Hock Ing Chiu

Tomatoes, rich in phenolics and antioxidants, offer a rich source of dietary antioxidants with potential health-promoting properties. Owing to the involvement of toxic solvents, high energy consumption, and hazardous waste, a safer and more sustainable extraction method has been preferred in the food and pharmaceutical industries. This study systematically investigated three advanced extraction techniques-microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), and accelerated solvent extraction (ASE)-to maximize phenolic yield and antioxidant capacity while concurrently minimizing the use of hazardous solvents, focusing Baccarat tomato variant. Among the tested methods, ASE demonstrated superior DPPH radical scavenging activity (87.480 ± 0.856%) with an IC50 of 4.65 mg/mL, while UAE achieved the highest total phenolic content (TPC, 9.060 ± 0.028 mg GAE/g DW). A strong correlation between TPC and antioxidant activities (DPPH and FRAP) was observed, emphasizing interdependence between phenolic content and bioactivity. Hierarchical cluster analysis (HCA) revealed 66.66% of ASE samples grouped into a cluster based on enhanced antioxidant properties. While UAE is superior for maximizing phenolic yield, ASE is the optimal method for producing extracts with the highest antioxidant potency, highlighting the critical role of technology selection in developing targeted ingredients for functional foods and therapeutic agents toward good health and well-being.

Mariposa Christia vespertilionis (MCV) has gained attention in cancer medicine development. Nowadays, plant-based nanoparticles have been widely used in drug delivery as they bring minimal effects to healthy cells and exhibiting antiproliferative effects to cancer cells. This study was conducted to investigate the antiproliferative properties of synthesised silver nanoparticles (AgNPs) using MCV aqueous leaf extract on HT29 cell line. The qualitative phytochemical analysis has proved that flavonoids, alkaloids, glycosides and tannins were present in MCV. Based on the ultraviolet-visible (UV-vis) spectrometry spectrum, the optimum conditions to synthesise highest amount of AgNPs were 15% v/v of extract concentration and 24 h of incubation period. The synthesised AgNPs were characterised by Fourier-transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) analysis. Flavonoids, alkaloids, glycosides and tannins were responsible in AgNPs formation based on FTIR analysis. In TEM analysis, the obtained nanoparticles were well-distributed with spherical shape. The particle size was in the range from 30 nm to 50 nm. From dimethylthiazol-diphenyltetrazolium bromide (MTT) assay, the synthesised AgNPs was proven to have ability in killing cancer cells (IC50: <12.5 µg/ml). They showed higher killing effect compared to the extract alone but lower than chemotherapy drug 5-fluorouracil (5FU). In conclusion, this study proved that MCV and synthesised AgNPs have the ability to kill cancer cells.

Cystamine-based polymers may help to achieve controlled and targeted drug delivery to the colon due to their susceptibility to breakage of the disulfide linkage in the low redox potential environment of the colon. In this study, two linear cystamine-based polymers with similar repeating units (LP1 and LP2) and a cross-linked cystamine-based polymer (BP) were synthesised and their kinetics and the various physical conditions underlying cystamine-based polymerisation were evaluated. In brief, N¹,N⁶-bis(2-(tritylthio)ethyl)adipamide (2) was synthesised from the reaction of triphenylmethanol and cysteamine. Next, the trityl group of 2 was removed with trifluoroacetic acid and triethylsilane before proceeding to oxidative polymerisation of the end product, N¹,N⁶-bis(2-mercaptoethyl)adipamide (3) to LP1. The Schotten-Bauman reaction was applied to synthesise LP2 and BP from the reaction of cystamine with adipoyl chloride or trimesoyl chloride. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, and mapping showed that oxygen, nitrogen, sulfur, and carbon were homogenously distributed in the polymers, with LP2 and BP having less porous morphologies compared to LP1. Results of zinc-acetic acid reduction showed that all polymers began to reduce after 15 min. Moreover, all synthesised polymers resisted stomach and small intestine conditions and only degraded in the presence of bacteria in the colon environment. Thus, these polymers have great potential for drug delivery applications. LP2 and BP, which were synthesised using the Schotten-Bauman reaction, were more promising than LP1 for colon-targeted drug delivery.

Plant essential oils are widely used in perfumes and insect repellent products. However, due to the high volatility of the constituents in essential oils, their efficacy as a repellent product is less effective than that of synthetic compounds. Using a nanoemulsion as a carrier is one way to overcome this disadvantage of essential oils. Nutmeg oil-loaded nanoemulsion (NT) was prepared using a high speed homogenizer and sonicator with varying amounts of surfactant, glycerol, and distilled water. Using a phase diagram, different formulations were tested for their droplet size and insect repellent activity. The nanoemulsion containing 6.25% surfactant and 91.25% glycerol (NT 6) had the highest percentage of protection (87.81%) in terms of repellent activity among the formulations tested for the 8 h duration of the experiment. The droplet size of NT 6 was 217.4 nm, and its polydispersity index (PDI) was 0.248. The zeta potential value was –44.2 mV, and the viscosity was 2.49 Pa.s at pH 5.6. The in vitro release profile was 71.5%. When the cytotoxicity of NT 6 at 400 μg/mL was tested using the MTS assay, cell viability was 97.38%. Physical appearance and stability of the nanoemulsion improved with the addition of glycerol as a co-solvent. In summary, a nutmeg oil-loaded nanoemulsion was successfully formulated and its controlled release of the essential oil showed mosquito repellent activity, thus eliminating the disadvantages of essential oils.

In this study, fluorescein-labelled wheat germ agglutinin (fWGA)-conjugated disulfide cross-linked sodium alginate nanoparticles were developed to specifically target docetaxel (DTX) to colon cancer cells. Different amounts of 3-mercaptopropionic acid (MPA) were covalently attached to sodium alginate to form thiolated sodium alginate (MPA1–5). These polymers were then self-assembled and air-oxidised to form disulfide cross-linked nanoparticles (MP1–5) under sonication. DTX was successfully loaded into the resulting MP1–5 to form DTX-loaded nanoparticles (DMP1–5). DMP2 had the highest loading efficiency (17.8%), thus was chosen for fWGA surface conjugation to form fWGA-conjugated nanoparticles (fDMP2) with a conjugation efficiency of 14.1%. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analyses showed spherical nanoparticles, and an in vitro drug release study recorded a cumulative drug release of 48.6%. Dynamic light scattering (DLS) analysis revealed a mean diameter (MD) of 289 nm with a polydispersity index (PDI) of 0.3 and a zeta potential of −2.2 mV for fDMP2. HT-29 human colon cancer cells treated with fDMP2 showed lower viability than that of L929 mouse fibroblast cells. These results indicate that fDMP2 was efficiently taken up by HT-29 cells (29.9%). Fluorescence and confocal imaging analyses also showed possible internalisation of nanoparticles by HT-29 cells. In conclusion, fDMP2 shows promise as a DTX carrier for colon cancer drug delivery.

Plant essential oils have been widely used as fragrance in perfumes or flavouring agents in food products due to their unique characteristic scent of the active constituents. The objective of this study is to qualitatively and quantitatively analyse the repellent activity, and the properties of the bioactive constituents in nutmeg, peppermint, and basil oils. The repellent activity of these essential oils was tested against Aedes aegypti and analysed using gas chromatography-flame ionisation (GC-FID) method. α-pinene, terpinen-4-ol and safrole in nutmeg oil, α-pinene, β-pinene, and menthol in peppermint oil, and methyl chavicol, geraniol, and methyl eugenol in basil oil, were selected for further analysis. Selected constituents were tested for accuracy, intra-and interday precision, recovery, limit of detection (LOD), and limit of quantification (LOQ). Nutmeg oil contributed to the highest percentage of repellence with 70.2%, with the accuracy values ranged from 99.25 - 99.71%. The precision for intra- and interday measurements for all tested constituents ranged between 1.083 - 7.296% and 1.308 - 7.924% respectively. The range of recovery was 97.43 - 100.86%. LOD ranged from 0.005 - 0.4 mol/L, and LOQ (with signal to noise ratio of 10:1) ranged from 0.0002 - 0.025 mol/L. In conclusion, the proposed method is simple, precise, and accurate, for qualitative and quantitative analysis of constituents present in essential oils. Nutmeg oil is an alternative natural mosquito repellent with α-pinene as the main active constituent.

The application of layer-by-layer (LbL) approach on nanoparticle surface coating improves the colon-specific drug delivery of insoluble drugs. Here, we aimed to formulate a self-assembled cysteamine-based disulphide cross-linked sodium alginate with LbL self-assembly to improve the delivery of paclitaxel (PCX) to colonic cancer cells. Cysteamine was conjugated to the backbone of oxidized SA to form a core of self-assembled disulphide cross-linked nanospheres. P3DL was selected for PCX loading and fabricated LbL with poly(allylamine hydrochloride) (PAH) and poly(4-styrenesulfonic acid-co-maleic acid) sodium salt (PSSCMA) resulting from characterization and drug release studies. P3DL-fabricated PCX-loaded nanospheres (P3DL/PAH/PSSCMA) exhibited an encapsulation efficiency of 77.1% with cumulative drug release of 45.1%. Dynamic light scattering analysis was reported at 173.6 ± 2.5 nm with polydispersity index of 0.394 ± 0.105 (zeta potential= −58.5 mV). P3DL/PAH/PSSCMA demonstrated a pH-dependent swelling transition; from pH 1 to 7 (102.2% increase). The size increased by 33.0% in reduction response study after incubating with 10 mM glutathione (day 7). HT-29 cells showed high viabilities (86.7%) after treatment with the fabricated nanospheres at 0.8 µg/mL. Cellular internalization was successful with more than 70.0% nanospheres detected in HT-29 cells. Therefore, this fabricated nanospheres may be considered as potential nanocarriers for colon cancer-targeted chemotherapeutic drug delivery.

In the field of medicine, nanomaterials, especially those derived using the green method, offer promise as anti-cancer agents and drug carriers. However, the biosafety of metallic nanoparticles used as anti-cancer agents remains a concern. The goal of this systematic review was to compare the cytotoxicity of different plant-mediated syntheses of metallic nanoparticles based on their potency, therapeutic index, and cancer cell type susceptibility in the hopes of identifying the most promising anti-cancer agents. A literature search of electronic databases including Science Direct, PubMed, Springer Link, Google Scholar, and ResearchGate, was conducted to obtain research articles. Keywords such as biosynthesis, plant synthesis, plant-mediated, metallic nanoparticle, cytotoxicity, and anticancer were used in the literature search. All types of research materials that met the inclusion criteria were included in the study regardless of whether the results were positive, negative, or null. The therapeutic index was used as a safety measure for the studied compound of interest. Data from 76 selected articles were extracted and synthesised. Seventy-two studies reported that the cytotoxicity of plant-mediated synthesis of metallic nanoparticles was time and/or dose-dependent. Biosynthesised silver nanoparticles demonstrated higher cytotoxicity potency compared to gold nanoparticles synthesised by the same plants (Plumbago zeylanica, Commelina nudiflora, and Cassia auriculata) irrespective of the cancer cell type tested. This review also identified a correlation between the nanoparticle size and morphology with the potency of cytotoxicity. Cytotoxicity was found to be inversely proportional to nanoparticle size. The plant-mediated syntheses of metallic nanoparticles were predominantly spherical or quasi-spherical, with the median lethal dose of 1–20 µg/mL. Nanoparticles with other shapes (triangular, hexagonal, and rods) were less potent. Metallic nanoparticles synthesised by Abutilon inducum, Butea monosperma, Gossypium hirsutum, Indoneesiella echioides, and Melia azedarach were acceptably safe as anti-cancer agents, as they had a therapeutic index of >2.0 when tested on both cancer cells and normal human cells. Most plant-mediated syntheses of metallic nanoparticles were found to be cytotoxic, although some were non-cytotoxic. The results from this study suggest a focus on a selected list of potential anti-cancer agents for further investigations of their pharmacodynamic/toxicodynamic and pharmacokinetic/toxicokinetic actions with the goal of reducing the Global Burden of Diseases and the second leading cause of mortality.