Determination and comparative analysis of major iridoids in different parts and cultivation sources of Morinda citrifolia.

Introduction: Noni is a medicinal plant with a long history of use as a folk remedy in many tropical areas, and is attracting more attention worldwide. A comprehensive study on the major phytochemicals in different plant parts (fruit, leaf, seed, root and flower) and sources is of great value for fully understanding their diverse medicinal benefits.

Objective: To quantitatively determine the major iridoid components in different parts of noni plants, and compare iridoids in noni fruits collected from different tropical areas worldwide.

Methodology: The optimal chromatographic conditions were achieved on a C(18) column with gradient elution using 0.1% formic acid aqueous formic acid and acetonitrile at 235  nm. The selective HPLC method was validated for precision, linearity, limit of detection, limit of quantitation and accuracy.

Results: Deacetylasperulosidic acid (DAA) was found to be the major iridoid in noni fruit. In order of predominance, DAA concentrations in different parts of the noni plant were dried noni fruit > fruit juice > seed > flower > leaf > root. The order of predominance for asperulosidic acid (AA) concentration was dried noni fruit > leaf > flower > root > fruit juice > seed. DAA and AA contents of methanolic extracts of noni fruits collected from different tropical regions were 13.8-42.9 and 0.7-8.9  mg/g, respectively, with French Polynesia containing the highest total iridoids and the Dominican Republic containing the lowest.

Conclusion: Iridoids DAA and AA are found to be present in leaf, root, seed and flower of noni plants, and were identified as the major components in noni fruit. Given the great variation of iridoid contents in noni fruit grown in different tropical areas worldwide, geographical factors appear to have significant effects on fruit composition. The iridoids in noni fruit were stable at the temperatures used during pasteurisation and, therefore, may be useful marker compounds for identity and quality testing of commercial noni products.