# Halophytes as Medicinal Plants against Human Infectious Diseases
## 3 Halophytes as a Source of Antimicrobial Compounds
### Antifungal Effects  
Many plants produce antifungal compounds as a strategy of defense against phytopathogenic agents [100]. Facing the emergence of resistance to antifungal drugs among human pathogenic fungi, there is a regaining interest in plants as an alternative source of fungicidals [101]. Evidence of the activity of halophyte metabolites against pathogenic fungi is less documented in the literature than antibacterial effects, although in many studies, bacterial and fungal strains are included in the panel of microbial targets of bioactive compounds. Often, extracts that are active against bacteria are ineffective against fungi [102]. There are, however, encouraging reports of the antifungal activity of halophytes (Table 4), which are mainly associated with essential oils and phenolic-rich extracts [102,103], although there is a strong variability in the antifungal activity of different extracts, depending on the solvents used. The cell wall, the cytoplasmic membrane and the cytoplasm are considered as the main targets of the phenol attack that underlies antifungal activity of plant extracts [104]. Efficiency of extraction of phenolic compounds increases with the polarity of the solvents; hence, the strongest antifungal activity of water: methanol extracts and the correlation with antioxidant activities [105]. _Candida_ species are normally represented in the human commensal microbiota, but some species are also among the most threatening fungal pathogens. _C. albicans_ accounts for the vast majority of skin, urinary system and blood infections [106]. _C. auris_ is an emergent pathogen that imposes concern because it is extremely invasive, multi-resistant to antifungal drugs, causes high mortality and has triggered research on plant-derived antifungals. Therefore, _Candida_ species are the most frequent fungal models for the testing of antifungal activity of halophyte metabolites [107,108]. There is evidence that _C. albicans_, _C. glabrata_, _C. holmini_, _C. rusei_, _C. parapysilosis_ and _C. tropicalis_ can be inactivated in vitro by extracts of many different halophytes, including _Avicentia marina_, _Erryingum_ sp., _Rhizophora_ sp. and _Xanthinium sibricum_ [PERSON]. [105]. Extracts of the facultative halophyte _Salsola kali_ L. were also effective on _C. albicans_, _C. glabrata_ and _C. holmi_, and the fungicidal activity was attributed to phenolic compounds such as syringic acid and kaempfer [109]. Essential oils of _Salsola vermiculata_ L. and _S. cyclophylla_ [PERSON]. strongly inhibited _C. albicans_[110]. Extracts of _Arthrocnemius macrostachyum_ [PERSON] and _Salicornia europaea_ inhibited _C. albicans_[105] and _C. albicans_, _C. glabrata_, _C. utilis_ and _C. tropicalis_[80], respectively. There are also reports of the inhibition of pathogenic molds. Extracts of _Cressa cretica_ [PERSON] inhibited several pathogenic fungi. The effect on the molds _Aspergillus fumigatus_ and _A. niger_ was even stronger than on the yeasts _Candida albicans_ and _C. tropicalis_[89]. Aqueous extracts and the essential oil of _Myrtus communis_ [PERSON] caused inhibition of the pathogenic mold _Aspergillus fumigatus_, and the effect was within the same order of magnitude as on _Candida albicans_[104].