Antibacterial activity of Achyrocline flaccida

The use of medicinal plants by Paraguayan migrants in the Atlantic Forest of Misiones, Argentina, is based on Guaraní tradition, colonial and current plant knowledge

ETHNOPHARMACOLOGICAL RELEVANCE

Information on the use of medicinal plants in the daily life by Paraguayan people is scarce in mainstream scientific literature. The study on the Paraguayan diaspora in the Provincia de Misiones, Argentina, gives an insight into Guaraní traditions, colonial legacy and current search for new medicinal plants to address new health challenges.

AIM OF THE STUDY

To document the use of medicinal plants by Paraguayan mestizo migrants who moved into a new country, yet within the same ecological region. The present and past uses of medicinal plants were compared to understand the continuity and change in the Paraguayan herbal pharmacopoeia.

MATERIALS AND METHODS

Fieldwork based on ethnographic and ethnobotanical techniques was carried out in the Provincia de Misiones, Argentina, in 2014, 2015, and 2019. Eighty-five Paraguayan migrants and their descendants from eastern Paraguay took part in the study. The list of recorded plants was compared with the information in historical sources from Paraguay, to examine the continuity and changes in Paraguayan herbal medicine, and with the present-day ethnobotanical studies from Paraguay. Ethnopharmacological and phytochemical studies on the medicinal plants with the highest consensus of uses were reviewed.

RESULTS

Altogether, 204 medicinal plant species were recorded. The most frequently mentioned species represented a combination of plants native to the New and Old World. Nearly 40% of the present-day Paraguayan pharmacopoeia shows continuity from colonial and post-colonial periods. Plants were used for 19 medical categories, of which digestive, circulatory and those belonging to humoral medicine were the most prevalent. The ongoing search of plants to treat new health problems is illustrated by reports of 40 species used for hypertension, 26 for diabetes and 18 to lower cholesterol. There is still little evidence for the effectiveness of these plants in the pharmacological literature. Paraguayan migrants were able to continue their traditional plant medicine in Misiones, Argentina, in a substantial way.

CONCLUSION

This study was carried out in a geographic area with a long-standing tradition of Guaraní medicine. Paraguayan migrants in Misiones integrate pre-Hispanic Guaraní names and uses of plants and old humoral concepts with current adaptation of plants to meet new health challenges. Several of the uses described in early colonial times are still practiced, giving a solid background for in-depth studies of the local pharmacopoeia.

Yerba Mate (Ilex paraguariensis) Beverage: Nutraceutical Ingredient or Conveyor for the Intake of Medicinal Plants? Evidence from Paraguayan Folk Medicine

The use of medicinal plants mixed with yerba mate (Ilex paraguariensis) has been poorly studied in the ethnopharmacological literature so far. The Paraguayan Mestizo people have the longest tradition of using the yerba mate beverage, apart from the indigenous Guarani people. This study analyses the role of yerba mate and medicinal plants in the treatment of illnesses within Paraguayan folk medicine. The research was conducted among 100 Paraguayan migrants living in Misiones, Argentina, in 2014 and 2015. Yerba mate is not considered to be a medicinal plant by its own virtues but is culturally a very important type of medicinal plant intake. Ninety-seven species are employed in hot and cold versions of the yerba mate beverage. The most important species are as follows: Allophylus edulis (highest number of citations), Aristolochia triangularis (highest relative importance value), and Achyrocline flaccida and Achyrocline tomentosa (highest score by Index of Agreement on Species). The plants are used in the treatment of 18 medicinal categories, which include illnesses traditionally treated with plants: digestive system, humoral medicine, and relatively new health conditions such as diabetes, hypertension, and high levels of cholesterol. Newly incorporated medicinal plants, such as Moringa oleifera, are ingested predominantly or exclusively with the mate beverage.

Antimicrobial activity of flavonoids

Flavonoids are ubiquitous in photosynthesising cells and are commonly found in fruit, vegetables, nuts, seeds, stems, flowers, tea, wine, propolis and honey. For centuries, preparations containing these compounds as the principal physiologically active constituents have been used to treat human diseases. Increasingly, this class of natural products is becoming the subject of anti-infective research, and many groups have isolated and identified the structures of flavonoids possessing antifungal, antiviral and antibacterial activity. Moreover, several groups have demonstrated synergy between active flavonoids as well as between flavonoids and existing chemotherapeutics. Reports of activity in the field of antibacterial flavonoid research are widely conflicting, probably owing to inter- and intra-assay variation in susceptibility testing. However, several high-quality investigations have examined the relationship between flavonoid structure and antibacterial activity and these are in close agreement. In addition, numerous research groups have sought to elucidate the antibacterial mechanisms of action of selected flavonoids. The activity of quercetin, for example, has been at least partially attributed to inhibition of DNA gyrase. It has also been proposed that sophoraflavone G and (-)-epigallocatechin gallate inhibit cytoplasmic membrane function, and that licochalcones A and C inhibit energy metabolism. Other flavonoids whose mechanisms of action have been investigated include robinetin, myricetin, apigenin, rutin, galangin, 2,4,2'-trihydroxy-5'-methylchalcone and lonchocarpol A. These compounds represent novel leads, and future studies may allow the development of a pharmacologically acceptable antimicrobial agent or class of agents.

Argentine plant extracts active against polymerase and ribonuclease H activities of HIV-1 reverse transcriptase

Lipophilic and hydrophilic extracts of four Argentine plants (Gamochaeta simplicaulis Cabr. 1, Achyrocline flaccida Wein. D. C. 2, Eupatorium buniifolium H. et A. 3, and Phyllanthus sellowianus Muell. Arg. 4) were examined in vitro for their ability to inhibit the polymerase and ribonuclease H (RNase H) activities of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) (wild and Y181C mutant types). The active extracts were also examined as inhibitors of viral replication in HLT4LacZ-1IIIB cell cultures, evaluating their cytotoxicity in parallel. Infusions 2I and 4I, among the crude extracts, showed the highest activity. These extracts were refractioned into four fractions; 2I4 and 4I4 were active as inhibitors of DNA-polymerase (wild and Y181C types) and RNase H activities. These fractions were potent as inhibitors of viral replication and were not cytotoxic. Refractionation of 2I4 yielded five new fractions, two of which, 2I4-4 and 2I4-5, showed notable activity. Refractionation of 4I4 yielded for new fractions; of these, 4I4-3 and 4I4-4 were active. The marked biological activity found in the infusion of A. flaccida and P. sellowianus makes them sufficiently attractive to be considered in the combined chemotherapy of the disease.

Leishmanicidal and trypanocidal activities of Bolivian medicinal plants

Cutaneous and mucocutaneous leishmaniasis are endemic diseases in South America, especially in the subandean areas of the humid lowlands of Bolivia. Fourteen plants used topically in folk medicine to treat cutaneous leishmaniasis were collected in the tropical regions of colonization and in the rain forest occupied by Chimane Indians. Three of four plants used by the Chimane Indians exhibited an in vitro activity against three species of Leishmania. Two of ten plants used by the colonists showed an in vitro activity. We have also included results obtained with extracts from 53 Bolivian medicinal plants used for other diseases and from 43 plants collected with basis of chemotaxonomic criteria from all parts of Bolivia. All extracts were also screened in vitro against three strains of Trypanosoma cruzi (Trypanosomatidae), the causative agent of Chagas' disease.

Screening of plants used in Argentine folk medicine for antimicrobial activity

Screening of 132 extracts from Argentine folk-medicinal plants for antimicrobial activity has been conducted using a penicillin G resistant strain of Staphylococcus aureus, Escherichia coli and Aspergillus niger as test microorganisms. Cephazolin, ampicillin and miconazole were used as standard antibiotics and concentration-response curves were obtained using the agar-well diffusion method. Boiling water extracts of plant materials were tested and 12 species were active against Staphylococcus aureus, whereas 10 were effective against Escherichia coli and 4 against Aspergillus niger. Tabebuia impetiginosa bark, Achyrocline sp. aerials parts, Larrea divaricata leaves, Rosa borboniana flowers, Punica granatum fruit pericarp, Psidium guineense fruit pericarp, Lithrea ternifolia leaves and Allium sativum bulbs produced some of the more active extracts.