*2.2. Subclass Polypodiidae*

Aqueous and polar organic extracts of ferns of the mangrove are moderately broad*spectrum* antibacterial and antifungal (Table 1). Data on the antiviral properties of ferns are lacking. The methanol extract of *Stenochlaena palustris* (Burm. f.) Bedd. (25 μL/6 mm disc of a 100 mg/mL solution) evoked halos against *Staphylococcus aureus*, *Bacillus subtilis*, *Escherichia coli*, *Klebsiella pneumoniae*, *Salmonella typhi*, *Penicillium chrysogenum*, *Aspergillus niger*, and *Saccharomyces cerevisae* [12]. From the leaves of this fern was identified the flavonol glycoside stenopalustroside A (**1**), which strongly repressed the *Staphylococcus epidermidis* [13].

Antimicrobials in this subclass are mainly phenolics. Other ferns with broad-spectrum antibacterial and antifungal properties are *Nephrolepis biserrate* (Sw.) Schott, *Drynaria quercifolia* (L.) J. Sm., *Drymoglossum piloselloides* (L.) Presl., *Pyrrosia piloselloides* (L.) Farw., *Microsorum punctatum* (L.) Copel. [14–16], *Phymatosorus scolopendria* (Burm. f.) Pic. Serm. [17], *Platycerium coronarium* (O.F. Müll.) Desv. [18], and the true mangrove fern *Acrostichum aureum* L. [19–21]. Of note, the ethyl acetate extract of roots of *Acrostichum speciosum* L., which is a true mangrove fern, was bactericidal for *E. coli* with the MIC/MBC of 40/40 μg/mL [21].

**Table 1.** Ferns and cycads from the mangroves, tidal rivers, and the seashores of Asia and the Pacific with antibacterial and/or antifungal activity.


Bold: true mangrove plants [3]. +: Activity of extract(s) reported in the literature.
