The effect of drying methods on chlorophyll, polyphenol, flavonoids, phenolic compounds contents, color and sensory properties, and <i>in vitro</i> antioxidant and anti-diabetic activities of dried wild guava leaves

Nguyen, Quang‐Vinh; Doan, Manh Dung; Thi, Bich-Huyen Bui; Nguyen, Minh-Trung; Minh, Dinh Tran; Nguyen, Anh Dzung; Le, Tam-Minh; Nguyen, Thi Huyen Tram; Nguyen, Thi-Dao; Tran, Van-Cuong; Hoang, Van-Chuyen

doi:10.1080/07373937.2022.2145305

Cited by 14 publications

(7 citation statements)

References 29 publications

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“…Basic recommendations for the sample preparation process of reference samples from plant material provide for the minimum possible impact on the organic matrix of the sample. In particular: sample drying mode (freeze-drying or at a temperature that does not cause the release of volatile substances; protein denaturation when using non-destructive methods); storage in a sealed container to prevent moisture loss, which may entail the removal of elements by aerosolization [23].…”

Section: Discussionmentioning

confidence: 99%

Development of a Reference Sample for Rapid Analysis of an Elemental Composition of Medicinal Plant Raw Materials

GAIDASHEV,

SYROESHKIN

2024

Int J App Pharm

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Objective: Development and validation of a technique for preparation of a reference sample for elemental microanalysis using the XRF technique in terms of repeatability, reproducibility, and optimization of the technique for rapid determination of the elemental composition of medicinal plants based on X-ray fluorescence analysis. Methods: Samples: fresh shoots of Kalanchoe daigremontiana, ready reference sample "Birch Leaf" LB-1 (A. P. Vinogradov Institute of Geochemistry, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russia), and IAEA reference sample SRM 2976 (IAEA, MEL, Monaco). The dispersed fraction was analyzed using a Master Sizer 2000 instrument (Malvern Panalytical, Worcestershire, UK). Elemental analysis using an energy dispersive X-ray fluorescence spectrometer EDX-7000 Shimadzu (Shimadzu Corporation, Kyoto, Japan), GZ-AAS using an Agilent instrument, model 240Z AA instrument (Agilent Technologies, Inc., Santa Clara, USA) with electrothermal atomization and Zeeman background correction, and ICP-MS using an Agilent 7500 CE instrument (Agilent Technologies, Inc., Santa Clara, USA). Results: By the LALLS method, they were separated by the maximum distribution, which was 63 microns, and a minor fraction of 39 microns. This indicates sufficient homogeneity in the sample. Further, homogeneity was proved by the XRF method by measuring six independent samples obtained by the quartering method. Also, the elemental composition of the reference samples was determined: completely dried, homogenized before sifting, and homogenized after sifting. Further, the obtained reference sample of K. daigremontiana was compared with reference samples: IAEA SRM 2976 and "birch leaf methods: ICP-MS, GZ-AAS, XRF. Conclusion: The reference sample will allow for rapid analysis of medicinal plant raw materials. Standardization of medicinal plants by the content of microelements will allow observing species differences as well as adjusting the concentrations of microelements for therapeutic purposes using medicinal plants.

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Section: Discussionmentioning

confidence: 99%

Development of a Reference Sample for Rapid Analysis of an Elemental Composition of Medicinal Plant Raw Materials

GAIDASHEV,

SYROESHKIN

2024

Int J App Pharm

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“…69 Tentatively, three groups of compounds, including terpenoids degradation and the formation of new compounds (possibly breaking and rebinding side groups) in leaf extracts. 71,72 Moreover, in comparison with the chromatogram of the freeze-dried leaf extract, the chromatogram of the microwave-dried leaf extract might have increased or decreased peaks because of splitting although these peaks represent the same compounds. In contrast, long thermal oven-drying significantly reduced the contents of phenolic and flavonoid compounds in Eclipta prostrata leaves, leading to the loss of many peaks without clear new peaks occurring.…”

Section: Effects Of Drying On Ppo Activitymentioning

confidence: 99%

Assessment of microwave drying for rapid and convenient analysis of medicinal plants for quality assurance

Bala,

Dey,

Patra

et al. 2024

Phytochemical Analysis

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IntroductionThe safety and quality of many medicinally important herbs are compromised since farmers and small organizations are involved in the cultivation, aggregation, and primary processing of these herbs. Such organizations often lack adequate quality control facilities. To improve the safety and quality of herbal products, simple, rapid, and affordable quality control systems are required.ObjectivesThe aim of this study was to assess the suitability of microwave oven‐drying for moisture content (MC) determination and sample preparation of herbs in small organizations.MethodsMicrowave oven‐drying (720 W) and convective oven‐drying at 105°C for MC determination were compared. The effects of three different drying methods (microwave oven‐drying, low‐temperature convective drying, and freeze‐drying) on in vitro antioxidant and polyphenol oxidase (PPO) activity were determined, similarity analysis was conducted using HPLC signature spectra, and validation was performed with LC‐MS focusing on one herb.ResultsMicrowave oven‐drying at 720 W significantly reduced the drying time (from hours to minutes), whereas the spatial variation of temperature in convective ovens set at 105°C can cause about 10% underestimation of MC. Microwave oven‐drying showed similar macro‐properties like freeze‐drying and higher extractability (10%–20%) and in vitro antioxidant capacity (33%–66%) and lower PPO activity compared to low‐temperature convective drying. HPLC signature spectra revealed strong similarity of soluble components between freeze‐dried and microwave oven‐dried herbs. LC‐MS analysis demonstrated more common compounds between freeze‐dried and microwave oven‐dried Centella asiatica extracts, whereas convective tray‐dried samples had fewer compounds common with samples obtained by freeze‐drying or microwave oven‐drying.ConclusionsMicrowave oven‐drying is rapid (tens of min) and shows small batch‐to‐batch variation compared to oven‐drying at 105°C. The in vitro antioxidant assays and signature spectra can be used for assessing the source and purity or quality of a specific herb variety.

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“…The study also concluded that these two drying techniques signi cantly increased the avonoid content of mint by 88%. Nguyen et al [20][20] observed the highest TFC in guava plants through the freeze-drying method compared to oven drying at 50°C, microwave at 450 W, vacuum drying, and sun drying. This nding demonstrated that freeze-drying at a high hydration level increased the concentration of bioactive compounds after bound water removal, which was limited in the guava leaf extract.…”

Section: Total Avonoid Contentmentioning

confidence: 99%

Essential oil production, chemical composition, bioactive compounds, and antioxidant activity of Thymus vulgaris as affected by harvesting season and drying conditions

Tohidi-Nejad,

Khajoei-Nejad,

Tohidi-Nejad

et al. 2023

Preprint

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In this study, the effects of seven distinct drying methods (sun, shade, freeze-drying [FD], oven drying at 40°C [OV40] and 70°C [OV70], and microwave 360 W [MW360] and 720 W [MW720]) were assessed in two harvesting seasons (spring and autumn) on the essential oil (EO) content, total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity, and volatile compounds of thyme (Thymus vulgaris L.). The analysis of essential oils facilitated the identification of numerous compounds, 18 of which accounted for approximately 67.84–64.94% of the total thyme EO compounds. Six significant compounds were investigated, including thymol, p-cymene, γ-terpinene, carvacrol, linalool, and borneol. The results demonstrated that the thyme samples harvested in spring possessed higher amounts of γ-terpinene, thymol, carvacrol, EO content, and TFC, while samples harvested in autumn exhibited the highest amounts of borneol, p-cymene, TPC, and higher antioxidant activity. Principal component analysis (PCA) findings revealed that thyme samples harvested in spring, dried in the sun, shade, and FD conditions were rich in EO content, γ-terpinene and samples dried in MW720, OV40, and FD conditions possessed the highest amounts of thymol, carvacrol, and TFC. Drying the samples under MW360, OV40, and FD indicated significantly higher TPC and linalool. Drying the autumn-harvested samples under the sun and shade also exhibited higher linalool and TFC than other methods. Overall, the results conclusively indicated that the harvesting season and drying conditions significantly affected bioactive compounds, antioxidant activity, and EO production and quality.

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The effect of drying methods on chlorophyll, polyphenol, flavonoids, phenolic compounds contents, color and sensory properties, and in vitro antioxidant and anti-diabetic activities of dried wild guava leaves

Cited by 14 publications

References 29 publications

Development of a Reference Sample for Rapid Analysis of an Elemental Composition of Medicinal Plant Raw Materials

Development of a Reference Sample for Rapid Analysis of an Elemental Composition of Medicinal Plant Raw Materials

Assessment of microwave drying for rapid and convenient analysis of medicinal plants for quality assurance

Essential oil production, chemical composition, bioactive compounds, and antioxidant activity of Thymus vulgaris as affected by harvesting season and drying conditions

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