(Syn: P.eremophilum, P.oblanceolatum, Kleinia linifolia)

also called Catinga-de-urubu, curupaimi, kilkina, quirquina, matapulgas (literal translation “killing insects”), yerba de la gama, ruda blanca, cominillo, yerba del venado, yerba del ciervo.

Another of the less well known species of porophyllum. Found south of Brazil into Paraguay and the north east of Argentina there is very little information to be found on this particular variety of pore leaf. Images of this herb are hard to come by and as is shown pictures of plants claiming to be P.obscurum are quite different. It has both culinary and medicinal uses.

The leaves of this herb are said to have diaphoretic (1) and antispasmodic (2) actions and like several others of the porophyllum species it has been used as a treatment for venereal disease. (Barboza et al 2009)

1. Diaphoretic/Sudorific – induces sweating/perspiration
2. Antispasmodic – an agent that suppresses muscle spasms or relaxes smooth muscle (ie the GIT)

In Argentina the leaves are used as an anti-inflammatory and as a digestive (Trillo etal 2010)

Some plants produce photosensitizing molecules to aid in protection against pathogens and predatory herbivory. These molecules, when stimulated by light of a certain wavelength exert toxic effects on various biomolecules and cells and destroy them. Antimicrobial photodynamic chemotherapy is a newly developed therapy that uses these photosensitizing molecules to induce oxidative damage in microbial pathogens. This therapy has a broad spectrum of action, causes minimal damage to healthy host tissue, has a low probability of generating resistant strains and is compatible with other antifungal therapies.

It has been posited that essential oils in P.obscurum have potential in the treatment of oral candidiasis through the use of these photodynamic therapies. In one study a hexane extract of P.obscurum has been shown to possess antifungal activity under UV-A light (Postigo etal). The activity was demonstrated against 25 Candida strains from patients with OPC (1) and the study showed that P.obscurum hexanic extract could be potentially developed as a photosensitizer in Photodynamic Therapy (2). This activity is believed to be due to the thiophenes in the plant. Qualitative and quantitative chemical analyses of seven samples of P.obscurum collected in four different phenological (3) stages were carried out showing that full flowering stage possesses the highest levels of thiophenes.

1. OPC – Oropharyngeal candidiasis – a yeast/fungal infection by the Candida albicans organism
2. Photodynamic therapy is a modern therapeutic strategy that involves interactions between a light source of a particular wavelength and a photosensitiser in the presence of oxygen.  This phototoxic and chemical reaction induces the production of reactive oxygen species that cause oxidative damage to the target cells including microbial cells and tumour cells
3. The scientific study of cyclical biological events, such as first bud appearance, the beginning of flowering, and the end of flowering, in relation to climatic conditions.

Listeria (L.monocytogenes) are bacteria that can cause a serious illness called listeriosis which can be fatal to the vulnerable. People at the greatest risk from listeriosis include pregnant women, their unborn and newborn babies, the elderly and other people whose immune systems have been weakened by illness or drugs (i.e. cancer patients, organ transplant recipients, and people on drugs like cortisone). Eating foods contaminated with Listeria is the most common way of contracting the illness. Unlike most bacteria, Listeria is tolerant to low temperature and can readily multiply in refrigerated foods (1).  Contact with infected farm animals, particularly stillborn animals, can also spread the infection.

1. Foods that can potentially carry listeria risk (and should be avoided by pregnant women) include, unpackaged ready-to-eat cold meats and packaged sliced ready-to-eat cold meats, cold cooked ready-to-eat chicken, refrigerated pâté or meat spreads, pre-prepared or pre-packaged fruit or vegetable salads, raw seafood, oysters, sashimi or sushi, cooked peeled prawns, soft, semi-soft and surface ripened cheeses, brie, camembert, ricotta, feta and blue, soft serve ice cream, other unpasteurised dairy products (i.e. raw goat’s milk).

Methanolic extracts of P.obscurum and P.lanceolatum have been shown to inhibit listeria biofilm production (by 32% and 35% respectively) and to reduce the already formed bacterial biofilm (by 78% and 70% respectively)(Mattana etal)

GC-MS analysis of the leaf oils of Porphyllum obscurum (Spreng.) DC showed the presence of 27 compounds. The main components were beta-pinene (16.3%), beta-caryophyllene (14.1%), trans-sabinene hydrate (12.8%) and undec-1-ene (12.4%). Flavonols, flavonoid glycosides, chlorogenic acid, caffeoyl esters and 1 coumarin (escopoletin) were also found to be present in P. obscurum (Labukas etal)

Barboza (Gloria E et al 2009) gives a more detailed account of the phytochemicals present in this herb.

Dried aerial parts. Quercimeritrin, avicularin, 3-0-rhamnoside, 7-0-arabinoside, isorhamnetin, quercetagetin: flavonoids
Leaf essential oil. Hexanal, α- and βpinene, sabinene, myrcene, Δ3-carene, p-cymene, (E)-β-ocimene, γ-terpinene, terpinolene, octa-2,4-dienal, terpinen-4-ol, decanal, trans-carveol, methyl thymol, deca-2,4-dienal, dodecenal, βelemene, β-gurjunene, β-humulene, αhimachalene, δ-cadinene, βcaryophyllene, trans-sabinene hydrate, undec-1-ene, spathulenol