When we talk about antibiotics and their discovery, the mind takes us back to the penicillin and molds from which it was isolated. Even higher plants, however, like most living organisms, produce substances with an antimicrobial action. Let's look at some examples:
- Several ranunculaceae produce protoanemonine, which has been shown to possess broad-spectrum and antifungal antibacterial activity.
- Some crucifers (Brassicaceae) produce sulfur-containing substances with antibiotic action, such as sulforaphane, active against Helicobacter pylori.
- Hypericum oil contains hyperforin, which in addition to exerting an anxiolytic and sedative action, has shown antibiotic properties against numerous bacterial species.
- Berberine, extracted, for example, from hydrates, has bacteriostatic properties at low doses and bactericides at higher dosages; it is also active against fungi, such as Candida albicans, and several parasites;
- Several lichens, such as Icelandic lichen, produce usnic acid, a substance with marked bacteriostatic and antifungal properties.
- In garlic and onions we find allicin, a powerful natural antibiotic. Allicin also appears to possess antiviral, antiprotozoal, antifungal, anti-inflammatory and analgesic activity.
- Beyond the individual substances contained therein, in general many essential oils are endowed with antimicrobial activity. Among the most used for this purpose, there are those of oregano, thyme, cinnamon, geranium, melaleuca and lemon.
Although in vitro studies are particularly encouraging, unfortunately, taking essential oils by mouth involves a certain risk, mainly linked to allergic reactions. A greater clinical commitment would therefore be needed to establish the optimal dosage.
Research on antibiotics of plant origin, as well as that on the so-called antimicrobial peptides, is driven by the need to isolate new antibiotics capable of overcoming the problems linked to the phenomenon of the so-called antibiotic resistance.
