The use of natural colorants enables the replacement of potentially dangerous synthetic dyes [178,179]. Natural pigments are currently used more frequently than that of are chemically synthesized [180]. While red and yellow colorants were once widely employed in food coloring, blue is becoming more and more popular as a food colorant [181]. Polyketide pigments of Monascus, which produce a variety of red, yellow, orange, green, and blue hues, have great potential in this regard [181]. Figure 4 shows the chemical structure of several colorants. The majority of study has focused on the possibility of using fungal pigments in various industries, notably as food colorants or additives in the food industry [113], which has long been known by many researchers [78,152,182].

Monascus pigments, Arpink red from P. oxalicum, riboflavin from Ashbya gossypii, and β-carotene from B. trispora have already reached the worldwide market as food colorants (Table 2) [78,183]. These fungal pigments also have good commercial production yields. For example, the production yield of β-carotene in a Blakeslea trispora culture medium was reported to be 17 g/L [53,184]. In a study by Abdel-Raheam et al. (2022), Monascus purpureus was employed as an coloring component in ice lollies. The study found that the ice lolly to which these colors were added was highly accepted [185]. Monascus pigments may additionally be applied to other foods, such as fruit-flavored yogurt [186], sweet drops [187], flavored milk [188], jelly beans, and lollipops [189]. Penicillium brevicompactum was identified as a novel source of colors for the food sector in a recent study [190].

Penicillium oxalicum produces the anthraquinone pigment Arpink red, a red pigment with bacteriostatic, antiviral, fungicidal, herbicidal, and insecticidal characteristics [54]. Foodstuffs can be supplemented with the Arpink red polyketide of Penicillium oxalicum without any stabilizing [191]. After evaluating the toxicological data of the Arpink red pigment [77], Codex Alimentarius Commmision (CAC) made the statement about the amount to be used in food products (Table 3) that will be non-objectionable [192].

The chemical structure of azaphilone has been identified in over 50 distinct ways, and it may readily be coupled with nitrogenous compounds [90]. Monascorubrin, an orange azaphilone pigment derived from Monascus sp., may combine with amino acids to produce a red hue in meals [175]. Again, the polyketide pigments have improved functionality with respect to light stability, water solubility [193], anti-atherogenic activity [194], and antioxidant properties [195] when added to specific food products. As polyketide pigments, azaphilones (red and yellow colorants) of Monascus sp. have been lawfully commercially manufactured and used as food colorants all over the world. In Southeast Asia, a traditionally produced, dry fermented red rice powder has been utilized for over one thousand years [29]. More than 50 patents have recently been issued in several countries, including Japan, the United States, France, and Germany, regarding the use of Monascus pigments in food items [174]. It has been shown that several Talaromyces species, such as T. aculeatus, T. funiculosus, T. pinophilus, and T. purpurogenus, generate azaphilones, Monascus pigment analogues (MPA) pigments, similar to those seen in Monascus without generating citrinin or any other recognized mycotoxins [95].

Riboflavin, often known as vitamin B₂, is a yellow pigment that is used as a food colorant in most countries and is legal to use. Salad, sherbet, drinks, ice creams, pharmaceuticals, and other goods are among the products in which this pigment is utilized [138]. However, because of its slightly unpleasant smell and bitter taste, its use in cereal-based goods is rather limited, despite the fact that it has an affinity for them. Several bacteria create riboflavin through fermentation. Riboflavin can be divided into three types based on fermentation yield: (i) weak overproducers (100 mg/L or less, e.g., Clostridium acetobutylicum), (ii) moderate overproducers (600 mg/L or more, e.g., Candida guilliermundii or Debaryomyces subglobosus), and (iii) strong overproducers (over 1 g/L). Due to the superior genetic stability of its pigment, Ashbya gossypi is chosen for fermentation over others [196].

Fungal pigments, according to several research studies [56], have numerous health benefits over synthetic pigments, including antibacterial action against a variety of harmful bacteria, yeast, and fungi. The researchers also proposed that these bioactive pigments may be employed in the food and pharmaceutical sectors as food preservatives or antibacterial agents [16,183,197]. It has also been studied whether they may be used to make medical items such as bandages, suture threads, and face masks, and the documented findings imply that it is quite possible [198]. The antimicrobial property of the red pigment generated by M. purpureus was discovered, and the extract of M. purpureus was shown to be 81% effective when compared to the antibiotic ciprofloxacin [199]. Pencolide, sclerotiorin, and isochromophilone were isolated from another fungal strain, P. sclerotiorum, in a large-scale liquid culture. Isochromophilone was found to have antibacterial properties against S. aureus [200]. It was shown that Aspergillus sclertiorum DPUA 585 generated Neoaspergillic acid, which has antibacterial action against Escherichia coli, Mycobacterium smegmatis, and Staphylococcus aureus and antifungal activity against C. albicans [60]. Antibacterial activity has also been observed in Aspergillus versicolor [61]. Furthermore, antibacterial activity was found in Penicillium species isolated from Brazilian cerrado soil, with considerable activity against C. albicans, Listeria monocytogenes, and Bacillus cereus, respectively [201]. A key fungus species in the synthesis of many colors is Rhodotorula glutinis. The industrial scale use of this type of yeast has included creating carotenoid colors and acting as a biological control against the post-harvest degradation of fruit [202]. Rhodotorula glutinis pigment may effectively kill both the planktonic type of food-spoilage bacteria and the bacteria that form food-spoilage biofilms [203]. Aspergillus nidulans JAS3, an Indian-Ocean-isolated pigmented fungal strain, was recently the subject of a study that included its extraction, characterization, and antagonistic activity toward clinical pathogens. When strain JAS3 was treated in enhanced Czapek Dox medium at 28 °C, it was discovered that the pigment it produced was of a pale yellow hue. When tested against several clinical pathogenic strains, the colored pigment demonstrated good bioactivity, including antimicrobial, anti-proteinase, and antifouling activities [204]. In another study, a pigment derived from Gonatophrgmium truiniae was found to have antibacterial properties against Bacillus subtilis, Staphylococcus aureus, and Micrococcus luteus [30]. According to Poorniammal and Prabhu (2022), the fungal pigments produced from Thermomyces sp. and Penicillium purpurogenum have antibacterial properties that are effective against Staphylococcus aureus [205].

Microbial pigments such as carotenoids, violacein, and naphthoquinones have been shown to have antioxidant properties through several studies. The antioxidant potential of pigments from various fungi has been mentioned in a number of review papers [12,177,206]. Studies on the antioxidant activity of pigments from several fungi, including Penicillium sp. (P. miczynskii, P. purpureogenum, P. purpuroscens), Fusarium sp., Thermomyces sp., Chaetomium sp., Sanghuangporus baumii, Stemphylium lycopersici, and Trichoderma sp. (T. afroharzianum) have revealed their promising antioxidant potential and their possible application in the healthcare industry [207]. Epicoccum nigrum has also been demonstrated to be a non-mycotoxigenic fungal producer of a polyketide pigment with antioxidant properties [95]. The extracted pigment generated by Monascus purpureus in the investigation. Zeng et al. (2021) showed a stronger antioxidant activity in scavenging free radicals and preventing lipid oxidation [208]. In the study by Nair and Abraham (2023), it was revealed that a pale yellow pigment produced by Aspergillus nidulans JAS3 demonstrated antioxidant activity [204]. In another study, Phoma sp. RDSE17 was isolated and characterized for its melanin pigment. The biological characteristics of the pure melanin of the fungus were examined for their antioxidant activities. The pure melanin demonstrated strong DPPH free-radical-scavenging activity with an EC₅₀ of 69 µg/mL [209]. In the study by Fonseca et al. (2022), natural pigments derived from Penicillium brevicompactum were tested and found to be mycotoxin-free with potential antioxidant action [209]. Extracellular fungi pigments from Penicillium murcianum and Talaromyces australis demonstrated biotechnological potential of antioxidant activities in a study [210]. In another study, Gonatophrgmium truiniae’s pigment demonstrated antioxidant activity with an IC50 value of 0.99 mg/mL [157].

Fungal pigments have been shown to have anticancer and antitumor effects. Several investigations have indicated that fungal pigments might be used as an anticancer medication. Pigments of Monascus species (M. purpureus and M. pilosus) such as monascin, ankaflavin, monaphilone A–B, monapilol A–D, and monapurone A–C have been shown to have anticancer/antitumor potential against various cancers, including mouse skin carcinoma, human laryngeal carcinoma, human colon adenocarcinoma, and human hepatocellular carcinoma [29]. In addition to Monascus, other fungal pigments with anticancer, antitumor, or antiproliferative activities include norsolorinic acid from A. nidulans, shiraiarin from Shiraia bambusicola, alterporriol K, alterporriol L, and alterporriol M from Alternaria sp., benzoquinone from Fusarium sp., and an uncharacterized red pigment F (MCF-7, MDA-MB-435, and MCF-7 b), whereas hypocrellin D from S. bambusicola has anticancer effects against many other cancer cell lines (Bel-7721, A-549, and Anip-973) [67,211]. As an example, the anticancer properties of the AUMC 5705 Monascus strain as well as that of the AUMC 4066 secondary metabolites, which have numerous uses in the food, pharmaceutical, and other sectors, are evident [52]. The anticancer potentiality of raw coix seed fermented by Monascus purpureus was demonstrated and observed thatthe HEp2 cell line of human laryngeal carcinoma, which makes up 25% of neck and head cancers, was used to test the extract’s anticancer potential [208]. In another study, 80 µg/mL of pure melanin extracted from Phoma sp. RDSE17 hindered the development of human lung cancer cells [209].

Sclerotiorin, a bioactive metabolite generated by P. sclerotiorum, has been utilized in the pharmaceutical sector [82]. Penicillium sp. NIMO-02 produces a pigment that is important in the food and pharmaceutical sectors [96]. P. purpurogenum generated greater extracellular pigments with antibacterial activity in darkness, which may be used in the pharmaceutical and healthcare industries [212], while Trichoderma virens has eco-friendly antifungal characteristics. Penicillium sp. generates various secondary metabolites with high bioactive chemicals; these are utilized in pharmacy to make medicines to treat a variety of ailments and in agriculture [213]. P. oxalicum var. Armeniaca CCM 8242 generated an anthraquinone chromophore. The anthraquinone derivative Arpink red possesses anticancer properties and is used in food and medicines [6,214]. Sorbicillinoid pigments from Stagonospora sp. SYSU-MS7888 demonstrated anti-inflammatory activity in a recent research study [215]. The effectiveness of a purified anthraquinone from Talaromyces purpureogenus as a powerful agent for kidney radio-imaging, which might be used in the diagnosis of kidney cancer, was demonstrated [215]. As intriguing alternative medication sources, several instances of true endophytic fungi generating anthraquinones similar to their various host plants have been documented [216]. A pale yellow pigment produced by Aspergillus nidulans JAS3 was found to have anti-inflammatory activities [204]. According to another study, cadmium can be reduced with melanin pigment derived from Aspergillus terreus LCM8 [217].