Antibacterial and antioxidant activities and acute toxicity of Bumelia sartorum Mart., Sapotaceae, a Brazilian medicinal plant

Insights into the Phytochemistry of the Cuban Endemic Medicinal Plant Phyllanthus orbicularis: Fideloside, a Novel Bioactive 8-C-glycosyl 2,3-Dihydroflavonol

Phyllanthus orbicularis (Phyllanthaceae) is an endemic evergreen tropical plant of Cuba that grows in the western part of the island and is used in traditional medicine as an infusion. The aqueous extract of this plant presents a wide range of pharmacological activitiessuch as antimutagenic, antioxidant and antiviral effects. Given the many beneficial effects and the great interest in the development of new pharmacological products from natural sources, the aim of this work was to investigate the phytochemistry of this species and to elucidate the structure of the main bioactive principles. Besides the presence of several known polyphenols, the major constituent was hitherto not described. The chemical structure of this compound, here named Fideloside, was elucidated by means of HR-ESIMS/MSn, 1D/2D NMR, FT-IR, and ECD as (2R,3R)-(-)-3',4',5,7-tetrahydroxydihydroflavonol-8-C-β-D-glucopyranoside. The compound, as well as the plant aqueous preparations, showed promising bioactive properties, i.e., anti-inflammatory capacity in human explanted monocytes, corroborating future pharmacological use for this new natural C-glycosyl flavanonol.

Antimicrobial Potential of Plant Extracts and Chemical Fractions of Sideroxylon obtusifolium (Roem. & Schult.) T.D. Penn on Oral Microorganisms

AIM

The aim of this study is to evaluate the in vitro antimicrobial activity of plant extracts and chemical fractions of Sideroxylon obtusifolium T.D. Penn on Streptococcus mutans, Streptococcus oralis, Streptococcus salivarius, Streptococcus parasanguinis, and Candida albicans as well as to identify the chemical classes found in the bioactive extracts possessing better activity.

MATERIALS AND METHODS

Freeze-dried hydroalcoholic extracts of the bark and leaves (LC and LF respectively) and ethanol extracts of bark and leaves (EC and EF respectively) of S. obtusifolium were assessed for antimicrobial potential by determining the minimum inhibitory concentration (MIC), minimum bactericidal concentration, and minimum fungicidal concentration (MFC). The tests were performed by microdilu-tion method (in triplicate) in three independent experiments. Phytochemical characterization was performed by quantification of total polyphenols, total flavonoids, and condensed tannins.

RESULTS

The EC extract presented weak antimicrobial potential on the growth of S. mutans (MIC = 1000 μg/mL); all extracts showed moderate inhibitory activity on the growth of C. albicans (MIC = 500 μg/mL). The dichloromethane and n-butanol fractions of LF extracts showed moderate growth inhibitory activity (MIC = 250 μg/mL) on C. albicans and fungicide potential (MFC/MIC = 2). The phytochemical characterization revealed a predominance of total polyphenols (EC = 29.23%; LC = 25.98%) and condensed tannins (LC = 38.84%; LF = 17.78%).

CONCLUSION

The dichloromethane and n-butanol fractions of S. obtusifolium LF extract showed antifungal activity against C. albicans, with the potential for bioprospection of phytocom-pounds for the treatment of periodontal fungal diseases caused by this microorganism. The effect may be related to phyto-chemical compounds from the polyphenol and condensed tannin classes.

CLINICAL SIGNIFICANCE

Research for new oral microbial disease treatment alternatives in bioactive compounds from medicinal plants is of clinical relevance and scientific interest since many therapeutic antifungal agents do not obtain the effectiveness expected due to microbial resistance, or to adverse effects on human tissues.

Antifungal potential of Sideroxylon obtusifolium and Syzygium cumini and their mode of action against Candida albicans

Context The emergence of resistant pathogens and toxicity of antifungals have encouraged an active search for novel candidates to manage Candida biofilms. Objective In this study, the little known species Sideroxylon obtusifolium T.D. Penn (Sapotacea) and Syzygium cumini (L.) Skeels (Myrtaceae), from the Caatinga biome in Brazil were chemically characterized and explored for their antifungal potential against C. albicans. Materials and methods We determined the effects of hydroalcoholic extracts/fractions upon fungal growth (minimum inhibitory and fungicidal concentrations, MIC/MFC), biofilm morphology (scanning electron microscopy) and viability (confocal laser scanning microscopy), proposed their mode of action (sorbitol and ergosterol assays), and finally investigated their effects against macrophage and keratinocyte cells in a cell-based assay. Data were analysed using one-way analysis of variance with Tukey-Kramer post-test (α = 0.05). Results The n-butanol (Nb) fraction from S. obtusifolium and S. cumini extract (Sc) showed flavonoids (39.11 ± 6.62 mg/g) and saponins (820.35 ± 225.38 mg/g), respectively, in their chemical composition and demonstrated antifungal activity, with MICs of 62.5 and 125 μg/mL, respectively. Nb and Sc may complex with ergosterol as there was a 4-16-fold increase in MICs in the presence of exogenous ergosterol, leading to disrupted permeability of cell membrane. Deleterious effects were observed on morphology and viability of treated biofilms from concentrations as low as their MICs and higher. Sc was not toxic to macrophages and keratinocytes at these concentrations (p > 0.05), unlike Nb. Conclusions Nb and Sc demonstrated considerable antifungal activity and should be further investigated as potential alternative candidates to treat Candida biofilms.

Multiple readout assay for hormonal (androgenic and antiandrogenic) and cytotoxic activity of plant and fungal extracts based on differential prostate cancer cell line behavior

ETHNOPHARMACOLOGICAL RELEVANCE

Prostate cancer is one of the most diagnosed forms of cancer among men in western regions. Many traditional applications or phytotherapeutic concepts propose to inhibit the proliferation of prostate cancer cells. In order to detect influences of plant or fungal extracts and derived fractions on androgen receptor signaling pathways, a differentiating cell proliferation assay was established, which enables the simultaneous detection of hormonal and cytotoxic effects.

MATERIAL AND METHODS

The well characterized prostate cancer cell lines LNCaP and PC-3 were used in a multiple readout assay. In all, 186 fractions of 23 traditionally used organisms were screened regarding their effects on proliferation of the two prostate cancer cell lines. The fractions were prepared by accelerated solvent extraction followed by gradient extrography. Extracts of the potential hormonally active plants Cibotium barometz, Heteropterys chrysophylla, and Sideroxylon obtusifolium (= Bumelia sartorum) were phytochemically investigated.

RESULTS

Fractions from Cibotium barometz, Cortinarius rubellus, Cyrtomium falcatum, Heteropterys chrysophylla, Nephrolepis exaltata, Salvia miltiorrhiza, Sideroxylon obtusifolium, Trichilia emetica, and Trimeria grandifolia exhibited hormonal influences on prostate cancer cells. Cytotoxic activity towards human cell lines was detected for the first time for fractions from Aglaia spectabilis (A. gigantea), Nephrolepis exaltata and Cortinarius brunneus.

CONCLUSIONS

The differential behavior of the two prostate cancer cell lines allows the discrimination between potential androgenic or antiandrogenic activities and effects on the estrogen or glucocorticoid receptor as well as cytotoxic activities. The combined cell lines assay can help to assess the biological activities of material used in traditional medicine.

Hypoglycemic Effect of Bumelia sartorum Polyphenolic Rich Extracts

Bumelia sartorum (Sapotaceae) is used ethnomedicinally for treatment of several diseases, including diabetes mellitus. The aim of this work was to investigate the hypoglycemic effect of B. sartorum extracts, rich in polyphenolic compounds, and the possible mechanisms of action. Assessment of B. sartorum hypoglycemic activity was performed from the blood glucose level in normoglycemic mice after administration of the extract by oral gavage. The hypothesis that sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) inhibition could prolong the increase in cytoplasmic Ca2+ concentration, thus leading to an increase of insulin release was evaluated. The enzyme inhibition was measured by ATP hydrolysis using SERCA1 isolated from rabbit skeletal muscle. The total content of phenolic compounds was determined by the Folin-Ciocalteau method. The ethyl acetate (EtOAc) partition and F5 fraction obtained from B. sartorum, both of them rich in polyphenolics, were shown to have a hypoglycemic effect on normoglycemic mice, more significant than that of the known antidiabetic drug, glibenclamide used as a standard comparable compound. Both samples significantly inhibited SERCA activity. Different extracts of B. sartorum, rich in polyphenolic compounds, were able to reduce blood glucose in normoglycemic mice and inhibit SERCA activity. SERCA inhibition may be one of the possible mechanisms involved in glucose decrease.