Antioxidative dolabellanes and dolastanes from brown seaweed as dual inhibitors of starch digestive enzymes.

New dolabellanes {6-methoxy-dolabella-8(17),12-diene-10,18-diol (), 3-methoxy-dolabella-12(18)-ene-4-ol (), 3-methoxy-dolabella-10,18(19)-diene-5,8-diol ()} and dolastanes {2,7-dimethoxy-14-hydroxy-dolasta-1(15),9-diene () and 4,7-dimethoxy-9,14-dihydroxy-dolasta-1-ene ()} were identified from brown seaweed (family Dictyotaceae), collected from the southeast coast of India. Compounds - were found to possess dolabellane skeleton with [9.3.0] cyclotetradecane framework whereas, - were composed of tricyclic diterpenes with linear arrangement of six-seven-five fused alicyclic rings. Compounds and registered greater antioxidative activities (IC ≤0.63 mg/mL) than other analogues (IC ≥0.65 mg/mL), whereas their attenuating potentials against carbolytics -amylase and -glucosidase (IC ∼0.12-0.14 mg/mL) were comparable with those displayed by acarbose (IC 0.14-0.12 mg/mL). Bioactive potentials of titled compounds were assessed by electronic and lipophilic parameters. The lesser binding energies of (-9.71 kcal/mol) and (-8.59 kcal/mol) through molecular docking demonstrated their effective hydrogen bonding interactions with -amylase. Thus, dolabellanes and dolastanes might be used as anti-diabetic and antioxidant leads to reduce the risk of hyperglycaemia.