“…Natural secondary metabolites are a major source of anti-infective drugs. These metabolites could be originated from plants [ 16 , 17 ], marine [ 18 , 19 ], or microbial sources [ 20 , 21 , 22 ], and found to belong to various types such as saponins [ 23 , 24 ], alkaloids [ 25 ], pyrones [ 26 ], isochromenes [ 27 ], diterpenes[ 28 ], flavonoids [ 29 , 30 ], and isoflavonoids [ 31 ].…”