Photoprotective activity from Colombian Caribbean brown algae using HPLC-DAD metabolic profiling by MCR-ALS data analysis

Abstract

Although synthetic UV filters are widely used for skin photoprotection, growing concerns about their environmental and health impacts underscore the need for new, effective photoprotective products. This study aimed to develop a screening methodology for selecting brown macroalgae extracts with potential photoprotective activity. The approach integrates in vitro photoprotection assays, antioxidant TLC-DPPH assays, and HPLC-DAD metabolic profiling of 17 algal samples from the Dictyota, Canistrocarpus, Stypopodium, Sargassum, Lobophora, Padina, and Turbinaria genera. The results revealed concentration-dependent sun protection factor (SPF) values ranging from 0.403 to 2.915, UVA ratios (UVAr) ranging from 0.167 to 3.623, critical wavelengths (λc) ranging from 335 to 393 nm, and antioxidant DPPH-TLC activity in 10 of the evaluated extracts. These findings were correlated with the HPLC-DAD metabolic profile using the Multivariate Curve Resolution- Alternating Least Squares (MCR-ALS) algorithm and multivariate data analysis tools. Extracts from Canistrocarpus cervicornis (CCe) and Stypopodium zonale (SS) presented the most promising photoprotective activity. Through NMR and MS analysis, 2,5,7-trihydroxy-2-pentadecylchroman-4-one (1), fucoxanthin, pheophytin a, and pheophorbide a were identified as the main contributors to this activity. This methodology was successfully implemented and could be further used to screen for photoprotective activity in algal species.

Keywords: MCR-ALS; Metabolic profiling; Ochrophyta; Photoprotection; Radiation; Screening.

Fig. 1

UV–Vis absorption spectra (λ = 290–500 nm) of the extracts obtained from 17 selected brown seaweed samples collected in Providencia. (a–d) spectra of extracts from Dictyota ( DI01, DI02, DI03, DI04, DI05, DM, DP01, and DP02) and Canistrocarpus ( CCe and CCr) genera: (a) FO extracts, (b) FB extracts, (c) FM extracts, and (d) FW extracts. (e–h) spectra of extracts from Stypopodium ( SS01, SS02, and SS03), Saragassum ( SP), Lobophora ( LV), Padina ( PG), and Turbinaria ( TT) genera: (e) FO extracts, (f) FB extracts, (g) FM extracts, and (h) FW extracts.

Fig. 2

Heatmap representation of the calculated in vitro sun protection factor (SPF at 50 ppm), UVA ratio (UVAr*), critical wavelength (λc), and antioxidant activity (AOX) assays. FO/FB/FM/FW stands for extract type. The numbers on the left differentiate the seven identified clusters, and the numbers in red indicate the clusters with the most promising photoprotective activity. * UVAr values correspond to the mean of three replicates at different concentrations, as no significant differences were observed between extracts at the evaluated concentrations.

Fig. 3

Principal Component Analysis (PCA) of the relative concentration matrix (RCM). (a) Score plot, (b) Hierarchical cluster analysis (HCA), (c) Loadings plot, and (d) UV–Vis spectra of selected loadings. C: Canistrocarpus cervicornis (CCe) cluster; S: Stypopodium zonale (SS) cluster; O: other samples cluster. The pure spectra matrix (S^T) was used to characterize the absorbance regions and color the variables in the loadings plot: () (UV absorption; λ = 290–400 nm); () (visible absorption; λ = 400–800 nm); () (UV–Vis absorption; λ = 290–800). The black circumferences represent sample clusters and important variables for extract differentiation.

Fig. 4

Partial least square analysis (PLS) of the relative concentration matrix (RCM). The outputs (Y-matrix) corresponded to the measured in vitro photoprotection parameters (SPF at 50 ppm, UVAr*, λc, and antioxidant activity). (a) Score plot, (b) VIP plot for variables with VIP scores grater than 1 (important variables), (c) Loadings plot, and (d) UV–Vis spectra of selected variables (81, 107, and 127). C: Canistrocarpus cervicornis (CCe) cluster; S: Stypopodium zonale (SS) cluster; O: Other samples cluster. The pure spectra matrix (S^T) was used to characterize the absorbance regions and color the variables: ( ) (UV absorption; λ = 290–400 nm); () (visible absorption; λ = 400 -800 nm); and () (UV–VIS absorption; λ = 290–800). The black circumferences represent sample clusters and important variables for extract differentiation.* UVAr values correspond to the mean of three replicates at different concentrations, as no significant differences were observed between extracts at the evaluated concentrations.

Fig. 5

Chemical structures of (a) isolinearol, (b) fucoxanthin (c) 2,5,7-trihydroxy-2-pentadecylchroman-4-one(1), (d) stypodiol, (e) stypoldione identified in Canistrocarpus cervicornis (CCe) and Stypopodium zonale (SS02) FO extracts.

Fig. 6

Results of the in vitro photoprotection activity assays for benzophenone-3 (BP-3), pheophytin a, fucoxanthin, 2,5,7-trihydroxy-2-pentadecylchroman-4-one (compound 1), and pheophorbide a identified in C. cervicornis (CCe-FO) and S. zonale (SS02-FO) organic extracts. (a) SPF (Sun Protection Factor); (b) UVAr (UVA ratio); (c) λc (critical wavelength). The error bars represent the standard deviation (For SPF, n = 3, mean of three replicates at each concentration. For UVAr, n = 3, mean of three replicates at different concentrations as no significant differences were observed between extracts at the evaluated concentrations).