Natural antioxidants derived from plants have shown a tremendous inhibitory effect on free radicals in actively metabolizing cells. Overproduction of free radicals increases the risk factor of chronic diseases associated with diabetes, cancer, arthritis and cardiovascular disease. Andrographis paniculata, Cinnamon zeylanicum, Curcuma xanthorrhiza, Eugenia polyantha and Orthosiphon stamineus are ethnomedicinal plants used in the Asian region to treat various illnesses from a common fever to metabolic disease. In this study, we have quantified the total phenolic (TPC) and flavonoid content (TFC) in these plants and its inhibitory effect on 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radicals as well as the cytotoxicity effect on cell lines proliferation and zebrafish embryogenesis. Results showed that Cinnamon zeylanicum and E. polyantha have the highest phenolic and flavonoid content. Furthermore, both herbs significantly inhibited the formation of DPPH and ABTS free radicals. Meanwhile, O. stamineus exhibited minimum cytotoxicity and embryotoxicity on tested models. Good correlation between IC50 of 3T3-L1 cells and LC50 embyrotoxicity was also found. This study revealed the potent activity of antioxidant against free radical and the toxicology levels of the tested herbal plants.

Rtg1 and Rtg3 are two basic helix-loop-helix (bHLH) transcription factors found in yeast Saccharomyces cerevisiae that are involved in the regulation of the mitochondrial retrograde (RTG) pathway. Under RTG response, anaplerotic synthesis of citrate is activated, consequently maintaining the supply of important precursors necessary for amino acid and nucleotide synthesis. Although the roles of Rtg1 and Rtg3 in TCA and glyoxylate cycles have been extensively reported, the investigation of other metabolic pathways has been lacking. Characteristic dimer formation in bHLH proteins, which allows for combinatorial gene expression, and the link between RTG and other regulatory pathways suggest more complex metabolic signaling involved in Rtg1/Rtg3 regulation. In this study, using a metabolomics approach, we examined metabolic alteration following RTG1 and RTG3 deletion. We found that apart from TCA and glyoxylate cycles, which have been previously reported, polyamine biosynthesis and other amino acid metabolism were significantly altered in RTG-deficient strains. We revealed that metabolic alterations occurred at various metabolic sites and that these changes relate to different growth phases, but the difference can be detected even at the mid-exponential phase, when mitochondrial function is repressed. Moreover, the effect of metabolic rearrangements can be seen through the chronological lifespan (CLS) measurement, where we confirmed the role of the RTG pathway in extending the yeast lifespan. Through a comprehensive metabolic profiling, we were able to explore metabolic phenotypes previously unidentified by other means and illustrate the possible correlations of Rtg1 and Rtg3 in different pathways.

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Biomass valorisation is conventionally associated with the production of green biofuels. However, this could extend beyond the conventional perception of biomass application into other domains such as medical sciences. Acid condensate (AC) obtained from pyrolysis promises a good potential for biomedical applications, notably for its antimicrobial, antioxidant, and anti-inflammatory properties. In this study, concentrated AC extract (CACE) obtained from microwave-assisted pyrolysis of palm kernel shells was fractionated, and the resulting fractions were pooled according to similar thin layer chromatography profiles into combined fractions (CFACs). CFACs were evaluated for total phenolic content, antioxidant level, cytotoxicity, and wound healing activities toward human skin fibroblast cells (HSF 1184). CFAC-3 showed the highest total phenolic content (624.98 ± 8.70 µg GAE/mg of sample) and antioxidant activities (DPPH IC50 of 29.47 ± 0.74 µg/mL, ABTS of 1247.13 ± 27.89 μg TE/mg sample, FRAP of 24.26 ± 0.71 mmol Fe(II)/mg sample, HFRS of 257.74 ± 1.74 µg/mL) compared to CACE (DPPH IC50 of 81.76 ± 2.81 µg/mL, ABTS of 816.95 ± 30.49 μg TE/mg sample, FRAP of 9.22 ± 0.66 mmol Fe(II)/mg sample, HFRS of 689.30 ± 36.00 µg/mL), no cytotoxic properties at ≤50 µg/mL, and significantly faster wound closure (at 1.25 µg/mL) compared to the control 12 h after treatment. The phosphorylation of the phosphatidylinositol 3-kinase (PI3K) and protein kinase B (AKT) were upregulated, thus indicating that wound healing of CFAC-3 followed through this signalling pathway. To conclude, phenolic-rich CFAC-3 obtained from the pyrolysis of palm kernel shells demonstrated potential biomedical application as an alternative wound healing agent with high antioxidant and wound-healing activity. To the best of our knowledge, this was the first study to report on the wound healing activity of AC and its wound healing mechanism.

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