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Human rhinoviruses (HRVs) are a major cause of the common cold and until now there is no registered clinically effective antiviral chemotherapeutic agent for treatment of diseases caused by HRVs. Our previous report showed that gallic acid from Woodfordia fruticosa flowers possessed antioxidant activity. Many studies reported that antioxidants possess antiviral activities against various viruses. Therefore, we examined antiviral activity of gallic acid against HRVs and mode of its actions by observing the effect of gallic acid on HRV-induced cytopathic effect (CPE) and the infectivity of HRV particles, and then carried out a time-addition study. As a result, gallic acid actively inhibited HRV2 and -3 replications with antiviral activity more than 55% without cytotoxicity in human epitheloid carcinoma cervix (HeLa) cells at a concentration of 100 mug/mL. Also, ribavirin showed lower anti-HRV3 activity than gallic acid and similar anti-HRV3 activity to it. The addition of gallic acid to HRV-infected HeLa cells directly reduced the formation of a visible CPE. Furthermore, gallic acid did directly interact or activate with HRV particles. Collectively, we concluded that the inhibition of HRV production by gallic acid is mainly due to a general action as an antioxidant and the mode of action derived from the inhibition of virus absorption.

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Background: Medicinal plants are the major sources of the crude drugs and natural antioxidants. Berberis species have been used in the treatment of various ailments around the world including Nepal. However, systematic study on phytochemistry and pharmacology of Berberis species from Nepal is lacking. Objectives: To evaluate the antioxidant activity, total phenolic and flavonoid contents of Berberis aristata and Berberis thomsoniana from Sagarmatha National Park. Materials and Methods: Antioxidant activity was measured through 2, 2-Diphenyl-1-Picrylhydrazyl assay. Total phenolic and flavonoid content were estimated using Folin-Ciocalteau and aluminum chloride method respectively. Results: Samples showed dose-dependent radical scavenging activity. Radical scavenging activity of the methanolic extracts of different parts of B. aristata and B. thomsoniana ranged from 19.38 to 98.47%, with leaf extracts of B. thomsoniana showing the strongest activity. The total phenolic content of the samples varied from 11.04 to 65.30 mg GAE g -1 dry weight whereas total flavonoid content was in between 2.4 to 16.46 mg quercetin/g dry weight. Conclusion: Among the tested samples, leaf extracts of B. thomsoniana showed the strongest antioxidant activity and contained the highest amount of total phenolic and flavonoid content. ABSTRACT SUMMARY• Present study showed that leaf extract of B. thomsoniana showed promising antioxidant ability and contained higher amount of phenolics and flavonoids.Dr. Lok Ranjan Bhatt is a Senior Scientific Officer at Nepal Academy of Science and Technology (NAST), Khumaltar, Lalitpur, Nepal. He has more than twenty years of experience in the areas of medicinal and aromatic plants, natural products and biomaterials. Currently, he has been working on nutritional composition of wild edible fruits and synthesis and characterization of herbal based polymer micro/nanospheres.

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