Enhanced production of cytotoxic secondary metabolites through garlic peel biotransformation using Paecilomyces maximusPQ584815

Abstract Research on garlic peel has identified a variety of bioactive compounds. This study highlights the significance of garlic peels and the marine fungal strain Paecilomycesmaximus PQ584815 in generating secondary metabolites with effective anticancer properties and potential applications in therapeutic drug development. Additionally, these findings high spot the economic value and waste reduction benefits associated with utilizing this by-product, thus reducing the environmental impact of the industry. The marine fungal strain Paecilomycesmaximus PQ584815 was isolated, identified via 18S rDNA sequencing, and evaluated for its capacity to produce secondary metabolites using garlic peels as a substrate. Optimization of metabolite production was achieved through using Plackett-Burman design (PBD) to determine key medium components, followed by Central Composite Design (CCD) optimization. Maximum metabolite activity was 416.15% under specific conditions. Statistical analyses demonstrated that CCD enhanced secondary metabolite productivity by 2.47 times compared to PBD and 3.5 times relative to the initial production medium. Five compounds: Phytol, Protocatechuic acid, 3,4,5-trimethoxycinnamic acid, 2,6-dimethoxybenzoquinone, and 3′,4′,5,7-Tetra-O-methylquercetin were isolated from the ethyl acetate extract of the fungal filtrate for the first timefrom this source, identified using chromatographic techniques and spectroscopic comparison with those previously reported inliterature data. Both the extract and isolated compounds were tested in vitro against human liver, colorectal, and breast cancer cell lines, as well as normal skin fibroblast cells, employing a lactate dehydrogenase assay. Cancer cells were inhibited by all compounds in a dose-dependent manner, selectively active towards colon cancer cells. Their cytotoxicity against cancer cells was notably higher than against normal cells relative to doxorubicin. Graphical Abstract