## 4 Discussion
For example, cyanorphylene metabolite, often found in flowering plants, was highly reactive to ozone stress [45]. Other than that, the terpenoid metabolites found in plants' essential oils have long been used as a flavouring and fragrance [46; 47; 48]. For example, [PERSON] et al. [49] reported the myrcene, \(\alpha\)-humulene, \(\beta\)-caryophyllene and linalool metabolites in lupulin glandular trichomes in the _Humulus lupulus_ species was used as a flavoring in brewing. In addition, monoterpene metabolites such as limonene, linalool, 1,8-cineole are widely used to favour lemon or lime-flavored beverages [50]. In this study, the \(\beta\)-ocimene metabolite from the terpenoid compound found in _H. cagayanesis_ has a high potential to be exploited and commercialized since it has an aroma comparable to neroli oil and is widely used in manufacturing essential oils [51]. Furthermore, terpenoid compounds (E)-\(\beta\)-Ocimene and myrcene are crucial compounds in the floral fragrances of many plant species [51; 52]. Due to their prevalence and abundance in floral odors, Ocimene is believed to have a significant ecological role in flowers. According to the list of identified floral-scent compounds compiled by [PERSON] et al. [30], trans- \(\beta\)-Ocimene can be found in the floral scents from 71% of the 90 plant families in the list of the discovered floral-scent compound. Furthermore, trans-\(\beta\)-Ocimene was detected in the floral fragrances from 47% of the 291 plant species and 75% of the 63 plant families studied [29]. In addition to its abundance in the flower odors, there is evidence that \(\beta\)-Ocimene acts as a pheromone in attracting pollinating agents such as bees, moths, and butterflies [33; 34; 51]. For example, in one observation at Mediterranean shrubland area, several low-density plant species such as _Muscari neglectum_, _Rannuculus gramineus_, _Euphoria flavicoma_, and _Iris lutescens_ were found to release high amounts of \(\beta\)-Ocimene to compete with two other dominant plant species, _Rosmarinus officinalis_ and _Thymus vulgaris_, to attract pollinating agents to compensate for low species abundance [33; 34]. Moreover, another study of floral scent composition of two _Hoya_ species, _Hoya incrasate_ and _Hoya heuschkeliana_, found that both species emitted high levels of ocimene metabolites, (Z)-Ocimene (26.4%) for _H. incrasate_ and (E)-Ocimene (37.5%) for _H. heuschkeliana_[39]. Furthermore, based on the morphology, both species were found to have less attractive flower colors similar to _H. cagayanensis_. Therefore, the release of a high amount of ocimene from the terpenoid group in _Hoya_ could be suggested to attract pollinating insects as a mechanism in the success of the pollination process. In general, terpenoids are important in pollinator attraction, reproduction, plant seed dispersal for pollination success [38; 46; 53], and defense against herbivorous and pathogenic attacks [54; 55]. In addition, terpenoids are widely used in the perfume and cosme industries and used as additives and flavors in food due to their distinctive scents and taste [56; 57]. Terpenoid metabolites also frequently have high medicinal value [58; 59; 60]. For example, Paclitaxel (Taxol\({}^{\beta}\)) is an anticancer medicine, whereas artemisinin is antimalarial. Both are new-generation medications based on terpenoid compounds with modern medicinal applications [61]. The terpenoid group has been found to dominate volatile scents in most flowering plants, including orchids species such as _Phalaenopsis bellina_ (geraniol and linalool), _Cymbidium goeringii_ (farnesol, methyl epi-jasmonate, (E)-\(\beta\)-farnesene and nerolidol), _Vanda_ [PERSON] (ocimene, linalool oxide and linalool), and _Maxillaria tentofolia_ (\(\beta\)-caryophyllene) [62; 63; 64; 65]. In addition, several compounds of terpenoids-based antimicrobial substances have also been produced by several bacterial strains from _Streptomyces_ sp. [58; 66].