Acanthaceae Acute oral toxicity Article Clinacanthus nutans Clinacanthus nutans extract LD50 Methanol extract NOAEL Subchronic oral toxicity acute toxicity alanine aminotransferase albumin alkaline phosphatase alkaloid derivative animal cell animal tissue aspartate aminotransferase autopsy bilirubin chronic toxicity controlled study creatinine dose response drug safety eosinophil count erythrocyte count female flavonoid hematocrit hematological parameters