Harnessing the Anti-Acne Potential of Locally Sourced Seaweeds from Coastal India: Toward Sustainable and Natural Skincare Alternatives ^†

With rising global awareness regarding sustainability, the exploration of marine bioresources for eco-friendly therapeutic applications has gained significant momentum. This study investigates the anti-acne potential of Ulva fasciata and Gracilaria edulis, locally abundant species of green and red seaweed from the coastal waters of Mangalore, Dakshina Kannada (Karnataka, India), against key acne-inducing bacteria: Propionibacterium acnes, Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa.

Crude methanolic extracts were subjected to flash chromatography for bioactive fractionation. Emphasizing sustainability, microwave-assisted aqueous extraction—a green and energy-efficient technique—was also employed to obtain eco-conscious bioactive preparations.

Antibacterial activity was evaluated against four acne-associated bacteria—Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Propionibacterium acnes—using the Kirby–Bauer disk diffusion method, the Minimum Inhibitory Concentration (MIC), the Minimum Bactericidal Concentration (MBC), growth curve kinetics, and the Resazurin microtiter viability assay. Among ten fractions obtained from Ulva fasciata, fractions 4 and 10 demonstrated notable antibacterial activity, with inhibition zones ranking in the following order: S. aureus > S. epidermidis > P. aeruginosa > P. acnes. Similarly, from seven fractions of Gracilaria edulis, fraction 3 showed activity following the same inhibition trend. Importantly, S1 exhibited inhibitory effects even against Gram-negative P. aeruginosa, highlighting its broad-spectrum antimicrobial potential.

Antioxidant activity, assessed using DPPH and ABTS assays, revealed that Ulva fasciata exhibited stronger free-radical-scavenging capacity compared to Gracilaria edulis. Active fractions were further analyzed using HPLC, LC-MS, and HRMS, leading to the preliminary identification of potential lead compounds responsible for the observed bioactivity, supporting these species’ therapeutic relevance in managing oxidative stress-associated dermal conditions like acne.

This research underscores a sustainable bioprospecting model: valorizing local marine biodiversity using green extraction technologies to develop effective, plant-based dermatological formulations using regional biodiversity.