**1. Introduction**

Throughout human history, food has been used to satisfy hunger and provide nutrition. Nowadays, food can be widely used not only to eliminate diseases, but also to improve the quality of life. Finding beneficial food resources from the wisdom of your ancestors is a fairly effective strategy.

Despite plants, fungi (e.g., *Actinomucor* spp., *Amylomyces* spp., *Rhizopus* spp., *Monascus* spp., *Neurospora* spp., *Aspergillus* spp., *Penicillium* spp., *Torulopsis* spp., *Trichosporon* spp., and *Zygosaccharomyces* spp.) also take an important place in producing various food products in fermented forms [1]. Fungi of the genus *Monascus* (Monascaceae) have been used to ferment rice in Asia for centuries. It has been widely utilized as food additives, natural food coloring agent, food antiseptic, and healthy food for nearly two thousand years [2,3]. The production of red yeas<sup>t</sup> rice was used as a Chinese folk medicine, recorded in old Chinese literature as a means of easing digestion and soothing pain. *Monascus* first became known in the West back in 1884, when van Tieghem introduced the usage of red powder (*Monascus ruber*) in Java local populations. Until 1979, Endo et al. isolated monacolin K analogues from *M. ruber* and opened up the investigation of ingredients and bioactivities from *Monascus* [4]. Monacolin K is the same compound as cholesterol-lowering medicine

**Citation:** Wu, M.-D.; Chen, J.-J.; Cheng, M.-J. Secondary Metabolites with Antifungal Activities from Mangrove Derived Fungus *Monascus purpureus* WMD2424. *Mar. Drugs* **2023**, *21*, 200. https://doi.org/ 10.3390/md21040200

Academic Editors: Wenhan Lin, Guoqiang Li and Jing Xu

Received: 13 January 2023 Revised: 14 February 2023 Accepted: 19 February 2023 Published: 24 March 2023

**Copyright:** © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

lovastatin, which has been approved by the FDA to become the first commercial statin in 1987 [5].

*Monascus*-fermented rice, also called anka, koji, or red yeas<sup>t</sup> rice, is obtained via the fermentation of rice with fungi of the genus *Monascus*, mainly *M. purpureus, M. pilosus, M. ruber, M. kaoliang,* and *M. anka* [3]. Recently, *Monascus*-fermented rice has been reported for various biological functions. For example, they are helpful for metabolism-related disease with cholesterol-lowering effects [6], cardiovascular diseases [6], and diabetes [7,8]. Also, much evidence has also depicted their anti-inflammation activity [9–11], which is also highly associated with cardiovascular disease [12], cancer [13–17], diabetes [18,19], and Alzheimer's disease [20,21]. Some investigations reveal the anti-microorganism activity of red yeas<sup>t</sup> rice such as anti-bacteria [22–29] and anti-HCV [30]. In recent years, the phytochemical investigation of *Monascus* species have has resulted in the isolation and identification of azaphilones (yellow, orange, and red pigments), monacolins, flavonoids, fatty acids, organic acids, dimerumic acid, and γ-aminobutyric acid, etc. [9,14,27,31–34]. However, studies on the secondary metabolites of *Monascus* grown in fermentation conditions other than red yeas<sup>t</sup> rice are limited. We recently isolated an unpublished novel strain, named WMD2424, from the mangrove wetland in Chiayi County, which had a unique morphology and possessed antimicrobial activities as determined by our preliminary screening. This strain was determined to be *Monascus purpureus* based on its phenotypic and genotypic data (Figure 1).

**Figure 1.** (**A**,**B**) Colony morphology, CYA, 25 ◦C, cultured for 7 days, ( **A**) the front of the colony; (**B**) the back of the colony. ( **C**–**F**) Microstructure: ( **C**) hyphae and branches (bar = 100 μm); (**D**) conidiophores and conidia (bar = 25 μm); (**E**) ascocarp (bar = 25 μm); (**F**) ascospores (bar = 10 μm).

As part of our continuing efforts to explore the chemical diversity of marine fungal metabolites, *Monascus purpureus* WMD2424, fermented using RGY medium (3% rice starch, 7% glycerol, 1.5% polypeptone, 3% soybean powder, 0.2% MgSO4, and 0.2% NaNO3), was investigated. The scaled-up fermentation and extensive chromatographic separation of the EtOAc extract resulted in the isolation of 5 new metabolites, monascuspurins A–E (**1**–**5**), and their antifungal activity was also evaluated. Herein, we report the structural determination of the new compounds (Figure 2) and the bioactivities of these compounds.

**Figure 2.** Compounds **1**–**5**, isolated from *Monascus purpureus* wmd2424.
