Biological significance of natural cyclic peptides: A review.

Background: Natural sources like plants, fungi, marine organisms, algae and bacteria are the most abundant sources of cyclic peptides of therapeutic use. Numerous novel cyclic peptides isolated from natural sources and successfully developed in to bioactive products. Recently, cyclic peptides derived from natural resources have attracted attention to explore their numerous beneficial effects. Moreover, literature review have reported that natural cyclic peptides exhibit various biological activities like anti-microbial, cyto-toxic, anthelmentic activity, immune-suppressive activity, anti-inflammatory activity, anti-HIV activity, repellent (anti-fouling) activity, anti-tubercular activity and anti-viral activity. In this review, we will present the structures and biological activities of cyclic peptides isolated from various natural sources.

Objective: The purpose of this review is to summarize the biological potentials associated with naturally occurring cyclic peptides.

Conclusion: The natural cyclic peptides possess a wide spectrum of biological activities and can be become drug of future for replacing the existing drugs which developed resistance.