Bioactive Effects of Plectranthus amboinicus Extract Using Microwave Techniques and Its Value Addition in...

Plectranthus amboinicus is an aromatic herb known for its medicinal properties and is increasingly explored for cosmetic applications. Its bioactive compounds possess antioxidant, antimicrobial, and anti-inflammatory properties, making it a promising candidate for multifunctional skincare formulations.

This study investigated the extraction of bioactive compounds from P. amboinicus leaves using microwave-assisted ethanol extraction. Two drying techniques-tray drying and freeze-drying-were compared to evaluate their impact on the extraction efficiency. The optimal extract (PF15), prepared using 15-minute microwave extraction and freeze-drying, was selected for further analysis. Bioactive content was assessed through quantification of caffeic acid, total phenolic content, and antioxidant activity via the DPPH assay. The antimicrobial activity of PF15 was tested against Staphylococcus aureus, Staphylococcus epidermidis, and Cutibacterium acnes. Anti-inflammatory potential of PF15 was evaluated in LPS-stimulated human THP-1 macrophages by measuring cytokine production.

The PF15 extract yielded the highest levels of bioactive compounds and demonstrated strong antioxidant activity. It exhibited significant antimicrobial effects against all tested skin pathogens. In the anti-inflammatory assay, PF15 significantly decreased pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) while upregulating the anti-inflammatory cytokine IL-10. The extract was formulated into a topical cream, which underwent accelerated stability testing over six heat-cool cycles. The cream remained stable with no signs of phase separation, discoloration, odor change, or microbial contamination, and maintained a pH of 5.5.

The PF15 extract of P. amboinicus demonstrates potent antioxidant, antimicrobial, and anti-inflammatory properties. Its successful incorporation into a stable cream formulation supports its potential as a multifunctional active ingredient in skincare products. These findings highlight P. amboinicus as a valuable natural source for the development of cosmetic formulations targeting oxidative stress, microbial infection, and inflammation.