Alejandro Tapia

The proximate composition and free radical scavenging effect of native food plants gathered in the Argentinian Yungas have been assessed. Some 25 samples were collected for proximate analysis and free radical scavenging effect of their MeOH-soluble extracts. Total acidity, phenolics and solid content of 16 preserves prepared from native fruits have been determined. The samples belong to 13 different species corresponding to eight plant families, mainly Myrtaceae, Solanaceae and Ulmaceae. The highest organic acid contents (as citric acid) were found in the preserves of Psidium guineense and Cyphomandra betaceae with the lowest in Sideroxylon obtusifolium and Myrciantes pungens. Total phenolics in the preserves ranged from 0.34 g kg−1 DM in Rhipsalis flocosa to 7.30 g kg−1 DM in Celtis iguanae. The MeOH-solubles of the fruits/petioles as well as the preserves were assessed for inhibition of the enzyme xanthine oxidase (XO), decoloration of the free radical 2,2-diphenyl-1-picryl-hydrazyl (DPPH) and scavenging of the superoxide anion. The highest effect of the solubles towards the DPPH assay was observed for M pungens and Rubus imperialis before processing. None of the samples was effective as a XO inhibitor or superoxide anion scavenger. The best protein sources in our study were the fruits of Carica quercifolia, Celtis iguanae and Sambucus nigra. Copyright © 2005 Society of Chemical Industry

This paper reports the in vitro antifungal activity of propolis extracts from the province of Tucuman (Argentina) as well as the identification of their main antifungal compounds and botanical origin. The antifungal activity was determined by the microdilution technique, using reference microorganisms and clinical isolates. All dermatophytes and yeasts tested were strongly inhibited by different propolis extracts (MICs between 16 and 125 microg mL(-1)). The most susceptible species were Microsporum gypseum, Trichophyton mentagrophytes, and Trichophyton rubrum. The main bioactive compounds were 2',4'-dihydroxy-3'-methoxychalcone 2 and 2',4'-dihydroxychalcone 3. Both displayed strong activity against clinical isolates of T. rubrum and T. mentagrophytes (MICs and MFCs between 1.9 and 2.9 microg mL(-1)). Additionally, galangin 5, pinocembrin 6, and 7-hydroxy-8-methoxyflavanone 9 were isolated from propolis samples and Zuccagnia punctata exudates, showing moderate antifungal activity. This is the first study matching the chemical profile of Z. punctata Cav. exudates with their corresponding propolis, giving strong evidence on the botanical origin of the studied propolis.

Petroleum ether and dichloromethane extracts of fruits, aerial parts and exudate of Zuccagnia punctata Cav. (Fabaceae) showed moderate antifungal activities against the yeasts C. albicans, S. cerevisiae and C. neoformans (MICs: 62.5 - 250 microg/mL) and very strong antifungal activities against the dermatophytes M. gypseum, T. rubrum and T. mentagrophytes (MICs: 8 - 16 microg/mL) thus supporting the ethnopharmacological use of this plant. Antifungal activity-directed fractionation of active extracts by using bioautography led to the isolation of 2',4'-dihydroxy-3'-methoxychalcone (1) and 2',4'-dihydroxychalcone (2) as the compounds responsible for the antifungal activity. Second-order studies included MIC (80), MIC (50) and MFC of both chalcones in an extended panel of clinical isolates of the most sensitive fungi, and also comprised a series of targeted assays. They showed that the most active chalcone 2 is fungicidal rather than fungistatic, does not disrupt the fungal membranes up to 4 x MFC and does not act by inhibiting the fungal cell wall. So, 2',4'-dihydroxychalcone would act by a different mechanism of action than the antifungal drugs in current clinical use, such as amphotericin B, azoles or echinocandins, and thus appears to be very promising as a novel antifungal agent.

The proximate composition and free radical scavenging effect of native food plants gathered in the Argentinian Yungas have been assessed. Some 25 samples were collected for proximate analysis and free radical scavenging effect of their MeOH-soluble extracts. Total acidity, phenolics and solid content of 16 preserves prepared from native fruits have been determined. The samples belong to 13 different species corresponding to eight plant families, mainly Myrtaceae, Solanaceae and Ulmaceae. The highest organic acid contents (as citric acid) were found in the preserves of Psidium guineense and Cyphomandra betaceae with the lowest in Sideroxylon obtusifolium and Myrciantes pungens. Total phenolics in the preserves ranged from 0.34 g kg−1 DM in Rhipsalis flocosa to 7.30 g kg−1 DM in Celtis iguanae. The MeOH-solubles of the fruits/petioles as well as the preserves were assessed for inhibition of the enzyme xanthine oxidase (XO), decoloration of the free radical 2,2-diphenyl-1-picryl-hydrazyl (DPPH) and scavenging of the superoxide anion. The highest effect of the solubles towards the DPPH assay was observed for M pungens and Rubus imperialis before processing. None of the samples was effective as a XO inhibitor or superoxide anion scavenger. The best protein sources in our study were the fruits of Carica quercifolia, Celtis iguanae and Sambucus nigra. Copyright © 2005 Society of Chemical Industry

This paper reports the in vitro antifungal activity of propolis extracts from the province of Tucuman (Argentina) as well as the identification of their main antifungal compounds and botanical origin. The antifungal activity was determined by the microdilution technique, using reference microorganisms and clinical isolates. All dermatophytes and yeasts tested were strongly inhibited by different propolis extracts (MICs between 16 and 125 microg mL(-1)). The most susceptible species were Microsporum gypseum, Trichophyton mentagrophytes, and Trichophyton rubrum. The main bioactive compounds were 2',4'-dihydroxy-3'-methoxychalcone 2 and 2',4'-dihydroxychalcone 3. Both displayed strong activity against clinical isolates of T. rubrum and T. mentagrophytes (MICs and MFCs between 1.9 and 2.9 microg mL(-1)). Additionally, galangin 5, pinocembrin 6, and 7-hydroxy-8-methoxyflavanone 9 were isolated from propolis samples and Zuccagnia punctata exudates, showing moderate antifungal activity. This is the first study matching the chemical profile of Z. punctata Cav. exudates with their corresponding propolis, giving strong evidence on the botanical origin of the studied propolis.

Petroleum ether and dichloromethane extracts of fruits, aerial parts and exudate of Zuccagnia punctata Cav. (Fabaceae) showed moderate antifungal activities against the yeasts C. albicans, S. cerevisiae and C. neoformans (MICs: 62.5 - 250 microg/mL) and very strong antifungal activities against the dermatophytes M. gypseum, T. rubrum and T. mentagrophytes (MICs: 8 - 16 microg/mL) thus supporting the ethnopharmacological use of this plant. Antifungal activity-directed fractionation of active extracts by using bioautography led to the isolation of 2',4'-dihydroxy-3'-methoxychalcone (1) and 2',4'-dihydroxychalcone (2) as the compounds responsible for the antifungal activity. Second-order studies included MIC (80), MIC (50) and MFC of both chalcones in an extended panel of clinical isolates of the most sensitive fungi, and also comprised a series of targeted assays. They showed that the most active chalcone 2 is fungicidal rather than fungistatic, does not disrupt the fungal membranes up to 4 x MFC and does not act by inhibiting the fungal cell wall. So, 2',4'-dihydroxychalcone would act by a different mechanism of action than the antifungal drugs in current clinical use, such as amphotericin B, azoles or echinocandins, and thus appears to be very promising as a novel antifungal agent.