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Fulltext Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

Klionsky DJ, Abdelmohsen K, Abe A, Abedin MJ, Abeliovich H, Acevedo Arozena A, et al.

Autophagy, 2016;12(1):1-222.
PMID: 26799652 DOI: 10.1080/15548627.2015.1100356
Fulltext The complete chloroplast genome and phylogenetic analysis of Christella dentata (Forssk.) Brownsey & Jermy (Thelypteridaceae)

Xu G, Zhang C, Lee SY, Chen Z, Zeng X

Mitochondrial DNA B Resour, 2023;8(1):181-185.
PMID: 36713297 DOI: 10.1080/23802359.2023.2168114

Christella dentata (Forssk.) Brownsey & Jermy (Thelypteridaceae) is endemic to the tropical and subtropical regions of Africa, Asia, and Asia Pacific. In this study, the complete chloroplast genome sequence of C. dentata was assembled using next-generation sequencing data. The complete chloroplast genome was 151,662 bp in length and had a typical quadripartite structure, which consisted of a small single-copy region (21,776 bp) and a large single-copy region (82,624 bp) that were separated by a pair of inverted repeats (23,631 bp each). A total of 131 genes were predicted, including 89 protein coding (CDS), 34 tRNA, and eight rRNA genes. The overall GC content of the chloroplast genome was 42.48%. Based on the concatenated shared unique CDS sequence dataset, phylogenetic analysis using both the maximum-likelihood and the Bayesian inference methods revealed that C. dentata is placed within Thelypteridaceae and is closely related to Christella appendiculata. Such genetic information would be useful for studies on the evolution pattern in ferns. The availability of chloroplast genome sequence for the species also paves the way to resolving the complicated relationship among members of Christella.
Impact of BRCA1/2 cascade testing on anxiety, depression, and cancer worry levels among unaffected relatives in a multiethnic Asian cohort

Padmanabhan H, Mariapun S, Lee SY, Hassan NT, Lee DS, Meiser B, et al.

J Genet Couns, 2023 Feb;32(1):43-56.
PMID: 35913122 DOI: 10.1002/jgc4.1619

Cascade testing for families with BRCA pathogenic variants is important to identify relatives who are carriers. These relatives can benefit from appropriate risk management and preventative strategies arising from an inherited increased risk of breast, ovarian, prostate, melanoma, and pancreatic cancers. Cascade testing has the potential to enable cost-effective cancer control even in low- and middle-income settings, but few studies have hitherto evaluated the psychosocial impact of cascade testing in an Asian population, where the cultural and religious beliefs around inheritance and destiny have previously been shown to influence perception and attitudes toward screening. In this study, we evaluated the short- and long-term psychosocial impact of genetic testing among unaffected relatives of probands identified through the Malaysian Breast Cancer Genetics Study and the Malaysian Ovarian Cancer Study, using validated questionnaires (Hospital Anxiety and Depression Scale and Cancer Worry Scale) administered at baseline, and 1-month and 2-year post-disclosure of results. Of the 305 unaffected relatives from 98 independent families who were offered cascade testing, 256 (84%) completed predictive testing and family history of cancers was the only factor significantly associated with uptake of predictive testing. We found that the levels of anxiety, depression, and cancer worry among unaffected relatives decreased significantly after result disclosure and remained low 2-year post-result disclosure. Younger relatives and relatives of Malay descent had higher cancer worry at both baseline and after result disclosure compared to those of Chinese and Indian descent, whereas relatives of Indian descent and those with family history of cancers had higher anxiety and depression levels post-result disclosure. Taken together, the results from this Asian cohort highlight the differences in psychosocial needs in different communities and inform the development of culture-specific genetic counseling strategies.
Fulltext The complete chloroplast genome sequence and phylogenetic analysis of Strobilanthes dalzielii (W.W.Sm.) Benoist 1935 (Acanthaceae)

Zeng N, Gao W, Chen Z, Chong JY, Lee SY, Xu G

Mitochondrial DNA B Resour, 2024;9(4):465-469.
PMID: 38591052 DOI: 10.1080/23802359.2024.2316069

Strobilanthes dalzielii of Acanthaceae is an herb species with potentially extensive applications for its pharmaceutical and ornamental values. Due to taxonomic complications and limited genetic information, the structural characteristics, and phylogenetic relationships of the S. dalzielii chloroplast genome were assembled and characterized here for the first time. The complete chloroplast genome of S. dalzielii was 144,580 bp in length. The genome is quadripartite in structure and consists of a large single-copy region (92,137 bp) and a small single-copy region (17,669 bp), which are separated by a pair of inverted repeats (each 17,387 bp). A total of 125 genes were annotated, including 80 protein-coding, 37 transfer RNA, and eight ribosomal RNA genes. The overall GC content was 36.4%. Phylogenetic analysis based on the complete chloroplast genome sequence of 21 taxa within the tribe Ruellieae of Acanthaceae using the maximum likelihood and Bayesian inference methods revealed that Strobilanthes diverged after Ruellia; S. dalzielii is closely related to S. tonkinensis. The genomic data obtained from this study will serve as valuable information to the species delimitation and genetic classification of Strobilanthes.
Modulation of the mechanical responses of synovial fibroblasts by osteoarthritis-associated inflammatory stressors

Jamal J, Roebuck MM, Lee SY, Frostick SP, Abbas AA, Merican AM, et al.

Int J Biochem Cell Biol, 2020 09;126:105800.
PMID: 32673644 DOI: 10.1016/j.biocel.2020.105800

OBJECTIVES: To compare mechanobiological response of synovial fibroblasts (SFb) from OA patient cohorts under mechanical load and inflammatory stressors for better understanding of SFb homeostatic functions.
METHODS: Primary SFb isolated from knee synovium of OA obese (OA-ob:SFb), OA-pre-obese (OA-Pob:SFb), non-OA arthroscopic (scope:SFb), and non-OA arthroscopic with cartilage damage (scope-CD:SFb) were exposed to OA-conditioned media (OACM), derived from OA obese (OA-ob:CM), OA-pre-obese (OA-Pob:CM), and mechanical stretch at either 0 %, 6 % or 10 % for 24 h. Differences in the mRNA levels of genes involved in extracellular matrix production, inflammation and secretory activity were measured.
RESULTS: Despite the significant BMI differences between the OA-ob and OA-Pob groups, OA-Pob has more patients with underlying dyslipidaemia, and low-grade synovitis with higher levels of secreted proteins, CXCL8, COL4A1, CCL4, SPARC and FGF2 in OA-Pob:CM. All primary SFb exhibited anti-proliferative activity with both OA-CM. Mechanical stretch stimulated lubricin production in scope:SFb, higher TGFβ1 and COL1A1 expressions in scope-CD:SFb. OA-Pob:CM stimulated greater detrimental effects than the OA-ob:CM, with higher pro-inflammatory cytokines, IL1β, IL6, COX2 and proteases such as aggrecanases, ADAMTS4 and ADAMTS5, and lower ECM matrix, COL1A1 expressions in all SFb. OA-ob:SFb were unresponsive but expressed higher pro-inflammatory cytokines under OA-Pob:CM treatment.
CONCLUSION: Both mechanical and inflammatory stressors regulate SFb molecular functions with heterogeneity in responses that are dependent on their pathological tissue of origins. While mechanical stretch promotes a favorable effect with enhanced lubricin production in scope:SFb and TGFβ1 and COL1A1 in scope-CD:SFb, the presence of excessively high OA-associated inflammatory mediators in OA-Pob:CM, predominantly SPARC, CXCL8 and FGF2 drive all SFb regardless of pathology, towards greater pro-inflammatory activities.
Fulltext Mangroves give cause for conservation optimism, for now

Friess DA, Yando ES, Abuchahla GMO, Adams JB, Cannicci S, Canty SWJ, et al.

Curr Biol, 2020 02 24;30(4):R153-R154.
PMID: 32097637 DOI: 10.1016/j.cub.2019.12.054

Friess et al. discuss the results of conservation efforts for mangrove forests in recent years.
DNA fluorescence shift sensor: a rapid method for the detection of DNA hybridization using silver nanoclusters

Lee SY, Hairul Bahara NH, Choong YS, Lim TS, Tye GJ

J Colloid Interface Sci, 2014 Nov 01;433:183-188.
PMID: 25129336 DOI: 10.1016/j.jcis.2014.07.033

DNA-templated silver nanoclusters (AgNC) are a class of subnanometer sized fluorophores with good photostability and brightness. It has been applied as a diagnostic tool mainly for deoxyribonucleic acid (DNA) detection. Integration of DNA oligomers to generate AgNCs is interesting as varying DNA sequences can result in different fluorescence spectra. This allows a simple fluorescence shifting effect to occur upon DNA hybridization with the hybridization efficiency being a pronominal factor for successful shifting. The ability to shift the fluorescence spectra as a result of hybridization overcomes the issue of background intensities in most fluorescent based assays. Here we describe an optimized method for the detection of single-stranded and double-stranded synthetic forkhead box P3 (FOXP3) target by hybridization with the DNA fluorescence shift sensor. The system forms a three-way junction by successful hybridization of AgNC, G-rich strand (G-rich) to the target DNA, which generated a shift in fluorescence spectra with a marked increase in fluorescence intensity. The DNA fluorescence shift sensor presents a rapid and specific alternative to conventional DNA detection.
DNA-templated silver nanocluster for live-intracellular FOXP3 detection

Lee SY, Fazlina N, Tye GJ

Anal Biochem, 2019 09 15;581:113352.
PMID: 31260647 DOI: 10.1016/j.ab.2019.113352

DNA-templated silver nanocluster (AgNC), a new promising fluorescence probe has gained importance in biosensing and bioimaging in recent years. We employed a label-free AgNC to detect an intracellular transcription factor known as forkhead box p3 (FOXP3), which is the master regulator of regulatory T cells (Tregs) suppressive function. We developed an optimized method for the detection of messenger ribonucleic acid (mRNA) of FOXP3 by hybridizing AgNC and G-rich to the target FOXP3 mRNA of a MCF-7 cells. MCF-7 cells are chosen as a model as it readily expresses FOXP3. The hybridized samples were examined with UV illuminator and further verified with fluorescence spectroscopy, fluorescence microscope and flow cytometry. The successful hybridization of a three-way junction with AgNC, G-rich and mRNA FOXP3 target generated an improved fluorescence intensity with a spectral shift. We have successfully delivered the green fluorescing AgNC and G-rich into MCF-7 cells, producing a shift to red fluorescing cells corroborated by flow cytometry results. In summary, our approach enables the detection of intracellular FOXP3 nucleic acid and holds considerable potential in establishing a non-lethal intracellular detection system which would be crucial for the isolation of regulatory T-cells (Tregs) when combined with other cell surface markers.
Job satisfaction of foreign-educated nurses in Malaysia: A cross-sectional study

Lee SY, Soh KL, Japar S, Ong SL, Soh KG, Tsujita Y

Belitung Nurs J, 2021;7(5):361-369.
PMID: 37496510 DOI: 10.33546/bnj.1682

BACKGROUND: The transition process of migration to work abroad can be challenging and, depending on how it is handled, can impact the job satisfaction level of these foreign-educated nurses. A clear understanding of migrant nurses' job satisfaction is critical for effective translation of nursing practice across the health systems and cultures.
OBJECTIVE: This study examined the job satisfaction of the foreign-educated nurses in Malaysia, which includes the job satisfaction dimensions and the significant difference between sociodemographic status and job satisfaction.
METHODS: A cross-sectional survey of 102 foreign-educated nurses working in private hospitals, clinics, hemodialysis centers, nursing homes, and private homes in Malaysia was conducted from September 2017 to March 2018. Data were collected using a structured questionnaire. Descriptive statistics, Mann-Whitney U, and Kruskal Wallis tests were used to analyze the data.
RESULTS: The study revealed that the participants had a median satisfaction score of 22 (IQR = 19 to 24). Serving the sick and needy and participants' self-respect were the highest satisfaction dimensions among the participants (Median = 3, IQR = 3 to 3). Moreover, the job satisfaction was significantly higher for registered foreign-educated nurses (mean rank = 62.5) than for unregistered foreign-educated nurses (mean rank = 48.65) when working in other countries (p = 0.02). Indian nurses (mean rank = 60.36) also expressed higher satisfaction in terms of working in other countries than Filipino nurses (mean rank = 46.88; p = 0.02). In addition, positive relationships with colleagues and superiors led to higher satisfaction among Indian nurses (mean rank = 61.02) than among Filipino nurses (mean rank = 47.24; p = 0.04). The job satisfaction of male foreign-educated nurses was significantly higher than their female counterparts in terms of self-respect, relationship with fellow nurses and superiors, working in other countries, career development, and ease of finding employment (p < 0.05).
CONCLUSION: The overall job satisfaction among the foreign-educated nurses in Malaysia is high, mainly when serving the sick and needy, and their degree of self-respect. Understanding job satisfaction among foreign-educated nurses in Malaysia enables the management team to develop effective strategies for addressing nursing shortages and improving the quality of patient care.
Fulltext Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1

Klionsky DJ, Abdel-Aziz AK, Abdelfatah S, Abdellatif M, Abdoli A, Abel S, et al.

Autophagy, 2021 Jan;17(1):1-382.
PMID: 33634751 DOI: 10.1080/15548627.2020.1797280

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field.
Fulltext The complete chloroplast genome of Aquilaria malaccensis Lam. (Thymelaeaceae), an important and threatened agarwood-producing tree species

Lee SY, Ng WL, Mohamed R, Terhem R

Mitochondrial DNA B Resour, 2018 Oct 29;3(2):1120-1121.
PMID: 33474439 DOI: 10.1080/23802359.2018.1519382

Known for its valuable agarwood, Aquilaria malaccensis Lam. is an evergreen tropical forest tree species endemic to the Indo-malesian region. Indiscriminate damaging and harvesting of the trees in the wild have resulted in it being listed in the CITES Appendix II for controlled trade and in the IUCN Red List as 'Vulnerable (VU)'. In this study, the complete chloroplast genome of A. malaccensis was assembled using data from high-throughput Illumina sequencing. The chloroplast genome was 174,832 bp in size, which included two inverted repeat regions of 42,091 bp each, separated by a large single copy region of 87,302 bp and a small single copy region of 3,348 bp. A total of 139 genes were predicted, including 39 tRNA, 8 rRNA, and 92 protein-coding genes. Phylogenetic analysis placed A. malaccensis within the family Thymelaeaceae. The chloroplast genome sequence of A. malaccensis offers a useful resource for future studies on the taxonomy and conservation of the threatened Aquilaria trees.
Fulltext Prevalence of PALB2 mutations in breast cancer patients in multi-ethnic Asian population in Malaysia and Singapore

Phuah SY, Lee SY, Kang P, Kang IN, Yoon SY, Thong MK, et al.

PLoS One, 2013;8(8):e73638.
PMID: 23977390 DOI: 10.1371/journal.pone.0073638

The partner and localizer of breast cancer 2 (PALB2) is responsible for facilitating BRCA2-mediated DNA repair by serving as a bridging molecule, acting as the physical and functional link between the breast cancer 1 (BRCA1) and breast cancer 2 (BRCA2) proteins. Truncating mutations in the PALB2 gene are rare but are thought to be associated with increased risks of developing breast cancer in various populations.
Fulltext BRCA1 and BRCA2 germline mutations in Malaysian women with early-onset breast cancer without a family history

Toh GT, Kang P, Lee SS, Lee DS, Lee SY, Selamat S, et al.

PLoS One, 2008;3(4):e2024.
PMID: 18431501 DOI: 10.1371/journal.pone.0002024

BACKGROUND: In Asia, breast cancer is characterised by an early age of onset: In Malaysia, approximately 50% of cases occur in women under the age of 50 years. A proportion of these cases may be attributable, at least in part, to genetic components, but to date, the contribution of genetic components to breast cancer in many of Malaysia's ethnic groups has not been well-characterised.
METHODOLOGY: Given that hereditary breast carcinoma is primarily due to germline mutations in one of two breast cancer susceptibility genes, BRCA1 and BRCA2, we have characterised the spectrum of BRCA mutations in a cohort of 37 individuals with early-onset disease (
Fulltext A case-control study of breast cancer risk factors in 7,663 women in Malaysia

Tan MM, Ho WK, Yoon SY, Mariapun S, Hasan SN, Lee DS, et al.

PLoS One, 2018;13(9):e0203469.
PMID: 30216346 DOI: 10.1371/journal.pone.0203469

BACKGROUND: Breast cancer risk factors have been examined extensively in Western setting and more developed Asian cities/countries. However, there are limited data on developing Asian countries. The purpose of this study was to examine breast cancer risk factors and the change of selected risk factors across birth cohorts in Malaysian women.
METHODS: An unmatched hospital based case-control study was conducted from October 2002 to December 2016 in Selangor, Malaysia. A total of 3,683 cases and 3,980 controls were included in this study. Unconditional logistic regressions, adjusted for potential confounding factors, were conducted. The breast cancer risk factors were compared across four birth cohorts by ethnicity.
RESULTS: Ever breastfed, longer breastfeeding duration, a higher soymilk and soy product intake, and a higher level of physical activity were associated with lower risk of breast cancer. Chinese had the lowest breastfeeding rate, shortest breastfeeding duration, lowest parity and highest age of first full term pregnancy.
CONCLUSIONS: Our study shows that breastfeeding, soy intake and physical activity are modifiable risk factors for breast cancer. With the increasing incidence of breast cancer there is an urgent need to educate the women about lifestyle intervention they can take to reduce their breast cancer risk.
Fulltext Inherited mutations in BRCA1 and BRCA2 in an unselected multiethnic cohort of Asian patients with breast cancer and healthy controls from Malaysia

Wen WX, Allen J, Lai KN, Mariapun S, Hasan SN, Ng PS, et al.

J Med Genet, 2018 02;55(2):97-103.
PMID: 28993434 DOI: 10.1136/jmedgenet-2017-104947

BACKGROUND: Genetic testing for BRCA1 and BRCA2 is offered typically to selected women based on age of onset and family history of cancer. However, current internationally accepted genetic testing referral guidelines are built mostly on data from cancer genetics clinics in women of European descent. To evaluate the appropriateness of such guidelines in Asians, we have determined the prevalence of germ line variants in an unselected cohort of Asian patients with breast cancer and healthy controls.
METHODS: Germ line DNA from a hospital-based study of 2575 unselected patients with breast cancer and 2809 healthy controls were subjected to amplicon-based targeted sequencing of exonic and proximal splice site junction regions of BRCA1 and BRCA2 using the Fluidigm Access Array system, with sequencing conducted on a Illumina HiSeq2500 platform. Variant calling was performed with GATK UnifiedGenotyper and were validated by Sanger sequencing.
RESULTS: Fifty-five (2.1%) BRCA1 and 66 (2.6%) BRCA2 deleterious mutations were identified among patients with breast cancer and five (0.18%) BRCA1 and six (0.21%) BRCA2 mutations among controls. One thousand one hundred and eighty-six (46%) patients and 97 (80%) carriers fulfilled the National Comprehensive Cancer Network guidelines for genetic testing.
CONCLUSION: Five per cent of unselected Asian patients with breast cancer carry deleterious variants in BRCA1 or BRCA2. While current referral guidelines identified the majority of carriers, one in two patients would be referred for genetic services. Given that such services are largely unavailable in majority of low-resource settings in Asia, our study highlights the need for more efficient guidelines to identify at-risk individuals in Asia.
Fulltext Evaluation of BRCA1 and BRCA2 mutations and risk-prediction models in a typical Asian country (Malaysia) with a relatively low incidence of breast cancer

Thirthagiri E, Lee SY, Kang P, Lee DS, Toh GT, Selamat S, et al.

Breast Cancer Res, 2008;10(4):R59.
PMID: 18627636 DOI: 10.1186/bcr2118

The cost of genetic testing and the limited knowledge about the BRCA1 and BRCA2 genes in different ethnic groups has limited its availability in medium- and low-resource countries, including Malaysia. In addition, the applicability of many risk-assessment tools, such as the Manchester Scoring System and BOADICEA (Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm) which were developed based on mutation rates observed primarily in Caucasian populations using data from multiplex families, and in populations where the rate of breast cancer is higher, has not been widely tested in Asia or in Asians living elsewhere. Here, we report the results of genetic testing for mutations in the BRCA1 or BRCA2 genes in a series of families with breast cancer in the multi-ethnic population (Malay, Chinese and Indian) of Malaysia.
Identification of germline alterations in breast cancer predisposition genes among Malaysian breast cancer patients using panel testing

Ng PS, Wen WX, Fadlullah MZ, Yoon SY, Lee SY, Thong MK, et al.

Clin Genet, 2016 10;90(4):315-23.
PMID: 26757417 DOI: 10.1111/cge.12735

Although an association between protein-truncating variants and breast cancer risk has been established for 11 genes, only alterations in BRCA1, BRCA2, TP53 and PALB2 have been reported in Asian populations. Given that the age of onset of breast cancer is lower in Asians, it is estimated that inherited predisposition to breast cancer may be more significant. To determine the potential utility of panel testing, we investigated the prevalence of germline alterations in 11 established and 4 likely breast cancer genes in a cross-sectional hospital-based cohort of 108 moderate to high-risk breast cancer patients using targeted next generation sequencing. Twenty patients (19%) were identified to carry deleterious mutations, of whom 13 (12%) were in the BRCA1 or BRCA2, 6 (6%) were in five other known breast cancer predisposition genes and 1 patient had a mutation in both BRCA2 and BARD1. Our study shows that BRCA1 and BRCA2 account for the majority of genetic predisposition to breast cancer in our cohort of Asian women. Although mutations in other known breast cancer genes are found, the functional significance and breast cancer risk have not yet been determined, thus limiting the clinical utility of panel testing in Asian populations.
Electrochemical genosensor assay using lyophilized gold nanoparticles/latex microsphere label for detection of Vibrio cholerae

Liew PS, Lertanantawong B, Lee SY, Manickam R, Lee YH, Surareungchai W

Talanta, 2015 Jul 1;139:167-73.
PMID: 25882423 DOI: 10.1016/j.talanta.2015.02.054

Vibrio cholerae is a Gram-negative bacterium that causes cholera, a diarrheal disease. Cholera is widespread in poor, under-developed or disaster-hit countries that have poor water sanitation. Hence, a rapid detection method for V. cholerae in the field under these resource-limited settings is required. In this paper, we describe the development of an electrochemical genosensor assay using lyophilized gold nanoparticles/latex microsphere (AuNPs-PSA) reporter label. The reporter label mixture was prepared by lyophilization of AuNPs-PSA-avidin conjugate with different types of stabilizers. The best stabilizer was 5% sorbitol, which was able to preserve the dried conjugate for up to 30 days. Three methods of DNA hybridization were compared and the one-step sandwich hybridization method was chosen as it was fastest and highly specific. The performance of the assay using the lyophilized reagents was comparable to the wet form for detection of 1aM to 1fM of linear target DNA. The assay was highly specific for V. cholerae, with a detection limit of 1fM of PCR products. The ability of the sensor is to detect LAMP products as low as 50ngµl(-1). The novel lyophilized AuNPs-PSA-avidin reporter label with electrochemical genosensor detection could facilitate the rapid on-site detection of V. cholerae.
Fulltext Effect of drying methods on yield, physicochemical properties, and total polyphenol content of chamomile extract powder

Lee SY, Ferdinand V, Siow LF

Front Pharmacol, 2022;13:1003209.
PMID: 36408266 DOI: 10.3389/fphar.2022.1003209

Chamomile (Matricaria chamomilla L.) is a traditional medicinal plant used to treat hay fever, inflammation, muscle spasms, menstrual disorders, insomnia ulcers, wounds, gastrointestinal disorders, rheumatic pain, and hemorrhoids. Dried chamomile flowers have a longer shelf life and the dried extract in form of powder offers much flexibility for new therapeutic formulations as it could be used as a replacement for liquid extract and serve as a shelf-stable ingredient in new applications. This study aims to determine the effect of drying methods, i.e., convection oven-drying at 45 °C, freeze-drying at -50°C, and spray-drying at 140°C at 10.5 and 12 ml/min, respectively) on powder yield, physicochemical properties (moisture content, water activity, and color attributes), and total polyphenol content of chamomile extract powder. Our findings showed that spray-drying conducted at 140°C, 12 ml/min resulted in the lowest yield of powder (16.67%) compared to convection oven-drying (90.17%) and freeze-drying (83.24%). Decreasing the feed flow rate to 10.5 ml/min during spraying caused an increase in powder yield to 26.99%. The moisture content of spray-dried chamomile extract powder obtained at 140°C, 10.5 ml/min was higher (11.00%) compared to that of convection oven-dried (8.50%) and freeze-dried (7.50%). Both convection oven-dried and freeze-dried chamomile extract powder displayed no significant difference (p > 0.05) in moisture content. The higher feed flow rate (12 ml/min) in spray-drying also led to an increase in the moisture content of chamomile extract powder to 12.00%. The higher residual moisture found in the spray-dried samples resulted in partial agglomeration of particles. In terms of water activity, freeze-dried chamomile extract powder was found to have the highest water activity (0.63) compared to that of convection oven-dried (0.52), spray-dried at 140°C, 10.5 ml/min (0.57), and spray-dried at 140°C, 12 ml/min (0.58). Spray-dried and freeze-dried chamomile extract powder with high moisture content and water activity could be highly susceptible to microbial growth. In terms of color attributes, higher drying temperature in spray-drying led to darker, redder, and more yellowish chamomile extract powder that could be caused by heat-induced Maillard reaction and caramelization. Since lower drying temperature was used in both convection oven-drying and freeze-drying, both convection oven-dried (56.94 mg GAE/g powder) and freeze-dried chamomile extract powder (55.98 mg GAE/g powder) were found to have higher total polyphenol content compared to those of spray-dried (42.79-46.79 mg GAE/g powder). The present findings allow us to understand the effect of drying methods on the properties of chamomile extract powder and provide a better drying option to dry chamomile extract. Due to higher powder yield with ideal powder properties such as low moisture content and water activity, desirable color, and high total polyphenol content obtained from convection oven-drying, convection oven-drying was a better option than freeze-drying and spray-drying for drying chamomile extract.
Fulltext A review on microalgae cultivation and harvesting, and their biomass extraction processing using ionic liquids

Tan JS, Lee SY, Chew KW, Lam MK, Lim JW, Ho SH, et al.

Bioengineered, 2020 12;11(1):116-129.
PMID: 31909681 DOI: 10.1080/21655979.2020.1711626

The richness of high-value bio-compounds derived from microalgae has made microalgae a promising and sustainable source of useful product. The present work starts with a review on the usage of open pond and photobioreactor in culturing various microalgae strains, followed by an in-depth evaluation on the common harvesting techniques used to collect microalgae from culture medium. The harvesting methods discussed include filtration, centrifugation, flocculation, and flotation. Additionally, the advanced extraction technologies using ionic liquids as extractive solvents applied to extract high-value bio-compounds such as lipids, carbohydrates, proteins, and other bioactive compounds from microalgae biomass are summarized and discussed. However, more work needs to be done to fully utilize the potential of microalgae biomass for the application in large-scale production of biofuels, food additives, and nutritive supplements.

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