Isolation, derivatization, and anti-microbial evaluation of secondary metabolites from Garcinia dryobalanoides.

A detailed study on secondary metabolites from the stem bark of Garcinia dryobalanoides has yielded one triterpenoid and four xanthones. Along with that, five novel rubraxanthone derivatives had been successfully synthesised via Williamson etherification with various alkyl halides. The antibacterial evaluation on crude extract, isolated secondary metabolites (1-5), and synthesised compounds (6-9) against Lactiplantibacillus plantarum, Enterobacter cloacae, Pseudomonas aeruginosa, and Serratia marcescens demonstrated moderate to active activities outlining their bacteriostatic potential. The structure-activity relationship (SAR) study conducted revealed the presence of prenyl and hydroxy groups on the xanthone attributed to good bacterial inhibition. The introduction of the alkyl chain to the hydroxy part eventually decreases the antibacterial activity of the compound which is probably due to the bulkiness that causes steric hindrances, therefore limiting the ability to bind to its target site within the bacterial cell.

In vitro antimicrobial activities, molecular docking and density functional theory (DFT) evaluation of natural product-based vanillin derivatives featuring halogenated azo dyes.

Chemical modification of active scaffolds from natural products has gained interest in pharmaceutical industries. Nevertheless, the metabolites extraction is time-consuming while the lead is frequently mismatched with the receptor. Here, the diazo coupling approach was introduced to generate a series of vanillin derivatives featuring halogenated azo dyes (1a-h). The vanillin derivatives showed effective inhibition of S. aureus (7-9 mm) and E. coli (7-8 mm) compared to the parent vanillin, while 1b had the highest inhibition zone (9 mm) against S. aureus comparable to the reference ampicillin. The presence of N = N, C = O, -OH, -OCH3 and halogens established strategic binding interactions with the receptor. The potential vanillin-azo as an antimicrobial drug was supported by in silico docking with penicillin-binding proteins and DFT (using Gaussian 09) with binding affinity -7.5 kcal/mol and energy gap (Egap) 3.77 eV, respectively. This study represents a significant advancement in drug discovery for effective antibiotics with excellent properties.

In vitro cytotoxicity evaluation of thiourea derivatives bearing Salix sp. constituent against HK-1 cell lines.

In searching for drugs from natural product scaffolds has gained interest among researchers. In this study, a series of twelve halogenated thiourea (ATX 1-12) via chemical modification of aspirin (a natural product derivative) and evaluated for cytotoxic activity against nasopharyngeal carcinoma (NPC) cell lines, HK-1 via MTS-based colorimetric assay. The cytotoxicity studies demonstrated that halogens at meta position of ATX showed promising activity against HK-1 cells (IC50 value ≤15 µM) in comparison to cisplatin, a positive cytotoxic drug (IC50 value =8.9 ± 1.9 µM). ATX 11, bearing iodine at meta position, showed robust cytotoxicity against HK-1 cells with an IC50 value of 4.7 ± 0.7 µM. Molecular docking interactions between ATX 11 and cyclooxygenase-2 demonstrated a robust binding affinity value of -8.1 kcal/mol as compared to aspirin's binding affinity value of -6.4 kcal/mol. The findings represent a promising lead molecule from natural product with excellent cytotoxic activity against NPC cell lines.