# Production of Fungal Pigments: Molecular Processes and Their Applications
## 5 Application of Pigments: Market Analyses and Future Trends
Similarly, red anthraquinones produced by _Fusarium oxysporum_ and by _Dermocyhe sanguinea_, as well as yellow pigments by _Trichoderma virens_ and melanins by _Curvularis lunata_, have been reported as promising dyes for fabrics (i.e., wool and silk), with good colorfastness and crocking properties [140; 141]. Pigments of other fungal species, such as _M. purpureus_, _Penicillium_ spp., _Fusarium_ spp., and _Isaria_ spp., were demonstrated as excellent biological dyestuffs for tannery [142]. At present, among the diverse anthraquinone-producing fungi, most research has focused on only a small number of species that meet the criteria proposed by [PERSON] et al. [143]: (1) non-pathogenic to humans; (2) non-toxician under a wide variety of manufacturing conditions; and (3) capable of growing and yielding pigments in liquid media. However, the chemical diversity and biological activities of fungal anthraquinones and their derivatives are enormous, especially those derived from untapped habitats like marine [144] and endophytic sources [145]. The utilization history of naphthoquinones has witnessed the extension of their functionality from the original purposes as dyes to medicinal benefits. Over 100 naphthoquinones with a diversity of structures and physicochemical properties have been characterized from more than 60 filamentous fungi [58; 146]. These compounds are found to possess fascinating bioactivities, such as antimicrobial, anti-inflammatory, and anticancer activities, due to their propensity of inhibiting respiration and damaging the DNA of pathogens and cancer cells [147]. Anticancer activity has been reported for 1,4-naphthoquinones and their analogues, the former of which are thought to be the most important and widely distributed compounds within the quinone family. The clinical significance of 1,4-naphthoquinones has kindled tremendous research interest in this class of compounds. _Monascus_ pigments are food colorants that have been widely used in East Asia for centuries [148]. _Monascus spp._ are known to produce three kinds of polyketides: citrinin, red pigments, and monacolin K [149; 150; 151]. Given that citrinin is nephrotoxic and hepatotoxic in mammals [151], many countries such as the United States, European countries, and Japan have enacted legislation to limit the usage of _Monascus_ pigments as food colorants/additives [152; 151]. Consequently, for decades, researchers have continued to explore _Monascus_ species and strains that do not produce any citrinins or amounts of citrinin below the legislated level [143]. A recent study [153] assessed the effects of different purple rice varieties on the production of citrinin and red pigments by the _M. purpureus_ strain CMU002U (UV-mutant). The lowest level of citrinin at 132 ppb was found in the Na variety, which fulfilled the threshold of food regulations in Japan and the European Union. The highest yield of red pigment was achieved using the fermented Doi Muser variety. Taken together, these data suggest that fermented purple rice is a promising candidate to be developed as a safe food supplement. On the other hand, as initially described by [PERSON] et al., a polyketide synthase _pkSCT_ was essential for citrinin biosynthesis in the industrial species _M. purpureus_[68]. [PERSON] et al. [154] removed citrinin in _M. purpureus_ by genetic engineering using _Agrobacterium tumefaciens_-mediated transformation to disrupt the polyketide synthase gene _pkSCT_ in _M. purpureus_ SM001. The resultant citrinin-free _pkSCT_ mutants were also found to yield the same level of _Monascus_ pigments as the wild-type strain. The established system was evaluated and showed a high efficiency in _Monascus_ strain improvement, thereby paving the road to manipulate the industrial strains for _Monascus_ pigment production. Metabolic regulation may also be used to eliminate the co-production of cittrinin during the _Monascus_ pigment biosynthesis. The metabolic behaviors of the cittrinin and red pigments were studied in _M.