Electrospray ionization mass spectrometry fingerprinting of essential oils: Spices from the Labiatae family

Polar components of the methanolic extracts of the essential oils of the spices Origanum dictamnus, Origanum vulgare, Origanum majorana and Rosmarinus officinalis, all four belonging to the Labiatae family, were investigated by direct infusion electrospray ionisation mass spectrometry (ESI-MS) both in the negative and positive ion modes. Characteristic ESI mass spectra with many diagnostic ions were obtained for the extracts of all four spices, serving for fast and reliable identification of these species. Tandem mass spectrometry (ESI-MS/MS), which often forms a series of fragment ions, and this additional MS dimension increases selectivity for authenticity and adulteration tests for spice essential oils. The MS technique also provides complementary information of component structures revealing the presence of important bioactive components.     

On-line separation and structural characterisation of feruloylated oligosaccharides from wheat bran using HPLC-ESI-MS

Water-soluble feruloylated oligosaccharides (FOs) from wheat bran, ferulic acid esters of arabinoxylan oligosaccharides, have been reported as natural antioxidants. In this study, structure features of FOs were studied by FT-IR spectroscopy, and high-performance liquid chromatography (HPLC) coupled to electrospray ionisation (ESI) mass spectrometry (MS) was used for separation and characterisation of FOs. Four components of FOs were resolved on a Dikma Technologies Diamonsil™ C₁₈ column eluted with water/acetonitrite (90:10) containing 0.5% HCOOH (V/V) and further analysed by ESI-MSⁿ. In ESI-MSⁿ, a predominant [M+NH₄]⁺ ion in positive mode and [M−H]⁻ ion in negative mode were observed for molecular mass information. The ESI-MSⁿ spectra of the deprotonated molecular [M−H]⁻ ion were used for structural elucidation. The structures of four isolated compounds were confirmed for the first time by on-line HPLC-ESI-MSⁿ.     

Protective effects of the crude extracts from yam (Dioscorea alata) peel on tert-butylhydroperoxide-induced oxidative stress in mouse liver cells

Researchers have shown that yam extracts contain antioxidative activity; however, there are few reports regarding the antioxidant activities of yam peel. The effects of water and 50% ethanolic extracts from Darsan yam (Dioscorea alata) peel on the oxidative status of tert-butylhydroperoxide (t-BHP)-treated mouse Hepa 1–6 and FL83B liver cell lines were investigated. The cytosols were analysed for H₂O₂ and malondialdehyde (MDA) levels and antioxidative enzymes activities, including superoxide dismutase, glutathione peroxidase (GPx) and catalase activities. Both water and 50% ethanolic extracts from yam peel did not affect cellular MDA level in t-BHP-treated cells, but they altered the level of H₂O₂. Water extract from yam peel amplified the t-BHP-induced cytotoxicity in Hepa 1–6 whilst the ethanolic extract showed protection in FL83B cells. GPx activity might play an important role in the protective effect associated with t-BHP-induced oxidative stress.     

Characterisation of phenolic acid derivatives and flavonoids from different morphological parts of Helichrysum obconicum by a RP-HPLC–DAD-(−)–ESI-MS method

The phenolic composition from different morphological parts of Helichrysum obconicum was investigated for the first time and 50 different phenolic compounds were detected. Phenolic acid conjugates, mainly mono- and di-caffeoylquinic acid derivatives, were the major components; some flavonoid derivatives were also detected in small amounts. Their separation and identification was performed by a high-performance liquid chromatography/electron spray ionisation tandem ion trap mass spectrometry method, with special emphasis on MSⁿ fragmentation. The presence of di- and tricaffeoylshikimic acid isomers in Helichrysum species extracts was reported for the first time, the spectra of these compounds were mainly characterised by the presence of a [caffeoylshikimic acid-H]⁻ ion at m/z 335. A lamiridosins-di-O-hexoside, an unusual component in Asteraceae species, was also detected.     

Antioxidative properties and stability of ethanolic extracts of Holy basil and Galangal

The aims of this work were to assess the influence of concentration, heat treatment, and pH value on antioxidant activity of ethanolic extracts obtained from Holy basil (Ocimum sanctum Linn) and Galangal (Alpinia galanga). The antioxidative properties were evaluated. The ethanolic extracts of Holy basil and Galangal showed good heat stability (80 °C, 1 h). At neutral and acidic pH, Holy basil extracts had high antioxidative stability, whereas Galangal extracts showed higher antioxidative stability at neutral than at acidic pH ranges. Antioxidant activity of both extracts at neutral pH was higher than at acidic pH ranges. Holy basil and Galangal extracts exhibited strong superoxide anion scavenging activity, Fe²⁺ chelating activity, and reducing power in a concentration-dependent manner. Antioxidant activity of both extracts correlated well with reducing power. Furthermore, ethanolic extracts of Holy basil and Galangal acted as radical scavenger and also as lipoxygenase inhibitor.     

Study of flavonoids in aqueous spinach extract using positive electrospray ionisation tandem quadrupole mass spectrometry

The presence of three flavonols (quercetin, kaempferol, myricetin) and two flavones (apigenin, luteolin) were investigated in the extract of fresh spinach leaves. Aqueous spinach extracts were prepared with a leaf/water ratio of 1:2 at 80 °C for 30 min stirring. Ferric ammonium sulphate method was used for measuring total polyphenols in the extracts and expressed as catechins and tannic acid equivalents. The flavonoids glycosides in the extract were hydrolysed to their aglycons with 1.2 M HCl in boiling 50% water methanol solution. The resulting aglycons were identified and quantified by a C18 reverse phase high-performance liquid chromatography (RP-HPLC). Furthermore, the results were confirmed by HPLC coupled to an electrospray ionisation tandem triple-quadrupole mass spectrometer ESI-MS performing low-energy collision induced dissociation (CID-MS/MS) in the collision cell (HPLC-ESI-MS/MS). Analyses were made in the multiple reaction monitory (MRM) mode. Results showed that total polyphenols contents in fresh spinach leaves were 270 mg kg⁻¹ and 390 mg kg⁻¹ as tannic acid and catechin equivalents, respectively, in which, major flavonoids aglycons were apigenin (170 mg kg⁻¹), quercetin (50 mg kg⁻¹) and kaempferol (30 mg kg⁻¹).     

Chemical profiling of Punica granatum peels from Jordan using LC–MS/MS and study on their biological activities

A paucity of local information concerning the chemical profiles and biological activities of extracts obtained from less-studied P. granatum peel of Jordanian origin was considered in this study for the first time. Fractionation of the crude ethanol extracts was performed because of their higher phenolic and flavonoid contents compared to the water and acetone extracts. The chemical compositions of the respective samples, that is, extracts/fractions were identified by LC–MS/MS, and the elemental content of the raw materials was also analysed using atomic absorption spectrometry. Antioxidant activities of extracts and fractions were evaluated against DPPH and ABTS radical scavenging assays, and the antibacterial activities were investigated by disc diffusion method and MIC (Minimum Inhibitory Concentration). The LC–MS/MS results correlated strongly with the total phenolic and flavonoid contents, where ethanol displayed higher efficacy for extracting bioactive ingredients. Overall, a total of 19 phenolics were detected in the ethanolic peel extract of P. granatum. All of the analysed extracts showed strong antioxidant activities. Fractionation of ethanolic extracts resulted in fractions with almost similar chemical LC–MS/MS profiles, but the relative proportion of constituents was different. All fractions showed lower intensities of antioxidant capacities than crude extracts, highlighting the superiority of some components, either individually or combined, as well as their relative proportion on the biological activity of each fraction. The results of the present study emphasise the need to further explore the effect of putative interactions among plant bioactive ingredients and focus on possible interactions with drugs along with foods.     

Induction of apoptosis by ethanolic extract of mango peel and comparative analysis of the chemical constitutes of mango peel and flesh

The underlying mechanisms of the anticancer activity of the ethanolic extract of mango peel (EEMP) and its constituents were investigated. EEMP induced death of human cervical carcinoma HeLa cells through apoptosis, as evidenced by the increased cell population in the sub-G1 phase and the appearance of fragmented nuclei. Treatment of the cells with EEMP also downregulated anti-apoptotic Bcl-2 expression, resulting in the proteolytic activation of caspase-3, 7, 8, and 9 and the degradation of poly (ADP-ribose) polymerase (PARP) protein. The major components of mango peel were identified by liquid chromatography–electrospray ionisation tandem mass spectrometry and gas chromatography–mass spectrometry. Our data suggest that EEMP is an excellent source of quercetin 3-O-galactoside, mangiferin gallate, isomangiferin gallate, quercetin-3-O-arabinopyranoside, and mangiferin along with unsaturated fatty acids oleic acid, linoleic acid, and ethyl linoleate, which may help to prevent cervical cancer and may be a useful agent for the treatment of some other malignancies.     

Characterisation of calamansi (Citrus microcarpa). Part I: Volatiles,aromatic profiles and phenolic acids in the peel

Volatile compounds in the peel of calamansi (Citrus microcarpa) from Malaysia, the Philippines and Vietnam were extracted with dichloromethane and hexane, and then analysed by gas chromatography–mass spectroscopy/flame ionisation detector. Seventy-nine compounds representing >98% of the volatiles were identified. Across the three geographical sources, a relatively small proportion of potent oxygenated compounds was significantly different, exemplified by the highest amount of methyl N-methylanthranilate in Malaysian calamansi peel. Principal component analysis and canonical discriminant analysis were applied to interpret the complex volatile compounds in the calamansi peel extracts, and to verify the discrimination among the different origins. In addition, four common hydroxycinnamic acids (caffeic, p-coumaric, ferulic and sinapic acids) were determined in the methanolic extracts of calamansi peel using ultra-fast liquid chromatography coupled to photodiode array detector. The Philippines calamansi peel contained the highest amount of total phenolic acids. In addition, p-Coumaric acid was the dominant free phenolic acids, whereas ferulic acid was the main bound phenolic acid.     

Antioxidant and antibacterial activities of Nephelium lappaceum L. extracts

Ether, methanolic and aqueous extracts of lyophilized rambutan (Nephelium lappaceum L.) peels and seeds were evaluated for phenolic contents, antioxidant and antibacterial activities. High amounts of phenolic compounds were found in the peel extracts and the highest content was in the methanolic fraction (542.2 mg/g dry extract). Several potential antioxidant activities, including reducing power, β-carotene bleaching, linoleic peroxidation and free radical scavenging activity, were evaluated. The peel extracts exhibited higher antioxidant activity than the seed extracts in all methods determined (P < 0.05). The methanolic fraction was found to be the most active antioxidant as shown by their 50% DPPH inhibition concentration, 4.94 μg/mL. The results indicated this fraction exhibited greater DPPH radical scavenging activity than BHT and ascorbic acid (0.32 g dry extract/g BHT or ascorbic acid). Antibacterial activity against eight bacterial strains was assessed by disc diffusion and broth macrodilution methods. All peel extracts exhibited antibacterial activity against five pathogenic bacteria. The most sensitive strain, Staphylococcus epidermidis, was inhibited by the methanolic extract (MIC 2.0 mg/mL).     

Effects of blanching, drying and extraction processes on the antioxidant activity of yam (Dioscorea alata)

The effects of blanching, drying and extraction processes on the antioxidant activities of one kind of Taiwanese yam peel, Darsan (Dioscorea alata), were investigated. The antioxidant measurements included total phenolic content, reducing power and α ,α‐diphenyl‐β‐pricryl‐hydrazyl (DPPH) radical‐scavenging activity. The 50% ethanolic, hot water and water extracts from the peel all had much higher antioxidant activities than those extracts from the flesh. Among three extraction methods, 50% ethanolic extraction resulted in the highest antioxidant activities in the peel, while hot water extraction was more appropriate for the flesh. Blanching by immersing the peel in 85 °C water for 30 s caused significant reductions in the antioxidant activities of all the extracts from the peel. Generally speaking, freeze‐dried peel maintained higher antioxidant activities than hot air‐dried peel.     

Polyphenolic compounds characterization and reactive nitrogen species scavenging capacity of Oenothera paradoxa defatted seed extracts

Biological investigations have revealed high scavenging capacity of Oenothera paradoxa defatted seed extract on reactive nitrogen species such as NO and ONOO⁻. The characteristics of the polyphenols present in the extracts were checked using high performance liquid chromatography coupled with electrospray negative ionization ion trap mass spectrometry. Extracts contained five groups of compound: phenolic acids (gallic acid, ethyl gallate, ellagic acid and ferulic acid pentoside), flavanols (catechin, catechin gallate) and oligomeric procyanidins, flavonols (quercetin-3-O-glucoside, quercetin-3-O-glucuronide, quercetin-3-O-pentoside and quercetin), and gallotannins (tetragalloyl glucose, pentagalloyl glucose and hexagalloyl glucose). Penta-O-galloyl-β-d-glucose were present in the extracts in concentrations from 9.44 to 16.75 mg/g, which demonstrated a significant NO and ONOO⁻ scavenging activity with IC₅₀ 0.20 and 0.06 μM, respectively, may be considered as an O. paradoxa extract quality marker.     

Discrimination of young and mature leaves of Melicope ptelefolia using H NMR and multivariate data analysis

The ‘Ulam’, a traditional Malay dish, are plants that can be eaten raw, as a form of local salad. The shoots and young leaves of Melicope ptelefolia are among the popular species, believed to be high in nutritional and medicinal values. The metabolomic fingerprinting analysis of the ethanolic extracts of leaves of M. ptelefolia was carried out using ¹H Nuclear Magnetic Resonance (NMR) spectroscopy and multivariate data analysis in order to differentiate young and mature leaves and to evaluate the variation of their chemical composition. Principle component analysis (PCA) of the ¹H NMR spectra showed a clear discrimination between the young and mature leaves extracts by PC3 and PC4. The compounds responsible for the differentiation were identified by comparison of ¹H NMR chemical shifts and qualitative HPLC. The young leaves were found to be richer in fatty acids and the levels of the three marker compounds, p-O-geranylcoumaric acid, 2,4,6-trihydroxy-3-geranylacetophenone and 2,4,6-trihydroxy-3-prenylacetophenone, were clearly higher. The mature leaves contain higher levels of sugars and glycosidic components.     

A new rapid spectrophotometric method to determine the rosmarinic acid level in plant extracts

A novel spectrophotometric method to determine the amount of rosmarinic acid in unpurified methanol extracts of the plants was developed. Rosmarinic acid is a naturally occurring bioactive compound in plants as an ester of caffeic acid with 3,4-dihydroxyphenyl lactic acid. The developed method was based on the complexation of rosmarinic acid with Zr⁴⁺ ions, giving a maximum absorbance at 362 nm. The absorptivity coefficient at this wavelength was found to be ε₃₆₂ = 2.66 × 10⁴ L mol⁻¹ cm⁻¹. In fact, this method is also specified giving two more absorption bands in UV region at 299.5 and 263.5 nm besides 362 nm. In addition, the accuracy and sensitivity of the new developed method are compared with the direct UV and rosmarinic acid–Fe²⁺ complex spectrophotometric methods by using methanol extracts of 11 Salvia species. As a conclusion, the present method is faster, cheaper, and more selective than the conventional methods for rosmarinic acid.     

On-line HPLC–MS–DPPH assay for the analysis of phenolic antioxidant compounds in fruit wine: Antidesma thwaitesianum Muell.

A reversed phase high performance liquid chromatography (RP-HPLC) separation coupled with an electrospray ionisation mass spectrometry detection (ESI-MS) and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay was used for the screening of multiple antioxidant compounds in Antidesma thwaitesianum Muell. fruit wine. The active compounds were identified by comparison with authentic standards and published mass spectra. With the help of the multidimensional information of LC–ESI-MS/MS and DPPH assay, the compounds with different chemical structures could be determined in one run successfully. The antioxidant compounds were separated and identified as gallic acid, cyanidin-3-sophoroside, monogalloyl glucoside, delphinidin-3-sambubioside, catechin, caffeic acid, and pelargonidin-3-malonyl glucoside. This result shows that an on-line HPLC–MS–DPPH assay can be a powerful technique for the rapid characterisation of antioxidant compounds in plant extracts.     

Evaluation of the antioxidant activity of three microalgal species for use as dietary supplements and in the preservation of foods

The antioxidant activity of the microalgal ethanolic extracts of Porphyridium cruentum, Phaeodactylum tricornutum and Chlorella vulgaris was determined by means of the β-carotene–linoleate model system. The results show that the activity of C. vulgaris extract was higher than those obtained for the other microalgal extracts tested and for the synthetics BHA (butylated hydroxyanisole), and BHT (butylated hydroxytoluene). In addition, the major constituents present in the ethanolic extracts of the three microalgae species were analyzed by means of GC and GC–mass spectrometry. The results showed that the tested microalgae may be an important source of natural antioxidants, as an alternative to higher plants or the production by chemical synthesis.     

Use of tea extracts for inhibition of polyphenoloxidase and retardation of quality loss of Pacific white shrimp during iced storage

Green tea and mulberry tea powder with and without prior chlorophyll removal were extracted with water and ethanol (800 mL L⁻¹). Extraction yield and total phenolic content of green tea extract were higher than those of mulberry tea extract, regardless of extraction media (P < 0.05). Extracts from green tea with and without prior chlorophyll removal showed the higher polyphenoloxidase (PPO) inhibitory activity, compared with mulberry tea extract, at the concentration used (0.1, 0.5 or 1 g L⁻¹). Additionally, green tea extracts had the higher reducing power, 2,2-diphenyl-1-picryl hydrazyl (DPPH) radical scavenging activities and copper chelating activity, compared with mulberry tea extract (P < 0.05). Ethanolic green tea extract with prior chlorophyll removal contained (+)-catechin (C), (−)-epicatechin (EC), (−)-epigallocatechin (EGC), (−)-epigallocatechin gallate (EGCg) and (−)-epicatechin gallate (ECG) at the levels of 242, 33.4, 125.6, 140.6 and 25.2 g kg⁻¹ dry extract, respectively. Whole white shrimp (Litopenaeus vannamei) treated with ethanolic green tea extract with prior chlorophyll removal at concentrations of 5 and 10 g L⁻¹ and stored in ice for up to 12 days had the lower psychrophilic bacterial count and lipid oxidation, compared with the control and shrimp treated with 12.5 g L⁻¹ sodium metabisulfite (SMS) (P < 0.05). Shrimp treated with 5 g L⁻¹ ethanolic green tea extract with prior chlorophyll removal possessed the lower melanosis, compared with the control, and showed similar score to those treated with SMS (P > 0.05). Furthermore, ethanolic green tea extract with prior chlorophyll removal had no adverse impact on sensory attributes of treated shrimp.     

Free radical scavenging properties and phenolic characterization of some edible plants

Antioxidant activity of the ethanolic extracts of the fruits of Fritillaria pontica Wahlenb. (Liliaceae), Euonymus latifolius (L.) Mill. ssp. latifolius (Celastraceae), and Vicia sativa L. ssp. nigra (L.) Ehrh. var. nigra L. (Fabaceae), the aerial parts of Turritis laxa (Sibth & Sm.) Hayek (Brassicaceae), Vicia cracca L. (Fabaceae), and Oxyria digyna (L.) Hill. (Polygonaceae) was screened by 2,2-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and ferric-reducing antioxidant power (FRAP) assays at 0.5, 1.0, and 2.0 mg ml⁻¹ concentrations. Total phenolic contents of the extracts were determined using Folin-Ciocalteau reagent. T. laxa was also tested for its anti-acetylcholinesterase activity. The extracts were analyzed by LC–DAD–MS for their flavonoid content and the ethanolic extract of T. laxa has been found to contain rutin in appreciable amounts (7.63 ± 0.2%). Rutin and hyperoside were detected qualitatively in F. pontica, where vitexin was identified in O. digyna. It was also the most active in the antioxidant tests.     

Phenolic compound characterisation and antiproliferative activity of “Annurca” apple,a southern Italian cultivar

In Annurca apples, a southern Italian variety, polyphenols were studied. The phenolic composition of Annurca apple peel was determined by HPLC coupled with electrospray negative ionisation multistage ion trap mass spectrometry (HPLC/ESI–ITMSⁿ). In addition, the antiproliferative and pro-apoptotic activities of peel extracts enriched in polyphenols and prepared from Annurca (APE), Red Delicious (RDPE) and Golden Delicious (GPE) varieties were evaluated on an HL-60 cell line. APE exhibited the highest total phenol content among the three apple cultivars tested, as determined by Folin–Ciocalteau’s procedure and HPLC–UV analysis. APE also showed higher amounts of chlorogenic acid, procyanidins, flavonols, dihydrochalcones and cyanidin-3-O-galactoside than GPE or RDPE. All three apple extracts were able to significantly decrease cell viability, from 50% to 80%, with APE appearing the most effective, while GPE was the least cytotoxic among the three samples. Similarly, APE and RDPE induced a significant increase of caspase-3 activity, whose activation represents a hallmark of apoptosis.     

Evaluation of the Antioxidant Properties of the Brazilian Cerrado Fruit Annona crassiflora (Araticum)

Annona crassiflora, known commonly as araticum, is an exotic tropical fruit consumed mainly by native people of the Brazilian Cerrado (2nd biggest biome of Brazil). In this study, pulp, seed, and peel of slight ripe and overripe fruits were extracted using ethanol and water. The extracts showed high content of total phenols and were screening for their potential as antioxidants using the in vitro model 1,1‐ dipheniyl‐2‐picryl hydrazyl (DPPH). The ethanol extracts of peel and seeds showed IC50 of 48.82 μg/mL and 31.14 μg/mL, respectively, for the slightly ripe fruits. As the ethanolic fractions of araticum showed the highest antioxidant activity, they were selected for testing of its effect on lipid peroxidation. The ethanolic extracts of slightly ripe fruits showed IC₅₀ of 4.44 μg/mL, 1.72 μg/mL, and 8.62 μg/mL for the peel, seed, and pulp, respectively. This is the 1st report on the antioxidant properties of the extracts of araticum. Owing to these properties, the studies can be further extending to exploit them for their possible application as natural antioxidant for cosmetic, supplements, and functional ingredients for food products.