Volatile compounds isolated and identified from Kohia (Passiflora tetrandra)
Plants biosynthesise and release a large diversity of volatile compounds. The dominant types of these volatiles can be divided into three categories: carbohydrate-derived compounds, fatty acid derived compounds and amino acid derivatives.
In this research, the volatile organic compounds were investigated in three different parts of the New Zealand native plant – Kohia (P. tetrandra), which is also known as New Zealand passion fruit. The parts included leaves, flowers and fruit. Solid phase microextraction (SPME) was chosen as the analytical method. The identification of volatiles was by gas chromatography – mass spectrometry.
It was found that the compositions of different parts of Kohia were distinctly different. The volatiles in the leaves were mostly alcohols and carbonyl compounds, whereas the major components in flowers were terpenes, and esters were the principal components of the fruit.
In addition, the volatiles in female and male of Kohia leaves were also different. The main components in female leaves were cyclopentenone (31.49%), cyclopentanone (13.10%) and 2-hexenol (8.38%), while the predominant compounds in male leaves were cyclopentanone (17.97%), cis-hexenyl acetate (14.06%) and 2-hexenol (14.02%). Attached (still on the plant) and excised (cut off) flowers of female Kohia were mainly contained (Z)-ocimene and α-farnesene.
For the fruit part, two different passion fruit species were studied in this study: Kohia fruit and purple passion fruit (P. edulis Sims). The results showed that hexyl hexanoate (17.72%) and hexyl butanoate (16.99%) followed by 1-methylhexyl hexanoate (10.68%) and 1-methylhexyl butyrate (10.35%) composed the majority of purple passion fruit flavour. Methyl decanoate (16.97%), cyclopentenone (14.21%) and methyl dec-4-enoate (10.38%) were important compounds in Kohia fruit.