Acetylcholinesterase and α-glucosidase inhibitory compounds from Callicarpa maingayi.

Phytochemical investigation on the soluble fractions of n-hexane and dichloromethane of methanolic leaves extract of the Callicarpa maingayi K. & G. led to the isolation of three triterpenoids [euscaphic acid (1), arjunic acid (2), and ursolic acid (3)] together with two flavones [apigenin (4) and acacetin (5)], two phytosterols [stigmasterol 3-O-ß-glycopyranoside (6) and sitosterol 3-O-ß-glycopyranoside (7)], and a fatty acid [n-hexacosanoic acid (8)]. Six (6) compounds (1, 2, 3, 4, 5, and 8) are reported for the first time from this species. Their structures were elucidated and identified by extensive NMR techniques, GC-MS and comparison with the previously reported literature. Compound 3 was found to displayed good inhibition against acetylcholinesterase with an IC50 value of 21.5 ± 0.022 µM, while 1 and 2 exhibited pronounced α-glucosidase inhibitory activity with IC50 values of 22.4 ± 0.016 µM and 24.9 ± 0.012 µM, respectively.

Processing of coconut sap into sugar syrup using rotary evaporation, microwave, and open-heat evaporation techniques.

BACKGROUND: Coconut sugar has a caramel color with a taste like brown sugar. It is commonly used as natural sweetener. However, coconut sugar has been produced from coconut sap using a traditional method that involves heating the sap at high temperature (>100 °C) in an open pan for a long period (3-5 h). This conventional method results in an over-cooked sugar, which leads to quality deterioration in terms of both its physical and chemical properties. The current study aimed to investigate the processing of coconut sap into sugar syrup using alternative processing techniques such as rotary vacuum evaporation (RE) and microwave evaporation (ME), comparing them with open-heat evaporation (OHE) technique. RESULTS: Coconut sugar syrup produced by rotary evaporation at 60 °C and 250 mbar vacuum (RE-60) required the shortest production time (12.2 min) and the lowest processing temperature (54.8 °C) when compared with ME (13 min and 103.2 °C) and OHE (46.8 min and 101.6 °C). It also had a light brownish color with a higher L* value (35.17) than the ME (29.84) and OHE (23.84) methods. It was found to contain higher amounts of monosaccharides (fructose and glucose) and lower amounts of disaccharides (sucrose). Furthermore, the amount of energy required for RE-60 (0.35 kWh) was much less than for OHE (0.83 kWh). CONCLUSION: This study provided an alternative processing method for the sugar processing industry to produce coconut sugar using the rotary evaporation method at 60 °C under 250 mbar vacuum with better physicochemical qualities, shorter processing time, and minimum input energy. © 2020 Society of Chemical Industry.

Fat properties and antinutrient content of rambutan (Nephelium lappaceum L.) seed during solid-state fermentation of rambutan fruit.

Rambutan seed is usually discarded during fruit processing. However, the seed contains a considerable amount of crude fat. Hence, the objective of this study was to investigate the fat properties and antinutrient content of the seed during fermentation of rambutan fruit. Results showed that the crude fat content of the seed reduced by 22% while its free fatty acid content increased by 4.3 folds after 10 days of fermentation. Arachidic acid was selectively reduced and was replaced by linoleic acid from the seventh day of fermentation onwards. Only 14.5% of triacylglycerol remained in the seed fat at the end of fermentation. The complete melting temperature, crystallization onset temperature and solid fat index at 37 °C of the fermented seed fat were higher than that of non-fermented seed fat. The saponin and tannin contents of the seed were reduced by 67% and 47%, respectively, after fermentation.

Changes in oxidation indices and minor components of low free fatty acid and freshly extracted crude palm oils under two different storage conditions.

This article reports on the changes of oxidation indices and minor components of low free fatty acid (FFA) and freshly extracted crude palm oils after storage at ambient (28 ± 1 C) and 60 C for 77 days. The changes in peroxide value (PV), FFA, extinction coefficient at 233 and 269 nm (K233 and K269), bleachability index (DOBI), carotene and vitamin E contents were monitored. PV, FFA, K233 and K269 of both oil samples increased as storage progressed while the values of carotene and vitamin E contents decreased. At the end of storage period at 60 °C, the carotene content of low FFA crude palm oil was 4.24 ppm. The storage conditions used led to the loss of entire vitamin E fractions of both oil samples as well as a reduction in DOBI values except for freshly extracted crude palm oil stored at ambient temperature.

Physicochemical and functional properties of yeast fermented brown rice flour.

In the current study, effects of fermentation on physicochemical and functional properties of brown rice flour (BRF) were investigated. Fermentation conditions were optimized using response surface methodology to achieve moderate acidity (pH 5-6), specifically pH 5.5 of brown rice batter with time, temperature and yeast concentration as the independent variables. The results indicated that brown rice batter was well fermented to maintain pH 5.5 at optimum conditions of 32 °C for 6.26 h using 1 % yeast concentration. Fermentation at moderate acidity significantly increased the levels of protein, total ash, insoluble fiber, soluble fibre, minerals, phenolics, antioxidants, resistant starch, riboflavin, pyridoxine, nicotinic acid, γ-tocotrienol, and δ-tocotrienol. However, it reduced the contents of γ-oryzanol, γ-tocopherol, α-tocopherol, phytic acid, amylose and total starch. Foaming capacity, foaming stability, oil holding capacity, gelatinization temperatures, enthalpy and whiteness of BRF were increased after fermentation. In contrast, its swelling power, water solubility index, hot paste viscosity, breakdown, and setback significantly decreased. Microstructure of BRF was also influenced, where its starch granules released from its enclosed structure after fermentation. This investigation shows evidence that yeast fermentation modified the functionality of BRF and can be used as a functional food ingredient.

Tocopherol and tocotrienol contents of different varieties of rice in Malaysia.

BACKGROUND: The present study examined the contents of tocopherols and tocotrienols and their distribution in 58 different varieties of whole rice cultivated in Malaysia. The analytical method used was saponification of samples followed by dispersive liquid-liquid microextraction and reverse phase high-performance liquid chromatography. RESULTS: The total vitamin E contents of different varieties of whole rice ranged between 19.36 and 63.29 mg kg⁻¹. Contents of vitamin E isomers varied among rice varieties both within and between grain color groups. Black-pigmented rice showed significantly higher mean contents of α-tocopherol, ß-tocopherol and α-tocotrienol than non-pigmented rice and red-pigmented rice. Red-pigmented rice had significantly lower mean contents of γ-tocotrienol and total vitamin E than non-pigmented rice. The mean contents of δ-tocotrienol and total vitamin E in non-pigmented rice, however, were similar to those in black-pigmented rice. γ-Tocotrienol was the predominant form of vitamin E isomer in all analyzed varieties. The Pearson correlations among vitamin E isomers and total vitamin E content of whole rice were also studied. CONCLUSION: This study provides information on vitamin E content of different rice varieties that would be beneficial for decision making in genetic breeding of bioactive compound-rich rice varieties.

Chemical profile and antiacetylcholinesterase, antityrosinase, antioxidant and α-glucosidase inhibitory activity of Cynometra cauliflora L. leaves.

BACKGROUND: The aim of the current study was (i) to evaluate the bioactive potential of the leaf methanolic extract of Cynometra cauliflora L., along with its respective hexane, dichloromethane, ethyl acetate (EtOAc), n-butanol (n-BuOH) and aqueous fractions, in inhibiting the enzymes α-glucosidase, acetylcholinesterase (AChE) and tyrosinase as well as evaluating their antioxidant activities. (ii) In addition, in view of the limited published information regarding the metabolite profile of C. cauliflora, we further characterized the profiles of the EtOAc and n-BuOH fractions using liquid chromatography-diode array detection-electrospray ionization-tandem mass spectrometry. RESULTS: The leaf methanolic extract of C. cauliflora exhibited potent inhibition of all three enzymes and high antioxidant activity. The bioactivity was found to be concentrated in the EtOAc and n-BuOH fractions. A total of 18 compounds were identified in these bioactive fractions, comprising a procyanidin trimer, procyanidin tetramer, procyanidin hexamer, taxifolin pentoside, catechin, vitexin, isovitexin, kaempferol hexoside, quercetin pentoside, quercetin hexoside, apigenin-6-C-glucoside-8-C-glucoside, kaempferol-coumaroyl hexoside and isorhamnetin hexoside. CONCLUSION: The results indicated that C. cauliflora, the leaves in particular, is a rich source of bioactive compounds and could be beneficial for further development of high-value phytomedicinal preparations and functional food products.

Partial characterization of an enzymatic extract from Bentong ginger (Zingiber officinale var. Bentong).

Extraction of protease from a local ginger rhizome (Zingiber officinale var. Bentong) was carried out. The effect of extraction pH (6.4, 6.8, 7.0, 7.2, 7.6, 8.0, 8.4, and 8.8) and stabilizers (0.2% ascorbic acid, 0.2% ascorbic acid and 5 mM EDTA, or 10 mM cysteine and 5 mM EDTA) on protease activity during extraction was examined. pH 7.0 potassium phosphate buffer and 10 mM cysteine in combination with 5 mM EDTA as stabilizer were found to be the most effective conditions. The extraction procedure yielded 0.73% of Bentong ginger protease (BGP) with a specific activity of 24.8±0.2 U/mg protein. Inhibitory tests with some protease inhibitors classified the enzyme as a cysteine protease. The protease showed optimum activity at 60 °C and pH 6-8, respectively. The enzyme was completely inhibited by heavy metal cations such as Cu2+, and Hg2+. SDS stimulated the activity of enzyme, while emulsifiers (Tween 80 and Tween 20) slightly reduced its activity. The kinetic analysis showed that the protease has Km and Vmax values of 0.21 mg mL-1 and 34.48 mg mL-1 min-1, respectively. The dried enzyme retained its activity for 22 months when stored at -20 °C.

Fermented Brown Rice Flour as Functional Food Ingredient.

As fermentation could reduce the negative effects of bran on final cereal products, the utilization of whole-cereal flour is recommended, such as brown rice flour as a functional food ingredient. Therefore, this study aimed to investigate the effect of fermented brown rice flour on white rice flour, white rice batter and its steamed bread qualities. Brown rice batter was fermented using commercial baker's yeast (Eagle brand) according to the optimum conditions for moderate acidity (pH 5.5) to obtain fermented brown rice flour (FBRF). The FBRF was added to white rice flour at 0%, 10%, 20%, 30%, 40% and 50% levels to prepare steamed rice bread. Based on the sensory evaluation test, steamed rice bread containing 40% FBRF had the highest overall acceptability score. Thus, pasting properties of the composite rice flour, rheological properties of its batter, volume and texture properties of its steamed bread were determined. The results showed that peak viscosity of the rice flour containing 40% FBRF was significantly increased, whereas its breakdown, final viscosity and setback significantly decreased. Viscous, elastic and complex moduli of the batter having 40% FBRF were also significantly reduced. However, volume, specific volume, chewiness, resilience and cohesiveness of its steamed bread were significantly increased, while hardness and springiness significantly reduced in comparison to the control. These results established the effectiveness of yeast fermentation in reducing the detrimental effects of bran on the sensory properties of steamed white rice bread and encourage the usage of brown rice flour to enhance the quality of rice products.

Anti- and pro-lipase activity of selected medicinal, herbal and aquatic plants, and structure elucidation of an anti-lipase compound.

Plants that help in slowing down the digestion of triacylglycerols (TAGs) in the pancreas and small intestine of humans play an important role in the reduction of obesity. On the other hand, there may be plants or plant parts that stimulate intestinal lipolytic activity, thus contributing to greater TAG assimilation. The aim of this study was to evaluate the aqueous methanolic extracts of ninety eight (98) medicinal, herbal and aquatic plant materials from Malaysia for their effect on porcine pancreatic lipase (PPL) activity and to identify the structure of an anti-lipase compound from one of the sources. The degree of inhibition was also quantified as relative to orlistat activity against PPL (orlistat equivalents). Results revealed that while 19.4% of the extracts were found to have anti-lipase activity ≥80%, 12% were actually found to promote PPL activity. Twenty two percent (22.4%) exhibited moderate inhibition (41%-80%) and 2% were neutral toward PPL activity. The ripe fruit of Averrhoa carambola and the leaves of Archidendron jiringa (Jack) I.C Nielsen L. (jering), Cynometra cauliflora (nam-nam) and Aleurites moluccana (L.) Willd (candle nut/buah keras) had the highest (100%) anti-lipase activity and are equivalent to 0.11 µg orlistat/mL. Plants that stimulated lipase activity included Pimpinella anisum L. (aniseed/jintan manis), activating the enzyme by 186.5%. Kaempferol 3-O-rhamnoside was isolated from the ethyl acetate fraction of C. cauliflora leaves and found to be an active lipase inhibitor. The structure was elucidated using 1H-NMR, 13C-NMR and 2D-NMR analyses.

Combination of saponification and dispersive liquid-liquid microextraction for the determination of tocopherols and tocotrienols in cereals by reversed-phase high-performance liquid chromatography.

A simple sample preparation technique coupled with reversed-phase high-performance liquid chromatography was developed for the determination of tocopherols and tocotrienols in cereals. The sample preparation procedure involved a small-scale hydrolysis of 0.5g cereal sample by saponification, followed by the extraction and concentration of tocopherols and tocotrienols from saponified extract using dispersive liquid-liquid microextraction (DLLME). Parameters affecting the DLLME performance were optimized to achieve the highest extraction efficiency and the performance of the developed DLLME method was evaluated. Good linearity was observed over the range assayed (0.031-4.0µg/mL) with regression coefficients greater than 0.9989 for all tocopherols and tocotrienols. Limits of detection and enrichment factors ranged from 0.01 to 0.11µg/mL and 50 to 73, respectively. Intra- and inter-day precision were lower than 8.9% and the recoveries were around 85.5-116.6% for all tocopherols and tocotrienols. The developed DLLME method was successfully applied to cereals: rice, barley, oat, wheat, corn and millet. This new sample preparation approach represents an inexpensive, rapid, simple and precise sample cleanup and concentration method for the determination of tocopherols and tocotrienols in cereals.