Anti-inflammatory, antiallodynic effects and quantitative analysis of gallic acid in spray dried powders from Phyllanthus niruri leaves, stems, roots and whole plant

The anti-inflammatory and antiallodynic effects of spray dried powders starting from leaves, stems, roots, the mixture of leaves and stems, as well as the whole plant aqueous solutions of Phyllanthus niruri L., Phyllanthaceae, were assessed. Gallic acid, used as chemical marker, was quantified by HPLC in the spray dried powders. Carrageenan-induced inflammatory and allodynic responses in the mouse paw were used as pharmacological models. Quantitative and qualitative differences among chemical composition of different herb parts were observed. The oral administration of leaves or leaves plus stems spray dried powders (100 mg/kg) significantly inhibited the carrageenan-induced allodynic effect (42 ± 5 and 54 ± 3%, respectively). Additionally, the spray dried powders of leaves significantly reduced carrageenan-induced paw oedema (35 ± 6%). The spray dried powders of roots, stems, or the mixture of leaves, stems and roots (100 mg/kg, p.o.) did not exhibit antiallodynic or antioedematogenic effect in the same model. In conclusion, differences in the chemical composition of spray dried powders from P. niruri are reflected in their in vivo pharmacological actions. Despite of a direct relationship of anti-inflammatory and antiallodynic effects with the gallic acid content had been observed, especially in the spray dried powders of leaves, the use of spray dried powders of leaves plus stems showed to be more effective, suggesting a synergic effect between their constituents.

The plants of the genus Phyllanthus as a potential source of new drugs

The plants of the genus Phyllanthus (Euphorbiaceae) comprise about 550 to 750 species which are widely distributed in most tropical and subtropical countries. About 200 species are believed to occur in the Americas, mainly in the Caribbean and Brazil. The plants of the genus Phyllanthus have long been used in folk medicine to treat, among others, kidney and urinary bladder disorders, intestinal infections, diabetes and hepatitis B. In recent years, substantial progress in chemical and pharmacological studies, and a few clinical studies of some Phyllanthus species, were made. This review discusses the current knowledge gained by the in vitro and in vivo pharmacological and biochemical studies performed with the extracts and the main active constituents isolated from different species of plants of the genus Phyllanthus. Data available in the literature strongly support the idea that the extract and some constituents isolated from these plants, including flavanoids, tannins, alkaloids, coumarins, lignans and terpenes, account for their reported antinociceptive, anti-inflammatory, antiviral, antispasmodic and antiallergic properties. In addition, some of these compounds were found to interact with most key enzymes, such as aldose reductase, angiotensin converting enzyme, mitochondrial ATPase, both cyclo- and lipooxygenases, phospholipase A2, tyrosine kinase, reverse transcriptase, and phosphodiesterases. The complex mechanism of action of such compounds could explain, at least in part, the wide therapeutic use of the plants of the genus Phyllanthus in folk medicine. Thus, the plants of the genus Phyllanthus present potential therapeutic interest as a source of new drugs.

Natural bradykinin antagonists

Bradykinin (BK) a nonapeptide generated in plasma during tissue injury, is involved in many physiological and pathological states. Kinin actions are mediated by specific membrane receptors and involve a complex signal transducer and also second messager mechanisms. Due to its inequivocal relevance, an intensive effort has been focused in recent years to develop selective and competitive BK antagonists. Thus, the development of a new series of peptide BK antagonists has made an important contribution to the understanding of the pharmacological, physiological and pathophysiological role of BK, and this is certain to provide a firm basis for developing new drugs to relieve pain and inflammation. However, BK antagonists derived from peptide origin reported to date have limited clinical use due to their poor oral absortion and short duration of effect. Thus, considerable effort has also been made in developing stable nonpeptide BK antagonists. Up to now, most nonpeptide compounds reported to exhibit BK antagonistic activity have been derived from plants, including many flavonoids, terpenes, and also synthetic substances with various molecular structures. Amongst them, the pregnane glycoside compounds isolated from the plant Mandevilla velutina are the most promising. These compounds are effective in antognizing BK responses in a variety of preparations, and they also exhibit potent and long-lasting analgesic and anti-inflammatory activities. The exact mechanism underlying their action however, is not yet completely understood.