Phytochemical Screening and Antibacterial Activity of an Epiphytic Orchid Rhynchostylis retusa (L.) Blume. Collected from Kannur District, Kerala, India

Treatment with medicinal plants consists of the ancient tradition of India and which has been continued for years. Our ancestors collected rare plants from forests and mountains for treatment purpose. At the same time, they give deep concern for the conservation of the species on the earth. Their knowledge and services are not profitable but valuable. The study is focused on the phytochemical and antimicrobial activity of the medicinal plant Rhynchostylis retusa of the family Orchidaceae. The plant is growing in sacred groves and local gardens of Payyanur of Kannur district, Kerala, India and used for traditional healing practices. The Orchidaceae family includes many plants having medicinal properties, but most of them were not studied or exploited yet. Qualitative analysis of primary metabolites and secondary metabolites indicates the presence of phytochemicals in Rhynchostylis retusa. The total alkaloid, carbohydrate, protein, phenolic compounds and flavonoids were seen in significant amount in this plant. In vitro antibacterial (agar well diffusion) activity was done by gram-negative Pseudomonas aeruginosa (ATCC 27853), gram-positive Streptococcus mutans (MTCC 890), Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922) and antifungal activity by Aspergillus niger (ATCC 16404). The plant extracts exhibited potent antimicrobial activity against these strains. The studies with the medicinal plant R.retusa make clear that the plant is rich in active components and phytochemicals. The plant contains a favourable amount of phytochemicals and this makes them cure various diseases. The plant also shows antioxidant and antibacterial activities.