Shipton, F N
(2017)
The in vitro pharmacological activities of Pericampylus glaucus (Lam.) Merr. and their relation to ethnomedicinal use.
PhD thesis, University of Nottingham.
Abstract
Malaysia’s rainforests have a great biodiversity, a lot of which has yet to be studied. This presents researchers with the opportunity for the discovery of new chemical structures which may be new leads in drug discovery. With problems such as antibiotic resistance and the need for improved drugs for the treatment of diseases such as cancer and neurodegenerative diseases, there is need for more research into drug discovery. The focus of the research covered in this document is on Pericampylus glaucus, a common climbing plant for which there is limited literature available. The aim of this study is to determine its pharmacological activities, based on what is known of its traditional use, in the hope that it can be used in the development of pharmaceutical drugs in the future.
The literature review of the traditional uses of P. glaucus suggests that the plant may be used in ethnomedicine for its anti-inflammatory and/or antibacterial activity as it is used to treat many conditions in which inflammation and infection is indicated. Components of P. glaucus extracts were investigated through a variety of phytochemical screening methods and were found to include polyphenols such as tannins and flavonoids, terpenes, sterols, alkaloids and saponins and similarities between the different extracts were observed. P. glaucus was found to possess antioxidant activity, with the stem chloroform extract possessing the greatest radical scavenging activity. The antibacterial assays revealed only mild antibacterial activity by P. glaucus extracts, making the use of the plant for treating infections seem unlikely, although this may be due to activity against specific strains of bacteria. The anti-inflammatory assays suggested a number of different mechanisms by which P. glaucus could exert anti-inflammatory activity, with many of the extracts and known compounds inhibiting COX-1 and COX-2 enzymes, and only the fruit hexane extract providing less than 50% inhibition of COX-1 and COX-2 at 500 µg/mL. The hexane extracts generally prevented protein denaturation to a greater extent compared to other extracts, as well as palmitic and stearic acid. The extracts showed a varying ability to prevent lysis of red blood cells, which were used as a model for lysosomes, depending on whether lysis was induced by hypotonicity or by heat. Some anticancer activity, cytotoxicity and growth promoting activity was recorded when cells were cultured with P. glaucus extracts. The ethanol extracts were found to exert the greatest cytotoxic activity, with the exception of the fruit ethanol extract. The root ethanol extract was the most toxic towards HK1 and MRC-5, while the stem hexane extract increased HK1 proliferation by over 200% and the root hexane extract increased MRC-5 proliferation by over 600%. Because of the growth promoting activity that was observed and the traditional use of P. glaucus for the treatment of wounds, the wound healing activity of the extracts was tested and found to be much less effective than the control of 10% FBS, although the greatest wound healing activity of around 20% wound coverage after 24 h was seen by the fruit extracts. Since P. glaucus is traditionally used for the treatment of venomous snake bites, its antivenom activity was assessed and found to have some antivenom activity, with the fruit hexane extract increasing cell proliferation by over 50% at 200 µg/mL and the alkaloid, periglaucine A, increasing proliferation by over 70% demonstrating significant antivenom activity.
The antioxidant activity is most likely attributable to the polyphenols as the total polyphenol content correlated with the results of the DPPH radical scavenging activity of the extracts. The mild antibacterial activity suggested that P. glaucus may be used more for its anti-inflammatory activity in traditional medicine rather than antibacterial activity. The findings of toxicity towards cancer cells supports the traditional use of P. glaucus for the treatment of cancer. The results of the wound healing activity would indicate that P. glaucus would have a mild effect in the treatment of wounds due to its ability to promote cell proliferation and migration, however, its anti-inflammatory activity and mild antibacterial activity may be beneficial in treating wounds. It did possess antivenom activity, which supports its use for the treatment of envenomation by snakes, although the fruit extracts had stronger antivenom activity compared to the root, which is the plant part traditionally used. The mild antibacterial activity of P. glaucus may partly contribute to its medicinal effects, however, this study reported stronger evidence of anti-inflammatory, cytotoxic and antivenom activity which may be the properties that practitioners of traditional medicine have found valuable when selecting this plant for treatment. The pharmacological activities reported support a number of the traditional uses for the plant, P. glaucus, suggesting that the traditional use may have a scientific ground and could be investigated further, possibly leading to the discovery or development of new anti-inflammatory, chemotherapeutic or antivenom drugs.
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