this underutilized seed. The review focuses on a brief introduction on kenaf plant, nutritional function, lipids and proteins composition and food applications of the seed. The review elaborately discusses the seed in terms of; bioactive components, antioxidants enrichment of wheat bread, antimicrobial agents, as edible flour, as edible oil and a source of protein in food system. The review closes with discussion on other possible food applications of kenaf seed. The need for food scientists and technologists to exploit this natural agricultural product as a value-added food ingredient is of great significance and is emphasized.

Effect of Accelerated Storage on Fatty Acids, Thermal Properties and Bioactive Compounds of Kenaf Seed Oil

The effects of thermal oxidation at 65 °C for 24 days on oxidation indices, fatty acid positional distribution, thermal properties, vitamin E composition and sterol composition of kenaf seed oil are investigated. The results showed that total oxidation value (TOTOX) of the oil increased from initial 8.83 to 130.74 at the end of 24 days storage. Linoleic acid at sn-1, 3 positon of kenaf seed oil was less stable than the one at sn-2 positon. Oxidative degradation changed the melting profile of kenaf seed oil, the value of endothermic enthalpy reduced from 58.17 to 20.25 J/g after 24 days of storage. Moreover, the content of vitamin E and total sterol decreased by 84.26% and 38.47%, respectively. Tocotrienols were more stable than tocopherols during the accelerated storage. Correlation analysis indicated vitamin E content was significantly related to p-anisidine value, while sterol content was significantly related to peroxide value. PRACTICAL APPLICATION: Kenaf seed oil is rich in polyunsaturated fatty acids and bioactive compounds. Heating process and long-term storage cause oil oxidation and bioactive compounds degradation. The oxidation process of kenaf seed oil is simulated with accelerated storage. The study evaluates fatty acid composition and distribution, vitamin E and sterol content, melting thermal characteristics of kenaf seed oil at different oxidation levels. The research shows the stability of fatty acid is related with its type and position in backbone of triacylglycerol molecule. There are good correlation among oxidation level, vitamin E and sterol content, and melting enthalpy value of kenaf seed oil.

Changes in 3-MCPD esters, glycidyl esters, bioactive compounds and oxidation indexes during kenaf seed oil refining

An optimized refining process for kenaf seed oil was conducted. The 3-monochloro-1,2-propanediol (3-MCPD) contents, triacylglycerol composition, fatty acids composition, bioactive compounds, phosphorus contents, and oxidation indexes of the kenaf seed oil during each stage of the refining process were determined. The results showed that there was no detected 3-MCPD ester in kenaf seed oil throughout the refining process. Deodorization had slightly increased the 2-MCPD ester (9.0 μg/kg) and glycidyl ester (54.8 μg/kg). Oleic (36.53%) and linoleic acids (36.52%) were presented in the largest amount in the refined kenaf seed oil, and triacylglycerols contributed to 99.96% in the oil. There was a removal of 31.6% of phytosterol content and 17.1% of tocopherol and tocotrienol contents in kenaf seed oil after refining. The refining process was totally removed the hydroperoxides, 93% of free fatty acids and 98.8% of phosphorus content in kenaf seed oil.