Phytochemical Findings Evidencing Botanical Origin of New Propolis Type from North-West Argentina.

Propolis samples from north-west Argentina (Amaicha del Valle, Tucumán) were evaluated by palynology, FT-IR spectra, and RP-HPTLC. In addition, the volatile fraction was studied by HS-SPME-GC/MS. The botanical species most visited by Apis mellifera L. near the apiaries were collected and their RP-HPTLC extracts profiles were compared with propolis samples. In addition, GC/MS was performed for volatile compounds from Zuccagnia punctata Cav. (Fabaceae). FT-IR spectra and RP-HPTLC fingerprints of propolis samples showed similar profiles. In RP-HPTLC analyses, only Z. punctata presented a similar fingerprint to Amaicha propolis. The major volatile compounds present in both were trans-linalool oxide (furanoid), 6-camphenone, linalool, trans-pinocarveol, p-cymen-8-ol, and 2,3,6-trimethylbenzaldehyde. Potential variations for the Amaicha del Valle propolis volatile fraction as consequence of propolis sample preparation were demonstrated.

The activity of propolis in the scavenging of vitamin B2-photogenerated ROS.

OBJECTIVES: The study was focused on the activity of propolis from Amaicha del Valle, Argentina (ProAV) as a promoter and scavenger of Riboflavin (Rf)--photogenerated reactive oxygen species (ROS). METHODS: Through a kinetic and mechanistic study, employing stationary and time-resolved photochemical and electrochemical techniques, the protecting activity of ProAV was investigated. RESULTS: In the absence of light and Rf, ProAV exerted a relatively efficient inhibitory effect on 1,1-diphenyl-2-picrylhydrazyl radicals and acts as a protector of artificially promoted linoleic acid oxidation. Under aerobic visible-light-irradiation conditions, in the presence of Rf as the only light-absorber species, a complex picture of competitive processes takes place, starting with the quenching of singlet and triplet electronically excited states of Rf by ProAV. The species O2(1 g), O2(•-), H2O2, and OH(•) are generated and interact with ProAV. DISCUSSION: ProAV behaves as an efficient ROS scavenger. It is scarcely photo-oxidized by interaction with the mentioned ROS. Quantitative results indicate that ProAV is even more resistant to photo-oxidation than the recognized antioxidant trolox. Two dihydroxychalcones, mostly present in the ProAV composition, are responsible for the protecting activity of the propolis.

Flavonoids from Argentine Tagetes (Asteraceae) with antimicrobial activity.

The flavonoids, constituting one of the most numerous and widespread groups of natural plant constituents, are important to humans not only because they contribute to plant colors but also because many members are physiologically active. These low-molecular-weight substances, found in all vascular plants, are phenylbenzopyrones. Over 4000 structures have been identified in plant sources, and they are categorized into several groups. Primarily recognized as pigments responsible for the autumnal burst of hues and the many shades of yellow, orange, and red in flowers and food, the flavonoids are found in fruits, vegetables, nuts, seeds, stems, flowers, and leaves as well as tea and wine and are important constituents of the human diet. They are prominent components of citrus fruits and other food sources. Flavonols (quercetin, myricetin, and kaempferol) and flavones (apigenin and luteolin) are the most common phenolics in plant-based foods. Quercetin is also a predominant component of onions, apples, and berries. Such flavanones as naringin are typically present in citrus fruit, and flavanols, particularly catechin, are present as catechin gallate in such beverages as green or black tea and wine. Some major sources of flavonoids are outlined in Table 1. The daily intake of flavonoids in humans has been estimated to be approx 25 mg/d, a quantity that could provide pharmacologically significant concentrations in body fluids and tissues, assuming good absorption from the gastrointestinal tract. Biological activity of flavonoids was first suggested by Szent-Gÿorgyi 1938, who reported that citrus peel flavonoids were effective in preventing the capillary bleeding and fragility associated with scurvy. The broad spectrum of biological activity within the group and the multiplicity of actions displayed by a certain individual members make the flavonoids one of the most promising classes of biologically active compounds.

Composition and anti-insect activity of essential oils from Tagetes L. species (Asteraceae, Helenieae) on Ceratitis capitata Wiedemann and Triatoma infestans Klug.

Essential oils from four species of the genus Tagetes L. (Asteraceae, Helenieae) collected in Tucumán province, Argentina, were evaluated for their chemical composition, toxicity, and olfactory activity on Mediterranean fruit fly Ceratitis capitata Wiedemann adults and for repellent properties on Triatoma infestans (Klug) (Chagas disease vector). Yields of essential oils range from 0.2 to 0.8% (v/w). The same main constituents among Tagetes minuta L., Tagestes rupestris Cabrera, and Tagetes terniflora Kunth, (cis-trans)-ocimenes, (cis-trans)-tagetones, and (cis-trans)-ocimenones showed important differences in their relative compositions. Tagetes filifolia Lag. was characterized by the recognized phenylpropanoids methylchavicol and trans-anethole as the main components. LD(50) was ≤20 µg/insect in topical bioassays. T. rupestris was the most toxic to C. capitata females, whereas the other oils presented similar toxicities against males and females. Tagetes rupestris oil attracted both sexes of C. capitata at 5 µg, whereas T. minuta showed opposite activities between males (attractant) and females (repellent). Oils from T. minuta and T. filifolia were the most repellent to T. infestans. The results suggest that compositions of essential oils influence their insecticidal and olfactory properties. The essential oils from Tagetes species show an important potential as infochemical agents on insects' behaviors. This study highlights the chemical variability of essential oils as a source of variation of anti-insect properties.