Phycobiliproteins (PBPs), captivating water-soluble proteins found in cyanobacteria, red algae, and cryptophytes, continue to fascinate researchers and industries due to their unique properties and multifaceted applications. These proteins consist of chromophores called phycobilins (PBs), covalently linked to specific protein subunits. Major phycobiliproteins include phycocyanin (PC), allophycocyanin (APC), and phycoerythrin (PE), each distinguished by distinct absorption and emission spectra. Beyond their colorful properties, PBs exhibit a broad spectrum of biological activities, including antibacterial, antifungal, antiviral, and antidiabetic effects, making them valuable for pharmaceutical, biotechnological, and medical purposes. The extraction and purification methods for PBs have been optimized to enhance their bioavailability and stability, opening new avenues for industrial production. For this review, a comprehensive literature search was conducted using scientific databases such as PubMed, Scopus, and Web of Science, prioritizing peer-reviewed articles published between 2000 and 2025, with an emphasis on recent advances from the last five years, using keywords such as “phycobiliproteins”, “phycobilins”, “bioactivities”, “therapeutic applications”, and “industrial use”. Studies were selected based on their relevance to the biological, technological, and pharmacological applications of PBPs and PBs. This review explores the diverse applications of PBs in therapeutic, diagnostic, and environmental fields, highlighting their potential as natural alternatives in the treatment of various diseases. The future perspectives for PBs focus on their incorporation into innovative drug delivery systems, biocompatible materials, and functional foods, presenting exciting opportunities for advancing human health and well-being.

Plant-associated microorganisms represent a potential source of new antitumor compounds. The aim of the present study was to isolate endophytic and rhizosphere Gram-positive bacteria from Ibervillea sonorae and produce extracts with antitumor activity. Methanol and ethyl acetate extracts were obtained from 28 d bacterial fermentation, after which murine L5178Y-R lymphoma cells growth inhibition was evaluated at concentrations ranging from 15.62 µg/mL to 500 µg/mL by the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide reduction colorimetric assay. IC₅₀ and the selectivity index (SI) were calculated and compared with healthy control human peripheral blood mononuclear cells (PBMC). Identification of the isolated strains was performed using the 16S ribosomal gene and by MALDI-TOF MS mass spectrometry. The endophytic and rhizosphere bacterial extracts from strains ISE-B22, ISE-B26, ISE-B27, ISS-A01, ISS-A06, and ISS-A16 showed significant (p < 0.05) L5178Y-R cell growth inhibition, compared with an untreated control. The rhizosphere Micromonospora echinospora isolate ISS-A16 showed the highest (90.48%) percentage of lymphoma cells growth inhibition and SI (19.1) for PBMC, whereas the Bacillus subtilis ISE-B26 isolate caused significant (p < 0.01) growth inhibition (84.32%) and a SI of 5.2. Taken together, results of the present study evidenced antitumor effects by I. sonorae endophytic and rhizosphere bacteria culture extracts. Further research will involve the elucidation of the compounds that exert the antitumor activity and their evaluation in pre-clinical studies.

Endophytic fungi have become potential sources of antitumor agents, particularly against antineoplastic-resistant cancer cells, with marginal or nil adverse effects for the oncological patient. Endophytic fungi were isolated from stems of the Lophocereus marginatus cactus, commonly found in Mexico. Methanol extracts were then obtained from fungus liquid cultures and their effects on tumor cell growth against murine lymphoma (L5178Y-R), human colorectal adenocarcinoma (HT-29), and human breast cancer (MCF-7) cells were evaluated at concentrations ranging from 31 µg/mL to 250 µg/mL via the colorimetric 3- [4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazoliumbromide reduction assay, using monkey kidney epithelial (MA-104) and human peripheral mononuclear (PBMC) cells as controls. Furthermore, we obtained the IC₅₀ and the selectivity index (SI) was calculated from the IC₅₀ ratio of normal and tumor cells. In addition, molecular identification of fungi showing cytotoxic activity was determined, using internal transcribed spacer molecular markers. PME-H001, PME-H002, PME-H005, PME-H007, and PME-H008 filamentous fungus strain extracts showed significant (p < 0.05) tumor cell growth inhibition. In particular, they significantly (p < 0.05) inhibited L5178Y-R cell growth, whereas the least susceptible cell line was HT-29. The endophytic strain PME-H008 of Cladosporium sp. caused the highest growth inhibition percentage against L5178Y-R and HT-29 cells with 96.6% (p < 0.01) and 42.5% (p < 0.05) respectively, and the highest SIs against L5178Y-R cells with 2.4 and 2.9 for MA-104 and PBMCs, respectively, whereas the PME-H005 extract showed SIs of 2.77 and 1.5 against MCF-7 and L5178Y-R cells, respectively, as compared with PBMCs. In addition, the endophytic strain PME-H007 of Metarhizium anisopliae caused the highest percentage of growth inhibition (p < 0.01) against MCF-7 cells with 55.8% at 250 µg/mL. We demonstrated in vitro antitumor effects of L. marginatus endophytic fungi. Further research will involve the isolation and in vivo testing of bioactive compounds.

Chlorella species are fast-growing microalgae with significant industrial applications. The aim of the present study was to investigate the antitumor, antioxidant, and hemolytic activities of Chlorella sorokiniana UTEX 1230 crude methanol extracts and fractions. Ch. sorokiniana crude methanol extracts and collective fractions (CFs) were obtained from lyophilized biomass by maceration and column chromatography. Antitumor assays against murine lymphoma L5178Y-R and human breast cancer MCF-7 cells were performed by the colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction technique, using human peripheral blood mononuclear cells (PBMC) as the control group. Antioxidant and hemolytic activities were evaluated using the 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay (DPPH) and erythrocyte hemolysis, respectively. We showed that crude methanol extracts (IC₅₀) increased L5178Y-R and MCF-7 cell growth inhibition, without affecting PBMC. In addition, all evaluated CFs showed significantly higher antioxidant activity than the positive control (ascorbic acid). CF3 and CF4 showed the highest cytotoxicity against L5178Y-R, whereas CF3, CF4, and CF5 caused the highest antitumor activity against MCF-7 cells. CF3, CF4, and CF5 induced significantly higher hemolytic activity compared with all other fractions. CF characterization revealed loliolide, cinnamic acid, methyl dihydrojasmonate, salsalvamide A, 1-monolinolenin, cryptophycin 29, costunolide, riboflavin lumicrome, and germicidin B, which have been related to antitumor and antioxidant activities. In conclusion, we demonstrated that Ch. sorokiniana extracts and fractions possess antitumor and antioxidant potential, without affecting human erythrocytes and PBMC.

Entomopathogenic fungi have been considered potential biological control agents against the fall armyworm Spodoptera frugiperda (J. E. Smith), the world’s most important pest of maize. In this study, we evaluated the natural infection, molecular characteristics, and biological activity of Metarhizium rileyi (Farlow) isolated from S. frugiperda larvae of this insect, collected from maize crops in five Mexican locations. Natural infection ranged from 23% to 90% across all locations analyzed. Twenty-four isolates were evaluated on S. frugiperda second instars at a concentration of 1.0 × 10⁸ conidia/mL, causing 70% to 98.7% mortality and 60.5% to 98.7% sporulation. Isolates T9-21, Z30-21, PP48-21, and L8-22 were selected to determine their phylogenetic relationships by β-tubulin gene analysis and to compare median lethal concentration (CL₅₀), median lethal time (LT₅₀), and larval survival. These isolates were grouped into three clades. The T9-21, PP48-21, and J10-22 isolates were closely related (clade A), but phylogenetically distant from Z30-21 (clade B) and L8-22 (clade C) isolates. These genetic differences were not always reflected in their pathogenicity characteristics since no differences were observed among the LC₅₀ values. Furthermore, isolates T9-21, J10-22, and L8-22 were the fastest to kill S. frugiperda larvae, causing lower survival rates. We conclude that native M. rileyi isolates represent an important alternative for the biocontrol of S. frugiperda.

Hirsutella citriformis Speare is the only entomopathogenic fungus that has been applied to control the hemipteran Diaphorina citri Kuwayama. However, the use of available commercial products under field conditions is limited due to conidia’s shelf life and short environmental persistence. We have previously reported the citrus psyllid D. citri adults’ biocontrol potential using H. citriformis strains. The aim of the present study was to evaluate different formulations based on H. citriformis (OP-Hir-3, OP-Hir-10, and OP-Hir-12 strains) conidia and gums as additives to improve D. citri adults’ biocontrol, under laboratory, greenhouse, and field conditions, using Hirsutella gums as conidia stabilizers to improve their viability under environmental drought conditions and as insecticide. Laboratory bioassay results showed that the highest (p < 0.05) D. citri mortality was achieved using FOP-Hir-10GH (63.5%), followed by the Hirsutella gum control (42.2%). Under greenhouse conditions, adults’ mortality reached up to 84.6% with FOP-Hir-12 and 49.0% with Hirsutella gum. In addition, we applied H. citriformis formulations under field conditions in a commercial citrus grove located in Tecomán, Colima, México, at 21.5 °C and 73.3% relative humidity (RH) in March and 25.7 °C and 72.5% RH in October 2022 and observed 67.3% and 94.0% mortality of D. citri adults, respectively. Hirsutella gum alone showed significant insecticidal activity against D. citri adults. In conclusion, this study demonstrated that Hirsutella gum functioned as additive to H. citriformis conidia formulations, improving D. citri adults’ mortality and showing potential for this pest biocontrol in citrus orchards.