Quantitative HPLC estimation of flavonoids in showy tick trefoil herbs

In vitro antiviral activity of fifteen plant extracts against avian infectious bronchitis virus

BACKGROUND

Avian infectious bronchitis (IB) is a disease that can result in huge economic losses in the poultry industry. The high level of mutations of the IB virus (IBV) leads to the emergence of new serotypes and genotypes, and limits the efficacy of routine prevention. Medicinal plants, or substances derived from them, are being tested as options in the prevention of infectious diseases such as IB in many countries. The objective of this study was to investigate extracts of 15 selected medicinal plants for anti-IBV activity.

RESULTS

Extracts of S. montana, O. vulgare, M. piperita, M. officinalis, T. vulgaris, H. officinalis, S. officinalis and D. canadense showed anti-IBV activity prior to and during infection, while S. montana showed activity prior to and after infection. M. piperita, O. vulgare and T. vulgaris extracts had > 60 SI. In further studies no virus plaques (plaque reduction rate 100%) or cytopathogenic effect (decrease of TCID₅₀ from 2.0 to 5.0 log₁₀) were detected after IBV treatment with extracts of M. piperita, D. canadense and T. vulgaris at concentrations of extracts ≥0.25 cytotoxic concentration (CC₅₀) (P < 0.05). Both PFU number and TCID₅₀ increased after the use of M. piperita, D. canadense, T. vulgaris and M. officinalis extracts, the concentrations of which were 0.125 CC₅₀ and 0.25 CC₅₀ (P < 0.05). Real-time PCR detected IBV RNA after treatment with all plant extracts using concentrations of 1:2 CC₅₀, 1:4 CC₅₀ and 1:8 CC₅₀. Delta cycle threshold (Ct) values decreased significantly comparing Ct values of 1:2 CC₅₀ and 1:8 CC₅₀ dilutions (P < 0.05).

CONCLUSIONS

Many extracts of plants acted against IBV prior to and during infection, but the most effective were those of M. piperita, T. vulgaris and D. canadense .

Activity-guided isolation, identification and quantification of biologically active isomeric compounds from folk medicinal plant Desmodium adscendens using high performance liquid chromatography with diode array detector, mass spectrometry and multidimentional nuclear magnetic resonance spectroscopy

The antioxidant activity of the crude extract (60% ethanol) from the leaves of Desmodium adscendens (Sw.) DC. (Fabaceae) was observed in DPPH, xanthine/xanthine oxidase, lipid peroxydation and neutrophils burst tests. Further activity-guided fractionation on C18 column (water, 20% methanol, 50% methanol and 100% methanol) resulted in the separation of the fraction (50% methanol) with the highest antioxidant capacity. HPLC-DAD analysis of biologically active fraction revealed the presence of two pairs of flavonoid isomers as the dominant constituents. Those compounds were isolated and purified by multi-step liquid column chromatography (Sephadex LH20). Their structures were elucidated by various spectroscopic techniques, including NMR, UV and MS. Based on 1D and 2D NMR spectra as well as ion fragmentation, flavonoids were identified as: isovitexin 2''-O-xyloside (1), vitexin 2''-O-xyloside (2), vitexin (3) and isovitexin (4). The hybrid HSQC-DEPT technique provided very fast determination of the glycosylation positions in aglycone and the type of glycosidic bond in the flavonoid isomers. This study provides novel information concerning identity of the major compounds present in the leaves of D. adscendens cultivated in Ghana, which broadens the knowledge about anti-inflammatory, antiallergic and antioxidant properties of their extracts.