Then, the plates were incubated at 37 °C for 24 h and the zone of inhibition was calculated. The methanolic extract obtained was yellowish
green in the day light with the yield weighing 1 gm. Later, the samples were subjected to identify the molecular functional groups by FT-IR. Earlier studies on S. tenerrimum revealed the presence of biologically active phytochemicals such as amino acids, alkaloids, carbohydrates, flavonoids, saponins, sterols, tannins, proteins and phenolic PD98059 clinical trial compounds. 10 Major FT-IR peaks were observed at 3400 cm−1, 1639 cm−1 and 711 cm−1 ( Fig. 1). An intense peak at 3400 cm−1 indicates the presence of phenolic compounds with free O–H group which is usually broad. A peak with mild intensity with C C at 1639 cm−1 indicates the presence of alkenes. Further, a peak at 711 cm−1 indicates the out of plane blending of CH2 stretching. It have been also reported that, similar kind of peaks were observed in the methanolic extract of S. tenerrimum without Soxhlet extraction. 10 GC–MS analysis revealed the presence of bioactive compounds in the methanolic extract of S. tenerrimum. A total of 12 peaks were observed during maximum run time of 40 min. The spectrum of unknown components was compared with known components stored in the WILEY.8LIB and NIST05.LIB respectively. Based on the maximum percentage XL184 of hit compound name, molecular weight
and structure were obtained and were tabulated in Table 1. The results revealed that, compounds such as 7-Octen-2-ol, Propanedinitrile, Propane, Nitro-benzene, 1-Propanol, 1-Pentyne, 1,2-Benzoldicarbonsaeure, 2,4,4-Trimethyl-2-penten-1-ol, Cyclopropanepentanoic acid, 6-Methoxy-6-oxohexanoic acid, 1-[2-(1-Methylethylidene) Cyclopropyl] ethanol and 3-Methyl-1-butanol were present in the methanolic extract of S. tenerrimum as shown in Table 1. The two unless peaks with a maximum area of intensity of 50.67% and 27.20% in the GC–MS analysis corresponds to 1, 2-Benzoldicarbonsaeure and Cyclopropanepentanoic acid respectively ( Fig. 2). Haider et al, 2009 reported that S. tenerrimum possess high amount of phlorotannin content that has anti-allergic property in mice model. 12 Similarly, Kumar
et al. 2012 have also reported the synthesis of silver nanoparticles with good antibacterial activity. 10 This reveals the presence bioactive functional groups are present in the methanolic extract of S. tenerrimum and it requires further detailed investigation. Methanolic extract was found to have significant antibacterial activity against all the tested pathogens at different concentrations (25, 50, 75 and 100 μg/ml) than the aqueous seaweed extract. The maximum antibacterial activity was observed against K. pneumoniae (12.1 mm) followed by S. aureus (11.9 mm), P. aeruginosa (11.8 mm), V. cholerae (11.7), E. coli (11.6 mm) and S. typhii (11.5 mm). The antibacterial effect of S. tenerrimum was could be due to the presence of phytocomponents ( Fig. 3).